/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=4 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "IPCMessageUtils.h"

#include "nsASCIIMask.h"
#include "nsStandardURL.h"
#include "nsCRT.h"
#include "nsEscape.h"
#include "nsIFile.h"
#include "nsIObjectInputStream.h"
#include "nsIObjectOutputStream.h"
#include "nsIIDNService.h"
#include "mozilla/Logging.h"
#include "nsAutoPtr.h"
#include "nsIURLParser.h"
#include "nsNetCID.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/ipc/URIUtils.h"
#include "mozilla/TextUtils.h"
#include <algorithm>
#include "nsContentUtils.h"
#include "prprf.h"
#include "nsReadableUtils.h"
#include "mozilla/net/MozURL_ffi.h"
#include "mozilla/TextUtils.h"

//
// setenv MOZ_LOG nsStandardURL:5
//
static LazyLogModule gStandardURLLog("nsStandardURL");

// The Chromium code defines its own LOG macro which we don't want
#undef LOG
#define LOG(args) MOZ_LOG(gStandardURLLog, LogLevel::Debug, args)
#undef LOG_ENABLED
#define LOG_ENABLED() MOZ_LOG_TEST(gStandardURLLog, LogLevel::Debug)

using namespace mozilla::ipc;

namespace mozilla {
namespace net {

static NS_DEFINE_CID(kThisImplCID, NS_THIS_STANDARDURL_IMPL_CID);
static NS_DEFINE_CID(kStandardURLCID, NS_STANDARDURL_CID);

// This will always be initialized and destroyed on the main thread, but
// can be safely used on other threads.
StaticRefPtr<nsIIDNService> nsStandardURL::gIDN;

// This value will only be updated on the main thread once. Worker threads
// may race when reading this values, but that's OK because in the worst
// case we will just dispatch a noop runnable to the main thread.
bool nsStandardURL::gInitialized = false;

const char nsStandardURL::gHostLimitDigits[] = {'/', '\\', '?', '#', 0};
bool nsStandardURL::gPunycodeHost = true;

// Invalid host characters
// Note that the array below will be initialized at compile time,
// so we do not need to "optimize" TestForInvalidHostCharacters.
//
constexpr bool TestForInvalidHostCharacters(char c) {
  // Testing for these:
  // CONTROL_CHARACTERS " #/:?@[\\]*<>|\"";
  return (c > 0 && c < 32) ||  // The control characters are [1, 31]
         c == ' ' || c == '#' || c == '/' || c == ':' || c == '?' || c == '@' ||
         c == '[' || c == '\\' || c == ']' || c == '*' || c == '<' ||
#if defined(MOZ_THUNDERBIRD) || defined(MOZ_SUITE)
         // Mailnews %-escapes file paths into URLs.
         c == '>' || c == '|' || c == '"';
#else
         c == '>' || c == '|' || c == '"' || c == '%';
#endif
}
constexpr ASCIIMaskArray sInvalidHostChars =
    CreateASCIIMask(TestForInvalidHostCharacters);

//----------------------------------------------------------------------------
// nsStandardURL::nsSegmentEncoder
//----------------------------------------------------------------------------

nsStandardURL::nsSegmentEncoder::nsSegmentEncoder(const Encoding *encoding)
    : mEncoding(encoding) {
  if (mEncoding == UTF_8_ENCODING) {
    mEncoding = nullptr;
  }
}

int32_t nsStandardURL::nsSegmentEncoder::EncodeSegmentCount(
    const char *aStr, const URLSegment &aSeg, int16_t aMask, nsCString &aOut,
    bool &aAppended, uint32_t aExtraLen) {
  // aExtraLen is characters outside the segment that will be
  // added when the segment is not empty (like the @ following
  // a username).
  if (!aStr || aSeg.mLen <= 0) {
    // Empty segment, so aExtraLen not added per above.
    aAppended = false;
    return 0;
  }

  uint32_t origLen = aOut.Length();

  Span<const char> span = MakeSpan(aStr + aSeg.mPos, aSeg.mLen);

  // first honor the origin charset if appropriate. as an optimization,
  // only do this if the segment is non-ASCII.  Further, if mEncoding is
  // null, then the origin charset is UTF-8 and there is nothing to do.
  if (mEncoding) {
    size_t upTo = Encoding::ASCIIValidUpTo(AsBytes(span));
    if (upTo != span.Length()) {
      // we have to encode this segment
      char bufferArr[512];
      Span<char> buffer = MakeSpan(bufferArr);

      auto encoder = mEncoding->NewEncoder();

      nsAutoCString valid;  // has to be declared in this scope
      if (MOZ_UNLIKELY(!IsUTF8(span.From(upTo)))) {
        MOZ_ASSERT_UNREACHABLE("Invalid UTF-8 passed to nsStandardURL.");
        // It's UB to pass invalid UTF-8 to
        // EncodeFromUTF8WithoutReplacement(), so let's make our input valid
        // UTF-8 by replacing invalid sequences with the REPLACEMENT
        // CHARACTER.
        UTF_8_ENCODING->Decode(
            nsDependentCSubstring(span.Elements(), span.Length()), valid);
        // This assigment is OK. `span` can't be used after `valid` has
        // been destroyed because the only way out of the scope that `valid`
        // was declared in is via return inside the loop below. Specifically,
        // the return is the only way out of the loop.
        span = valid;
      }

      size_t totalRead = 0;
      for (;;) {
        uint32_t encoderResult;
        size_t read;
        size_t written;
        Tie(encoderResult, read, written) =
            encoder->EncodeFromUTF8WithoutReplacement(
                AsBytes(span.From(totalRead)), AsWritableBytes(buffer), true);
        totalRead += read;
        auto bufferWritten = buffer.To(written);
        if (!NS_EscapeURLSpan(bufferWritten, aMask, aOut)) {
          aOut.Append(bufferWritten);
        }
        if (encoderResult == kInputEmpty) {
          aAppended = true;
          // Difference between original and current output
          // string lengths plus extra length
          return aOut.Length() - origLen + aExtraLen;
        }
        if (encoderResult == kOutputFull) {
          continue;
        }
        aOut.AppendLiteral("%26%23");
        aOut.AppendInt(encoderResult);
        aOut.AppendLiteral("%3B");
      }
      MOZ_RELEASE_ASSERT(
          false,
          "There's supposed to be no way out of the above loop except return.");
    }
  }

  if (NS_EscapeURLSpan(span, aMask, aOut)) {
    aAppended = true;
    // Difference between original and current output
    // string lengths plus extra length
    return aOut.Length() - origLen + aExtraLen;
  }
  aAppended = false;
  // Original segment length plus extra length
  return span.Length() + aExtraLen;
}

const nsACString &nsStandardURL::nsSegmentEncoder::EncodeSegment(
    const nsACString &str, int16_t mask, nsCString &result) {
  const char *text;
  bool encoded;
  EncodeSegmentCount(str.BeginReading(text), URLSegment(0, str.Length()), mask,
                     result, encoded);
  if (encoded) return result;
  return str;
}

//----------------------------------------------------------------------------
// nsStandardURL <public>
//----------------------------------------------------------------------------

#ifdef DEBUG_DUMP_URLS_AT_SHUTDOWN
static StaticMutex gAllURLsMutex;
static LinkedList<nsStandardURL> gAllURLs;
#endif

nsStandardURL::nsStandardURL(bool aSupportsFileURL, bool aTrackURL)
    : mDefaultPort(-1),
      mPort(-1),
      mDisplayHost(nullptr),
      mURLType(URLTYPE_STANDARD),
      mSupportsFileURL(aSupportsFileURL),
      mCheckedIfHostA(false) {
  LOG(("Creating nsStandardURL @%p\n", this));

  // gInitialized changes value only once (false->true) on the main thread.
  // It's OK to race here because in the worst case we'll just
  // dispatch a noop runnable to the main thread.
  MOZ_ASSERT(gInitialized);

  // default parser in case nsIStandardURL::Init is never called
  mParser = net_GetStdURLParser();

#ifdef DEBUG_DUMP_URLS_AT_SHUTDOWN
  if (NS_IsMainThread()) {
    if (aTrackURL) {
      StaticMutexAutoLock lock(gAllURLsMutex);
      gAllURLs.insertBack(this);
    }
  }
#endif
}

nsStandardURL::~nsStandardURL() {
  LOG(("Destroying nsStandardURL @%p\n", this));

#ifdef DEBUG_DUMP_URLS_AT_SHUTDOWN
  {
    StaticMutexAutoLock lock(gAllURLsMutex);
    if (isInList()) {
      remove();
    }
  }
#endif
}

#ifdef DEBUG_DUMP_URLS_AT_SHUTDOWN
struct DumpLeakedURLs {
  DumpLeakedURLs() = default;
  ~DumpLeakedURLs();
};

DumpLeakedURLs::~DumpLeakedURLs() {
  MOZ_ASSERT(NS_IsMainThread());
  StaticMutexAutoLock lock(gAllURLsMutex);
  if (!gAllURLs.isEmpty()) {
    printf("Leaked URLs:\n");
    for (auto url : gAllURLs) {
      url->PrintSpec();
    }
    gAllURLs.clear();
  }
}
#endif

void nsStandardURL::InitGlobalObjects() {
  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());

  if (gInitialized) {
    return;
  }

  gInitialized = true;

  Preferences::AddBoolVarCache(&gPunycodeHost,
                               "network.standard-url.punycode-host", true);
  nsCOMPtr<nsIIDNService> serv(do_GetService(NS_IDNSERVICE_CONTRACTID));
  if (serv) {
    gIDN = serv;
  }
  MOZ_DIAGNOSTIC_ASSERT(gIDN);

  // Make sure nsURLHelper::InitGlobals() gets called on the main thread
  nsCOMPtr<nsIURLParser> parser = net_GetStdURLParser();
  MOZ_DIAGNOSTIC_ASSERT(parser);
  Unused << parser;
}

void nsStandardURL::ShutdownGlobalObjects() {
  MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
  gIDN = nullptr;

#ifdef DEBUG_DUMP_URLS_AT_SHUTDOWN
  if (gInitialized) {
    // This instanciates a dummy class, and will trigger the class
    // destructor when libxul is unloaded. This is equivalent to atexit(),
    // but gracefully handles dlclose().
    StaticMutexAutoLock lock(gAllURLsMutex);
    static DumpLeakedURLs d;
  }
#endif
}

//----------------------------------------------------------------------------
// nsStandardURL <private>
//----------------------------------------------------------------------------

void nsStandardURL::Clear() {
  mSpec.Truncate();

  mPort = -1;

  mScheme.Reset();
  mAuthority.Reset();
  mUsername.Reset();
  mPassword.Reset();
  mHost.Reset();

  mPath.Reset();
  mFilepath.Reset();
  mDirectory.Reset();
  mBasename.Reset();

  mExtension.Reset();
  mQuery.Reset();
  mRef.Reset();

  InvalidateCache();
}

void nsStandardURL::InvalidateCache(bool invalidateCachedFile) {
  if (invalidateCachedFile) {
    mFile = nullptr;
  }
}

// Return the number of "dots" in the string, or -1 if invalid.  Note that the
// number of relevant entries in the bases/starts/ends arrays is number of
// dots + 1.
// Since the trailing dot is allowed, we pass and adjust "length".
//
// length is assumed to be <= host.Length(); the callers is responsible for that
//
// Note that the value returned is guaranteed to be in [-1, 3] range.
inline int32_t ValidateIPv4Number(const nsACString &host, int32_t bases[4],
                                  int32_t dotIndex[3], bool &onlyBase10,
                                  int32_t &length) {
  MOZ_ASSERT(length <= (int32_t)host.Length());
  if (length <= 0) {
    return -1;
  }

  bool lastWasNumber = false;  // We count on this being false for i == 0
  int32_t dotCount = 0;
  onlyBase10 = true;

  for (int32_t i = 0; i < length; i++) {
    char current = host[i];
    if (current == '.') {
      if (!lastWasNumber) {  // A dot should not follow an X or a dot, or be
                             // first
        return -1;
      }

      if (dotCount > 0 &&
          i == (length - 1)) {  // Trailing dot is OK; shorten and return
        length--;
        return dotCount;
      }

      if (dotCount > 2) {
        return -1;
      }
      lastWasNumber = false;
      dotIndex[dotCount] = i;
      dotCount++;
    } else if (current == 'X' || current == 'x') {
      if (!lastWasNumber ||  // An X should not follow an X or a dot or be first
          i == (length - 1) ||  // No trailing Xs allowed
          (dotCount == 0 &&
           i != 1) ||            // If we had no dots, an X should be second
          host[i - 1] != '0' ||  // X should always follow a 0.  Guaranteed i >
                                 // 0 as lastWasNumber is true
          (dotCount > 0 &&
           host[i - 2] != '.')) {  // And that zero follows a dot if it exists
        return -1;
      }
      lastWasNumber = false;
      bases[dotCount] = 16;
      onlyBase10 = false;

    } else if (current == '0') {
      if (i < length - 1 &&      // Trailing zero doesn't signal octal
          host[i + 1] != '.' &&  // Lone zero is not octal
          (i == 0 || host[i - 1] == '.')) {  // Zero at start or following a dot
                                             // is a candidate for octal
        bases[dotCount] = 8;  // This will turn to 16 above if X shows up
        onlyBase10 = false;
      }
      lastWasNumber = true;

    } else if (current >= '1' && current <= '7') {
      lastWasNumber = true;

    } else if (current >= '8' && current <= '9') {
      if (bases[dotCount] == 8) {
        return -1;
      }
      lastWasNumber = true;

    } else if ((current >= 'a' && current <= 'f') ||
               (current >= 'A' && current <= 'F')) {
      if (bases[dotCount] != 16) {
        return -1;
      }
      lastWasNumber = true;

    } else {
      return -1;
    }
  }

  return dotCount;
}

inline nsresult ParseIPv4Number10(const nsACString &input, uint32_t &number,
                                  uint32_t maxNumber) {
  uint64_t value = 0;
  const char *current = input.BeginReading();
  const char *end = input.EndReading();
  for (; current < end; ++current) {
    char c = *current;
    MOZ_ASSERT(c >= '0' && c <= '9');
    value *= 10;
    value += c - '0';
  }
  if (value <= maxNumber) {
    number = value;
    return NS_OK;
  }

  // The error case
  number = 0;
  return NS_ERROR_FAILURE;
}

inline nsresult ParseIPv4Number(const nsACString &input, int32_t base,
                                uint32_t &number, uint32_t maxNumber) {
  // Accumulate in the 64-bit value
  uint64_t value = 0;
  const char *current = input.BeginReading();
  const char *end = input.EndReading();
  switch (base) {
    case 16:
      ++current;
      MOZ_FALLTHROUGH;
    case 8:
      ++current;
      break;
    case 10:
    default:
      break;
  }
  for (; current < end; ++current) {
    value *= base;
    char c = *current;
    MOZ_ASSERT((base == 10 && IsAsciiDigit(c)) ||
               (base == 8 && c >= '0' && c <= '7') ||
               (base == 16 && IsAsciiHexDigit(c)));
    if (IsAsciiDigit(c)) {
      value += c - '0';
    } else if (c >= 'a' && c <= 'f') {
      value += c - 'a' + 10;
    } else if (c >= 'A' && c <= 'F') {
      value += c - 'A' + 10;
    }
  }

  if (value <= maxNumber) {
    number = value;
    return NS_OK;
  }

  // The error case
  number = 0;
  return NS_ERROR_FAILURE;
}

// IPv4 parser spec: https://url.spec.whatwg.org/#concept-ipv4-parser
/* static */
nsresult nsStandardURL::NormalizeIPv4(const nsACString &host,
                                      nsCString &result) {
  int32_t bases[4] = {10, 10, 10, 10};
  bool onlyBase10 = true;  // Track this as a special case
  int32_t dotIndex[3];     // The positions of the dots in the string

  // The length may be adjusted by ValidateIPv4Number (ignoring the trailing
  // period) so use "length", rather than host.Length() after that call.
  int32_t length = static_cast<int32_t>(host.Length());
  int32_t dotCount =
      ValidateIPv4Number(host, bases, dotIndex, onlyBase10, length);
  if (dotCount < 0 || length <= 0) {
    return NS_ERROR_FAILURE;
  }

  // Max values specified by the spec
  static const uint32_t upperBounds[] = {0xffffffffu, 0xffffffu, 0xffffu,
                                         0xffu};
  uint32_t ipv4;
  int32_t start = (dotCount > 0 ? dotIndex[dotCount - 1] + 1 : 0);

  nsresult res;
  // Doing a special case for all items being base 10 gives ~35% speedup
  res = (onlyBase10
             ? ParseIPv4Number10(Substring(host, start, length - start), ipv4,
                                 upperBounds[dotCount])
             : ParseIPv4Number(Substring(host, start, length - start),
                               bases[dotCount], ipv4, upperBounds[dotCount]));
  if (NS_FAILED(res)) {
    return NS_ERROR_FAILURE;
  }

  int32_t lastUsed = -1;
  for (int32_t i = 0; i < dotCount; i++) {
    uint32_t number;
    start = lastUsed + 1;
    lastUsed = dotIndex[i];
    res =
        (onlyBase10 ? ParseIPv4Number10(
                          Substring(host, start, lastUsed - start), number, 255)
                    : ParseIPv4Number(Substring(host, start, lastUsed - start),
                                      bases[i], number, 255));
    if (NS_FAILED(res)) {
      return NS_ERROR_FAILURE;
    }
    ipv4 += number << (8 * (3 - i));
  }

  uint8_t ipSegments[4];
  NetworkEndian::writeUint32(ipSegments, ipv4);
  result = nsPrintfCString("%d.%d.%d.%d", ipSegments[0], ipSegments[1],
                           ipSegments[2], ipSegments[3]);
  return NS_OK;
}

nsresult nsStandardURL::NormalizeIDN(const nsACString &host,
                                     nsCString &result) {
  // If host is ACE, then convert to UTF-8.  Else, if host is already UTF-8,
  // then make sure it is normalized per IDN.

  // this function returns true if normalization succeeds.

  result.Truncate();
  nsresult rv;

  if (!gIDN) {
    return NS_ERROR_UNEXPECTED;
  }

  bool isAscii;
  nsAutoCString normalized;
  rv = gIDN->ConvertToDisplayIDN(host, &isAscii, normalized);
  if (NS_FAILED(rv)) {
    return rv;
  }

  // The result is ASCII. No need to convert to ACE.
  if (isAscii) {
    result = normalized;
    mCheckedIfHostA = true;
    mDisplayHost.Truncate();
    return NS_OK;
  }

  rv = gIDN->ConvertUTF8toACE(normalized, result);
  if (NS_FAILED(rv)) {
    return rv;
  }

  mCheckedIfHostA = true;
  mDisplayHost = normalized;

  return NS_OK;
}

bool nsStandardURL::ValidIPv6orHostname(const char *host, uint32_t length) {
  if (!host || !*host) {
    // Should not be NULL or empty string
    return false;
  }

  if (length != strlen(host)) {
    // Embedded null
    return false;
  }

  bool openBracket = host[0] == '[';
  bool closeBracket = host[length - 1] == ']';

  if (openBracket && closeBracket) {
    return net_IsValidIPv6Addr(host + 1, length - 2);
  }

  if (openBracket || closeBracket) {
    // Fail if only one of the brackets is present
    return false;
  }

  const char *end = host + length;
  const char *iter = host;
  for (; iter != end && *iter; ++iter) {
    if (ASCIIMask::IsMasked(sInvalidHostChars, *iter)) {
      return false;
    }
  }
  return true;
}

void nsStandardURL::CoalescePath(netCoalesceFlags coalesceFlag, char *path) {
  net_CoalesceDirs(coalesceFlag, path);
  int32_t newLen = strlen(path);
  if (newLen < mPath.mLen) {
    int32_t diff = newLen - mPath.mLen;
    mPath.mLen = newLen;
    mDirectory.mLen += diff;
    mFilepath.mLen += diff;
    ShiftFromBasename(diff);
  }
}

uint32_t nsStandardURL::AppendSegmentToBuf(char *buf, uint32_t i,
                                           const char *str,
                                           const URLSegment &segInput,
                                           URLSegment &segOutput,
                                           const nsCString *escapedStr,
                                           bool useEscaped, int32_t *diff) {
  MOZ_ASSERT(segInput.mLen == segOutput.mLen);

  if (diff) *diff = 0;

  if (segInput.mLen > 0) {
    if (useEscaped) {
      MOZ_ASSERT(diff);
      segOutput.mLen = escapedStr->Length();
      *diff = segOutput.mLen - segInput.mLen;
      memcpy(buf + i, escapedStr->get(), segOutput.mLen);
    } else {
      memcpy(buf + i, str + segInput.mPos, segInput.mLen);
    }
    segOutput.mPos = i;
    i += segOutput.mLen;
  } else {
    segOutput.mPos = i;
  }
  return i;
}

uint32_t nsStandardURL::AppendToBuf(char *buf, uint32_t i, const char *str,
                                    uint32_t len) {
  memcpy(buf + i, str, len);
  return i + len;
}

// basic algorithm:
//  1- escape url segments (for improved GetSpec efficiency)
//  2- allocate spec buffer
//  3- write url segments
//  4- update url segment positions and lengths
nsresult nsStandardURL::BuildNormalizedSpec(const char *spec,
                                            const Encoding *encoding) {
  // Assumptions: all member URLSegments must be relative the |spec| argument
  // passed to this function.

  // buffers for holding escaped url segments (these will remain empty unless
  // escaping is required).
  nsAutoCString encUsername, encPassword, encHost, encDirectory, encBasename,
      encExtension, encQuery, encRef;
  bool useEncUsername, useEncPassword, useEncHost = false, useEncDirectory,
                                       useEncBasename, useEncExtension,
                                       useEncQuery, useEncRef;
  nsAutoCString portbuf;

  //
  // escape each URL segment, if necessary, and calculate approximate normalized
  // spec length.
  //
  // [scheme://][username[:password]@]host[:port]/path[?query_string][#ref]

  uint32_t approxLen = 0;

  // the scheme is already ASCII
  if (mScheme.mLen > 0)
    approxLen +=
        mScheme.mLen + 3;  // includes room for "://", which we insert always

  // encode URL segments; convert UTF-8 to origin charset and possibly escape.
  // results written to encXXX variables only if |spec| is not already in the
  // appropriate encoding.
  {
    nsSegmentEncoder encoder;
    nsSegmentEncoder queryEncoder(encoding);
    // Username@
    approxLen += encoder.EncodeSegmentCount(spec, mUsername, esc_Username,
                                            encUsername, useEncUsername, 0);
    approxLen += 1;  // reserve length for @
    // :password - we insert the ':' even if there's no actual password if
    // "user:@" was in the spec
    if (mPassword.mLen > 0) {
      approxLen += 1 + encoder.EncodeSegmentCount(spec, mPassword, esc_Password,
                                                  encPassword, useEncPassword);
    }
    // mHost is handled differently below due to encoding differences
    MOZ_ASSERT(mPort >= -1, "Invalid negative mPort");
    if (mPort != -1 && mPort != mDefaultPort) {
      // :port
      portbuf.AppendInt(mPort);
      approxLen += portbuf.Length() + 1;
    }

    approxLen +=
        1;  // reserve space for possible leading '/' - may not be needed
    // Should just use mPath?  These are pessimistic, and thus waste space
    approxLen += encoder.EncodeSegmentCount(spec, mDirectory, esc_Directory,
                                            encDirectory, useEncDirectory, 1);
    approxLen += encoder.EncodeSegmentCount(spec, mBasename, esc_FileBaseName,
                                            encBasename, useEncBasename);
    approxLen += encoder.EncodeSegmentCount(spec, mExtension, esc_FileExtension,
                                            encExtension, useEncExtension, 1);

    // These next ones *always* add their leading character even if length is 0
    // Handles items like "http://#"
    // ?query
    if (mQuery.mLen >= 0)
      approxLen += 1 + queryEncoder.EncodeSegmentCount(spec, mQuery, esc_Query,
                                                       encQuery, useEncQuery);
    // #ref

    if (mRef.mLen >= 0) {
      approxLen += 1 + encoder.EncodeSegmentCount(spec, mRef, esc_Ref, encRef,
                                                  useEncRef);
    }
  }

  // do not escape the hostname, if IPv6 address literal, mHost will
  // already point to a [ ] delimited IPv6 address literal.
  // However, perform Unicode normalization on it, as IDN does.
  // Note that we don't disallow URLs without a host - file:, etc
  if (mHost.mLen > 0) {
    nsAutoCString tempHost;
    NS_UnescapeURL(spec + mHost.mPos, mHost.mLen, esc_AlwaysCopy | esc_Host,
                   tempHost);
    if (tempHost.Contains('\0'))
      return NS_ERROR_MALFORMED_URI;  // null embedded in hostname
    if (tempHost.Contains(' '))
      return NS_ERROR_MALFORMED_URI;  // don't allow spaces in the hostname
    nsresult rv = NormalizeIDN(tempHost, encHost);
    if (NS_FAILED(rv)) {
      return rv;
    }
    if (!SegmentIs(spec, mScheme, "resource") &&
        !SegmentIs(spec, mScheme, "chrome")) {
      nsAutoCString ipString;
      if (encHost.Length() > 0 && encHost.First() == '[' &&
          encHost.Last() == ']' &&
          ValidIPv6orHostname(encHost.get(), encHost.Length())) {
        rv = (nsresult)rusturl_parse_ipv6addr(&encHost, &ipString);
        if (NS_FAILED(rv)) {
          return rv;
        }
        encHost = ipString;
      } else if (NS_SUCCEEDED(NormalizeIPv4(encHost, ipString))) {
        encHost = ipString;
      }
    }

    // NormalizeIDN always copies, if the call was successful.
    useEncHost = true;
    approxLen += encHost.Length();

    if (!ValidIPv6orHostname(encHost.BeginReading(), encHost.Length())) {
      return NS_ERROR_MALFORMED_URI;
    }
  } else {
    // empty host means empty mDisplayHost
    mDisplayHost.Truncate();
    mCheckedIfHostA = true;
  }

  // We must take a copy of every single segment because they are pointing to
  // the |spec| while we are changing their value, in case we must use
  // encoded strings.
  URLSegment username(mUsername);
  URLSegment password(mPassword);
  URLSegment host(mHost);
  URLSegment path(mPath);
  URLSegment directory(mDirectory);
  URLSegment basename(mBasename);
  URLSegment extension(mExtension);
  URLSegment query(mQuery);
  URLSegment ref(mRef);

  // The encoded string could be longer than the original input, so we need
  // to check the final URI isn't longer than the max length.
  if (approxLen + 1 > (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  //
  // generate the normalized URL string
  //
  // approxLen should be correct or 1 high
  if (!mSpec.SetLength(approxLen + 1,
                       fallible))  // buf needs a trailing '\0' below
    return NS_ERROR_OUT_OF_MEMORY;
  char *buf = mSpec.BeginWriting();
  uint32_t i = 0;
  int32_t diff = 0;

  if (mScheme.mLen > 0) {
    i = AppendSegmentToBuf(buf, i, spec, mScheme, mScheme);
    net_ToLowerCase(buf + mScheme.mPos, mScheme.mLen);
    i = AppendToBuf(buf, i, "://", 3);
  }

  // record authority starting position
  mAuthority.mPos = i;

  // append authority
  if (mUsername.mLen > 0 || mPassword.mLen > 0) {
    if (mUsername.mLen > 0) {
      i = AppendSegmentToBuf(buf, i, spec, username, mUsername, &encUsername,
                             useEncUsername, &diff);
      ShiftFromPassword(diff);
    } else {
      mUsername.mLen = -1;
    }
    if (password.mLen > 0) {
      buf[i++] = ':';
      i = AppendSegmentToBuf(buf, i, spec, password, mPassword, &encPassword,
                             useEncPassword, &diff);
      ShiftFromHost(diff);
    } else {
      mPassword.mLen = -1;
    }
    buf[i++] = '@';
  } else {
    mUsername.mLen = -1;
    mPassword.mLen = -1;
  }
  if (host.mLen > 0) {
    i = AppendSegmentToBuf(buf, i, spec, host, mHost, &encHost, useEncHost,
                           &diff);
    ShiftFromPath(diff);

    net_ToLowerCase(buf + mHost.mPos, mHost.mLen);
    MOZ_ASSERT(mPort >= -1, "Invalid negative mPort");
    if (mPort != -1 && mPort != mDefaultPort) {
      buf[i++] = ':';
      // Already formatted while building approxLen
      i = AppendToBuf(buf, i, portbuf.get(), portbuf.Length());
    }
  }

  // record authority length
  mAuthority.mLen = i - mAuthority.mPos;

  // path must always start with a "/"
  if (mPath.mLen <= 0) {
    LOG(("setting path=/"));
    mDirectory.mPos = mFilepath.mPos = mPath.mPos = i;
    mDirectory.mLen = mFilepath.mLen = mPath.mLen = 1;
    // basename must exist, even if empty (bug 113508)
    mBasename.mPos = i + 1;
    mBasename.mLen = 0;
    buf[i++] = '/';
  } else {
    uint32_t leadingSlash = 0;
    if (spec[path.mPos] != '/') {
      LOG(("adding leading slash to path\n"));
      leadingSlash = 1;
      buf[i++] = '/';
      // basename must exist, even if empty (bugs 113508, 429347)
      if (mBasename.mLen == -1) {
        mBasename.mPos = basename.mPos = i;
        mBasename.mLen = basename.mLen = 0;
      }
    }

    // record corrected (file)path starting position
    mPath.mPos = mFilepath.mPos = i - leadingSlash;

    i = AppendSegmentToBuf(buf, i, spec, directory, mDirectory, &encDirectory,
                           useEncDirectory, &diff);
    ShiftFromBasename(diff);

    // the directory must end with a '/'
    if (buf[i - 1] != '/') {
      buf[i++] = '/';
      mDirectory.mLen++;
    }

    i = AppendSegmentToBuf(buf, i, spec, basename, mBasename, &encBasename,
                           useEncBasename, &diff);
    ShiftFromExtension(diff);

    // make corrections to directory segment if leadingSlash
    if (leadingSlash) {
      mDirectory.mPos = mPath.mPos;
      if (mDirectory.mLen >= 0)
        mDirectory.mLen += leadingSlash;
      else
        mDirectory.mLen = 1;
    }

    if (mExtension.mLen >= 0) {
      buf[i++] = '.';
      i = AppendSegmentToBuf(buf, i, spec, extension, mExtension, &encExtension,
                             useEncExtension, &diff);
      ShiftFromQuery(diff);
    }
    // calculate corrected filepath length
    mFilepath.mLen = i - mFilepath.mPos;

    if (mQuery.mLen >= 0) {
      buf[i++] = '?';
      i = AppendSegmentToBuf(buf, i, spec, query, mQuery, &encQuery,
                             useEncQuery, &diff);
      ShiftFromRef(diff);
    }
    if (mRef.mLen >= 0) {
      buf[i++] = '#';
      i = AppendSegmentToBuf(buf, i, spec, ref, mRef, &encRef, useEncRef,
                             &diff);
    }
    // calculate corrected path length
    mPath.mLen = i - mPath.mPos;
  }

  buf[i] = '\0';

  // https://url.spec.whatwg.org/#path-state (1.4.1.2)
  // https://url.spec.whatwg.org/#windows-drive-letter
  if (SegmentIs(buf, mScheme, "file")) {
    char *path = &buf[mPath.mPos];
    if (mPath.mLen >= 3 && path[0] == '/' && IsAsciiAlpha(path[1]) &&
        path[2] == '|') {
      buf[mPath.mPos + 2] = ':';
    }
  }

  if (mDirectory.mLen > 1) {
    netCoalesceFlags coalesceFlag = NET_COALESCE_NORMAL;
    if (SegmentIs(buf, mScheme, "ftp")) {
      coalesceFlag =
          (netCoalesceFlags)(coalesceFlag | NET_COALESCE_ALLOW_RELATIVE_ROOT |
                             NET_COALESCE_DOUBLE_SLASH_IS_ROOT);
    }
    CoalescePath(coalesceFlag, buf + mDirectory.mPos);
  }
  mSpec.Truncate(strlen(buf));
  NS_ASSERTION(mSpec.Length() <= approxLen,
               "We've overflowed the mSpec buffer!");
  MOZ_ASSERT(mSpec.Length() <= (uint32_t)net_GetURLMaxLength(),
             "The spec should never be this long, we missed a check.");

  MOZ_ASSERT(mUsername.mLen != 0 && mPassword.mLen != 0);
  return NS_OK;
}

bool nsStandardURL::SegmentIs(const URLSegment &seg, const char *val,
                              bool ignoreCase) {
  // one or both may be null
  if (!val || mSpec.IsEmpty())
    return (!val && (mSpec.IsEmpty() || seg.mLen < 0));
  if (seg.mLen < 0) return false;
  // if the first |seg.mLen| chars of |val| match, then |val| must
  // also be null terminated at |seg.mLen|.
  if (ignoreCase)
    return !PL_strncasecmp(mSpec.get() + seg.mPos, val, seg.mLen) &&
           (val[seg.mLen] == '\0');

  return !strncmp(mSpec.get() + seg.mPos, val, seg.mLen) &&
         (val[seg.mLen] == '\0');
}

bool nsStandardURL::SegmentIs(const char *spec, const URLSegment &seg,
                              const char *val, bool ignoreCase) {
  // one or both may be null
  if (!val || !spec) return (!val && (!spec || seg.mLen < 0));
  if (seg.mLen < 0) return false;
  // if the first |seg.mLen| chars of |val| match, then |val| must
  // also be null terminated at |seg.mLen|.
  if (ignoreCase)
    return !PL_strncasecmp(spec + seg.mPos, val, seg.mLen) &&
           (val[seg.mLen] == '\0');

  return !strncmp(spec + seg.mPos, val, seg.mLen) && (val[seg.mLen] == '\0');
}

bool nsStandardURL::SegmentIs(const URLSegment &seg1, const char *val,
                              const URLSegment &seg2, bool ignoreCase) {
  if (seg1.mLen != seg2.mLen) return false;
  if (seg1.mLen == -1 || (!val && mSpec.IsEmpty()))
    return true;  // both are empty
  if (!val) return false;
  if (ignoreCase)
    return !PL_strncasecmp(mSpec.get() + seg1.mPos, val + seg2.mPos, seg1.mLen);

  return !strncmp(mSpec.get() + seg1.mPos, val + seg2.mPos, seg1.mLen);
}

int32_t nsStandardURL::ReplaceSegment(uint32_t pos, uint32_t len,
                                      const char *val, uint32_t valLen) {
  if (val && valLen) {
    if (len == 0)
      mSpec.Insert(val, pos, valLen);
    else
      mSpec.Replace(pos, len, nsDependentCString(val, valLen));
    return valLen - len;
  }

  // else remove the specified segment
  mSpec.Cut(pos, len);
  return -int32_t(len);
}

int32_t nsStandardURL::ReplaceSegment(uint32_t pos, uint32_t len,
                                      const nsACString &val) {
  if (len == 0)
    mSpec.Insert(val, pos);
  else
    mSpec.Replace(pos, len, val);
  return val.Length() - len;
}

nsresult nsStandardURL::ParseURL(const char *spec, int32_t specLen) {
  nsresult rv;

  if (specLen > net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  //
  // parse given URL string
  //
  rv = mParser->ParseURL(spec, specLen, &mScheme.mPos, &mScheme.mLen,
                         &mAuthority.mPos, &mAuthority.mLen, &mPath.mPos,
                         &mPath.mLen);
  if (NS_FAILED(rv)) return rv;

#ifdef DEBUG
  if (mScheme.mLen <= 0) {
    printf("spec=%s\n", spec);
    NS_WARNING("malformed url: no scheme");
  }
#endif

  if (mAuthority.mLen > 0) {
    rv = mParser->ParseAuthority(spec + mAuthority.mPos, mAuthority.mLen,
                                 &mUsername.mPos, &mUsername.mLen,
                                 &mPassword.mPos, &mPassword.mLen, &mHost.mPos,
                                 &mHost.mLen, &mPort);
    if (NS_FAILED(rv)) return rv;

    // Don't allow mPort to be set to this URI's default port
    if (mPort == mDefaultPort) mPort = -1;

    mUsername.mPos += mAuthority.mPos;
    mPassword.mPos += mAuthority.mPos;
    mHost.mPos += mAuthority.mPos;
  }

  if (mPath.mLen > 0) rv = ParsePath(spec, mPath.mPos, mPath.mLen);

  return rv;
}

nsresult nsStandardURL::ParsePath(const char *spec, uint32_t pathPos,
                                  int32_t pathLen) {
  LOG(("ParsePath: %s pathpos %d len %d\n", spec, pathPos, pathLen));

  if (pathLen > net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  nsresult rv = mParser->ParsePath(spec + pathPos, pathLen, &mFilepath.mPos,
                                   &mFilepath.mLen, &mQuery.mPos, &mQuery.mLen,
                                   &mRef.mPos, &mRef.mLen);
  if (NS_FAILED(rv)) return rv;

  mFilepath.mPos += pathPos;
  mQuery.mPos += pathPos;
  mRef.mPos += pathPos;

  if (mFilepath.mLen > 0) {
    rv = mParser->ParseFilePath(spec + mFilepath.mPos, mFilepath.mLen,
                                &mDirectory.mPos, &mDirectory.mLen,
                                &mBasename.mPos, &mBasename.mLen,
                                &mExtension.mPos, &mExtension.mLen);
    if (NS_FAILED(rv)) return rv;

    mDirectory.mPos += mFilepath.mPos;
    mBasename.mPos += mFilepath.mPos;
    mExtension.mPos += mFilepath.mPos;
  }
  return NS_OK;
}

char *nsStandardURL::AppendToSubstring(uint32_t pos, int32_t len,
                                       const char *tail) {
  // Verify pos and length are within boundaries
  if (pos > mSpec.Length()) return nullptr;
  if (len < 0) return nullptr;
  if ((uint32_t)len > (mSpec.Length() - pos)) return nullptr;
  if (!tail) return nullptr;

  uint32_t tailLen = strlen(tail);

  // Check for int overflow for proposed length of combined string
  if (UINT32_MAX - ((uint32_t)len + 1) < tailLen) return nullptr;

  char *result = (char *)moz_xmalloc(len + tailLen + 1);
  memcpy(result, mSpec.get() + pos, len);
  memcpy(result + len, tail, tailLen);
  result[len + tailLen] = '\0';
  return result;
}

nsresult nsStandardURL::ReadSegment(nsIBinaryInputStream *stream,
                                    URLSegment &seg) {
  nsresult rv;

  rv = stream->Read32(&seg.mPos);
  if (NS_FAILED(rv)) return rv;

  rv = stream->Read32((uint32_t *)&seg.mLen);
  if (NS_FAILED(rv)) return rv;

  return NS_OK;
}

nsresult nsStandardURL::WriteSegment(nsIBinaryOutputStream *stream,
                                     const URLSegment &seg) {
  nsresult rv;

  rv = stream->Write32(seg.mPos);
  if (NS_FAILED(rv)) return rv;

  rv = stream->Write32(uint32_t(seg.mLen));
  if (NS_FAILED(rv)) return rv;

  return NS_OK;
}

#define SHIFT_FROM(name, what)             \
  void nsStandardURL::name(int32_t diff) { \
    if (!diff) return;                     \
    if (what.mLen >= 0) {                  \
      CheckedInt<int32_t> pos = what.mPos; \
      pos += diff;                         \
      MOZ_ASSERT(pos.isValid());           \
      what.mPos = pos.value();             \
    }

#define SHIFT_FROM_NEXT(name, what, next) \
  SHIFT_FROM(name, what)                  \
  next(diff);                             \
  }

#define SHIFT_FROM_LAST(name, what) \
  SHIFT_FROM(name, what)            \
  }

SHIFT_FROM_NEXT(ShiftFromAuthority, mAuthority, ShiftFromUsername)
SHIFT_FROM_NEXT(ShiftFromUsername, mUsername, ShiftFromPassword)
SHIFT_FROM_NEXT(ShiftFromPassword, mPassword, ShiftFromHost)
SHIFT_FROM_NEXT(ShiftFromHost, mHost, ShiftFromPath)
SHIFT_FROM_NEXT(ShiftFromPath, mPath, ShiftFromFilepath)
SHIFT_FROM_NEXT(ShiftFromFilepath, mFilepath, ShiftFromDirectory)
SHIFT_FROM_NEXT(ShiftFromDirectory, mDirectory, ShiftFromBasename)
SHIFT_FROM_NEXT(ShiftFromBasename, mBasename, ShiftFromExtension)
SHIFT_FROM_NEXT(ShiftFromExtension, mExtension, ShiftFromQuery)
SHIFT_FROM_NEXT(ShiftFromQuery, mQuery, ShiftFromRef)
SHIFT_FROM_LAST(ShiftFromRef, mRef)

//----------------------------------------------------------------------------
// nsStandardURL::nsISupports
//----------------------------------------------------------------------------

NS_IMPL_ADDREF(nsStandardURL)
NS_IMPL_RELEASE(nsStandardURL)

NS_INTERFACE_MAP_BEGIN(nsStandardURL)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIStandardURL)
  NS_INTERFACE_MAP_ENTRY(nsIURI)
  NS_INTERFACE_MAP_ENTRY(nsIURL)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIFileURL, mSupportsFileURL)
  NS_INTERFACE_MAP_ENTRY(nsIStandardURL)
  NS_INTERFACE_MAP_ENTRY(nsISerializable)
  NS_INTERFACE_MAP_ENTRY(nsIClassInfo)
  NS_INTERFACE_MAP_ENTRY(nsISensitiveInfoHiddenURI)
  // see nsStandardURL::Equals
  if (aIID.Equals(kThisImplCID))
    foundInterface = static_cast<nsIURI *>(this);
  else
    NS_INTERFACE_MAP_ENTRY(nsISizeOf)
NS_INTERFACE_MAP_END

//----------------------------------------------------------------------------
// nsStandardURL::nsIURI
//----------------------------------------------------------------------------

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetSpec(nsACString &result) {
  MOZ_ASSERT(mSpec.Length() <= (uint32_t)net_GetURLMaxLength(),
             "The spec should never be this long, we missed a check.");
  nsresult rv = NS_OK;
  if (gPunycodeHost) {
    result = mSpec;
  } else {  // XXX: This code path may be slow
    rv = GetDisplaySpec(result);
  }
  return rv;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetSensitiveInfoHiddenSpec(nsACString &result) {
  nsresult rv = GetSpec(result);
  if (NS_FAILED(rv)) {
    return rv;
  }
  if (mPassword.mLen > 0) {
    result.ReplaceLiteral(mPassword.mPos, mPassword.mLen, "****");
  }
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetSpecIgnoringRef(nsACString &result) {
  // URI without ref is 0 to one char before ref
  if (mRef.mLen < 0) {
    return GetSpec(result);
  }

  URLSegment noRef(0, mRef.mPos - 1);
  result = Segment(noRef);

  MOZ_ASSERT(mCheckedIfHostA);
  if (!gPunycodeHost && !mDisplayHost.IsEmpty()) {
    result.Replace(mHost.mPos, mHost.mLen, mDisplayHost);
  }

  return NS_OK;
}

nsresult nsStandardURL::CheckIfHostIsAscii() {
  nsresult rv;
  if (mCheckedIfHostA) {
    return NS_OK;
  }

  mCheckedIfHostA = true;

  if (!gIDN) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  nsAutoCString displayHost;
  bool isAscii;
  rv = gIDN->ConvertToDisplayIDN(Host(), &isAscii, displayHost);
  if (NS_FAILED(rv)) {
    mDisplayHost.Truncate();
    mCheckedIfHostA = false;
    return rv;
  }

  if (!isAscii) {
    mDisplayHost = displayHost;
  }

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetDisplaySpec(nsACString &aUnicodeSpec) {
  aUnicodeSpec.Assign(mSpec);
  MOZ_ASSERT(mCheckedIfHostA);
  if (!mDisplayHost.IsEmpty()) {
    aUnicodeSpec.Replace(mHost.mPos, mHost.mLen, mDisplayHost);
  }

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetDisplayHostPort(nsACString &aUnicodeHostPort) {
  nsAutoCString unicodeHostPort;

  nsresult rv = GetDisplayHost(unicodeHostPort);
  if (NS_FAILED(rv)) {
    return rv;
  }

  if (StringBeginsWith(Hostport(), NS_LITERAL_CSTRING("["))) {
    aUnicodeHostPort.AssignLiteral("[");
    aUnicodeHostPort.Append(unicodeHostPort);
    aUnicodeHostPort.AppendLiteral("]");
  } else {
    aUnicodeHostPort.Assign(unicodeHostPort);
  }

  uint32_t pos = mHost.mPos + mHost.mLen;
  if (pos < mPath.mPos)
    aUnicodeHostPort += Substring(mSpec, pos, mPath.mPos - pos);

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetDisplayHost(nsACString &aUnicodeHost) {
  MOZ_ASSERT(mCheckedIfHostA);
  if (mDisplayHost.IsEmpty()) {
    return GetAsciiHost(aUnicodeHost);
  }

  aUnicodeHost = mDisplayHost;
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetPrePath(nsACString &result) {
  result = Prepath();
  MOZ_ASSERT(mCheckedIfHostA);
  if (!gPunycodeHost && !mDisplayHost.IsEmpty()) {
    result.Replace(mHost.mPos, mHost.mLen, mDisplayHost);
  }
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetDisplayPrePath(nsACString &result) {
  result = Prepath();
  MOZ_ASSERT(mCheckedIfHostA);
  if (!mDisplayHost.IsEmpty()) {
    result.Replace(mHost.mPos, mHost.mLen, mDisplayHost);
  }
  return NS_OK;
}

// result is strictly US-ASCII
NS_IMETHODIMP
nsStandardURL::GetScheme(nsACString &result) {
  result = Scheme();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetUserPass(nsACString &result) {
  result = Userpass();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetUsername(nsACString &result) {
  result = Username();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetPassword(nsACString &result) {
  result = Password();
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetHostPort(nsACString &result) {
  nsresult rv;
  if (gPunycodeHost) {
    rv = GetAsciiHostPort(result);
  } else {
    rv = GetDisplayHostPort(result);
  }
  return rv;
}

NS_IMETHODIMP
nsStandardURL::GetHost(nsACString &result) {
  nsresult rv;
  if (gPunycodeHost) {
    rv = GetAsciiHost(result);
  } else {
    rv = GetDisplayHost(result);
  }
  return rv;
}

NS_IMETHODIMP
nsStandardURL::GetPort(int32_t *result) {
  // should never be more than 16 bit
  MOZ_ASSERT(mPort <= std::numeric_limits<uint16_t>::max());
  *result = mPort;
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetPathQueryRef(nsACString &result) {
  result = Path();
  return NS_OK;
}

// result is ASCII
NS_IMETHODIMP
nsStandardURL::GetAsciiSpec(nsACString &result) {
  result = mSpec;
  return NS_OK;
}

// result is ASCII
NS_IMETHODIMP
nsStandardURL::GetAsciiHostPort(nsACString &result) {
  result = Hostport();
  return NS_OK;
}

// result is ASCII
NS_IMETHODIMP
nsStandardURL::GetAsciiHost(nsACString &result) {
  result = Host();
  return NS_OK;
}

static bool IsSpecialProtocol(const nsACString &input) {
  nsACString::const_iterator start, end;
  input.BeginReading(start);
  nsACString::const_iterator iterator(start);
  input.EndReading(end);

  while (iterator != end && *iterator != ':') {
    iterator++;
  }

  nsAutoCString protocol(nsDependentCSubstring(start.get(), iterator.get()));

  return protocol.LowerCaseEqualsLiteral("http") ||
         protocol.LowerCaseEqualsLiteral("https") ||
         protocol.LowerCaseEqualsLiteral("ftp") ||
         protocol.LowerCaseEqualsLiteral("ws") ||
         protocol.LowerCaseEqualsLiteral("wss") ||
         protocol.LowerCaseEqualsLiteral("file") ||
         protocol.LowerCaseEqualsLiteral("gopher");
}

nsresult nsStandardURL::SetSpecInternal(const nsACString &input) {
  return SetSpecWithEncoding(input, nullptr);
}

nsresult nsStandardURL::SetSpecWithEncoding(const nsACString &input,
                                            const Encoding *encoding) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(input);
  LOG(("nsStandardURL::SetSpec [spec=%s]\n", flat.get()));

  if (input.Length() > (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  // filter out unexpected chars "\r\n\t" if necessary
  nsAutoCString filteredURI;
  net_FilterURIString(flat, filteredURI);

  if (filteredURI.Length() == 0) {
    return NS_ERROR_MALFORMED_URI;
  }

  // Make a backup of the curent URL
  nsStandardURL prevURL(false, false);
  prevURL.CopyMembers(this, eHonorRef, EmptyCString());
  Clear();

  if (IsSpecialProtocol(filteredURI)) {
    // Bug 652186: Replace all backslashes with slashes when parsing paths
    // Stop when we reach the query or the hash.
    auto start = filteredURI.BeginWriting();
    auto end = filteredURI.EndWriting();
    while (start != end) {
      if (*start == '?' || *start == '#') {
        break;
      }
      if (*start == '\\') {
        *start = '/';
      }
      start++;
    }
  }

  const char *spec = filteredURI.get();
  int32_t specLength = filteredURI.Length();

  // parse the given URL...
  nsresult rv = ParseURL(spec, specLength);
  if (NS_SUCCEEDED(rv)) {
    // finally, use the URLSegment member variables to build a normalized
    // copy of |spec|
    rv = BuildNormalizedSpec(spec, encoding);
  }

  // Make sure that a URLTYPE_AUTHORITY has a non-empty hostname.
  if (mURLType == URLTYPE_AUTHORITY && mHost.mLen == -1) {
    rv = NS_ERROR_MALFORMED_URI;
  }

  if (NS_FAILED(rv)) {
    Clear();
    // If parsing the spec has failed, restore the old URL
    // so we don't end up with an empty URL.
    CopyMembers(&prevURL, eHonorRef, EmptyCString());
    return rv;
  }

  if (LOG_ENABLED()) {
    LOG((" spec      = %s\n", mSpec.get()));
    LOG((" port      = %d\n", mPort));
    LOG((" scheme    = (%u,%d)\n", mScheme.mPos, mScheme.mLen));
    LOG((" authority = (%u,%d)\n", mAuthority.mPos, mAuthority.mLen));
    LOG((" username  = (%u,%d)\n", mUsername.mPos, mUsername.mLen));
    LOG((" password  = (%u,%d)\n", mPassword.mPos, mPassword.mLen));
    LOG((" hostname  = (%u,%d)\n", mHost.mPos, mHost.mLen));
    LOG((" path      = (%u,%d)\n", mPath.mPos, mPath.mLen));
    LOG((" filepath  = (%u,%d)\n", mFilepath.mPos, mFilepath.mLen));
    LOG((" directory = (%u,%d)\n", mDirectory.mPos, mDirectory.mLen));
    LOG((" basename  = (%u,%d)\n", mBasename.mPos, mBasename.mLen));
    LOG((" extension = (%u,%d)\n", mExtension.mPos, mExtension.mLen));
    LOG((" query     = (%u,%d)\n", mQuery.mPos, mQuery.mLen));
    LOG((" ref       = (%u,%d)\n", mRef.mPos, mRef.mLen));
  }

  return rv;
}

nsresult nsStandardURL::SetScheme(const nsACString &input) {
  const nsPromiseFlatCString &scheme = PromiseFlatCString(input);

  LOG(("nsStandardURL::SetScheme [scheme=%s]\n", scheme.get()));

  if (scheme.IsEmpty()) {
    NS_WARNING("cannot remove the scheme from an url");
    return NS_ERROR_UNEXPECTED;
  }
  if (mScheme.mLen < 0) {
    NS_WARNING("uninitialized");
    return NS_ERROR_NOT_INITIALIZED;
  }

  if (!net_IsValidScheme(scheme)) {
    NS_WARNING("the given url scheme contains invalid characters");
    return NS_ERROR_UNEXPECTED;
  }

  if (mSpec.Length() + input.Length() - Scheme().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  int32_t shift = ReplaceSegment(mScheme.mPos, mScheme.mLen, scheme);

  if (shift) {
    mScheme.mLen = scheme.Length();
    ShiftFromAuthority(shift);
  }

  // ensure new scheme is lowercase
  //
  // XXX the string code unfortunately doesn't provide a ToLowerCase
  //     that operates on a substring.
  net_ToLowerCase((char *)mSpec.get(), mScheme.mLen);
  return NS_OK;
}

nsresult nsStandardURL::SetUserPass(const nsACString &input) {
  const nsPromiseFlatCString &userpass = PromiseFlatCString(input);

  LOG(("nsStandardURL::SetUserPass [userpass=%s]\n", userpass.get()));

  if (mURLType == URLTYPE_NO_AUTHORITY) {
    if (userpass.IsEmpty()) return NS_OK;
    NS_WARNING("cannot set user:pass on no-auth url");
    return NS_ERROR_UNEXPECTED;
  }
  if (mAuthority.mLen < 0) {
    NS_WARNING("uninitialized");
    return NS_ERROR_NOT_INITIALIZED;
  }

  if (mSpec.Length() + input.Length() - Userpass(true).Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  NS_ASSERTION(mHost.mLen >= 0, "uninitialized");

  nsresult rv;
  uint32_t usernamePos, passwordPos;
  int32_t usernameLen, passwordLen;

  rv = mParser->ParseUserInfo(userpass.get(), userpass.Length(), &usernamePos,
                              &usernameLen, &passwordPos, &passwordLen);
  if (NS_FAILED(rv)) return rv;

  // build new user:pass in |buf|
  nsAutoCString buf;
  if (usernameLen > 0 || passwordLen > 0) {
    nsSegmentEncoder encoder;
    bool ignoredOut;
    usernameLen = encoder.EncodeSegmentCount(
        userpass.get(), URLSegment(usernamePos, usernameLen),
        esc_Username | esc_AlwaysCopy, buf, ignoredOut);
    if (passwordLen > 0) {
      buf.Append(':');
      passwordLen = encoder.EncodeSegmentCount(
          userpass.get(), URLSegment(passwordPos, passwordLen),
          esc_Password | esc_AlwaysCopy, buf, ignoredOut);
    } else {
      passwordLen = -1;
    }
    if (mUsername.mLen < 0 && mPassword.mLen < 0) {
      buf.Append('@');
    }
  }

  int32_t shift = 0;

  if (mUsername.mLen < 0 && mPassword.mLen < 0) {
    // no existing user:pass
    if (!buf.IsEmpty()) {
      mSpec.Insert(buf, mHost.mPos);
      mUsername.mPos = mHost.mPos;
      shift = buf.Length();
    }
  } else {
    // replace existing user:pass
    uint32_t userpassLen = 0;
    if (mUsername.mLen > 0) {
      userpassLen += mUsername.mLen;
    }
    if (mPassword.mLen > 0) {
      userpassLen += (mPassword.mLen + 1);
    }
    if (buf.IsEmpty()) {
      // remove `@` character too
      userpassLen++;
    }
    mSpec.Replace(mAuthority.mPos, userpassLen, buf);
    shift = buf.Length() - userpassLen;
  }
  if (shift) {
    ShiftFromHost(shift);
    MOZ_DIAGNOSTIC_ASSERT(mAuthority.mLen >= -shift);
    mAuthority.mLen += shift;
  }
  // update positions and lengths
  mUsername.mLen = usernameLen > 0 ? usernameLen : -1;
  mUsername.mPos = mAuthority.mPos;
  mPassword.mLen = passwordLen > 0 ? passwordLen : -1;
  if (passwordLen > 0) {
    if (mUsername.mLen > 0) {
      mPassword.mPos = mUsername.mPos + mUsername.mLen + 1;
    } else {
      mPassword.mPos = mAuthority.mPos + 1;
    }
  }

  MOZ_ASSERT(mUsername.mLen != 0 && mPassword.mLen != 0);
  return NS_OK;
}

nsresult nsStandardURL::SetUsername(const nsACString &input) {
  const nsPromiseFlatCString &username = PromiseFlatCString(input);

  LOG(("nsStandardURL::SetUsername [username=%s]\n", username.get()));

  if (mURLType == URLTYPE_NO_AUTHORITY) {
    if (username.IsEmpty()) return NS_OK;
    NS_WARNING("cannot set username on no-auth url");
    return NS_ERROR_UNEXPECTED;
  }

  if (mSpec.Length() + input.Length() - Username().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  // escape username if necessary
  nsAutoCString buf;
  nsSegmentEncoder encoder;
  const nsACString &escUsername =
      encoder.EncodeSegment(username, esc_Username, buf);

  int32_t shift = 0;

  if (mUsername.mLen < 0 && escUsername.IsEmpty()) {
    return NS_OK;
  }

  if (mUsername.mLen < 0 && mPassword.mLen < 0) {
    MOZ_ASSERT(!escUsername.IsEmpty(), "Should not be empty at this point");
    mUsername.mPos = mAuthority.mPos;
    mSpec.Insert(escUsername + NS_LITERAL_CSTRING("@"), mUsername.mPos);
    shift = escUsername.Length() + 1;
    mUsername.mLen = escUsername.Length() > 0 ? escUsername.Length() : -1;
  } else {
    uint32_t pos = mUsername.mLen < 0 ? mAuthority.mPos : mUsername.mPos;
    int32_t len = mUsername.mLen < 0 ? 0 : mUsername.mLen;

    if (mPassword.mLen < 0 && escUsername.IsEmpty()) {
      len++;  // remove the @ character too
    }
    shift = ReplaceSegment(pos, len, escUsername);
    mUsername.mLen = escUsername.Length() > 0 ? escUsername.Length() : -1;
  }

  if (shift) {
    mAuthority.mLen += shift;
    ShiftFromPassword(shift);
  }

  MOZ_ASSERT(mUsername.mLen != 0 && mPassword.mLen != 0);
  return NS_OK;
}

nsresult nsStandardURL::SetPassword(const nsACString &input) {
  const nsPromiseFlatCString &password = PromiseFlatCString(input);

  auto clearedPassword = MakeScopeExit([&password, this]() {
    // Check that if this method is called with the empty string then the
    // password is definitely cleared when exiting this method.
    if (password.IsEmpty()) {
      MOZ_DIAGNOSTIC_ASSERT(this->Password().IsEmpty());
    }
    Unused << this;  // silence compiler -Wunused-lambda-capture
  });

  LOG(("nsStandardURL::SetPassword [password=%s]\n", password.get()));

  if (mURLType == URLTYPE_NO_AUTHORITY) {
    if (password.IsEmpty()) return NS_OK;
    NS_WARNING("cannot set password on no-auth url");
    return NS_ERROR_UNEXPECTED;
  }

  if (mSpec.Length() + input.Length() - Password().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  if (password.IsEmpty()) {
    if (mPassword.mLen > 0) {
      // cut(":password")
      int32_t len = mPassword.mLen;
      if (mUsername.mLen < 0) {
        len++;  // also cut the @ character
      }
      len++;  // for the : character
      mSpec.Cut(mPassword.mPos - 1, len);
      ShiftFromHost(-len);
      mAuthority.mLen -= len;
      mPassword.mLen = -1;
    }
    MOZ_ASSERT(mUsername.mLen != 0 && mPassword.mLen != 0);
    return NS_OK;
  }

  // escape password if necessary
  nsAutoCString buf;
  nsSegmentEncoder encoder;
  const nsACString &escPassword =
      encoder.EncodeSegment(password, esc_Password, buf);

  int32_t shift;

  if (mPassword.mLen < 0) {
    if (mUsername.mLen > 0) {
      mPassword.mPos = mUsername.mPos + mUsername.mLen + 1;
      mSpec.Insert(NS_LITERAL_CSTRING(":") + escPassword, mPassword.mPos - 1);
      shift = escPassword.Length() + 1;
    } else {
      mPassword.mPos = mAuthority.mPos + 1;
      mSpec.Insert(
          NS_LITERAL_CSTRING(":") + escPassword + NS_LITERAL_CSTRING("@"),
          mPassword.mPos - 1);
      shift = escPassword.Length() + 2;
    }
  } else
    shift = ReplaceSegment(mPassword.mPos, mPassword.mLen, escPassword);

  if (shift) {
    mPassword.mLen = escPassword.Length();
    mAuthority.mLen += shift;
    ShiftFromHost(shift);
  }

  MOZ_ASSERT(mUsername.mLen != 0 && mPassword.mLen != 0);
  return NS_OK;
}

void nsStandardURL::FindHostLimit(nsACString::const_iterator &aStart,
                                  nsACString::const_iterator &aEnd) {
  for (int32_t i = 0; gHostLimitDigits[i]; ++i) {
    nsACString::const_iterator c(aStart);
    if (FindCharInReadable(gHostLimitDigits[i], c, aEnd)) {
      aEnd = c;
    }
  }
}

// If aValue only has a host part and no port number, the port
// will not be reset!!!
nsresult nsStandardURL::SetHostPort(const nsACString &aValue) {
  // We cannot simply call nsIURI::SetHost because that would treat the name as
  // an IPv6 address (like http:://[server:443]/).  We also cannot call
  // nsIURI::SetHostPort because that isn't implemented.  Sadfaces.

  nsACString::const_iterator start, end;
  aValue.BeginReading(start);
  aValue.EndReading(end);
  nsACString::const_iterator iter(start);
  bool isIPv6 = false;

  FindHostLimit(start, end);

  if (*start == '[') {  // IPv6 address
    if (!FindCharInReadable(']', iter, end)) {
      // the ] character is missing
      return NS_ERROR_MALFORMED_URI;
    }
    // iter now at the ']' character
    isIPv6 = true;
  } else {
    nsACString::const_iterator iter2(start);
    if (FindCharInReadable(']', iter2, end)) {
      // if the first char isn't [ then there should be no ] character
      return NS_ERROR_MALFORMED_URI;
    }
  }

  FindCharInReadable(':', iter, end);

  if (!isIPv6 && iter != end) {
    nsACString::const_iterator iter2(iter);
    iter2++;  // Skip over the first ':' character
    if (FindCharInReadable(':', iter2, end)) {
      // If there is more than one ':' character it suggests an IPv6
      // The format should be [2001::1]:80 where the port is optional
      return NS_ERROR_MALFORMED_URI;
    }
  }

  nsresult rv = SetHost(Substring(start, iter));
  NS_ENSURE_SUCCESS(rv, rv);

  if (iter == end) {
    // does not end in colon
    return NS_OK;
  }

  iter++;  // advance over the colon
  if (iter == end) {
    // port number is missing
    return NS_OK;
  }

  nsCString portStr(Substring(iter, end));
  int32_t port = portStr.ToInteger(&rv);
  if (NS_FAILED(rv)) {
    // Failure parsing the port number
    return NS_OK;
  }

  Unused << SetPort(port);
  return NS_OK;
}

nsresult nsStandardURL::SetHost(const nsACString &input) {
  const nsPromiseFlatCString &hostname = PromiseFlatCString(input);

  nsACString::const_iterator start, end;
  hostname.BeginReading(start);
  hostname.EndReading(end);

  FindHostLimit(start, end);

  const nsCString unescapedHost(Substring(start, end));
  // Do percent decoding on the the input.
  nsAutoCString flat;
  NS_UnescapeURL(unescapedHost.BeginReading(), unescapedHost.Length(),
                 esc_AlwaysCopy | esc_Host, flat);
  const char *host = flat.get();

  LOG(("nsStandardURL::SetHost [host=%s]\n", host));

  if (mURLType == URLTYPE_NO_AUTHORITY) {
    if (flat.IsEmpty()) return NS_OK;
    NS_WARNING("cannot set host on no-auth url");
    return NS_ERROR_UNEXPECTED;
  }
  if (flat.IsEmpty()) {
    // Setting an empty hostname is not allowed for
    // URLTYPE_STANDARD and URLTYPE_AUTHORITY.
    return NS_ERROR_UNEXPECTED;
  }

  if (strlen(host) < flat.Length())
    return NS_ERROR_MALFORMED_URI;  // found embedded null

  // For consistency with SetSpec/nsURLParsers, don't allow spaces
  // in the hostname.
  if (strchr(host, ' ')) return NS_ERROR_MALFORMED_URI;

  if (mSpec.Length() + strlen(host) - Host().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  uint32_t len;
  nsAutoCString hostBuf;
  nsresult rv = NormalizeIDN(flat, hostBuf);
  if (NS_FAILED(rv)) {
    return rv;
  }

  if (!SegmentIs(mScheme, "resource") && !SegmentIs(mScheme, "chrome")) {
    nsAutoCString ipString;
    if (hostBuf.Length() > 0 && hostBuf.First() == '[' &&
        hostBuf.Last() == ']' &&
        ValidIPv6orHostname(hostBuf.get(), hostBuf.Length())) {
      rv = (nsresult)rusturl_parse_ipv6addr(&hostBuf, &ipString);
      if (NS_FAILED(rv)) {
        return rv;
      }
      hostBuf = ipString;
    } else if (NS_SUCCEEDED(NormalizeIPv4(hostBuf, ipString))) {
      hostBuf = ipString;
    }
  }

  // NormalizeIDN always copies if the call was successful
  host = hostBuf.get();
  len = hostBuf.Length();

  if (!ValidIPv6orHostname(host, len)) {
    return NS_ERROR_MALFORMED_URI;
  }

  if (mHost.mLen < 0) {
    int port_length = 0;
    if (mPort != -1) {
      nsAutoCString buf;
      buf.Assign(':');
      buf.AppendInt(mPort);
      port_length = buf.Length();
    }
    if (mAuthority.mLen > 0) {
      mHost.mPos = mAuthority.mPos + mAuthority.mLen - port_length;
      mHost.mLen = 0;
    } else if (mScheme.mLen > 0) {
      mHost.mPos = mScheme.mPos + mScheme.mLen + 3;
      mHost.mLen = 0;
    }
  }

  int32_t shift = ReplaceSegment(mHost.mPos, mHost.mLen, host, len);

  if (shift) {
    mHost.mLen = len;
    mAuthority.mLen += shift;
    ShiftFromPath(shift);
  }

  // Now canonicalize the host to lowercase
  net_ToLowerCase(mSpec.BeginWriting() + mHost.mPos, mHost.mLen);
  return NS_OK;
}

nsresult nsStandardURL::SetPort(int32_t port) {
  LOG(("nsStandardURL::SetPort [port=%d]\n", port));

  if ((port == mPort) || (mPort == -1 && port == mDefaultPort)) return NS_OK;

  // ports must be >= 0 and 16 bit
  // -1 == use default
  if (port < -1 || port > std::numeric_limits<uint16_t>::max())
    return NS_ERROR_MALFORMED_URI;

  if (mURLType == URLTYPE_NO_AUTHORITY) {
    NS_WARNING("cannot set port on no-auth url");
    return NS_ERROR_UNEXPECTED;
  }

  InvalidateCache();
  if (port == mDefaultPort) {
    port = -1;
  }

  ReplacePortInSpec(port);

  mPort = port;
  return NS_OK;
}

/**
 * Replaces the existing port in mSpec with aNewPort.
 *
 * The caller is responsible for:
 *  - Calling InvalidateCache (since our mSpec is changing).
 *  - Checking whether aNewPort is mDefaultPort (in which case the
 *    caller should pass aNewPort=-1).
 */
void nsStandardURL::ReplacePortInSpec(int32_t aNewPort) {
  NS_ASSERTION(aNewPort != mDefaultPort || mDefaultPort == -1,
               "Caller should check its passed-in value and pass -1 instead of "
               "mDefaultPort, to avoid encoding default port into mSpec");

  // Create the (possibly empty) string that we're planning to replace:
  nsAutoCString buf;
  if (mPort != -1) {
    buf.Assign(':');
    buf.AppendInt(mPort);
  }
  // Find the position & length of that string:
  const uint32_t replacedLen = buf.Length();
  const uint32_t replacedStart =
      mAuthority.mPos + mAuthority.mLen - replacedLen;

  // Create the (possibly empty) replacement string:
  if (aNewPort == -1) {
    buf.Truncate();
  } else {
    buf.Assign(':');
    buf.AppendInt(aNewPort);
  }
  // Perform the replacement:
  mSpec.Replace(replacedStart, replacedLen, buf);

  // Bookkeeping to reflect the new length:
  int32_t shift = buf.Length() - replacedLen;
  mAuthority.mLen += shift;
  ShiftFromPath(shift);
}

nsresult nsStandardURL::SetPathQueryRef(const nsACString &input) {
  const nsPromiseFlatCString &path = PromiseFlatCString(input);
  LOG(("nsStandardURL::SetPathQueryRef [path=%s]\n", path.get()));

  InvalidateCache();

  if (!path.IsEmpty()) {
    nsAutoCString spec;

    spec.Assign(mSpec.get(), mPath.mPos);
    if (path.First() != '/') spec.Append('/');
    spec.Append(path);

    return SetSpecInternal(spec);
  }
  if (mPath.mLen >= 1) {
    mSpec.Cut(mPath.mPos + 1, mPath.mLen - 1);
    // these contain only a '/'
    mPath.mLen = 1;
    mDirectory.mLen = 1;
    mFilepath.mLen = 1;
    // these are no longer defined
    mBasename.mLen = -1;
    mExtension.mLen = -1;
    mQuery.mLen = -1;
    mRef.mLen = -1;
  }
  return NS_OK;
}

// When updating this also update SubstitutingURL::Mutator
// Queries this list of interfaces. If none match, it queries mURI.
NS_IMPL_NSIURIMUTATOR_ISUPPORTS(nsStandardURL::Mutator, nsIURISetters,
                                nsIURIMutator, nsIStandardURLMutator,
                                nsIURLMutator, nsIFileURLMutator,
                                nsISerializable)

NS_IMETHODIMP
nsStandardURL::Mutate(nsIURIMutator **aMutator) {
  RefPtr<nsStandardURL::Mutator> mutator = new nsStandardURL::Mutator();
  nsresult rv = mutator->InitFromURI(this);
  if (NS_FAILED(rv)) {
    return rv;
  }
  mutator.forget(aMutator);
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::Equals(nsIURI *unknownOther, bool *result) {
  return EqualsInternal(unknownOther, eHonorRef, result);
}

NS_IMETHODIMP
nsStandardURL::EqualsExceptRef(nsIURI *unknownOther, bool *result) {
  return EqualsInternal(unknownOther, eIgnoreRef, result);
}

nsresult nsStandardURL::EqualsInternal(
    nsIURI *unknownOther, nsStandardURL::RefHandlingEnum refHandlingMode,
    bool *result) {
  NS_ENSURE_ARG_POINTER(unknownOther);
  MOZ_ASSERT(result, "null pointer");

  RefPtr<nsStandardURL> other;
  nsresult rv =
      unknownOther->QueryInterface(kThisImplCID, getter_AddRefs(other));
  if (NS_FAILED(rv)) {
    *result = false;
    return NS_OK;
  }

  // First, check whether one URIs is an nsIFileURL while the other
  // is not.  If that's the case, they're different.
  if (mSupportsFileURL != other->mSupportsFileURL) {
    *result = false;
    return NS_OK;
  }

  // Next check parts of a URI that, if different, automatically make the
  // URIs different
  if (!SegmentIs(mScheme, other->mSpec.get(), other->mScheme) ||
      // Check for host manually, since conversion to file will
      // ignore the host!
      !SegmentIs(mHost, other->mSpec.get(), other->mHost) ||
      !SegmentIs(mQuery, other->mSpec.get(), other->mQuery) ||
      !SegmentIs(mUsername, other->mSpec.get(), other->mUsername) ||
      !SegmentIs(mPassword, other->mSpec.get(), other->mPassword) ||
      Port() != other->Port()) {
    // No need to compare files or other URI parts -- these are different
    // beasties
    *result = false;
    return NS_OK;
  }

  if (refHandlingMode == eHonorRef &&
      !SegmentIs(mRef, other->mSpec.get(), other->mRef)) {
    *result = false;
    return NS_OK;
  }

  // Then check for exact identity of URIs.  If we have it, they're equal
  if (SegmentIs(mDirectory, other->mSpec.get(), other->mDirectory) &&
      SegmentIs(mBasename, other->mSpec.get(), other->mBasename) &&
      SegmentIs(mExtension, other->mSpec.get(), other->mExtension)) {
    *result = true;
    return NS_OK;
  }

  // At this point, the URIs are not identical, but they only differ in the
  // directory/filename/extension.  If these are file URLs, then get the
  // corresponding file objects and compare those, since two filenames that
  // differ, eg, only in case could still be equal.
  if (mSupportsFileURL) {
    // Assume not equal for failure cases... but failures in GetFile are
    // really failures, more or less, so propagate them to caller.
    *result = false;

    rv = EnsureFile();
    nsresult rv2 = other->EnsureFile();
    // special case for resource:// urls that don't resolve to files
    if (rv == NS_ERROR_NO_INTERFACE && rv == rv2) return NS_OK;

    if (NS_FAILED(rv)) {
      LOG(("nsStandardURL::Equals [this=%p spec=%s] failed to ensure file",
           this, mSpec.get()));
      return rv;
    }
    NS_ASSERTION(mFile, "EnsureFile() lied!");
    rv = rv2;
    if (NS_FAILED(rv)) {
      LOG(
          ("nsStandardURL::Equals [other=%p spec=%s] other failed to ensure "
           "file",
           other.get(), other->mSpec.get()));
      return rv;
    }
    NS_ASSERTION(other->mFile, "EnsureFile() lied!");
    return mFile->Equals(other->mFile, result);
  }

  // The URLs are not identical, and they do not correspond to the
  // same file, so they are different.
  *result = false;

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::SchemeIs(const char *scheme, bool *result) {
  MOZ_ASSERT(result, "null pointer");
  if (!scheme) {
    *result = false;
    return NS_OK;
  }

  *result = SegmentIs(mScheme, scheme);
  return NS_OK;
}

/* virtual */ nsStandardURL *nsStandardURL::StartClone() {
  nsStandardURL *clone = new nsStandardURL();
  return clone;
}

nsresult nsStandardURL::Clone(nsIURI **result) {
  return CloneInternal(eHonorRef, EmptyCString(), result);
}

nsresult nsStandardURL::CloneInternal(
    nsStandardURL::RefHandlingEnum refHandlingMode, const nsACString &newRef,
    nsIURI **result)

{
  RefPtr<nsStandardURL> clone = StartClone();
  if (!clone) return NS_ERROR_OUT_OF_MEMORY;

  // Copy local members into clone.
  // Also copies the cached members mFile, mDisplayHost
  clone->CopyMembers(this, refHandlingMode, newRef, true);

  clone.forget(result);
  return NS_OK;
}

nsresult nsStandardURL::CopyMembers(
    nsStandardURL *source, nsStandardURL::RefHandlingEnum refHandlingMode,
    const nsACString &newRef, bool copyCached) {
  mSpec = source->mSpec;
  mDefaultPort = source->mDefaultPort;
  mPort = source->mPort;
  mScheme = source->mScheme;
  mAuthority = source->mAuthority;
  mUsername = source->mUsername;
  mPassword = source->mPassword;
  mHost = source->mHost;
  mPath = source->mPath;
  mFilepath = source->mFilepath;
  mDirectory = source->mDirectory;
  mBasename = source->mBasename;
  mExtension = source->mExtension;
  mQuery = source->mQuery;
  mRef = source->mRef;
  mURLType = source->mURLType;
  mParser = source->mParser;
  mSupportsFileURL = source->mSupportsFileURL;
  mCheckedIfHostA = source->mCheckedIfHostA;
  mDisplayHost = source->mDisplayHost;

  if (copyCached) {
    mFile = source->mFile;
  } else {
    InvalidateCache(true);
  }

  if (refHandlingMode == eIgnoreRef) {
    SetRef(EmptyCString());
  } else if (refHandlingMode == eReplaceRef) {
    SetRef(newRef);
  }

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::Resolve(const nsACString &in, nsACString &out) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(in);
  // filter out unexpected chars "\r\n\t" if necessary
  nsAutoCString buf;
  net_FilterURIString(flat, buf);

  const char *relpath = buf.get();
  int32_t relpathLen = buf.Length();

  char *result = nullptr;

  LOG(("nsStandardURL::Resolve [this=%p spec=%s relpath=%s]\n", this,
       mSpec.get(), relpath));

  NS_ASSERTION(mParser, "no parser: unitialized");

  // NOTE: there is no need for this function to produce normalized
  // output.  normalization will occur when the result is used to
  // initialize a nsStandardURL object.

  if (mScheme.mLen < 0) {
    NS_WARNING("unable to Resolve URL: this URL not initialized");
    return NS_ERROR_NOT_INITIALIZED;
  }

  nsresult rv;
  URLSegment scheme;
  char *resultPath = nullptr;
  bool relative = false;
  uint32_t offset = 0;
  netCoalesceFlags coalesceFlag = NET_COALESCE_NORMAL;

  // relative urls should never contain a host, so we always want to use
  // the noauth url parser.
  // use it to extract a possible scheme
  rv = mParser->ParseURL(relpath, relpathLen, &scheme.mPos, &scheme.mLen,
                         nullptr, nullptr, nullptr, nullptr);

  // if the parser fails (for example because there is no valid scheme)
  // reset the scheme and assume a relative url
  if (NS_FAILED(rv)) scheme.Reset();

  nsAutoCString protocol(Segment(scheme));
  nsAutoCString baseProtocol(Scheme());

  // We need to do backslash replacement for the following cases:
  // 1. The input is an absolute path with a http/https/ftp scheme
  // 2. The input is a relative path, and the base URL has a http/https/ftp
  // scheme
  if ((protocol.IsEmpty() && IsSpecialProtocol(baseProtocol)) ||
      IsSpecialProtocol(protocol)) {
    auto start = buf.BeginWriting();
    auto end = buf.EndWriting();
    while (start != end) {
      if (*start == '?' || *start == '#') {
        break;
      }
      if (*start == '\\') {
        *start = '/';
      }
      start++;
    }
  }

  if (scheme.mLen >= 0) {
    // add some flags to coalesceFlag if it is an ftp-url
    // need this later on when coalescing the resulting URL
    if (SegmentIs(relpath, scheme, "ftp", true)) {
      coalesceFlag =
          (netCoalesceFlags)(coalesceFlag | NET_COALESCE_ALLOW_RELATIVE_ROOT |
                             NET_COALESCE_DOUBLE_SLASH_IS_ROOT);
    }
    // this URL appears to be absolute
    // but try to find out more
    if (SegmentIs(mScheme, relpath, scheme, true)) {
      // mScheme and Scheme are the same
      // but this can still be relative
      if (strncmp(relpath + scheme.mPos + scheme.mLen, "://", 3) == 0) {
        // now this is really absolute
        // because a :// follows the scheme
        result = NS_xstrdup(relpath);
      } else {
        // This is a deprecated form of relative urls like
        // http:file or http:/path/file
        // we will support it for now ...
        relative = true;
        offset = scheme.mLen + 1;
      }
    } else {
      // the schemes are not the same, we are also done
      // because we have to assume this is absolute
      result = NS_xstrdup(relpath);
    }
  } else {
    // add some flags to coalesceFlag if it is an ftp-url
    // need this later on when coalescing the resulting URL
    if (SegmentIs(mScheme, "ftp")) {
      coalesceFlag =
          (netCoalesceFlags)(coalesceFlag | NET_COALESCE_ALLOW_RELATIVE_ROOT |
                             NET_COALESCE_DOUBLE_SLASH_IS_ROOT);
    }
    if (relpath[0] == '/' && relpath[1] == '/') {
      // this URL //host/path is almost absolute
      result = AppendToSubstring(mScheme.mPos, mScheme.mLen + 1, relpath);
    } else {
      // then it must be relative
      relative = true;
    }
  }
  if (relative) {
    uint32_t len = 0;
    const char *realrelpath = relpath + offset;
    switch (*realrelpath) {
      case '/':
        // overwrite everything after the authority
        len = mAuthority.mPos + mAuthority.mLen;
        break;
      case '?':
        // overwrite the existing ?query and #ref
        if (mQuery.mLen >= 0)
          len = mQuery.mPos - 1;
        else if (mRef.mLen >= 0)
          len = mRef.mPos - 1;
        else
          len = mPath.mPos + mPath.mLen;
        break;
      case '#':
      case '\0':
        // overwrite the existing #ref
        if (mRef.mLen < 0)
          len = mPath.mPos + mPath.mLen;
        else
          len = mRef.mPos - 1;
        break;
      default:
        if (coalesceFlag & NET_COALESCE_DOUBLE_SLASH_IS_ROOT) {
          if (Filename().Equals(NS_LITERAL_CSTRING("%2F"),
                                nsCaseInsensitiveCStringComparator())) {
            // if ftp URL ends with %2F then simply
            // append relative part because %2F also
            // marks the root directory with ftp-urls
            len = mFilepath.mPos + mFilepath.mLen;
          } else {
            // overwrite everything after the directory
            len = mDirectory.mPos + mDirectory.mLen;
          }
        } else {
          // overwrite everything after the directory
          len = mDirectory.mPos + mDirectory.mLen;
        }
    }
    result = AppendToSubstring(0, len, realrelpath);
    // locate result path
    resultPath = result + mPath.mPos;
  }
  if (!result) return NS_ERROR_OUT_OF_MEMORY;

  if (resultPath)
    net_CoalesceDirs(coalesceFlag, resultPath);
  else {
    // locate result path
    resultPath = PL_strstr(result, "://");
    if (resultPath) {
      resultPath = PL_strchr(resultPath + 3, '/');
      if (resultPath) net_CoalesceDirs(coalesceFlag, resultPath);
    }
  }
  out.Adopt(result);
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetCommonBaseSpec(nsIURI *uri2, nsACString &aResult) {
  NS_ENSURE_ARG_POINTER(uri2);

  // if uri's are equal, then return uri as is
  bool isEquals = false;
  if (NS_SUCCEEDED(Equals(uri2, &isEquals)) && isEquals)
    return GetSpec(aResult);

  aResult.Truncate();

  // check pre-path; if they don't match, then return empty string
  RefPtr<nsStandardURL> stdurl2;
  nsresult rv = uri2->QueryInterface(kThisImplCID, getter_AddRefs(stdurl2));
  isEquals = NS_SUCCEEDED(rv) &&
             SegmentIs(mScheme, stdurl2->mSpec.get(), stdurl2->mScheme) &&
             SegmentIs(mHost, stdurl2->mSpec.get(), stdurl2->mHost) &&
             SegmentIs(mUsername, stdurl2->mSpec.get(), stdurl2->mUsername) &&
             SegmentIs(mPassword, stdurl2->mSpec.get(), stdurl2->mPassword) &&
             (Port() == stdurl2->Port());
  if (!isEquals) {
    return NS_OK;
  }

  // scan for first mismatched character
  const char *thisIndex, *thatIndex, *startCharPos;
  startCharPos = mSpec.get() + mDirectory.mPos;
  thisIndex = startCharPos;
  thatIndex = stdurl2->mSpec.get() + mDirectory.mPos;
  while ((*thisIndex == *thatIndex) && *thisIndex) {
    thisIndex++;
    thatIndex++;
  }

  // backup to just after previous slash so we grab an appropriate path
  // segment such as a directory (not partial segments)
  // todo:  also check for file matches which include '?' and '#'
  while ((thisIndex != startCharPos) && (*(thisIndex - 1) != '/')) thisIndex--;

  // grab spec from beginning to thisIndex
  aResult = Substring(mSpec, mScheme.mPos, thisIndex - mSpec.get());

  return rv;
}

NS_IMETHODIMP
nsStandardURL::GetRelativeSpec(nsIURI *uri2, nsACString &aResult) {
  NS_ENSURE_ARG_POINTER(uri2);

  aResult.Truncate();

  // if uri's are equal, then return empty string
  bool isEquals = false;
  if (NS_SUCCEEDED(Equals(uri2, &isEquals)) && isEquals) return NS_OK;

  RefPtr<nsStandardURL> stdurl2;
  nsresult rv = uri2->QueryInterface(kThisImplCID, getter_AddRefs(stdurl2));
  isEquals = NS_SUCCEEDED(rv) &&
             SegmentIs(mScheme, stdurl2->mSpec.get(), stdurl2->mScheme) &&
             SegmentIs(mHost, stdurl2->mSpec.get(), stdurl2->mHost) &&
             SegmentIs(mUsername, stdurl2->mSpec.get(), stdurl2->mUsername) &&
             SegmentIs(mPassword, stdurl2->mSpec.get(), stdurl2->mPassword) &&
             (Port() == stdurl2->Port());
  if (!isEquals) {
    return uri2->GetSpec(aResult);
  }

  // scan for first mismatched character
  const char *thisIndex, *thatIndex, *startCharPos;
  startCharPos = mSpec.get() + mDirectory.mPos;
  thisIndex = startCharPos;
  thatIndex = stdurl2->mSpec.get() + mDirectory.mPos;

#ifdef XP_WIN
  bool isFileScheme = SegmentIs(mScheme, "file");
  if (isFileScheme) {
    // on windows, we need to match the first segment of the path
    // if these don't match then we need to return an absolute path
    // skip over any leading '/' in path
    while ((*thisIndex == *thatIndex) && (*thisIndex == '/')) {
      thisIndex++;
      thatIndex++;
    }
    // look for end of first segment
    while ((*thisIndex == *thatIndex) && *thisIndex && (*thisIndex != '/')) {
      thisIndex++;
      thatIndex++;
    }

    // if we didn't match through the first segment, return absolute path
    if ((*thisIndex != '/') || (*thatIndex != '/')) {
      return uri2->GetSpec(aResult);
    }
  }
#endif

  while ((*thisIndex == *thatIndex) && *thisIndex) {
    thisIndex++;
    thatIndex++;
  }

  // backup to just after previous slash so we grab an appropriate path
  // segment such as a directory (not partial segments)
  // todo:  also check for file matches with '#' and '?'
  while ((*(thatIndex - 1) != '/') && (thatIndex != startCharPos)) thatIndex--;

  const char *limit = mSpec.get() + mFilepath.mPos + mFilepath.mLen;

  // need to account for slashes and add corresponding "../"
  for (; thisIndex <= limit && *thisIndex; ++thisIndex) {
    if (*thisIndex == '/') aResult.AppendLiteral("../");
  }

  // grab spec from thisIndex to end
  uint32_t startPos = stdurl2->mScheme.mPos + thatIndex - stdurl2->mSpec.get();
  aResult.Append(
      Substring(stdurl2->mSpec, startPos, stdurl2->mSpec.Length() - startPos));

  return rv;
}

//----------------------------------------------------------------------------
// nsStandardURL::nsIURL
//----------------------------------------------------------------------------

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetFilePath(nsACString &result) {
  result = Filepath();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetQuery(nsACString &result) {
  result = Query();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetRef(nsACString &result) {
  result = Ref();
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetHasRef(bool *result) {
  *result = (mRef.mLen >= 0);
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetDirectory(nsACString &result) {
  result = Directory();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetFileName(nsACString &result) {
  result = Filename();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetFileBaseName(nsACString &result) {
  result = Basename();
  return NS_OK;
}

// result may contain unescaped UTF-8 characters
NS_IMETHODIMP
nsStandardURL::GetFileExtension(nsACString &result) {
  result = Extension();
  return NS_OK;
}

nsresult nsStandardURL::SetFilePath(const nsACString &input) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(input);
  const char *filepath = flat.get();

  LOG(("nsStandardURL::SetFilePath [filepath=%s]\n", filepath));

  // if there isn't a filepath, then there can't be anything
  // after the path either.  this url is likely uninitialized.
  if (mFilepath.mLen < 0) return SetPathQueryRef(flat);

  if (filepath && *filepath) {
    nsAutoCString spec;
    uint32_t dirPos, basePos, extPos;
    int32_t dirLen, baseLen, extLen;
    nsresult rv;

    rv = mParser->ParseFilePath(filepath, flat.Length(), &dirPos, &dirLen,
                                &basePos, &baseLen, &extPos, &extLen);
    if (NS_FAILED(rv)) return rv;

    // build up new candidate spec
    spec.Assign(mSpec.get(), mPath.mPos);

    // ensure leading '/'
    if (filepath[dirPos] != '/') spec.Append('/');

    nsSegmentEncoder encoder;

    // append encoded filepath components
    if (dirLen > 0)
      encoder.EncodeSegment(
          Substring(filepath + dirPos, filepath + dirPos + dirLen),
          esc_Directory | esc_AlwaysCopy, spec);
    if (baseLen > 0)
      encoder.EncodeSegment(
          Substring(filepath + basePos, filepath + basePos + baseLen),
          esc_FileBaseName | esc_AlwaysCopy, spec);
    if (extLen >= 0) {
      spec.Append('.');
      if (extLen > 0)
        encoder.EncodeSegment(
            Substring(filepath + extPos, filepath + extPos + extLen),
            esc_FileExtension | esc_AlwaysCopy, spec);
    }

    // compute the ending position of the current filepath
    if (mFilepath.mLen >= 0) {
      uint32_t end = mFilepath.mPos + mFilepath.mLen;
      if (mSpec.Length() > end)
        spec.Append(mSpec.get() + end, mSpec.Length() - end);
    }

    return SetSpecInternal(spec);
  }
  if (mPath.mLen > 1) {
    mSpec.Cut(mPath.mPos + 1, mFilepath.mLen - 1);
    // left shift query, and ref
    ShiftFromQuery(1 - mFilepath.mLen);
    // these contain only a '/'
    mPath.mLen = 1;
    mDirectory.mLen = 1;
    mFilepath.mLen = 1;
    // these are no longer defined
    mBasename.mLen = -1;
    mExtension.mLen = -1;
  }
  return NS_OK;
}

inline bool IsUTFEncoding(const Encoding *aEncoding) {
  return aEncoding == UTF_8_ENCODING || aEncoding == UTF_16BE_ENCODING ||
         aEncoding == UTF_16LE_ENCODING;
}

nsresult nsStandardURL::SetQuery(const nsACString &input) {
  return SetQueryWithEncoding(input, nullptr);
}

nsresult nsStandardURL::SetQueryWithEncoding(const nsACString &input,
                                             const Encoding *encoding) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(input);
  const char *query = flat.get();

  LOG(("nsStandardURL::SetQuery [query=%s]\n", query));

  if (IsUTFEncoding(encoding)) {
    encoding = nullptr;
  }

  if (mPath.mLen < 0) return SetPathQueryRef(flat);

  if (mSpec.Length() + input.Length() - Query().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  if (!query || !*query) {
    // remove existing query
    if (mQuery.mLen >= 0) {
      // remove query and leading '?'
      mSpec.Cut(mQuery.mPos - 1, mQuery.mLen + 1);
      ShiftFromRef(-(mQuery.mLen + 1));
      mPath.mLen -= (mQuery.mLen + 1);
      mQuery.mPos = 0;
      mQuery.mLen = -1;
    }
    return NS_OK;
  }

  int32_t queryLen = flat.Length();
  if (query[0] == '?') {
    query++;
    queryLen--;
  }

  if (mQuery.mLen < 0) {
    if (mRef.mLen < 0)
      mQuery.mPos = mSpec.Length();
    else
      mQuery.mPos = mRef.mPos - 1;
    mSpec.Insert('?', mQuery.mPos);
    mQuery.mPos++;
    mQuery.mLen = 0;
    // the insertion pushes these out by 1
    mPath.mLen++;
    mRef.mPos++;
  }

  // encode query if necessary
  nsAutoCString buf;
  bool encoded;
  nsSegmentEncoder encoder(encoding);
  encoder.EncodeSegmentCount(query, URLSegment(0, queryLen), esc_Query, buf,
                             encoded);
  if (encoded) {
    query = buf.get();
    queryLen = buf.Length();
  }

  int32_t shift = ReplaceSegment(mQuery.mPos, mQuery.mLen, query, queryLen);

  if (shift) {
    mQuery.mLen = queryLen;
    mPath.mLen += shift;
    ShiftFromRef(shift);
  }
  return NS_OK;
}

nsresult nsStandardURL::SetRef(const nsACString &input) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(input);
  const char *ref = flat.get();

  LOG(("nsStandardURL::SetRef [ref=%s]\n", ref));

  if (mPath.mLen < 0) return SetPathQueryRef(flat);

  if (mSpec.Length() + input.Length() - Ref().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  if (!ref || !*ref) {
    // remove existing ref
    if (mRef.mLen >= 0) {
      // remove ref and leading '#'
      mSpec.Cut(mRef.mPos - 1, mRef.mLen + 1);
      mPath.mLen -= (mRef.mLen + 1);
      mRef.mPos = 0;
      mRef.mLen = -1;
    }
    return NS_OK;
  }

  int32_t refLen = flat.Length();
  if (ref[0] == '#') {
    ref++;
    refLen--;
  }

  if (mRef.mLen < 0) {
    mSpec.Append('#');
    ++mPath.mLen;  // Include the # in the path.
    mRef.mPos = mSpec.Length();
    mRef.mLen = 0;
  }

  // If precent encoding is necessary, `ref` will point to `buf`'s content.
  // `buf` needs to outlive any use of the `ref` pointer.
  nsAutoCString buf;
  // encode ref if necessary
  bool encoded;
  nsSegmentEncoder encoder;
  encoder.EncodeSegmentCount(ref, URLSegment(0, refLen), esc_Ref, buf, encoded);
  if (encoded) {
    ref = buf.get();
    refLen = buf.Length();
  }

  int32_t shift = ReplaceSegment(mRef.mPos, mRef.mLen, ref, refLen);
  mPath.mLen += shift;
  mRef.mLen = refLen;
  return NS_OK;
}

nsresult nsStandardURL::SetFileNameInternal(const nsACString &input) {
  const nsPromiseFlatCString &flat = PromiseFlatCString(input);
  const char *filename = flat.get();

  LOG(("nsStandardURL::SetFileNameInternal [filename=%s]\n", filename));

  if (mPath.mLen < 0) return SetPathQueryRef(flat);

  if (mSpec.Length() + input.Length() - Filename().Length() >
      (uint32_t)net_GetURLMaxLength()) {
    return NS_ERROR_MALFORMED_URI;
  }

  int32_t shift = 0;

  if (!(filename && *filename)) {
    // remove the filename
    if (mBasename.mLen > 0) {
      if (mExtension.mLen >= 0) mBasename.mLen += (mExtension.mLen + 1);
      mSpec.Cut(mBasename.mPos, mBasename.mLen);
      shift = -mBasename.mLen;
      mBasename.mLen = 0;
      mExtension.mLen = -1;
    }
  } else {
    nsresult rv;
    URLSegment basename, extension;

    // let the parser locate the basename and extension
    rv = mParser->ParseFileName(filename, flat.Length(), &basename.mPos,
                                &basename.mLen, &extension.mPos,
                                &extension.mLen);
    if (NS_FAILED(rv)) return rv;

    if (basename.mLen < 0) {
      // remove existing filename
      if (mBasename.mLen >= 0) {
        uint32_t len = mBasename.mLen;
        if (mExtension.mLen >= 0) len += (mExtension.mLen + 1);
        mSpec.Cut(mBasename.mPos, len);
        shift = -int32_t(len);
        mBasename.mLen = 0;
        mExtension.mLen = -1;
      }
    } else {
      nsAutoCString newFilename;
      bool ignoredOut;
      nsSegmentEncoder encoder;
      basename.mLen = encoder.EncodeSegmentCount(
          filename, basename, esc_FileBaseName | esc_AlwaysCopy, newFilename,
          ignoredOut);
      if (extension.mLen >= 0) {
        newFilename.Append('.');
        extension.mLen = encoder.EncodeSegmentCount(
            filename, extension, esc_FileExtension | esc_AlwaysCopy,
            newFilename, ignoredOut);
      }

      if (mBasename.mLen < 0) {
        // insert new filename
        mBasename.mPos = mDirectory.mPos + mDirectory.mLen;
        mSpec.Insert(newFilename, mBasename.mPos);
        shift = newFilename.Length();
      } else {
        // replace existing filename
        uint32_t oldLen = uint32_t(mBasename.mLen);
        if (mExtension.mLen >= 0) oldLen += (mExtension.mLen + 1);
        mSpec.Replace(mBasename.mPos, oldLen, newFilename);
        shift = newFilename.Length() - oldLen;
      }

      mBasename.mLen = basename.mLen;
      mExtension.mLen = extension.mLen;
      if (mExtension.mLen >= 0)
        mExtension.mPos = mBasename.mPos + mBasename.mLen + 1;
    }
  }
  if (shift) {
    ShiftFromQuery(shift);
    mFilepath.mLen += shift;
    mPath.mLen += shift;
  }
  return NS_OK;
}

nsresult nsStandardURL::SetFileBaseNameInternal(const nsACString &input) {
  nsAutoCString extension;
  nsresult rv = GetFileExtension(extension);
  NS_ENSURE_SUCCESS(rv, rv);

  nsAutoCString newFileName(input);

  if (!extension.IsEmpty()) {
    newFileName.Append('.');
    newFileName.Append(extension);
  }

  return SetFileNameInternal(newFileName);
}

nsresult nsStandardURL::SetFileExtensionInternal(const nsACString &input) {
  nsAutoCString newFileName;
  nsresult rv = GetFileBaseName(newFileName);
  NS_ENSURE_SUCCESS(rv, rv);

  if (!input.IsEmpty()) {
    newFileName.Append('.');
    newFileName.Append(input);
  }

  return SetFileNameInternal(newFileName);
}

//----------------------------------------------------------------------------
// nsStandardURL::nsIFileURL
//----------------------------------------------------------------------------

nsresult nsStandardURL::EnsureFile() {
  MOZ_ASSERT(mSupportsFileURL,
             "EnsureFile() called on a URL that doesn't support files!");

  if (mFile) {
    // Nothing to do
    return NS_OK;
  }

  // Parse the spec if we don't have a cached result
  if (mSpec.IsEmpty()) {
    NS_WARNING("url not initialized");
    return NS_ERROR_NOT_INITIALIZED;
  }

  if (!SegmentIs(mScheme, "file")) {
    NS_WARNING("not a file URL");
    return NS_ERROR_FAILURE;
  }

  return net_GetFileFromURLSpec(mSpec, getter_AddRefs(mFile));
}

NS_IMETHODIMP
nsStandardURL::GetFile(nsIFile **result) {
  MOZ_ASSERT(mSupportsFileURL,
             "GetFile() called on a URL that doesn't support files!");

  nsresult rv = EnsureFile();
  if (NS_FAILED(rv)) return rv;

  if (LOG_ENABLED()) {
    LOG(("nsStandardURL::GetFile [this=%p spec=%s resulting_path=%s]\n", this,
         mSpec.get(), mFile->HumanReadablePath().get()));
  }

  // clone the file, so the caller can modify it.
  // XXX nsIFileURL.idl specifies that the consumer must _not_ modify the
  // nsIFile returned from this method; but it seems that some folks do
  // (see bug 161921). until we can be sure that all the consumers are
  // behaving themselves, we'll stay on the safe side and clone the file.
  // see bug 212724 about fixing the consumers.
  return mFile->Clone(result);
}

nsresult nsStandardURL::SetFile(nsIFile *file) {
  NS_ENSURE_ARG_POINTER(file);

  nsresult rv;
  nsAutoCString url;

  rv = net_GetURLSpecFromFile(file, url);
  if (NS_FAILED(rv)) return rv;

  uint32_t oldURLType = mURLType;
  uint32_t oldDefaultPort = mDefaultPort;
  rv = Init(nsIStandardURL::URLTYPE_NO_AUTHORITY, -1, url, nullptr, nullptr);

  if (NS_FAILED(rv)) {
    // Restore the old url type and default port if the call to Init fails.
    mURLType = oldURLType;
    mDefaultPort = oldDefaultPort;
    return rv;
  }

  // must clone |file| since its value is not guaranteed to remain constant
  InvalidateCache();
  if (NS_FAILED(file->Clone(getter_AddRefs(mFile)))) {
    NS_WARNING("nsIFile::Clone failed");
    // failure to clone is not fatal (GetFile will generate mFile)
    mFile = nullptr;
  }

  return NS_OK;
}

//----------------------------------------------------------------------------
// nsStandardURL::nsIStandardURL
//----------------------------------------------------------------------------

nsresult nsStandardURL::Init(uint32_t urlType, int32_t defaultPort,
                             const nsACString &spec, const char *charset,
                             nsIURI *baseURI) {
  if (spec.Length() > (uint32_t)net_GetURLMaxLength() ||
      defaultPort > std::numeric_limits<uint16_t>::max()) {
    return NS_ERROR_MALFORMED_URI;
  }

  InvalidateCache();

  switch (urlType) {
    case URLTYPE_STANDARD:
      mParser = net_GetStdURLParser();
      break;
    case URLTYPE_AUTHORITY:
      mParser = net_GetAuthURLParser();
      break;
    case URLTYPE_NO_AUTHORITY:
      mParser = net_GetNoAuthURLParser();
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("bad urlType");
      return NS_ERROR_INVALID_ARG;
  }
  mDefaultPort = defaultPort;
  mURLType = urlType;

  auto encoding = charset
                      ? Encoding::ForLabelNoReplacement(MakeStringSpan(charset))
                      : nullptr;
  // URI can't be encoded in UTF-16BE or UTF-16LE. Truncate encoding
  // if it is one of utf encodings (since a null encoding implies
  // UTF-8, this is safe even if encoding is UTF-8).
  if (IsUTFEncoding(encoding)) {
    encoding = nullptr;
  }

  if (baseURI && net_IsAbsoluteURL(spec)) {
    baseURI = nullptr;
  }

  if (!baseURI) return SetSpecWithEncoding(spec, encoding);

  nsAutoCString buf;
  nsresult rv = baseURI->Resolve(spec, buf);
  if (NS_FAILED(rv)) return rv;

  return SetSpecWithEncoding(buf, encoding);
}

nsresult nsStandardURL::SetDefaultPort(int32_t aNewDefaultPort) {
  InvalidateCache();

  // should never be more than 16 bit
  if (aNewDefaultPort >= std::numeric_limits<uint16_t>::max()) {
    return NS_ERROR_MALFORMED_URI;
  }

  // If we're already using the new default-port as a custom port, then clear
  // it off of our mSpec & set mPort to -1, to indicate that we'll be using
  // the default from now on (which happens to match what we already had).
  if (mPort == aNewDefaultPort) {
    ReplacePortInSpec(-1);
    mPort = -1;
  }
  mDefaultPort = aNewDefaultPort;

  return NS_OK;
}

//----------------------------------------------------------------------------
// nsStandardURL::nsISerializable
//----------------------------------------------------------------------------

NS_IMETHODIMP
nsStandardURL::Read(nsIObjectInputStream *stream) {
  MOZ_ASSERT_UNREACHABLE("Use nsIURIMutator.read() instead");
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult nsStandardURL::ReadPrivate(nsIObjectInputStream *stream) {
  MOZ_ASSERT(mDisplayHost.IsEmpty(), "Shouldn't have cached unicode host");

  nsresult rv;

  uint32_t urlType;
  rv = stream->Read32(&urlType);
  if (NS_FAILED(rv)) return rv;
  mURLType = urlType;
  switch (mURLType) {
    case URLTYPE_STANDARD:
      mParser = net_GetStdURLParser();
      break;
    case URLTYPE_AUTHORITY:
      mParser = net_GetAuthURLParser();
      break;
    case URLTYPE_NO_AUTHORITY:
      mParser = net_GetNoAuthURLParser();
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("bad urlType");
      return NS_ERROR_FAILURE;
  }

  rv = stream->Read32((uint32_t *)&mPort);
  if (NS_FAILED(rv)) return rv;

  rv = stream->Read32((uint32_t *)&mDefaultPort);
  if (NS_FAILED(rv)) return rv;

  rv = NS_ReadOptionalCString(stream, mSpec);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mScheme);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mAuthority);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mUsername);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mPassword);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mHost);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mPath);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mFilepath);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mDirectory);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mBasename);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mExtension);
  if (NS_FAILED(rv)) return rv;

  // handle forward compatibility from older serializations that included mParam
  URLSegment old_param;
  rv = ReadSegment(stream, old_param);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mQuery);
  if (NS_FAILED(rv)) return rv;

  rv = ReadSegment(stream, mRef);
  if (NS_FAILED(rv)) return rv;

  nsAutoCString oldOriginCharset;
  rv = NS_ReadOptionalCString(stream, oldOriginCharset);
  if (NS_FAILED(rv)) return rv;

  bool isMutable;
  rv = stream->ReadBoolean(&isMutable);
  if (NS_FAILED(rv)) return rv;
  Unused << isMutable;

  bool supportsFileURL;
  rv = stream->ReadBoolean(&supportsFileURL);
  if (NS_FAILED(rv)) return rv;
  mSupportsFileURL = supportsFileURL;

  // wait until object is set up, then modify path to include the param
  if (old_param.mLen >= 0) {  // note that mLen=0 is ";"
    // If this wasn't empty, it marks characters between the end of the
    // file and start of the query - mPath should include the param,
    // query and ref already.  Bump the mFilePath and
    // directory/basename/extension components to include this.
    mFilepath.Merge(mSpec, ';', old_param);
    mDirectory.Merge(mSpec, ';', old_param);
    mBasename.Merge(mSpec, ';', old_param);
    mExtension.Merge(mSpec, ';', old_param);
  }

  rv = CheckIfHostIsAscii();
  if (NS_FAILED(rv)) {
    return rv;
  }

  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::Write(nsIObjectOutputStream *stream) {
  MOZ_ASSERT(mSpec.Length() <= (uint32_t)net_GetURLMaxLength(),
             "The spec should never be this long, we missed a check.");
  nsresult rv;

  rv = stream->Write32(mURLType);
  if (NS_FAILED(rv)) return rv;

  rv = stream->Write32(uint32_t(mPort));
  if (NS_FAILED(rv)) return rv;

  rv = stream->Write32(uint32_t(mDefaultPort));
  if (NS_FAILED(rv)) return rv;

  rv = NS_WriteOptionalStringZ(stream, mSpec.get());
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mScheme);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mAuthority);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mUsername);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mPassword);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mHost);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mPath);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mFilepath);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mDirectory);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mBasename);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mExtension);
  if (NS_FAILED(rv)) return rv;

  // for backwards compatibility since we removed mParam.  Note that this will
  // mean that an older browser will read "" for mParam, and the param(s) will
  // be part of mPath (as they after the removal of special handling).  It only
  // matters if you downgrade a browser to before the patch.
  URLSegment empty;
  rv = WriteSegment(stream, empty);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mQuery);
  if (NS_FAILED(rv)) return rv;

  rv = WriteSegment(stream, mRef);
  if (NS_FAILED(rv)) return rv;

  // former origin charset
  rv = NS_WriteOptionalStringZ(stream, EmptyCString().get());
  if (NS_FAILED(rv)) return rv;

  // former mMutable
  rv = stream->WriteBoolean(false);
  if (NS_FAILED(rv)) return rv;

  rv = stream->WriteBoolean(mSupportsFileURL);
  if (NS_FAILED(rv)) return rv;

  // mDisplayHost is just a cache that can be recovered as needed.

  return NS_OK;
}

inline ipc::StandardURLSegment ToIPCSegment(
    const nsStandardURL::URLSegment &aSegment) {
  return ipc::StandardURLSegment(aSegment.mPos, aSegment.mLen);
}

inline MOZ_MUST_USE bool FromIPCSegment(const nsACString &aSpec,
                                        const ipc::StandardURLSegment &aSegment,
                                        nsStandardURL::URLSegment &aTarget) {
  // This seems to be just an empty segment.
  if (aSegment.length() == -1) {
    aTarget = nsStandardURL::URLSegment();
    return true;
  }

  // A value of -1 means an empty segment, but < -1 is undefined.
  if (NS_WARN_IF(aSegment.length() < -1)) {
    return false;
  }

  CheckedInt<uint32_t> segmentLen = aSegment.position();
  segmentLen += aSegment.length();
  // Make sure the segment does not extend beyond the spec.
  if (NS_WARN_IF(!segmentLen.isValid() ||
                 segmentLen.value() > aSpec.Length())) {
    return false;
  }

  aTarget.mPos = aSegment.position();
  aTarget.mLen = aSegment.length();

  return true;
}

void nsStandardURL::Serialize(URIParams &aParams) {
  MOZ_ASSERT(mSpec.Length() <= (uint32_t)net_GetURLMaxLength(),
             "The spec should never be this long, we missed a check.");
  StandardURLParams params;

  params.urlType() = mURLType;
  params.port() = mPort;
  params.defaultPort() = mDefaultPort;
  params.spec() = mSpec;
  params.scheme() = ToIPCSegment(mScheme);
  params.authority() = ToIPCSegment(mAuthority);
  params.username() = ToIPCSegment(mUsername);
  params.password() = ToIPCSegment(mPassword);
  params.host() = ToIPCSegment(mHost);
  params.path() = ToIPCSegment(mPath);
  params.filePath() = ToIPCSegment(mFilepath);
  params.directory() = ToIPCSegment(mDirectory);
  params.baseName() = ToIPCSegment(mBasename);
  params.extension() = ToIPCSegment(mExtension);
  params.query() = ToIPCSegment(mQuery);
  params.ref() = ToIPCSegment(mRef);
  params.supportsFileURL() = !!mSupportsFileURL;
  // mDisplayHost is just a cache that can be recovered as needed.

  aParams = params;
}

bool nsStandardURL::Deserialize(const URIParams &aParams) {
  MOZ_ASSERT(mDisplayHost.IsEmpty(), "Shouldn't have cached unicode host");
  MOZ_ASSERT(!mFile, "Shouldn't have cached file");

  if (aParams.type() != URIParams::TStandardURLParams) {
    NS_ERROR("Received unknown parameters from the other process!");
    return false;
  }

  const StandardURLParams &params = aParams.get_StandardURLParams();

  mURLType = params.urlType();
  switch (mURLType) {
    case URLTYPE_STANDARD:
      mParser = net_GetStdURLParser();
      break;
    case URLTYPE_AUTHORITY:
      mParser = net_GetAuthURLParser();
      break;
    case URLTYPE_NO_AUTHORITY:
      mParser = net_GetNoAuthURLParser();
      break;
    default:
      MOZ_ASSERT_UNREACHABLE("bad urlType");
      return false;
  }

  mPort = params.port();
  mDefaultPort = params.defaultPort();
  mSpec = params.spec();
  NS_ENSURE_TRUE(mSpec.Length() <= (uint32_t)net_GetURLMaxLength(), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.scheme(), mScheme), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.authority(), mAuthority), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.username(), mUsername), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.password(), mPassword), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.host(), mHost), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.path(), mPath), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.filePath(), mFilepath), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.directory(), mDirectory), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.baseName(), mBasename), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.extension(), mExtension), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.query(), mQuery), false);
  NS_ENSURE_TRUE(FromIPCSegment(mSpec, params.ref(), mRef), false);

  mSupportsFileURL = params.supportsFileURL();

  nsresult rv = CheckIfHostIsAscii();
  if (NS_FAILED(rv)) {
    return false;
  }

  // Some sanity checks
  NS_ENSURE_TRUE(mScheme.mPos == 0, false);
  NS_ENSURE_TRUE(mScheme.mLen > 0, false);
  // Make sure scheme is followed by :// (3 characters)
  NS_ENSURE_TRUE(mScheme.mLen < INT32_MAX - 3, false);  // avoid overflow
  NS_ENSURE_TRUE(mSpec.Length() >= (uint32_t)mScheme.mLen + 3, false);
  NS_ENSURE_TRUE(
      nsDependentCSubstring(mSpec, mScheme.mLen, 3).EqualsLiteral("://"),
      false);
  NS_ENSURE_TRUE(mPath.mLen != -1 && mSpec.CharAt(mPath.mPos) == '/', false);
  NS_ENSURE_TRUE(mPath.mPos == mFilepath.mPos, false);
  NS_ENSURE_TRUE(mQuery.mLen == -1 ||
                     (mQuery.mPos > 0 && mSpec.CharAt(mQuery.mPos - 1) == '?'),
                 false);
  NS_ENSURE_TRUE(
      mRef.mLen == -1 || (mRef.mPos > 0 && mSpec.CharAt(mRef.mPos - 1) == '#'),
      false);

  return true;
}

//----------------------------------------------------------------------------
// nsStandardURL::nsIClassInfo
//----------------------------------------------------------------------------

NS_IMETHODIMP
nsStandardURL::GetInterfaces(nsTArray<nsIID> &array) {
  array.Clear();
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetScriptableHelper(nsIXPCScriptable **_retval) {
  *_retval = nullptr;
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetContractID(nsACString &aContractID) {
  aContractID.SetIsVoid(true);
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetClassDescription(nsACString &aClassDescription) {
  aClassDescription.SetIsVoid(true);
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetClassID(nsCID **aClassID) {
  *aClassID = (nsCID *)moz_xmalloc(sizeof(nsCID));
  return GetClassIDNoAlloc(*aClassID);
}

NS_IMETHODIMP
nsStandardURL::GetFlags(uint32_t *aFlags) {
  *aFlags = nsIClassInfo::MAIN_THREAD_ONLY;
  return NS_OK;
}

NS_IMETHODIMP
nsStandardURL::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc) {
  *aClassIDNoAlloc = kStandardURLCID;
  return NS_OK;
}

//----------------------------------------------------------------------------
// nsStandardURL::nsISizeOf
//----------------------------------------------------------------------------

size_t nsStandardURL::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
  return mSpec.SizeOfExcludingThisIfUnshared(aMallocSizeOf) +
         mDisplayHost.SizeOfExcludingThisIfUnshared(aMallocSizeOf);

  // Measurement of the following members may be added later if DMD finds it is
  // worthwhile:
  // - mParser
  // - mFile
}

size_t nsStandardURL::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
}

}  // namespace net
}  // namespace mozilla

// For unit tests.  Including nsStandardURL.h seems to cause problems
nsresult Test_NormalizeIPv4(const nsACString &host, nsCString &result) {
  return mozilla::net::nsStandardURL::NormalizeIPv4(host, result);
}