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gecko-dev/xpcom/io/nsEscape.cpp

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18 KiB
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsEscape.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/CheckedInt.h"
#include "nsTArray.h"
#include "nsCRT.h"
#include "plstr.h"
#include "nsASCIIMask.h"
static const char hexCharsUpper[] = "0123456789ABCDEF";
static const char hexCharsUpperLower[] = "0123456789ABCDEFabcdef";
static const int netCharType[256] =
// clang-format off
/* Bit 0 xalpha -- the alphas
** Bit 1 xpalpha -- as xalpha but
** converts spaces to plus and plus to %2B
** Bit 3 ... path -- as xalphas but doesn't escape '/'
*/
/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
{ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 0x */
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 1x */
0,0,0,0,0,0,0,0,0,0,7,4,0,7,7,4, /* 2x !"#$%&'()*+,-./ */
7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,0, /* 3x 0123456789:;<=>? */
0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, /* 4x @ABCDEFGHIJKLMNO */
/* bits for '@' changed from 7 to 0 so '@' can be escaped */
/* in usernames and passwords in publishing. */
7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,7, /* 5X PQRSTUVWXYZ[\]^_ */
0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, /* 6x `abcdefghijklmno */
7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,0, /* 7X pqrstuvwxyz{\}~ DEL */
0,
};
/* decode % escaped hex codes into character values
*/
#define UNHEX(C) \
((C >= '0' && C <= '9') ? C - '0' : \
((C >= 'A' && C <= 'F') ? C - 'A' + 10 : \
((C >= 'a' && C <= 'f') ? C - 'a' + 10 : 0)))
// clang-format on
#define IS_OK(C) (netCharType[((unsigned int)(C))] & (aFlags))
#define HEX_ESCAPE '%'
static const uint32_t ENCODE_MAX_LEN = 6; // %uABCD
static uint32_t
AppendPercentHex(char* aBuffer, unsigned char aChar)
{
uint32_t i = 0;
aBuffer[i++] = '%';
aBuffer[i++] = hexCharsUpper[aChar >> 4]; // high nibble
aBuffer[i++] = hexCharsUpper[aChar & 0xF]; // low nibble
return i;
}
static uint32_t
AppendPercentHex(char16_t* aBuffer, char16_t aChar)
{
uint32_t i = 0;
aBuffer[i++] = '%';
if (aChar & 0xff00) {
aBuffer[i++] = 'u';
aBuffer[i++] = hexCharsUpper[aChar >> 12]; // high-byte high nibble
aBuffer[i++] = hexCharsUpper[(aChar >> 8) & 0xF]; // high-byte low nibble
}
aBuffer[i++] = hexCharsUpper[(aChar >> 4) & 0xF]; // low-byte high nibble
aBuffer[i++] = hexCharsUpper[aChar & 0xF]; // low-byte low nibble
return i;
}
//----------------------------------------------------------------------------------------
char*
nsEscape(const char* aStr, size_t aLength, size_t* aOutputLength,
nsEscapeMask aFlags)
//----------------------------------------------------------------------------------------
{
if (!aStr) {
return nullptr;
}
size_t charsToEscape = 0;
const unsigned char* src = (const unsigned char*)aStr;
for (size_t i = 0; i < aLength; ++i) {
if (!IS_OK(src[i])) {
charsToEscape++;
}
}
// calculate how much memory should be allocated
// original length + 2 bytes for each escaped character + terminating '\0'
// do the sum in steps to check for overflow
size_t dstSize = aLength + 1 + charsToEscape;
if (dstSize <= aLength) {
return nullptr;
}
dstSize += charsToEscape;
if (dstSize < aLength) {
return nullptr;
}
// fail if we need more than 4GB
if (dstSize > UINT32_MAX) {
return nullptr;
}
char* result = (char*)moz_xmalloc(dstSize);
if (!result) {
return nullptr;
}
unsigned char* dst = (unsigned char*)result;
src = (const unsigned char*)aStr;
if (aFlags == url_XPAlphas) {
for (size_t i = 0; i < aLength; ++i) {
unsigned char c = *src++;
if (IS_OK(c)) {
*dst++ = c;
} else if (c == ' ') {
*dst++ = '+'; /* convert spaces to pluses */
} else {
*dst++ = HEX_ESCAPE;
*dst++ = hexCharsUpper[c >> 4]; /* high nibble */
*dst++ = hexCharsUpper[c & 0x0f]; /* low nibble */
}
}
} else {
for (size_t i = 0; i < aLength; ++i) {
unsigned char c = *src++;
if (IS_OK(c)) {
*dst++ = c;
} else {
*dst++ = HEX_ESCAPE;
*dst++ = hexCharsUpper[c >> 4]; /* high nibble */
*dst++ = hexCharsUpper[c & 0x0f]; /* low nibble */
}
}
}
*dst = '\0'; /* tack on eos */
if (aOutputLength) {
*aOutputLength = dst - (unsigned char*)result;
}
return result;
}
//----------------------------------------------------------------------------------------
char*
nsUnescape(char* aStr)
//----------------------------------------------------------------------------------------
{
nsUnescapeCount(aStr);
return aStr;
}
//----------------------------------------------------------------------------------------
int32_t
nsUnescapeCount(char* aStr)
//----------------------------------------------------------------------------------------
{
char* src = aStr;
char* dst = aStr;
char c1[] = " ";
char c2[] = " ";
char* const pc1 = c1;
char* const pc2 = c2;
if (!*src) {
// A null string was passed in. Nothing to escape.
// Returns early as the string might not actually be mutable with
// length 0.
return 0;
}
while (*src) {
c1[0] = *(src + 1);
if (*(src + 1) == '\0') {
c2[0] = '\0';
} else {
c2[0] = *(src + 2);
}
if (*src != HEX_ESCAPE || PL_strpbrk(pc1, hexCharsUpperLower) == 0 ||
PL_strpbrk(pc2, hexCharsUpperLower) == 0) {
*dst++ = *src++;
} else {
src++; /* walk over escape */
if (*src) {
*dst = UNHEX(*src) << 4;
src++;
}
if (*src) {
*dst = (*dst + UNHEX(*src));
src++;
}
dst++;
}
}
*dst = 0;
return (int)(dst - aStr);
} /* NET_UnEscapeCnt */
void
nsAppendEscapedHTML(const nsACString& aSrc, nsACString& aDst)
{
// Preparation: aDst's length will increase by at least aSrc's length. If the
// addition overflows, we skip this, which is fine, and we'll likely abort
// while (infallibly) appending due to aDst becoming too large.
mozilla::CheckedInt<nsACString::size_type> newCapacity = aDst.Length();
newCapacity += aSrc.Length();
if (newCapacity.isValid()) {
aDst.SetCapacity(newCapacity.value());
}
for (auto cur = aSrc.BeginReading(); cur != aSrc.EndReading(); cur++) {
if (*cur == '<') {
aDst.AppendLiteral("&lt;");
} else if (*cur == '>') {
aDst.AppendLiteral("&gt;");
} else if (*cur == '&') {
aDst.AppendLiteral("&amp;");
} else if (*cur == '"') {
aDst.AppendLiteral("&quot;");
} else if (*cur == '\'') {
aDst.AppendLiteral("&#39;");
} else {
aDst.Append(*cur);
}
}
}
//----------------------------------------------------------------------------------------
//
// The following table encodes which characters needs to be escaped for which
// parts of an URL. The bits are the "url components" in the enum EscapeMask,
// see nsEscape.h.
//
// esc_Scheme = 1
// esc_Username = 2
// esc_Password = 4
// esc_Host = 8
// esc_Directory = 16
// esc_FileBaseName = 32
// esc_FileExtension = 64
// esc_Param = 128
// esc_Query = 256
// esc_Ref = 512
static const uint32_t EscapeChars[256] =
// clang-format off
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 1x
0,1023, 0, 512,1023, 0,1023, 624,1023,1023,1023,1023,1023,1023, 953, 784, // 2x !"#$%&'()*+,-./
1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1008,1008, 0,1008, 0, 768, // 3x 0123456789:;<=>?
1008,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023, // 4x @ABCDEFGHIJKLMNO
1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1008, 896,1008, 896,1023, // 5x PQRSTUVWXYZ[\]^_
384,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023, // 6x `abcdefghijklmno
1023,1023,1023,1023,1023,1023,1023,1023,1023,1023,1023, 896,1012, 896,1023, 0, // 7x pqrstuvwxyz{|}~ DEL
0 // 80 to FF are zero
};
// clang-format on
static uint16_t dontNeedEscape(unsigned char aChar, uint32_t aFlags)
{
return EscapeChars[(uint32_t)aChar] & aFlags;
}
static uint16_t dontNeedEscape(uint16_t aChar, uint32_t aFlags)
{
return aChar < mozilla::ArrayLength(EscapeChars) ?
(EscapeChars[(uint32_t)aChar] & aFlags) : 0;
}
//----------------------------------------------------------------------------------------
/**
* Templated helper for URL escaping a portion of a string.
*
* @param aPart The pointer to the beginning of the portion of the string to
* escape.
* @param aPartLen The length of the string to escape.
* @param aFlags Flags used to configure escaping. @see EscapeMask
* @param aResult String that has the URL escaped portion appended to. Only
* altered if the string is URL escaped or |esc_AlwaysCopy| is specified.
* @param aDidAppend Indicates whether or not data was appended to |aResult|.
* @return NS_ERROR_INVALID_ARG, NS_ERROR_OUT_OF_MEMORY on failure.
*/
template<class T>
static nsresult
T_EscapeURL(const typename T::char_type* aPart, size_t aPartLen,
uint32_t aFlags, const ASCIIMaskArray* aFilterMask,
T& aResult, bool& aDidAppend)
{
typedef nsCharTraits<typename T::char_type> traits;
typedef typename traits::unsigned_char_type unsigned_char_type;
static_assert(sizeof(*aPart) == 1 || sizeof(*aPart) == 2,
"unexpected char type");
if (!aPart) {
NS_NOTREACHED("null pointer");
return NS_ERROR_INVALID_ARG;
}
bool forced = !!(aFlags & esc_Forced);
bool ignoreNonAscii = !!(aFlags & esc_OnlyASCII);
bool ignoreAscii = !!(aFlags & esc_OnlyNonASCII);
bool writing = !!(aFlags & esc_AlwaysCopy);
bool colon = !!(aFlags & esc_Colon);
auto src = reinterpret_cast<const unsigned_char_type*>(aPart);
typename T::char_type tempBuffer[100];
unsigned int tempBufferPos = 0;
bool previousIsNonASCII = false;
for (size_t i = 0; i < aPartLen; ++i) {
unsigned_char_type c = *src++;
// If there is a filter, we wish to skip any characters which match it.
// This is needed so we don't perform an extra pass just to extract the
// filtered characters.
if (aFilterMask && mozilla::ASCIIMask::IsMasked(*aFilterMask, c)) {
if (!writing) {
if (!aResult.Append(aPart, i, mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
writing = true;
}
continue;
}
// if the char has not to be escaped or whatever follows % is
// a valid escaped string, just copy the char.
//
// Also the % will not be escaped until forced
// See bugzilla bug 61269 for details why we changed this
//
// And, we will not escape non-ascii characters if requested.
// On special request we will also escape the colon even when
// not covered by the matrix.
// ignoreAscii is not honored for control characters (C0 and DEL)
//
// And, we should escape the '|' character when it occurs after any
// non-ASCII character as it may be aPart of a multi-byte character.
//
// 0x20..0x7e are the valid ASCII characters. We also escape spaces
// (0x20) since they are not legal in URLs.
if ((dontNeedEscape(c, aFlags) || (c == HEX_ESCAPE && !forced)
|| (c > 0x7f && ignoreNonAscii)
|| (c > 0x20 && c < 0x7f && ignoreAscii))
&& !(c == ':' && colon)
&& !(previousIsNonASCII && c == '|' && !ignoreNonAscii)) {
if (writing) {
tempBuffer[tempBufferPos++] = c;
}
} else { /* do the escape magic */
if (!writing) {
if (!aResult.Append(aPart, i, mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
writing = true;
}
uint32_t len = ::AppendPercentHex(tempBuffer + tempBufferPos, c);
tempBufferPos += len;
MOZ_ASSERT(len <= ENCODE_MAX_LEN, "potential buffer overflow");
}
// Flush the temp buffer if it doesnt't have room for another encoded char.
if (tempBufferPos >= mozilla::ArrayLength(tempBuffer) - ENCODE_MAX_LEN) {
NS_ASSERTION(writing, "should be writing");
if (!aResult.Append(tempBuffer, tempBufferPos, mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
tempBufferPos = 0;
}
previousIsNonASCII = (c > 0x7f);
}
if (writing) {
if (!aResult.Append(tempBuffer, tempBufferPos, mozilla::fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
}
aDidAppend = writing;
return NS_OK;
}
bool
NS_EscapeURL(const char* aPart, int32_t aPartLen, uint32_t aFlags,
nsACString& aResult)
{
if (aPartLen < 0) {
aPartLen = strlen(aPart);
}
bool result = false;
nsresult rv = T_EscapeURL(aPart, aPartLen, aFlags, nullptr, aResult, result);
if (NS_FAILED(rv)) {
::NS_ABORT_OOM(aResult.Length() * sizeof(nsACString::char_type));
}
return result;
}
nsresult
NS_EscapeURL(const nsACString& aStr, uint32_t aFlags, nsACString& aResult,
const mozilla::fallible_t&)
{
bool appended = false;
nsresult rv = T_EscapeURL(aStr.Data(), aStr.Length(), aFlags, nullptr, aResult, appended);
if (NS_FAILED(rv)) {
aResult.Truncate();
return rv;
}
if (!appended) {
aResult = aStr;
}
return rv;
}
nsresult
NS_EscapeAndFilterURL(const nsACString& aStr, uint32_t aFlags,
const ASCIIMaskArray* aFilterMask,
nsACString& aResult, const mozilla::fallible_t&)
{
bool appended = false;
nsresult rv = T_EscapeURL(aStr.Data(), aStr.Length(), aFlags, aFilterMask, aResult, appended);
if (NS_FAILED(rv)) {
aResult.Truncate();
return rv;
}
if (!appended) {
if (!aResult.Assign(aStr, fallible)) {
return NS_ERROR_OUT_OF_MEMORY;
}
}
return rv;
}
const nsAString&
NS_EscapeURL(const nsAString& aStr, uint32_t aFlags, nsAString& aResult)
{
bool result = false;
nsresult rv = T_EscapeURL<nsAString>(aStr.Data(), aStr.Length(), aFlags, nullptr, aResult, result);
if (NS_FAILED(rv)) {
::NS_ABORT_OOM(aResult.Length() * sizeof(nsAString::char_type));
}
if (result) {
return aResult;
}
return aStr;
}
// Starting at aStr[aStart] find the first index in aStr that matches any
// character in aForbidden. Return false if not found.
static bool
FindFirstMatchFrom(const nsString& aStr, size_t aStart,
const nsTArray<char16_t>& aForbidden, size_t* aIndex)
{
const size_t len = aForbidden.Length();
for (size_t j = aStart, l = aStr.Length(); j < l; ++j) {
size_t unused;
if (mozilla::BinarySearch(aForbidden, 0, len, aStr[j], &unused)) {
*aIndex = j;
return true;
}
}
return false;
}
const nsAString&
NS_EscapeURL(const nsString& aStr, const nsTArray<char16_t>& aForbidden,
nsAString& aResult)
{
bool didEscape = false;
for (size_t i = 0, strLen = aStr.Length(); i < strLen; ) {
size_t j;
if (MOZ_UNLIKELY(FindFirstMatchFrom(aStr, i, aForbidden, &j))) {
if (i == 0) {
didEscape = true;
aResult.Truncate();
aResult.SetCapacity(aStr.Length());
}
if (j != i) {
// The substring from 'i' up to 'j' that needs no escaping.
aResult.Append(nsDependentSubstring(aStr, i, j - i));
}
char16_t buffer[ENCODE_MAX_LEN];
uint32_t bufferLen = ::AppendPercentHex(buffer, aStr[j]);
MOZ_ASSERT(bufferLen <= ENCODE_MAX_LEN, "buffer overflow");
aResult.Append(buffer, bufferLen);
i = j + 1;
} else {
if (MOZ_UNLIKELY(didEscape)) {
// The tail of the string that needs no escaping.
aResult.Append(nsDependentSubstring(aStr, i, strLen - i));
}
break;
}
}
if (MOZ_UNLIKELY(didEscape)) {
return aResult;
}
return aStr;
}
#define ISHEX(c) memchr(hexCharsUpperLower, c, sizeof(hexCharsUpperLower)-1)
bool
NS_UnescapeURL(const char* aStr, int32_t aLen, uint32_t aFlags,
nsACString& aResult)
{
if (!aStr) {
NS_NOTREACHED("null pointer");
return false;
}
MOZ_ASSERT(aResult.IsEmpty(),
"Passing a non-empty string as an out parameter!");
if (aLen < 0) {
aLen = strlen(aStr);
}
bool ignoreNonAscii = !!(aFlags & esc_OnlyASCII);
bool ignoreAscii = !!(aFlags & esc_OnlyNonASCII);
bool writing = !!(aFlags & esc_AlwaysCopy);
bool skipControl = !!(aFlags & esc_SkipControl);
bool skipInvalidHostChar = !!(aFlags & esc_Host);
if (writing) {
aResult.SetCapacity(aLen);
}
const char* last = aStr;
const char* p = aStr;
for (int i = 0; i < aLen; ++i, ++p) {
if (*p == HEX_ESCAPE && i < aLen - 2) {
unsigned char c1 = *((unsigned char*)p + 1);
unsigned char c2 = *((unsigned char*)p + 2);
unsigned char u = (UNHEX(c1) << 4) + UNHEX(c2);
if (ISHEX(c1) && ISHEX(c2) &&
(!skipInvalidHostChar || dontNeedEscape(u, aFlags) || c1 >= '8') &&
((c1 < '8' && !ignoreAscii) || (c1 >= '8' && !ignoreNonAscii)) &&
!(skipControl &&
(c1 < '2' || (c1 == '7' && (c2 == 'f' || c2 == 'F'))))) {
if (!writing) {
writing = true;
aResult.SetCapacity(aLen);
}
if (p > last) {
aResult.Append(last, p - last);
last = p;
}
aResult.Append(u);
i += 2;
p += 2;
last += 3;
}
}
}
if (writing && last < aStr + aLen) {
aResult.Append(last, aStr + aLen - last);
}
return writing;
}
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