gecko-dev/netwerk/dns/GetAddrInfo.cpp

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C++

/* -*- 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 "GetAddrInfo.h"
#include "mozilla/net/DNS.h"
#include "prnetdb.h"
#include "nsHostResolver.h"
#include "nsError.h"
#include "mozilla/Mutex.h"
#include "nsAutoPtr.h"
#include "mozilla/StaticPtr.h"
#include "MainThreadUtils.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/net/DNS.h"
#include <algorithm>
#include "prerror.h"
#include "mozilla/Logging.h"
#if DNSQUERY_AVAILABLE
// There is a bug in windns.h where the type of parameter ppQueryResultsSet for
// DnsQuery_A is dependent on UNICODE being set. It should *always* be
// PDNS_RECORDA, but if UNICODE is set it is PDNS_RECORDW. To get around this
// we make sure that UNICODE is unset.
#undef UNICODE
#include <ws2tcpip.h>
#undef GetAddrInfo
#include <windns.h>
#endif
namespace mozilla {
namespace net {
static LazyLogModule gGetAddrInfoLog("GetAddrInfo");
#define LOG(msg, ...) \
MOZ_LOG(gGetAddrInfoLog, LogLevel::Debug, ("[DNS]: " msg, ##__VA_ARGS__))
#define LOG_WARNING(msg, ...) \
MOZ_LOG(gGetAddrInfoLog, LogLevel::Warning, ("[DNS]: " msg, ##__VA_ARGS__))
#if DNSQUERY_AVAILABLE
////////////////////////////
// WINDOWS IMPLEMENTATION //
////////////////////////////
// Ensure consistency of PR_* and AF_* constants to allow for legacy usage of
// PR_* constants with this API.
static_assert(PR_AF_INET == AF_INET && PR_AF_INET6 == AF_INET6
&& PR_AF_UNSPEC == AF_UNSPEC, "PR_AF_* must match AF_*");
// We intentionally leak this mutex. This is because we can run into a
// situation where the worker threads are still running until the process
// is actually fully shut down, and at any time one of those worker
// threads can access gDnsapiInfoLock.
static OffTheBooksMutex* gDnsapiInfoLock = nullptr;
struct DnsapiInfo
{
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DnsapiInfo);
HMODULE mLibrary;
decltype(&DnsQuery_A) mDnsQueryFunc;
decltype(&DnsFree) mDnsFreeFunc;
private:
// This will either be called during shutdown of the GetAddrInfo module, or
// when a worker thread is done doing a lookup (ie: within
// _GetAddrInfo_Windows). Note that the lock must be held when this is
// called.
~DnsapiInfo()
{
if (gDnsapiInfoLock) {
gDnsapiInfoLock->AssertCurrentThreadOwns();
} else {
MOZ_ASSERT_UNREACHABLE("No mutex available during GetAddrInfo "
"shutdown.");
return;
}
LOG("Freeing Dnsapi.dll");
MOZ_ASSERT(mLibrary);
DebugOnly<BOOL> rv = FreeLibrary(mLibrary);
NS_WARNING_ASSERTION(rv, "Failed to free Dnsapi.dll.");
}
};
static StaticRefPtr<DnsapiInfo> gDnsapiInfo;
static MOZ_ALWAYS_INLINE nsresult
_GetAddrInfoInit_Windows()
{
// This is necessary to ensure strict thread safety because if two threads
// run this function at the same time they can potentially create two
// mutexes.
MOZ_ASSERT(NS_IsMainThread(),
"Do not initialize GetAddrInfo off main thread!");
if (!gDnsapiInfoLock) {
gDnsapiInfoLock = new OffTheBooksMutex("GetAddrInfo.cpp::gDnsapiInfoLock");
}
OffTheBooksMutexAutoLock lock(*gDnsapiInfoLock);
if (gDnsapiInfo) {
MOZ_ASSERT_UNREACHABLE("GetAddrInfo is being initialized multiple times!");
return NS_ERROR_ALREADY_INITIALIZED;
}
HMODULE library = LoadLibraryA("Dnsapi.dll");
if (NS_WARN_IF(!library)) {
return NS_ERROR_FAILURE;
}
FARPROC dnsQueryFunc = GetProcAddress(library, "DnsQuery_A");
FARPROC dnsFreeFunc = GetProcAddress(library, "DnsFree");
if (NS_WARN_IF(!dnsQueryFunc) || NS_WARN_IF(!dnsFreeFunc)) {
DebugOnly<BOOL> rv = FreeLibrary(library);
NS_WARNING_ASSERTION(rv, "Failed to free Dnsapi.dll.");
return NS_ERROR_FAILURE;
}
DnsapiInfo* info = new DnsapiInfo;
info->mLibrary = library;
info->mDnsQueryFunc = (decltype(info->mDnsQueryFunc)) dnsQueryFunc;
info->mDnsFreeFunc = (decltype(info->mDnsFreeFunc)) dnsFreeFunc;
gDnsapiInfo = info;
return NS_OK;
}
static MOZ_ALWAYS_INLINE nsresult
_GetAddrInfoShutdown_Windows()
{
OffTheBooksMutexAutoLock lock(*gDnsapiInfoLock);
if (NS_WARN_IF(!gDnsapiInfo) || NS_WARN_IF(!gDnsapiInfoLock)) {
MOZ_ASSERT_UNREACHABLE("GetAddrInfo not initialized!");
return NS_ERROR_NOT_INITIALIZED;
}
gDnsapiInfo = nullptr;
return NS_OK;
}
// If successful, returns in aResult a TTL value that is smaller or
// equal with the one already there. Gets the TTL value by calling
// to dnsapi->mDnsQueryFunc and iterating through the returned
// records to find the one with the smallest TTL value.
static MOZ_ALWAYS_INLINE nsresult
_GetMinTTLForRequestType_Windows(DnsapiInfo * dnsapi, const char* aHost,
uint16_t aRequestType, unsigned int* aResult)
{
MOZ_ASSERT(dnsapi);
MOZ_ASSERT(aHost);
MOZ_ASSERT(aResult);
PDNS_RECORDA dnsData = nullptr;
DNS_STATUS status = dnsapi->mDnsQueryFunc(
aHost,
aRequestType,
(DNS_QUERY_STANDARD | DNS_QUERY_NO_NETBT | DNS_QUERY_NO_HOSTS_FILE
| DNS_QUERY_NO_MULTICAST | DNS_QUERY_ACCEPT_TRUNCATED_RESPONSE
| DNS_QUERY_DONT_RESET_TTL_VALUES),
nullptr,
&dnsData,
nullptr);
if (status == DNS_INFO_NO_RECORDS || status == DNS_ERROR_RCODE_NAME_ERROR
|| !dnsData) {
LOG("No DNS records found for %s. status=%X. aRequestType = %X\n",
aHost, status, aRequestType);
return NS_ERROR_FAILURE;
} else if (status != NOERROR) {
LOG_WARNING("DnsQuery_A failed with status %X.\n", status);
return NS_ERROR_UNEXPECTED;
}
for (PDNS_RECORDA curRecord = dnsData; curRecord; curRecord = curRecord->pNext) {
// Only records in the answer section are important
if (curRecord->Flags.S.Section != DnsSectionAnswer) {
continue;
}
if (curRecord->wType == aRequestType) {
*aResult = std::min<unsigned int>(*aResult, curRecord->dwTtl);
} else {
LOG("Received unexpected record type %u in response for %s.\n",
curRecord->wType, aHost);
}
}
dnsapi->mDnsFreeFunc(dnsData, DNS_FREE_TYPE::DnsFreeRecordList);
return NS_OK;
}
static MOZ_ALWAYS_INLINE nsresult
_GetTTLData_Windows(const char* aHost, uint16_t* aResult, uint16_t aAddressFamily)
{
MOZ_ASSERT(aHost);
MOZ_ASSERT(aResult);
if (aAddressFamily != PR_AF_UNSPEC &&
aAddressFamily != PR_AF_INET &&
aAddressFamily != PR_AF_INET6) {
return NS_ERROR_UNEXPECTED;
}
RefPtr<DnsapiInfo> dnsapi = nullptr;
{
OffTheBooksMutexAutoLock lock(*gDnsapiInfoLock);
dnsapi = gDnsapiInfo;
}
if (!dnsapi) {
LOG_WARNING("GetAddrInfo has been shutdown or has not been initialized.");
return NS_ERROR_NOT_INITIALIZED;
}
// In order to avoid using ANY records which are not always implemented as a
// "Gimme what you have" request in hostname resolvers, we should send A
// and/or AAAA requests, based on the address family requested.
unsigned int ttl = -1;
if (aAddressFamily == PR_AF_UNSPEC || aAddressFamily == PR_AF_INET) {
_GetMinTTLForRequestType_Windows(dnsapi, aHost, DNS_TYPE_A, &ttl);
}
if (aAddressFamily == PR_AF_UNSPEC || aAddressFamily == PR_AF_INET6) {
_GetMinTTLForRequestType_Windows(dnsapi, aHost, DNS_TYPE_AAAA, &ttl);
}
{
// dnsapi's destructor is not thread-safe, so we release explicitly here
OffTheBooksMutexAutoLock lock(*gDnsapiInfoLock);
dnsapi = nullptr;
}
if (ttl == -1) {
LOG("No useable TTL found.");
return NS_ERROR_FAILURE;
}
*aResult = ttl;
return NS_OK;
}
#endif
////////////////////////////////////
// PORTABLE RUNTIME IMPLEMENTATION//
////////////////////////////////////
static MOZ_ALWAYS_INLINE nsresult
_GetAddrInfo_Portable(const char* aCanonHost, uint16_t aAddressFamily,
uint16_t aFlags, const char* aNetworkInterface,
AddrInfo** aAddrInfo)
{
MOZ_ASSERT(aCanonHost);
MOZ_ASSERT(aAddrInfo);
// We accept the same aFlags that nsHostResolver::ResolveHost accepts, but we
// need to translate the aFlags into a form that PR_GetAddrInfoByName
// accepts.
int prFlags = PR_AI_ADDRCONFIG;
if (!(aFlags & nsHostResolver::RES_CANON_NAME)) {
prFlags |= PR_AI_NOCANONNAME;
}
// We need to remove IPv4 records manually because PR_GetAddrInfoByName
// doesn't support PR_AF_INET6.
bool disableIPv4 = aAddressFamily == PR_AF_INET6;
if (disableIPv4) {
aAddressFamily = PR_AF_UNSPEC;
}
PRAddrInfo* prai = PR_GetAddrInfoByName(aCanonHost, aAddressFamily, prFlags);
if (!prai) {
return NS_ERROR_UNKNOWN_HOST;
}
const char* canonName = nullptr;
if (aFlags & nsHostResolver::RES_CANON_NAME) {
canonName = PR_GetCanonNameFromAddrInfo(prai);
}
bool filterNameCollision = !(aFlags & nsHostResolver::RES_ALLOW_NAME_COLLISION);
nsAutoPtr<AddrInfo> ai(new AddrInfo(aCanonHost, prai, disableIPv4,
filterNameCollision, canonName));
PR_FreeAddrInfo(prai);
if (ai->mAddresses.isEmpty()) {
return NS_ERROR_UNKNOWN_HOST;
}
*aAddrInfo = ai.forget();
return NS_OK;
}
//////////////////////////////////////
// COMMON/PLATFORM INDEPENDENT CODE //
//////////////////////////////////////
nsresult
GetAddrInfoInit() {
LOG("Initializing GetAddrInfo.\n");
#if DNSQUERY_AVAILABLE
return _GetAddrInfoInit_Windows();
#else
return NS_OK;
#endif
}
nsresult
GetAddrInfoShutdown() {
LOG("Shutting down GetAddrInfo.\n");
#if DNSQUERY_AVAILABLE
return _GetAddrInfoShutdown_Windows();
#else
return NS_OK;
#endif
}
nsresult
GetAddrInfo(const char* aHost, uint16_t aAddressFamily, uint16_t aFlags,
const char* aNetworkInterface, AddrInfo** aAddrInfo, bool aGetTtl)
{
if (NS_WARN_IF(!aHost) || NS_WARN_IF(!aAddrInfo)) {
return NS_ERROR_NULL_POINTER;
}
#if DNSQUERY_AVAILABLE
// The GetTTLData needs the canonical name to function properly
if (aGetTtl) {
aFlags |= nsHostResolver::RES_CANON_NAME;
}
#endif
*aAddrInfo = nullptr;
nsresult rv = _GetAddrInfo_Portable(aHost, aAddressFamily, aFlags,
aNetworkInterface, aAddrInfo);
#if DNSQUERY_AVAILABLE
if (aGetTtl && NS_SUCCEEDED(rv)) {
// Figure out the canonical name, or if that fails, just use the host name
// we have.
const char *name = nullptr;
if (*aAddrInfo != nullptr && (*aAddrInfo)->mCanonicalName) {
name = (*aAddrInfo)->mCanonicalName;
} else {
name = aHost;
}
LOG("Getting TTL for %s (cname = %s).", aHost, name);
uint16_t ttl = 0;
nsresult ttlRv = _GetTTLData_Windows(name, &ttl, aAddressFamily);
if (NS_SUCCEEDED(ttlRv)) {
(*aAddrInfo)->ttl = ttl;
LOG("Got TTL %u for %s (name = %s).", ttl, aHost, name);
} else {
LOG_WARNING("Could not get TTL for %s (cname = %s).", aHost, name);
}
}
#endif
return rv;
}
} // namespace net
} // namespace mozilla