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TRR.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=4 sw=2 sts=2 et cin: */
/* 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 "DNS.h"
#include "nsCharSeparatedTokenizer.h"
#include "nsContentUtils.h"
#include "nsHttpHandler.h"
#include "nsIHttpChannel.h"
#include "nsIHttpChannelInternal.h"
#include "nsIIOService.h"
#include "nsIInputStream.h"
#include "nsISupportsBase.h"
#include "nsISupportsUtils.h"
#include "nsITimedChannel.h"
#include "nsIUploadChannel2.h"
#include "nsIURIMutator.h"
#include "nsNetUtil.h"
#include "nsStringStream.h"
#include "nsThreadUtils.h"
#include "nsURLHelper.h"
#include "TRR.h"
#include "TRRService.h"
#include "TRRServiceChannel.h"
#include "TRRLoadInfo.h"
#include "mozilla/Base64.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Logging.h"
#include "mozilla/Preferences.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/SyncRunnable.h"
#include "mozilla/Telemetry.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/Tokenizer.h"
#include "mozilla/UniquePtr.h"
namespace mozilla {
namespace net {
#undef LOG
extern mozilla::LazyLogModule gHostResolverLog;
#define LOG(args) MOZ_LOG(gHostResolverLog, mozilla::LogLevel::Debug, args)
#define LOG_ENABLED() \
MOZ_LOG_TEST(mozilla::net::gHostResolverLog, mozilla::LogLevel::Debug)
NS_IMPL_ISUPPORTS(TRR, nsIHttpPushListener, nsIInterfaceRequestor,
nsIStreamListener, nsIRunnable)
const uint8_t kDNS_CLASS_IN = 1;
NS_IMETHODIMP
TRR::Notify(nsITimer* aTimer) {
if (aTimer == mTimeout) {
mTimeout = nullptr;
Cancel();
} else {
MOZ_CRASH("Unknown timer");
}
return NS_OK;
}
// convert a given host request to a DOH 'body'
//
nsresult TRR::DohEncode(nsCString& aBody, bool aDisableECS) {
aBody.Truncate();
// Header
aBody += '\0';
aBody += '\0'; // 16 bit id
aBody += 0x01; // |QR| Opcode |AA|TC|RD| Set the RD bit
aBody += '\0'; // |RA| Z | RCODE |
aBody += '\0';
aBody += 1; // QDCOUNT (number of entries in the question section)
aBody += '\0';
aBody += '\0'; // ANCOUNT
aBody += '\0';
aBody += '\0'; // NSCOUNT
aBody += '\0'; // ARCOUNT
aBody += aDisableECS ? 1 : '\0'; // ARCOUNT low byte for EDNS(0)
// Question
// The input host name should be converted to a sequence of labels, where
// each label consists of a length octet followed by that number of
// octets. The domain name terminates with the zero length octet for the
// null label of the root.
// Followed by 16 bit QTYPE and 16 bit QCLASS
int32_t index = 0;
int32_t offset = 0;
do {
bool dotFound = false;
int32_t labelLength;
index = mHost.FindChar('.', offset);
if (kNotFound != index) {
dotFound = true;
labelLength = index - offset;
} else {
labelLength = mHost.Length() - offset;
}
if (labelLength > 63) {
// too long label!
return NS_ERROR_ILLEGAL_VALUE;
}
if (labelLength > 0) {
aBody += static_cast<unsigned char>(labelLength);
nsDependentCSubstring label = Substring(mHost, offset, labelLength);
aBody.Append(label);
}
if (!dotFound) {
aBody += '\0'; // terminate with a final zero
break;
}
offset += labelLength + 1; // move over label and dot
} while (true);
aBody += static_cast<uint8_t>(mType >> 8); // upper 8 bit TYPE
aBody += static_cast<uint8_t>(mType);
aBody += '\0'; // upper 8 bit CLASS
aBody += kDNS_CLASS_IN; // IN - "the Internet"
if (aDisableECS) {
// EDNS(0) is RFC 6891, ECS is RFC 7871
aBody += '\0'; // NAME | domain name | MUST be 0 (root domain) |
aBody += '\0';
aBody += 41; // TYPE | u_int16_t | OPT (41) |
aBody += 16; // CLASS | u_int16_t | requestor's UDP payload size |
aBody +=
'\0'; // advertise 4K (high-byte: 16 | low-byte: 0), ignored by DoH
aBody += '\0'; // TTL | u_int32_t | extended RCODE and flags |
aBody += '\0';
aBody += '\0';
aBody += '\0';
aBody += '\0'; // upper 8 bit RDLEN
aBody += 8; // RDLEN | u_int16_t | length of all RDATA |
// RDATA | octet stream | {attribute,value} pairs |
// The RDATA is just the ECS option setting zero subnet prefix
aBody += '\0'; // upper 8 bit OPTION-CODE ECS
aBody += 8; // OPTION-CODE, 2 octets, for ECS is 8
aBody += '\0'; // upper 8 bit OPTION-LENGTH
aBody += 4; // OPTION-LENGTH, 2 octets, contains the length of the payload
// after OPTION-LENGTH
aBody += '\0'; // upper 8 bit FAMILY. IANA Address Family Numbers registry,
// not the AF_* constants!
aBody += 1; // FAMILY (Ipv4), 2 octets
aBody += '\0'; // SOURCE PREFIX-LENGTH | SCOPE PREFIX-LENGTH |
aBody += '\0';
// ADDRESS, minimum number of octets == nothing because zero bits
}
return NS_OK;
}
NS_IMETHODIMP
TRR::Run() {
MOZ_ASSERT_IF(XRE_IsParentProcess() && gTRRService,
NS_IsMainThread() || gTRRService->IsOnTRRThread());
MOZ_ASSERT_IF(XRE_IsSocketProcess(), NS_IsMainThread());
if ((gTRRService == nullptr) || NS_FAILED(SendHTTPRequest())) {
FailData(NS_ERROR_FAILURE);
// The dtor will now be run
}
return NS_OK;
}
static void InitHttpHandler() {
nsresult rv;
nsCOMPtr<nsIIOService> ios = do_GetIOService(&rv);
if (NS_FAILED(rv)) {
return;
}
nsCOMPtr<nsIProtocolHandler> handler;
rv = ios->GetProtocolHandler("http", getter_AddRefs(handler));
if (NS_FAILED(rv)) {
return;
}
}
nsresult TRR::CreateChannelHelper(nsIURI* aUri, nsIChannel** aResult) {
*aResult = nullptr;
if (NS_IsMainThread() && !XRE_IsSocketProcess()) {
nsresult rv;
nsCOMPtr<nsIIOService> ios(do_GetIOService(&rv));
NS_ENSURE_SUCCESS(rv, rv);
return NS_NewChannel(aResult, aUri, nsContentUtils::GetSystemPrincipal(),
nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL,
nsIContentPolicy::TYPE_OTHER,
nullptr, // nsICookieJarSettings
nullptr, // PerformanceStorage
nullptr, // aLoadGroup
nullptr, // aCallbacks
nsIRequest::LOAD_NORMAL, ios);
}
// Unfortunately, we can only initialize gHttpHandler on main thread.
if (!gHttpHandler) {
nsCOMPtr<nsIEventTarget> main = GetMainThreadEventTarget();
if (main) {
// Forward to the main thread synchronously.
SyncRunnable::DispatchToThread(
main, new SyncRunnable(NS_NewRunnableFunction(
"InitHttpHandler", []() { InitHttpHandler(); })));
}
}
if (!gHttpHandler) {
return NS_ERROR_UNEXPECTED;
}
RefPtr<TRRLoadInfo> loadInfo =
new TRRLoadInfo(aUri, nsIContentPolicy::TYPE_OTHER);
return gHttpHandler->CreateTRRServiceChannel(aUri,
nullptr, // givenProxyInfo
0, // proxyResolveFlags
nullptr, // proxyURI
loadInfo, // aLoadInfo
aResult);
}
nsresult TRR::SendHTTPRequest() {
// This is essentially the "run" method - created from nsHostResolver
if ((mType != TRRTYPE_A) && (mType != TRRTYPE_AAAA) &&
(mType != TRRTYPE_NS) && (mType != TRRTYPE_TXT) &&
(mType != TRRTYPE_HTTPSSVC)) {
// limit the calling interface because nsHostResolver has explicit slots for
// these types
return NS_ERROR_FAILURE;
}
if (((mType == TRRTYPE_A) || (mType == TRRTYPE_AAAA)) &&
mRec->mEffectiveTRRMode != nsIRequest::TRR_ONLY_MODE) {
// let NS resolves skip the blacklist check
// we also don't check the blacklist for TRR only requests
MOZ_ASSERT(mRec);
if (UseDefaultServer() &&
gTRRService->IsTRRBlacklisted(mHost, mOriginSuffix, mPB, true)) {
if (mType == TRRTYPE_A) {
// count only blacklist for A records to avoid double counts
Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED2,
TRRService::AutoDetectedKey(), true);
}
// not really an error but no TRR is issued
return NS_ERROR_UNKNOWN_HOST;
}
if (UseDefaultServer() && (mType == TRRTYPE_A)) {
Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED2,
TRRService::AutoDetectedKey(), false);
}
}
bool useGet = gTRRService->UseGET();
nsAutoCString body;
nsCOMPtr<nsIURI> dnsURI;
bool disableECS = gTRRService->DisableECS();
nsresult rv;
LOG(("TRR::SendHTTPRequest resolve %s type %u\n", mHost.get(), mType));
if (useGet) {
nsAutoCString tmp;
rv = DohEncode(tmp, disableECS);
NS_ENSURE_SUCCESS(rv, rv);
/* For GET requests, the outgoing packet needs to be Base64url-encoded and
then appended to the end of the URI. */
rv = Base64URLEncode(tmp.Length(),
reinterpret_cast<const unsigned char*>(tmp.get()),
Base64URLEncodePaddingPolicy::Omit, body);
NS_ENSURE_SUCCESS(rv, rv);
nsAutoCString uri;
if (UseDefaultServer()) {
gTRRService->GetURI(uri);
} else {
uri = mRec->mTrrServer;
}
rv = NS_NewURI(getter_AddRefs(dnsURI), uri);
if (NS_FAILED(rv)) {
LOG(("TRR:SendHTTPRequest: NewURI failed!\n"));
return rv;
}
nsAutoCString query;
rv = dnsURI->GetQuery(query);
if (NS_FAILED(rv)) {
return rv;
}
if (query.IsEmpty()) {
query.Assign("?dns="_ns);
} else {
query.Append("&dns="_ns);
}
query.Append(body);
rv = NS_MutateURI(dnsURI).SetQuery(query).Finalize(dnsURI);
LOG(("TRR::SendHTTPRequest GET dns=%s\n", body.get()));
} else {
rv = DohEncode(body, disableECS);
NS_ENSURE_SUCCESS(rv, rv);
nsAutoCString uri;
if (UseDefaultServer()) {
gTRRService->GetURI(uri);
} else {
uri = mRec->mTrrServer;
}
rv = NS_NewURI(getter_AddRefs(dnsURI), uri);
}
if (NS_FAILED(rv)) {
LOG(("TRR:SendHTTPRequest: NewURI failed!\n"));
return rv;
}
nsCOMPtr<nsIChannel> channel;
rv = CreateChannelHelper(dnsURI, getter_AddRefs(channel));
if (NS_FAILED(rv) || !channel) {
LOG(("TRR:SendHTTPRequest: NewChannel failed!\n"));
return rv;
}
channel->SetLoadFlags(
nsIRequest::LOAD_ANONYMOUS | nsIRequest::INHIBIT_CACHING |
nsIRequest::LOAD_BYPASS_CACHE | nsIChannel::LOAD_BYPASS_URL_CLASSIFIER);
NS_ENSURE_SUCCESS(rv, rv);
rv = channel->SetNotificationCallbacks(this);
NS_ENSURE_SUCCESS(rv, rv);
nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(channel);
if (!httpChannel) {
return NS_ERROR_UNEXPECTED;
}
// This connection should not use TRR
rv = httpChannel->SetTRRMode(nsIRequest::TRR_DISABLED_MODE);
NS_ENSURE_SUCCESS(rv, rv);
rv = httpChannel->SetRequestHeader("Accept"_ns, "application/dns-message"_ns,
false);
NS_ENSURE_SUCCESS(rv, rv);
nsAutoCString cred;
if (UseDefaultServer()) {
gTRRService->GetCredentials(cred);
}
if (!cred.IsEmpty()) {
rv = httpChannel->SetRequestHeader("Authorization"_ns, cred, false);
NS_ENSURE_SUCCESS(rv, rv);
}
nsCOMPtr<nsIHttpChannelInternal> internalChannel = do_QueryInterface(channel);
if (!internalChannel) {
return NS_ERROR_UNEXPECTED;
}
// setting a small stream window means the h2 stack won't pipeline a window
// update with each HEADERS or reply to a DATA with a WINDOW UPDATE
rv = internalChannel->SetInitialRwin(127 * 1024);
NS_ENSURE_SUCCESS(rv, rv);
rv = internalChannel->SetIsTRRServiceChannel(true);
NS_ENSURE_SUCCESS(rv, rv);
mAllowRFC1918 = gTRRService->AllowRFC1918();
if (useGet) {
rv = httpChannel->SetRequestMethod("GET"_ns);
NS_ENSURE_SUCCESS(rv, rv);
} else {
nsCOMPtr<nsIUploadChannel2> uploadChannel = do_QueryInterface(httpChannel);
if (!uploadChannel) {
return NS_ERROR_UNEXPECTED;
}
uint32_t streamLength = body.Length();
nsCOMPtr<nsIInputStream> uploadStream;
rv =
NS_NewCStringInputStream(getter_AddRefs(uploadStream), std::move(body));
NS_ENSURE_SUCCESS(rv, rv);
rv = uploadChannel->ExplicitSetUploadStream(uploadStream,
"application/dns-message"_ns,
streamLength, "POST"_ns, false);
NS_ENSURE_SUCCESS(rv, rv);
}
rv = SetupTRRServiceChannelInternal(httpChannel, useGet);
if (NS_FAILED(rv)) {
return rv;
}
rv = httpChannel->AsyncOpen(this);
if (NS_FAILED(rv)) {
return rv;
}
// If the asyncOpen succeeded we can say that we actually attempted to
// use the TRR connection.
RefPtr<AddrHostRecord> addrRec = do_QueryObject(mRec);
if (addrRec) {
addrRec->mTRRUsed = true;
}
NS_NewTimerWithCallback(getter_AddRefs(mTimeout), this,
gTRRService->GetRequestTimeout(),
nsITimer::TYPE_ONE_SHOT);
mChannel = channel;
return NS_OK;
}
// static
nsresult TRR::SetupTRRServiceChannelInternal(nsIHttpChannel* aChannel,
bool aUseGet) {
nsCOMPtr<nsIHttpChannel> httpChannel = aChannel;
MOZ_ASSERT(httpChannel);
nsresult rv = NS_OK;
if (!aUseGet) {
rv =
httpChannel->SetRequestHeader("Cache-Control"_ns, "no-store"_ns, false);
NS_ENSURE_SUCCESS(rv, rv);
}
// Sanitize the request by removing the Accept-Language header so we minimize
// the amount of fingerprintable information we send to the server.
if (!StaticPrefs::network_trr_send_accept_language_headers()) {
rv = httpChannel->SetRequestHeader("Accept-Language"_ns, EmptyCString(),
false);
NS_ENSURE_SUCCESS(rv, rv);
}
// Sanitize the request by removing the User-Agent
if (!StaticPrefs::network_trr_send_user_agent_headers()) {
rv = httpChannel->SetRequestHeader("User-Agent"_ns, EmptyCString(), false);
NS_ENSURE_SUCCESS(rv, rv);
}
if (StaticPrefs::network_trr_send_empty_accept_encoding_headers()) {
rv = httpChannel->SetEmptyRequestHeader("Accept-Encoding"_ns);
NS_ENSURE_SUCCESS(rv, rv);
}
// set the *default* response content type
if (NS_FAILED(httpChannel->SetContentType("application/dns-message"_ns))) {
LOG(("TRR::SetupTRRServiceChannelInternal: couldn't set content-type!\n"));
}
nsCOMPtr<nsITimedChannel> timedChan(do_QueryInterface(httpChannel));
if (timedChan) {
timedChan->SetTimingEnabled(true);
}
return NS_OK;
}
NS_IMETHODIMP
TRR::GetInterface(const nsIID& iid, void** result) {
if (!iid.Equals(NS_GET_IID(nsIHttpPushListener))) {
return NS_ERROR_NO_INTERFACE;
}
nsCOMPtr<nsIHttpPushListener> copy(this);
*result = copy.forget().take();
return NS_OK;
}
nsresult TRR::DohDecodeQuery(const nsCString& query, nsCString& host,
enum TrrType& type) {
FallibleTArray<uint8_t> binary;
bool found_dns = false;
LOG(("TRR::DohDecodeQuery %s!\n", query.get()));
// extract "dns=" from the query string
nsCCharSeparatedTokenizer tokenizer(query, '&');
nsAutoCString data;
while (tokenizer.hasMoreTokens()) {
const nsACString& token = tokenizer.nextToken();
nsDependentCSubstring dns = Substring(token, 0, 4);
nsAutoCString check(dns);
if (check.Equals("dns=")) {
nsDependentCSubstring q = Substring(token, 4, -1);
data = q;
found_dns = true;
break;
}
}
if (!found_dns) {
LOG(("TRR::DohDecodeQuery no dns= in pushed URI query string\n"));
return NS_ERROR_ILLEGAL_VALUE;
}
nsresult rv =
Base64URLDecode(data, Base64URLDecodePaddingPolicy::Ignore, binary);
NS_ENSURE_SUCCESS(rv, rv);
uint32_t avail = binary.Length();
if (avail < 12) {
return NS_ERROR_FAILURE;
}
// check the query bit and the opcode
if ((binary[2] & 0xf8) != 0) {
return NS_ERROR_FAILURE;
}
uint32_t qdcount = (binary[4] << 8) + binary[5];
if (!qdcount) {
return NS_ERROR_FAILURE;
}
uint32_t index = 12;
uint32_t length = 0;
host.Truncate();
do {
if (avail < (index + 1)) {
return NS_ERROR_UNEXPECTED;
}
length = binary[index];
if (length) {
if (host.Length()) {
host.Append(".");
}
if (avail < (index + 1 + length)) {
return NS_ERROR_UNEXPECTED;
}
host.Append((const char*)(&binary[0]) + index + 1, length);
}
index += 1 + length; // skip length byte + label
} while (length);
LOG(("TRR::DohDecodeQuery host %s\n", host.get()));
if (avail < (index + 2)) {
return NS_ERROR_UNEXPECTED;
}
uint16_t i16 = 0;
i16 += binary[index] << 8;
i16 += binary[index + 1];
type = (enum TrrType)i16;
LOG(("TRR::DohDecodeQuery type %d\n", (int)type));
return NS_OK;
}
nsresult TRR::ReceivePush(nsIHttpChannel* pushed, nsHostRecord* pushedRec) {
if (!mHostResolver) {
return NS_ERROR_UNEXPECTED;
}
LOG(("TRR::ReceivePush: PUSH incoming!\n"));
nsCOMPtr<nsIURI> uri;
pushed->GetURI(getter_AddRefs(uri));
nsAutoCString query;
if (uri) {
uri->GetQuery(query);
}
PRNetAddr tempAddr;
if (NS_FAILED(DohDecodeQuery(query, mHost, mType)) ||
(PR_StringToNetAddr(mHost.get(), &tempAddr) == PR_SUCCESS)) { // literal
LOG(("TRR::ReceivePush failed to decode %s\n", mHost.get()));
return NS_ERROR_UNEXPECTED;
}
if ((mType != TRRTYPE_A) && (mType != TRRTYPE_AAAA) &&
(mType != TRRTYPE_TXT) && (mType != TRRTYPE_HTTPSSVC)) {
LOG(("TRR::ReceivePush unknown type %d\n", mType));
return NS_ERROR_UNEXPECTED;
}
if (gTRRService->IsExcludedFromTRR(mHost)) {
return NS_ERROR_FAILURE;
}
uint32_t type = nsIDNSService::RESOLVE_TYPE_DEFAULT;
if (mType == TRRTYPE_TXT) {
type = nsIDNSService::RESOLVE_TYPE_TXT;
} else if (mType == TRRTYPE_HTTPSSVC) {
type = nsIDNSService::RESOLVE_TYPE_HTTPSSVC;
}
RefPtr<nsHostRecord> hostRecord;
nsresult rv;
rv = mHostResolver->GetHostRecord(
mHost, EmptyCString(), type, pushedRec->flags, pushedRec->af,
pushedRec->pb, pushedRec->originSuffix, getter_AddRefs(hostRecord));
if (NS_FAILED(rv)) {
return rv;
}
// Since we don't ever call nsHostResolver::NameLookup for this record,
// we need to copy the trr mode from the previous record
if (hostRecord->mEffectiveTRRMode == nsIRequest::TRR_DEFAULT_MODE) {
hostRecord->mEffectiveTRRMode = pushedRec->mEffectiveTRRMode;
}
rv = mHostResolver->TrrLookup_unlocked(hostRecord, this);
if (NS_FAILED(rv)) {
return rv;
}
rv = pushed->AsyncOpen(this);
if (NS_FAILED(rv)) {
return rv;
}
// OK!
mChannel = pushed;
mRec.swap(hostRecord);
return NS_OK;
}
NS_IMETHODIMP
TRR::OnPush(nsIHttpChannel* associated, nsIHttpChannel* pushed) {
LOG(("TRR::OnPush entry\n"));
MOZ_ASSERT(associated == mChannel);
if (!mRec) {
return NS_ERROR_FAILURE;
}
if (!UseDefaultServer()) {
return NS_ERROR_FAILURE;
}
RefPtr<TRR> trr = new TRR(mHostResolver, mPB);
return trr->ReceivePush(pushed, mRec);
}
NS_IMETHODIMP
TRR::OnStartRequest(nsIRequest* aRequest) {
LOG(("TRR::OnStartRequest %p %s %d\n", this, mHost.get(), mType));
return NS_OK;
}
static uint16_t get16bit(const unsigned char* aData, unsigned int index) {
return ((aData[index] << 8) | aData[index + 1]);
}
static uint32_t get32bit(const unsigned char* aData, unsigned int index) {
return (aData[index] << 24) | (aData[index + 1] << 16) |
(aData[index + 2] << 8) | aData[index + 3];
}
nsresult TRR::PassQName(unsigned int& index) {
uint8_t length;
do {
if (mBodySize < (index + 1)) {
LOG(("TRR: PassQName:%d fail at index %d\n", __LINE__, index));
return NS_ERROR_ILLEGAL_VALUE;
}
length = static_cast<uint8_t>(mResponse[index]);
if ((length & 0xc0) == 0xc0) {
// name pointer, advance over it and be done
if (mBodySize < (index + 2)) {
return NS_ERROR_ILLEGAL_VALUE;
}
index += 2;
break;
}
if (length & 0xc0) {
LOG(("TRR: illegal label length byte (%x) at index %d\n", length, index));
return NS_ERROR_ILLEGAL_VALUE;
}
// pass label
if (mBodySize < (index + 1 + length)) {
LOG(("TRR: PassQName:%d fail at index %d\n", __LINE__, index));
return NS_ERROR_ILLEGAL_VALUE;
}
index += 1 + length;
} while (length);
return NS_OK;
}
// GetQname: retrieves the qname (stores in 'aQname') and stores the index
// after qname was parsed into the 'aIndex'.
nsresult TRR::GetQname(nsACString& aQname, unsigned int& aIndex) {
uint8_t clength = 0;
unsigned int cindex = aIndex;
unsigned int loop = 128; // a valid DNS name can never loop this much
unsigned int endindex = 0; // index position after this data
do {
if (cindex >= mBodySize) {
LOG(("TRR: bad Qname packet\n"));
return NS_ERROR_ILLEGAL_VALUE;
}
clength = static_cast<uint8_t>(mResponse[cindex]);
if ((clength & 0xc0) == 0xc0) {
// name pointer, get the new offset (14 bits)
if ((cindex + 1) >= mBodySize) {
return NS_ERROR_ILLEGAL_VALUE;
}
// extract the new index position for the next label
uint16_t newpos = (clength & 0x3f) << 8 | mResponse[cindex + 1];
if (!endindex) {
// only update on the first "jump"
endindex = cindex + 2;
}
cindex = newpos;
continue;
}
if (clength & 0xc0) {
// any of those bits set individually is an error
LOG(("TRR: bad Qname packet\n"));
return NS_ERROR_ILLEGAL_VALUE;
}
cindex++;
if (clength) {
if (!aQname.IsEmpty()) {
aQname.Append(".");
}
if ((cindex + clength) > mBodySize) {
return NS_ERROR_ILLEGAL_VALUE;
}
aQname.Append((const char*)(&mResponse[cindex]), clength);
cindex += clength; // skip label
}
} while (clength && --loop);
if (!loop) {
LOG(("TRR::DohDecode pointer loop error\n"));
return NS_ERROR_ILLEGAL_VALUE;
}
if (!endindex) {
// there was no "jump"
endindex = cindex;
}
aIndex = endindex;
return NS_OK;
}
//
// DohDecode() collects the TTL and the IP addresses in the response
//
nsresult TRR::DohDecode(nsCString& aHost) {
// The response has a 12 byte header followed by the question (returned)
// and then the answer. The answer section itself contains the name, type
// and class again and THEN the record data.
// www.example.com response:
// header:
// abcd 8180 0001 0001 0000 0000
// the question:
// 0377 7777 0765 7861 6d70 6c65 0363 6f6d 0000 0100 01
// the answer:
// 03 7777 7707 6578 616d 706c 6503 636f 6d00 0001 0001
// 0000 0080 0004 5db8 d822
unsigned int index = 12;
uint8_t length;
nsAutoCString host;
nsresult rv;
LOG(("doh decode %s %d bytes\n", aHost.get(), mBodySize));
mCname.Truncate();
if (mBodySize < 12 || mResponse[0] || mResponse[1]) {
LOG(("TRR bad incoming DOH, eject!\n"));
return NS_ERROR_ILLEGAL_VALUE;
}
uint8_t rcode = mResponse[3] & 0x0F;
if (rcode) {
LOG(("TRR Decode %s RCODE %d\n", aHost.get(), rcode));
return NS_ERROR_FAILURE;
}
uint16_t questionRecords = get16bit(mResponse, 4); // qdcount
// iterate over the single(?) host name in question
while (questionRecords) {
do {
if (mBodySize < (index + 1)) {
LOG(("TRR Decode 1 index: %u size: %u", index, mBodySize));
return NS_ERROR_ILLEGAL_VALUE;
}
length = static_cast<uint8_t>(mResponse[index]);
if (length) {
if (host.Length()) {
host.Append(".");
}
if (mBodySize < (index + 1 + length)) {
LOG(("TRR Decode 2 index: %u size: %u len: %u", index, mBodySize,
length));
return NS_ERROR_ILLEGAL_VALUE;
}
host.Append(((char*)mResponse) + index + 1, length);
}
index += 1 + length; // skip length byte + label
} while (length);
if (mBodySize < (index + 4)) {
LOG(("TRR Decode 3 index: %u size: %u", index, mBodySize));
return NS_ERROR_ILLEGAL_VALUE;
}
index += 4; // skip question's type, class
questionRecords--;
}
// Figure out the number of answer records from ANCOUNT
uint16_t answerRecords = get16bit(mResponse, 6);
LOG(("TRR Decode: %d answer records (%u bytes body) %s index=%u\n",
answerRecords, mBodySize, host.get(), index));
while (answerRecords) {
nsAutoCString qname;
rv = GetQname(qname, index);
if (NS_FAILED(rv)) {
return rv;
}
// 16 bit TYPE
if (mBodySize < (index + 2)) {
LOG(("TRR: Dohdecode:%d fail at index %d\n", __LINE__, index + 2));
return NS_ERROR_ILLEGAL_VALUE;
}
uint16_t TYPE = get16bit(mResponse, index);
if ((TYPE != TRRTYPE_CNAME) && (TYPE != TRRTYPE_HTTPSSVC) &&
(TYPE != static_cast<uint16_t>(mType))) {
// Not the same type as was asked for nor CNAME
LOG(("TRR: Dohdecode:%d asked for type %d got %d\n", __LINE__, mType,
TYPE));
return NS_ERROR_UNEXPECTED;
}
index += 2;
// 16 bit class
if (mBodySize < (index + 2)) {
LOG(("TRR: Dohdecode:%d fail at index %d\n", __LINE__, index + 2));
return NS_ERROR_ILLEGAL_VALUE;
}
uint16_t CLASS = get16bit(mResponse, index);
if (kDNS_CLASS_IN != CLASS) {
LOG(("TRR bad CLASS (%u) at index %d\n", CLASS, index));
return NS_ERROR_UNEXPECTED;
}
index += 2;
// 32 bit TTL (seconds)
if (mBodySize < (index + 4)) {
LOG(("TRR: Dohdecode:%d fail at index %d\n", __LINE__, index));
return NS_ERROR_ILLEGAL_VALUE;
}
uint32_t TTL = get32bit(mResponse, index);
index += 4;
// 16 bit RDLENGTH
if (mBodySize < (index + 2)) {
LOG(("TRR: Dohdecode:%d fail at index %d\n", __LINE__, index));
return NS_ERROR_ILLEGAL_VALUE;
}
uint16_t RDLENGTH = get16bit(mResponse, index);
index += 2;
if (mBodySize < (index + RDLENGTH)) {
LOG(("TRR: Dohdecode:%d fail RDLENGTH=%d at index %d\n", __LINE__,
RDLENGTH, index));
return NS_ERROR_ILLEGAL_VALUE;
}
// We check if the qname is a case-insensitive match for the host or the
// FQDN version of the host
bool responseMatchesQuestion =
(qname.Length() == aHost.Length() ||
(aHost.Length() == qname.Length() + 1 && aHost.Last() == '.')) &&
qname.Compare(aHost.BeginReading(), true, qname.Length()) == 0;
if (responseMatchesQuestion) {
// RDATA
// - A (TYPE 1): 4 bytes
// - AAAA (TYPE 28): 16 bytes
// - NS (TYPE 2): N bytes
switch (TYPE) {
case TRRTYPE_A:
if (RDLENGTH != 4) {
LOG(("TRR bad length for A (%u)\n", RDLENGTH));
return NS_ERROR_UNEXPECTED;
}
rv = mDNS.Add(TTL, mResponse, index, RDLENGTH, mAllowRFC1918);
if (NS_FAILED(rv)) {
LOG(
("TRR:DohDecode failed: local IP addresses or unknown IP "
"family\n"));
return rv;
}
break;
case TRRTYPE_AAAA:
if (RDLENGTH != 16) {
LOG(("TRR bad length for AAAA (%u)\n", RDLENGTH));
return NS_ERROR_UNEXPECTED;
}
rv = mDNS.Add(TTL, mResponse, index, RDLENGTH, mAllowRFC1918);
if (NS_FAILED(rv)) {
LOG(("TRR got unique/local IPv6 address!\n"));
return rv;
}
break;
case TRRTYPE_NS:
break;
case TRRTYPE_CNAME:
if (mCname.IsEmpty()) {
nsAutoCString qname;
unsigned int qnameindex = index;
rv = GetQname(qname, qnameindex);
if (NS_FAILED(rv)) {
return rv;
}
if (!qname.IsEmpty()) {
ToLowerCase(qname);
mCname = qname;
LOG(("TRR::DohDecode CNAME host %s => %s\n", host.get(),
mCname.get()));
} else {
LOG(("TRR::DohDecode empty CNAME for host %s!\n", host.get()));
}
} else {
LOG(("TRR::DohDecode CNAME - ignoring another entry\n"));
}
break;
case TRRTYPE_TXT: {
// TXT record RRDATA sections are a series of character-strings
// each character string is a length byte followed by that many data
// bytes
nsAutoCString txt;
unsigned int txtIndex = index;
uint16_t available = RDLENGTH;
while (available > 0) {
uint8_t characterStringLen = mResponse[txtIndex++];
available--;
if (characterStringLen > available) {
LOG(("TRR::DohDecode MALFORMED TXT RECORD\n"));
break;
}
txt.Append((const char*)(&mResponse[txtIndex]), characterStringLen);
txtIndex += characterStringLen;
available -= characterStringLen;
}
if (!mResult.is<TypeRecordTxt>()) {
mResult = AsVariant(CopyableTArray<nsCString>());
}
{
auto& results = mResult.as<TypeRecordTxt>();
results.AppendElement(txt);
}
if (mTTL > TTL) {
mTTL = TTL;
}
LOG(("TRR::DohDecode TXT host %s => %s\n", host.get(), txt.get()));
break;
}
case TRRTYPE_HTTPSSVC: {
struct SVCB parsed;
unsigned int svcbIndex = index;
CheckedInt<uint16_t> available = RDLENGTH;
// Should have at least 2 bytes for the priority and one for the
// qname length.
if (available.value() < 3) {
return NS_ERROR_UNEXPECTED;
}
parsed.mSvcFieldPriority = get16bit(mResponse, svcbIndex);
svcbIndex += 2;
rv = GetQname(parsed.mSvcDomainName, svcbIndex);
if (NS_FAILED(rv)) {
return rv;
}
available -= (svcbIndex - index);
if (!available.isValid()) {
return NS_ERROR_UNEXPECTED;
}
while (available.value() >= 4) {
// Every SvcFieldValues must have at least 4 bytes for the