From 2a8de594e17b77e3171de6be22c28617780329c9 Mon Sep 17 00:00:00 2001
From: Alexander David Frick <Alex313031@gmail.com>
Date: Thu, 17 Feb 2022 11:43:10 -0600
Subject: [PATCH] Update dns_transaction.cc

---
 net/dns/dns_transaction.cc | 39 ++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/net/dns/dns_transaction.cc b/net/dns/dns_transaction.cc
index 4972bc07..ddd5219b 100644
--- a/net/dns/dns_transaction.cc
+++ b/net/dns/dns_transaction.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2022 The Chromium Authors. All rights reserved.
+// Copyright (c) 2022 The Chromium Authors and Alex313031. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -451,12 +451,14 @@ class DnsHTTPAttempt : public DnsAttempt, public URLRequest::Delegate {
 
   int Start(CompletionOnceCallback callback) override {
     callback_ = std::move(callback);
-    request_->Start();
+    // Start the request asynchronously to avoid reentrancy in
+    // the network stack.
+    base::SequencedTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::BindOnce(&DnsHTTPAttempt::StartAsync,
+                                  weak_factory_.GetWeakPtr()));
     return ERR_IO_PENDING;
   }
 
-  void Cancel() { request_.reset(); }
-
   const DnsQuery* GetQuery() const override { return query_.get(); }
   const DnsResponse* GetResponse() const override {
     const DnsResponse* resp = response_.get();
@@ -561,6 +563,11 @@ class DnsHTTPAttempt : public DnsAttempt, public URLRequest::Delegate {
   bool IsPending() const override { return !callback_.is_null(); }
 
  private:
+  void StartAsync() {
+    DCHECK(request_);
+    request_->Start();
+  }
+
   void ResponseCompleted(int net_error) {
     request_.reset();
     std::move(callback_).Run(CompleteResponse(net_error));
@@ -618,14 +625,14 @@ void ConstructDnsHTTPAttempt(DnsSession* session,
     query = std::make_unique<DnsQuery>(*attempts->at(0)->GetQuery());
   }
 
-  DCHECK_LT(doh_server_index, session->config().dns_over_https_servers.size());
-  const DnsOverHttpsServerConfig& doh_config =
-      session->config().dns_over_https_servers[doh_server_index];
+  DCHECK_LT(doh_server_index, session->config().doh_config.servers().size());
+  const DnsOverHttpsServerConfig& doh_server =
+      session->config().doh_config.servers()[doh_server_index];
   GURL gurl_without_parameters(
-      GetURLFromTemplateWithoutParameters(doh_config.server_template()));
+      GetURLFromTemplateWithoutParameters(doh_server.server_template()));
   attempts->push_back(std::make_unique<DnsHTTPAttempt>(
-      doh_server_index, std::move(query), doh_config.server_template(),
-      gurl_without_parameters, doh_config.use_post(), url_request_context,
+      doh_server_index, std::move(query), doh_server.server_template(),
+      gurl_without_parameters, doh_server.use_post(), url_request_context,
       isolation_info, request_priority));
 }
 
@@ -913,12 +920,12 @@ class DnsOverHttpsProbeRunner : public DnsProbeRunner {
                           base::WeakPtr<ResolveContext> context)
       : session_(session), context_(context) {
     DCHECK(session_);
-    DCHECK(!session_->config().dns_over_https_servers.empty());
+    DCHECK(!session_->config().doh_config.servers().empty());
     DCHECK(context_);
 
     DNSDomainFromDot(kDoHProbeHostname, &formatted_probe_hostname_);
 
-    for (size_t i = 0; i < session_->config().dns_over_https_servers.size();
+    for (size_t i = 0; i < session_->config().doh_config.servers().size();
          i++) {
       probe_stats_list_.push_back(nullptr);
     }
@@ -930,9 +937,9 @@ class DnsOverHttpsProbeRunner : public DnsProbeRunner {
     DCHECK(session_);
     DCHECK(context_);
 
+    const auto& config = session_->config().doh_config;
     // Start probe sequences for any servers where it is not currently running.
-    for (size_t i = 0; i < session_->config().dns_over_https_servers.size();
-         i++) {
+    for (size_t i = 0; i < config.servers().size(); i++) {
       if (!probe_stats_list_[i]) {
         probe_stats_list_[i] = std::make_unique<ProbeStats>();
         ContinueProbe(i, probe_stats_list_[i]->weak_factory.GetWeakPtr(),
@@ -1254,7 +1261,7 @@ class DnsTransactionImpl : public DnsTransaction,
     if (secure_ && result.attempt) {
       size_t server_index = result.attempt->server_index();
       doh_provider_id = GetDohProviderIdForHistogramFromServerConfig(
-          session_->config().dns_over_https_servers[server_index]);
+          session_->config().doh_config.servers()[server_index]);
     }
 
     std::move(callback_).Run(this, result.rv, response, doh_provider_id);
@@ -1270,7 +1277,7 @@ class DnsTransactionImpl : public DnsTransaction,
 
     DnsConfig config = session_->config();
     if (secure_) {
-      DCHECK_GT(config.dns_over_https_servers.size(), 0u);
+      DCHECK(!config.doh_config.servers().empty());
       RecordAttemptUma(DnsAttemptType::kHttp);
       return MakeHTTPAttempt();
     }