From 857f8f55b8bc84a145d484ef5f38eed0bc1710db Mon Sep 17 00:00:00 2001
From: klzgrad <kizdiv@gmail.com>
Date: Thu, 30 Apr 2026 22:38:52 +0800
Subject: [PATCH] net/spdy: Support tunnel preamble requests

---
 src/net/spdy/spdy_proxy_client_socket.cc | 54 ++++++++++++++++++++++++
 src/net/spdy/spdy_proxy_client_socket.h  |  1 +
 2 files changed, 55 insertions(+)

diff --git a/src/net/spdy/spdy_proxy_client_socket.cc b/src/net/spdy/spdy_proxy_client_socket.cc
index 804ef7ba72..a8ae6ae9dd 100644
--- a/src/net/spdy/spdy_proxy_client_socket.cc
+++ b/src/net/spdy/spdy_proxy_client_socket.cc
@@ -58,6 +58,15 @@ SpdyProxyClientSocket::SpdyProxyClientSocket(
       source_dependency_(source_net_log.source()) {
   request_.method = "CONNECT";
   request_.url = GURL("https://" + endpoint.ToString());
+  if (endpoint.host() == "preamble") {
+    preamble_index_ = endpoint.port();
+    CHECK(!proxy_chain.is_direct());
+    CHECK_EQ(proxy_chain_index, proxy_chain.length() - 1);
+    const ProxyServer& proxy_server =
+        proxy_chain.GetProxyServer(proxy_chain_index);
+    CHECK(proxy_server.is_secure_http_like());
+    request_.url = GURL("https://" + proxy_server.host_port_pair().ToString());
+  }
   net_log_.BeginEventReferencingSource(NetLogEventType::SOCKET_ALIVE,
                                        source_net_log.source());
   net_log_.AddEventReferencingSource(
@@ -425,6 +434,12 @@ int SpdyProxyClientSocket::DoCalculateHeaders() {
   }
 
   if (proxy_delegate_) {
+    if (preamble_index_.has_value()) {
+      proxy_delegate_->OnBeforePreambleRequest(proxy_chain_, proxy_chain_index_,
+                                               *preamble_index_,
+                                               proxy_delegate_headers_);
+      return OK;
+    }
     ASSIGN_OR_RETURN(
         proxy_delegate_headers_,
         proxy_delegate_->OnBeforeTunnelRequest(
@@ -452,6 +467,32 @@ int SpdyProxyClientSocket::DoCalculateHeadersComplete(int result) {
     proxy_delegate_headers_.RemoveHeader("fastopen");
     use_fastopen_ = true;
   }
+  if (preamble_index_.has_value()) {
+    authorization_headers_.Clear();
+    std::optional<std::string_view> method =
+        proxy_delegate_headers_.GetHeaderView("_method");
+    if (method.has_value()) {
+      request_.method = *method;
+      proxy_delegate_headers_.RemoveHeader("_method");
+    } else {
+      LOG(ERROR) << "Missing preamble method";
+      return ERR_INVALID_ARGUMENT;
+    }
+    std::optional<std::string_view> path =
+        proxy_delegate_headers_.GetHeaderView("_path");
+    if (path.has_value()) {
+      if (*path == "/" || path->ends_with(".css")) {
+        spdy_stream_->SetPriority(HIGHEST);
+      } else if (path->ends_with(".js")) {
+        spdy_stream_->SetPriority(LOW);
+      }
+      request_.url = request_.url.Resolve(*path);
+      proxy_delegate_headers_.RemoveHeader("_path");
+    } else {
+      LOG(ERROR) << "Missing preamble path";
+      return ERR_INVALID_ARGUMENT;
+    }
+  }
   request_.extra_headers.MergeFrom(proxy_delegate_headers_);
   return result;
 }
@@ -471,6 +512,10 @@ int SpdyProxyClientSocket::DoSendRequest() {
   CreateSpdyHeadersFromHttpRequest(request_, std::nullopt,
                                    request_.extra_headers, &headers);
 
+  if (preamble_index_.has_value()) {
+    return spdy_stream_->SendRequestHeaders(std::move(headers),
+                                            NO_MORE_DATA_TO_SEND);
+  }
   return spdy_stream_->SendRequestHeaders(std::move(headers),
                                           MORE_DATA_TO_SEND);
 }
@@ -514,6 +559,11 @@ int SpdyProxyClientSocket::DoProcessResponseHeaders() {
   next_state_ = STATE_PROCESS_RESPONSE_HEADERS_COMPLETE;
 
   if (proxy_delegate_) {
+    if (preamble_index_.has_value()) {
+      proxy_delegate_->OnPreambleHeadersReceived(
+          proxy_chain_, proxy_chain_index_, *preamble_index_, response_.headers);
+      return OK;
+    }
     return proxy_delegate_->OnTunnelHeadersReceived(
         proxy_chain_, proxy_chain_index_, *response_.headers,
         base::BindOnce(&SpdyProxyClientSocket::OnIOComplete,
@@ -545,6 +595,10 @@ int SpdyProxyClientSocket::DoProcessResponseCode() {
       return HandleProxyAuthChallenge(auth_.get(), &response_, net_log_);
 
     default:
+      if (preamble_index_.has_value()) {
+        next_state_ = STATE_OPEN;
+        return OK;
+      }
       // Ignore response to avoid letting the proxy impersonate the target
       // server.  (See http://crbug.com/137891.)
       return ERR_TUNNEL_CONNECTION_FAILED;
diff --git a/src/net/spdy/spdy_proxy_client_socket.h b/src/net/spdy/spdy_proxy_client_socket.h
index aca80e455b..cd3c408529 100644
--- a/src/net/spdy/spdy_proxy_client_socket.h
+++ b/src/net/spdy/spdy_proxy_client_socket.h
@@ -201,6 +201,7 @@ class NET_EXPORT_PRIVATE SpdyProxyClientSocket : public ProxyClientSocket,
   bool was_ever_used_ = false;
 
   bool use_fastopen_ = false;
+  std::optional<size_t> preamble_index_;
   bool read_headers_pending_ = false;
 
   const NetLogWithSource net_log_;