Add HttpEncoder method to serialize ACCEPT_CH frame.

PiperOrigin-RevId: 345446123
Change-Id: I55e45926e6d94cdcde4022b9620d6d3868475eeb

quic/core/http/http_encoder.cc

diff --git a/quic/core/http/http_encoder.cc b/quic/core/http/http_encoder.cc
index 4f86d45..0689a77 100644
--- a/quic/core/http/http_encoder.cc
+++ b/quic/core/http/http_encoder.cc
@@ -258,6 +258,42 @@
 }
 
 // static
+QuicByteCount HttpEncoder::SerializeAcceptChFrame(
+    const AcceptChFrame& accept_ch,
+    std::unique_ptr<char[]>* output) {
+  QuicByteCount payload_length = 0;
+  for (const auto& entry : accept_ch.entries) {
+    payload_length += QuicDataWriter::GetVarInt62Len(entry.origin.size());
+    payload_length += entry.origin.size();
+    payload_length += QuicDataWriter::GetVarInt62Len(entry.value.size());
+    payload_length += entry.value.size();
+  }
+
+  QuicByteCount total_length =
+      GetTotalLength(payload_length, HttpFrameType::ACCEPT_CH);
+
+  output->reset(new char[total_length]);
+  QuicDataWriter writer(total_length, output->get());
+
+  if (!WriteFrameHeader(payload_length, HttpFrameType::ACCEPT_CH, &writer)) {
+    QUIC_DLOG(ERROR)
+        << "Http encoder failed to serialize ACCEPT_CH frame header.";
+    return 0;
+  }
+
+  for (const auto& entry : accept_ch.entries) {
+    if (!writer.WriteStringPieceVarInt62(entry.origin) ||
+        !writer.WriteStringPieceVarInt62(entry.value)) {
+      QUIC_DLOG(ERROR)
+          << "Http encoder failed to serialize ACCEPT_CH frame payload.";
+      return 0;
+    }
+  }
+
+  return total_length;
+}
+
+// static
 QuicByteCount HttpEncoder::SerializeGreasingFrame(
     std::unique_ptr<char[]>* output) {
   uint64_t frame_type;

quic/core/http/http_encoder.h

diff --git a/quic/core/http/http_encoder.h b/quic/core/http/http_encoder.h
index 4d6a54a..dfa236a 100644
--- a/quic/core/http/http_encoder.h
+++ b/quic/core/http/http_encoder.h
@@ -67,6 +67,11 @@
       const PriorityUpdateFrame& priority_update,
       std::unique_ptr<char[]>* output);
 
+  // Serializes an ACCEPT_CH frame into a new buffer stored in |output|.
+  // Returns the length of the buffer on success, or 0 otherwise.
+  static QuicByteCount SerializeAcceptChFrame(const AcceptChFrame& accept_ch,
+                                              std::unique_ptr<char[]>* output);
+
   // Serializes a frame with reserved frame type specified in
   // https://tools.ietf.org/html/draft-ietf-quic-http-25#section-7.2.9.
   static QuicByteCount SerializeGreasingFrame(std::unique_ptr<char[]>* output);

quic/core/http/http_encoder_test.cc

diff --git a/quic/core/http/http_encoder_test.cc b/quic/core/http/http_encoder_test.cc
index 2466326..df2b523 100644
--- a/quic/core/http/http_encoder_test.cc
+++ b/quic/core/http/http_encoder_test.cc
@@ -184,5 +184,28 @@
                                               ABSL_ARRAYSIZE(output2));
 }
 
+TEST(HttpEncoderTest, SerializeAcceptChFrame) {
+  AcceptChFrame accept_ch;
+  char output1[] = {0x40, 0x89,  // type (ACCEPT_CH)
+                    0x00};       // length
+
+  std::unique_ptr<char[]> buffer;
+  uint64_t length = HttpEncoder::SerializeAcceptChFrame(accept_ch, &buffer);
+  EXPECT_EQ(ABSL_ARRAYSIZE(output1), length);
+  quiche::test::CompareCharArraysWithHexError("ACCEPT_CH", buffer.get(), length,
+                                              output1, ABSL_ARRAYSIZE(output1));
+
+  accept_ch.entries.push_back({"foo", "bar"});
+  char output2[] = {0x40, 0x89,               // type (ACCEPT_CH)
+                    0x08,                     // payload length
+                    0x03, 0x66, 0x6f, 0x6f,   // length of "foo"; "foo"
+                    0x03, 0x62, 0x61, 0x72};  // length of "bar"; "bar"
+
+  length = HttpEncoder::SerializeAcceptChFrame(accept_ch, &buffer);
+  EXPECT_EQ(ABSL_ARRAYSIZE(output2), length);
+  quiche::test::CompareCharArraysWithHexError("ACCEPT_CH", buffer.get(), length,
+                                              output2, ABSL_ARRAYSIZE(output2));
+}
+
 }  // namespace test
 }  // namespace quic