h2load: Add qlog output support

src/h2load.cc

@@ -111,6 +111,7 @@ Config::Config()
       encoder_header_table_size(4_k),
       data_fd(-1),
       log_fd(-1),
+      qlog_file_base(),
       port(0),
       default_port(0),
       connect_to_port(0),
@@ -2200,6 +2201,13 @@ Options:
               response  time when  using  one worker  thread, but  may
               appear slightly  out of order with  multiple threads due
               to buffering.  Status code is -1 for failed streams.
+  --qlog-file-base=<PATH>
+              Enable qlog output and specify base file name for qlogs.
+              Qlog  is emitted  for each connection.
+              For  a  given  base  name "base", each  output file name
+              becomes  "base.M.N.qlog"  where M is worker ID  and N is
+              client ID (e.g. "base.0.3.qlog").
+              Only effective in QUIC runs.
   --connect-to=<HOST>[:<PORT>]
               Host and port to connect  instead of using the authority
               in <URI>.
@@ -2238,6 +2246,7 @@ int main(int argc, char **argv) {
 
   std::string datafile;
   std::string logfile;
+  std::string qlog_base;
   bool nreqs_set_manually = false;
   while (1) {
     static int flag = 0;
@@ -2274,6 +2283,7 @@ int main(int argc, char **argv) {
         {"groups", required_argument, &flag, 13},
         {"tls13-ciphers", required_argument, &flag, 14},
         {"no-udp-gso", no_argument, &flag, 15},
+        {"qlog-file-base", required_argument, &flag, 16},
         {nullptr, 0, nullptr, 0}};
     int option_index = 0;
     auto c = getopt_long(argc, argv,
@@ -2536,6 +2546,10 @@ int main(int argc, char **argv) {
         // --no-udp-gso
         config.no_udp_gso = true;
         break;
+      case 16:
+        // --qlog-file-base
+        qlog_base = optarg;
+        break;
       }
       break;
     default:
@@ -2720,6 +2734,14 @@ int main(int argc, char **argv) {
     }
   }
 
+  if (!qlog_base.empty()) {
+    if (!config.is_quic()) {
+      std::cerr << "Warning: --qlog-file-base: only effective in quic, ignoring." << std::endl;
+    } else {
+      config.qlog_file_base = qlog_base;
+    }
+  }
+
   struct sigaction act {};
   act.sa_handler = SIG_IGN;
   sigaction(SIGPIPE, &act, nullptr);

src/h2load.h

@@ -109,6 +109,8 @@ struct Config {
   int data_fd;
   // file descriptor to write per-request stats to.
   int log_fd;
+  // base file name of qlog output files
+  std::string qlog_file_base;
   uint16_t port;
   uint16_t default_port;
   uint16_t connect_to_port;
@@ -340,6 +342,7 @@ struct Client {
     std::array<Crypto, 2> crypto;
     size_t max_pktlen;
     bool close_requested;
+    FILE *qlog_file;
   } quic;
   ev_timer request_timeout_watcher;
   addrinfo *next_addr;
@@ -481,6 +484,7 @@ struct Client {
                                    const uint8_t *data, size_t datalen);
   int quic_pkt_timeout();
   void quic_restart_pkt_timer();
+  void quic_write_qlog(const void *data, size_t datalen);
 };
 
 } // namespace h2load

src/h2load_quic.cc

@@ -34,6 +34,8 @@
 
 #include "h2load_http3_session.h"
 
+#include <sstream>
+
 namespace h2load {
 
 namespace {
@@ -284,6 +286,20 @@ auto quic_method = SSL_QUIC_METHOD{
 };
 } // namespace
 
+// qlog write callback -- excerpted from ngtcp2/examples/client_base.cc
+namespace {
+void qlog_write_cb(void *user_data, uint32_t flags, const void *data,
+                   size_t datalen) {
+  auto c = static_cast<Client *>(user_data);
+  c->quic_write_qlog(data, datalen);
+}
+} // namespace
+
+void Client::quic_write_qlog(const void *data, size_t datalen) {
+  assert(quic.qlog_file != nullptr);
+  fwrite(data, 1, datalen, quic.qlog_file);
+}
+
 int Client::quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
                       const sockaddr *remote_addr, socklen_t remote_addrlen) {
   int rv;
@@ -354,6 +370,17 @@ int Client::quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
     settings.log_printf = debug_log_printf;
   }
   settings.initial_ts = timestamp(worker->loop);
+  if (!config->qlog_file_base.empty()) {
+    assert(quic.qlog_file == nullptr);
+    std::ostringstream oss(config->qlog_file_base, std::ios::app);
+    oss << '.' << worker->id << '.' << id << ".qlog";
+    quic.qlog_file = fopen(oss.str().c_str(), "w");
+    if (quic.qlog_file == nullptr) {
+      std::cerr << "Failed to open a qlog file: " << oss.str() << std::endl;
+      return -1;
+    }
+    settings.qlog.write = qlog_write_cb;
+  }
 
   ngtcp2_transport_params params;
   ngtcp2_transport_params_default(&params);
@@ -393,7 +420,13 @@ int Client::quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
   return 0;
 }
 
-void Client::quic_free() { ngtcp2_conn_del(quic.conn); }
+void Client::quic_free() {
+  ngtcp2_conn_del(quic.conn);
+  if (quic.qlog_file != nullptr) {
+    fclose(quic.qlog_file);
+    quic.qlog_file = nullptr;
+  }
+}
 
 void Client::quic_close_connection() {
   if (!quic.conn) {