nghttpx: Add $tls_sni access log variable

gennghttpxfun.py

@@ -188,6 +188,7 @@ LOGVARS = [
     "tls_protocol",
     "tls_session_id",
     "tls_session_reused",
+    "tls_sni",
     "backend_host",
     "backend_port",
 ]

src/shrpx.cc

@@ -2452,6 +2452,7 @@ Logging:
               * $tls_session_id: session ID for SSL/TLS connection.
               * $tls_session_reused:  "r"   if  SSL/TLS   session  was
                 reused.  Otherwise, "."
+              * $tls_sni: SNI server name for SSL/TLS connection.
               * $backend_host:  backend  host   used  to  fulfill  the
                 request.  "-" if backend host is not available.
               * $backend_port:  backend  port   used  to  fulfill  the

src/shrpx_client_handler.cc

@@ -1216,7 +1216,7 @@ void ClientHandler::write_accesslog(Downstream *downstream) {
   upstream_accesslog(
       config->logging.access.format,
       LogSpec{
-          downstream, ipaddr_, alpn_,
+          downstream, ipaddr_, alpn_, sni_,
           nghttp2::tls::get_tls_session_info(&tls_info, conn_.tls.ssl),
           std::chrono::high_resolution_clock::now(), // request_end_time
           port_, faddr_->port, config->pid,

src/shrpx_config.cc

@@ -401,6 +401,11 @@ LogFragmentType log_var_lookup_token(const char *name, size_t namelen) {
     break;
   case 7:
     switch (name[6]) {
+    case 'i':
+      if (util::strieq_l("tls_sn", name, 6)) {
+        return SHRPX_LOGF_TLS_SNI;
+      }
+      break;
     case 't':
       if (util::strieq_l("reques", name, 6)) {
         return SHRPX_LOGF_REQUEST;

src/shrpx_log.cc

@@ -518,6 +518,13 @@ void upstream_accesslog(const std::vector<LogFragment> &lfv,
       std::tie(p, last) =
           copy(lgsp.tls_info->session_reused ? 'r' : '.', p, last);
       break;
+    case SHRPX_LOGF_TLS_SNI:
+      if (lgsp.sni.empty()) {
+        std::tie(p, last) = copy('-', p, last);
+        break;
+      }
+      std::tie(p, last) = copy_escape(lgsp.sni, p, last);
+      break;
     case SHRPX_LOGF_BACKEND_HOST:
       if (!downstream_addr) {
         std::tie(p, last) = copy('-', p, last);

src/shrpx_log.h

@@ -137,6 +137,7 @@ enum LogFragmentType {
   SHRPX_LOGF_SSL_SESSION_ID = SHRPX_LOGF_TLS_SESSION_ID,
   SHRPX_LOGF_TLS_SESSION_REUSED,
   SHRPX_LOGF_SSL_SESSION_REUSED = SHRPX_LOGF_TLS_SESSION_REUSED,
+  SHRPX_LOGF_TLS_SNI,
   SHRPX_LOGF_BACKEND_HOST,
   SHRPX_LOGF_BACKEND_PORT,
 };
@@ -152,6 +153,7 @@ struct LogSpec {
   Downstream *downstream;
   StringRef remote_addr;
   StringRef alpn;
+  StringRef sni;
   const nghttp2::tls::TLSSessionInfo *tls_info;
   std::chrono::high_resolution_clock::time_point request_end_time;
   StringRef remote_port;