nghttpx: Add client-no-http2-cipher-black-list option

This commit adds client-no-http2-cipher-black-list option to disable
enforcement of HTTP/2 cipher black list on backend HTTP/2 connection.
Previously, existing no-http2-cipher-black-list option disables it for
both frontend and backend connections.  Now no-http2-cipher-black-list
option only disables it for frontend connection.

gennghttpxfun.py

@@ -155,6 +155,7 @@ OPTIONS = [
     "frontend-keep-alive-timeout",
     "psk-secrets",
     "client-psk-secrets",
+    "client-no-http2-cipher-black-list",
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -2091,9 +2091,15 @@ SSL/TLS:
               Default: )"
       << util::duration_str(config->tls.dyn_rec.idle_timeout) << R"(
   --no-http2-cipher-black-list
-              Allow black  listed cipher  suite on  HTTP/2 connection.
-              See  https://tools.ietf.org/html/rfc7540#appendix-A  for
-              the complete HTTP/2 cipher suites black list.
+              Allow  black  listed  cipher suite  on  frontend  HTTP/2
+              connection.                                          See
+              https://tools.ietf.org/html/rfc7540#appendix-A  for  the
+              complete HTTP/2 cipher suites black list.
+  --client-no-http2-cipher-black-list
+              Allow  black  listed  cipher  suite  on  backend  HTTP/2
+              connection.                                          See
+              https://tools.ietf.org/html/rfc7540#appendix-A  for  the
+              complete HTTP/2 cipher suites black list.
   --tls-sct-dir=<DIR>
               Specifies the  directory where  *.sct files  exist.  All
               *.sct   files   in  <DIR>   are   read,   and  sent   as
@@ -3096,6 +3102,8 @@ int main(int argc, char **argv) {
          &flag, 146},
         {SHRPX_OPT_PSK_SECRETS.c_str(), required_argument, &flag, 147},
         {SHRPX_OPT_CLIENT_PSK_SECRETS.c_str(), required_argument, &flag, 148},
+        {SHRPX_OPT_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST.c_str(), no_argument,
+         &flag, 149},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -3794,6 +3802,11 @@ int main(int argc, char **argv) {
         // --client-psk-secrets
         cmdcfgs.emplace_back(SHRPX_OPT_CLIENT_PSK_SECRETS, StringRef{optarg});
         break;
+      case 149:
+        // --client-no-http2-cipher-black-list
+        cmdcfgs.emplace_back(SHRPX_OPT_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST,
+                             StringRef::from_lit("yes"));
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -2004,6 +2004,11 @@ int option_lookup_token(const char *name, size_t namelen) {
         return SHRPX_OPTID_TLS_TICKET_KEY_MEMCACHED_MAX_FAIL;
       }
       break;
+    case 't':
+      if (util::strieq_l("client-no-http2-cipher-black-lis", name, 32)) {
+        return SHRPX_OPTID_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST;
+      }
+      break;
     }
     break;
   case 34:
@@ -3274,6 +3279,11 @@ int parse_config(Config *config, int optid, const StringRef &opt,
     return parse_psk_secrets(config, optarg);
   case SHRPX_OPTID_CLIENT_PSK_SECRETS:
     return parse_client_psk_secrets(config, optarg);
+  case SHRPX_OPTID_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST:
+    config->tls.client.no_http2_cipher_black_list =
+        util::strieq_l("yes", optarg);
+
+    return 0;
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";
 

src/shrpx_config.h

@@ -322,6 +322,8 @@ constexpr auto SHRPX_OPT_FRONTEND_KEEP_ALIVE_TIMEOUT =
 constexpr auto SHRPX_OPT_PSK_SECRETS = StringRef::from_lit("psk-secrets");
 constexpr auto SHRPX_OPT_CLIENT_PSK_SECRETS =
     StringRef::from_lit("client-psk-secrets");
+constexpr auto SHRPX_OPT_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST =
+    StringRef::from_lit("client-no-http2-cipher-black-list");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -556,6 +558,7 @@ struct TLSConfig {
     } psk;
     StringRef private_key_file;
     StringRef cert_file;
+    bool no_http2_cipher_black_list;
   } client;
 
   // PSK secrets.  The key is identity, and the associated value is
@@ -924,6 +927,7 @@ enum {
   SHRPX_OPTID_CIPHERS,
   SHRPX_OPTID_CLIENT,
   SHRPX_OPTID_CLIENT_CERT_FILE,
+  SHRPX_OPTID_CLIENT_NO_HTTP2_CIPHER_BLACK_LIST,
   SHRPX_OPTID_CLIENT_PRIVATE_KEY_FILE,
   SHRPX_OPTID_CLIENT_PROXY,
   SHRPX_OPTID_CLIENT_PSK_SECRETS,

src/shrpx_connection.cc

@@ -141,7 +141,10 @@ void Connection::disconnect() {
 
 void Connection::prepare_client_handshake() { SSL_set_connect_state(tls.ssl); }
 
-void Connection::prepare_server_handshake() { SSL_set_accept_state(tls.ssl); }
+void Connection::prepare_server_handshake() {
+  SSL_set_accept_state(tls.ssl);
+  tls.server_handshake = true;
+}
 
 // BIO implementation is inspired by openldap implementation:
 // http://www.openldap.org/devel/cvsweb.cgi/~checkout~/libraries/libldap/tls_o.c
@@ -530,7 +533,15 @@ int Connection::check_http2_requirement() {
     }
     return -1;
   }
-  if (!get_config()->tls.no_http2_cipher_black_list &&
+
+  auto check_black_list = false;
+  if (tls.server_handshake) {
+    check_black_list = !get_config()->tls.no_http2_cipher_black_list;
+  } else {
+    check_black_list = !get_config()->tls.client.no_http2_cipher_black_list;
+  }
+
+  if (check_black_list &&
       nghttp2::ssl::check_http2_cipher_black_list(tls.ssl)) {
     if (LOG_ENABLED(INFO)) {
       LOG(INFO) << "The negotiated cipher suite is in HTTP/2 cipher suite "

src/shrpx_connection.h

@@ -64,6 +64,8 @@ struct TLSConnection {
   int handshake_state;
   bool initial_handshake_done;
   bool reneg_started;
+  // true if ssl is prepared to do handshake as server.
+  bool server_handshake;
 };
 
 struct TCPHint {