API: add ea_alpn that is used when not in HTTP mode

include/lsquic.h

@@ -1019,6 +1019,12 @@ struct lsquic_engine_api
      */
     const struct lsquic_keylog_if       *ea_keylog_if;
     void                                *ea_keylog_ctx;
+
+    /**
+     * The optional ALPN string is used by the client @ref LSENG_HTTP
+     * is not set.
+     */
+    const char                          *ea_alpn;
 };
 
 /**

src/liblsquic/lsquic_enc_sess_ietf.c

@@ -70,7 +70,7 @@
 static const struct alpn_map {
     enum lsquic_version  version;
     const unsigned char *alpn;
-} s_alpns[] = {
+} s_h3_alpns[] = {
     {   LSQVER_ID25, (unsigned char *) "\x05h3-25",     },
     {   LSQVER_ID27, (unsigned char *) "\x05h3-27",     },
     {   LSQVER_VERNEG, (unsigned char *) "\x05h3-27",     },
@@ -1097,17 +1097,19 @@ iquic_esfi_init_server (enc_session_t *enc_session_p)
         unsigned char trans_params[sizeof(struct transport_params)];
     } u;
 
-    for (am = s_alpns; am < s_alpns + sizeof(s_alpns)
+    if (enc_sess->esi_enpub->enp_alpn)
-                                                / sizeof(s_alpns[0]); ++am)
+        enc_sess->esi_alpn = enc_sess->esi_enpub->enp_alpn;
-        if (am->version == enc_sess->esi_conn->cn_version)
+    else if (enc_sess->esi_enpub->enp_flags & ENPUB_HTTP)
-            goto ok;
+    {
-
+        for (am = s_h3_alpns; am < s_h3_alpns + sizeof(s_h3_alpns)
-    LSQ_ERROR("version %s has no matching ALPN",
+                                                / sizeof(s_h3_alpns[0]); ++am)
-                            lsquic_ver2str[enc_sess->esi_conn->cn_version]);
+            if (am->version == enc_sess->esi_conn->cn_version)
-    return -1;
+                goto ok;
-
+        LSQ_ERROR("version %s has no matching ALPN",
-  ok:
+                                lsquic_ver2str[enc_sess->esi_conn->cn_version]);
-    enc_sess->esi_alpn = am->alpn;
+        return -1;
+  ok:   enc_sess->esi_alpn = am->alpn;
+    }
 
     ssl_ctx = enc_sess->esi_enpub->enp_get_ssl_ctx(
                     lsquic_conn_get_peer_ctx(enc_sess->esi_conn, NULL));
@@ -1261,17 +1263,20 @@ init_client (struct enc_sess_iquic *const enc_sess)
 #endif
     ];
 
-    for (am = s_alpns; am < s_alpns + sizeof(s_alpns)
+    if (enc_sess->esi_enpub->enp_alpn)
-                                                / sizeof(s_alpns[0]); ++am)
+        enc_sess->esi_alpn = enc_sess->esi_enpub->enp_alpn;
-        if (am->version == enc_sess->esi_ver_neg->vn_ver)
+    else if (enc_sess->esi_enpub->enp_flags & ENPUB_HTTP)
-            goto ok;
+    {
+        for (am = s_h3_alpns; am < s_h3_alpns + sizeof(s_h3_alpns)
+                                                / sizeof(s_h3_alpns[0]); ++am)
+            if (am->version == enc_sess->esi_ver_neg->vn_ver)
+                goto ok;
+        LSQ_ERROR("version %s has no matching ALPN",
+                                lsquic_ver2str[enc_sess->esi_ver_neg->vn_ver]);
+        return -1;
+  ok:   enc_sess->esi_alpn = am->alpn;
+    }
 
-    LSQ_ERROR("version %s has no matching ALPN",
-                            lsquic_ver2str[enc_sess->esi_ver_neg->vn_ver]);
-    return -1;
-
-  ok:
-    enc_sess->esi_alpn = am->alpn;
     LSQ_DEBUG("Create new SSL_CTX");
     ssl_ctx = SSL_CTX_new(TLS_method());
     if (!ssl_ctx)
@@ -1320,7 +1325,9 @@ init_client (struct enc_sess_iquic *const enc_sess)
             ERR_error_string(ERR_get_error(), errbuf));
         goto err;
     }
-    if (0 != SSL_set_alpn_protos(enc_sess->esi_ssl, am->alpn, am->alpn[0] + 1))
+    if (enc_sess->esi_alpn &&
+            0 != SSL_set_alpn_protos(enc_sess->esi_ssl, enc_sess->esi_alpn,
+                                                    enc_sess->esi_alpn[0] + 1))
     {
         LSQ_ERROR("cannot set ALPN: %s",
             ERR_error_string(ERR_get_error(), errbuf));
@@ -2437,7 +2444,8 @@ cry_sm_set_encryption_secret (SSL *ssl, enum ssl_encryption_level_t level,
     if (!enc_sess)
         return 0;
 
-    if ((enc_sess->esi_flags & (ESI_ALPN_CHECKED|ESI_SERVER)) == ESI_SERVER)
+    if ((enc_sess->esi_flags & (ESI_ALPN_CHECKED|ESI_SERVER)) == ESI_SERVER
+                                                        && enc_sess->esi_alpn)
     {
         enc_sess->esi_flags |= ESI_ALPN_CHECKED;
         SSL_get0_alpn_selected(enc_sess->esi_ssl, &alpn, &alpn_len);

src/liblsquic/lsquic_engine.c

@@ -463,6 +463,7 @@ lsquic_engine_new (unsigned flags,
                    const struct lsquic_engine_api *api)
 {
     lsquic_engine_t *engine;
+    size_t alpn_len;
     char err_buf[100];
 
     if (!api->ea_packets_out)
@@ -477,6 +478,18 @@ lsquic_engine_new (unsigned flags,
         return NULL;
     }
 
+    if (!(flags & LSENG_HTTP) && api->ea_alpn)
+    {
+        alpn_len = strlen(api->ea_alpn);
+        if (alpn_len < 1 || alpn_len > 255)
+        {
+            LSQ_ERROR("ALPN string length invalid: %zd bytes", alpn_len);
+            return NULL;
+        }
+    }
+    else
+        alpn_len = 0;
+
     if (api->ea_settings &&
                 0 != lsquic_engine_check_settings(api->ea_settings, flags,
                                                     err_buf, sizeof(err_buf)))
@@ -605,6 +618,21 @@ lsquic_engine_new (unsigned flags,
         }
     }
 
+    if (alpn_len)
+    {
+        engine->pub.enp_alpn = malloc(alpn_len + 1);
+        if (!engine->pub.enp_alpn)
+        {
+            lsquic_engine_destroy(engine);
+            return NULL;
+        }
+        engine->pub.enp_alpn[0] = alpn_len;
+        memcpy(engine->pub.enp_alpn + 1, api->ea_alpn, alpn_len);
+    }
+
+    if (flags & LSENG_HTTP)
+        engine->pub.enp_flags |= ENPUB_HTTP;
+
 #ifndef NDEBUG
     {
         const char *env;
@@ -1458,6 +1486,7 @@ lsquic_engine_destroy (lsquic_engine_t *engine)
 #endif
     if (engine->pub.enp_retry_aead_ctx)
         EVP_AEAD_CTX_cleanup(engine->pub.enp_retry_aead_ctx);
+    free(engine->pub.enp_alpn);
     free(engine);
 }
 

src/liblsquic/lsquic_engine_public.h

@@ -59,11 +59,13 @@ struct lsquic_engine_public {
                                  * functions.
                                  */
         ENPUB_CAN_SEND = (1 << 1),
+        ENPUB_HTTP  = (1 << 2), /* Engine in HTTP mode */
     }                               enp_flags;
     unsigned char                   enp_ver_tags_buf[ sizeof(lsquic_ver_tag_t) * N_LSQVER ];
     unsigned                        enp_ver_tags_len;
     struct crand                   *enp_crand;
     struct evp_aead_ctx_st         *enp_retry_aead_ctx;
+    unsigned char                  *enp_alpn;   /* May be set if not HTTP */
 };
 
 /* Put connection onto the Tickable Queue if it is not already on it.  If