HTTP/2: "http2" directive.

The directive enables HTTP/2 in the current server.  The previous way to
enable HTTP/2 via "listen ... http2" is now deprecated.  The new approach
allows to share HTTP/2 and HTTP/0.9-1.1 on the same port.

For SSL connections, HTTP/2 is now selected by ALPN callback based on whether
the protocol is enabled in the virtual server chosen by SNI.  This however only
works since OpenSSL 1.0.2h, where ALPN callback is invoked after SNI callback.
For older versions of OpenSSL, HTTP/2 is enabled based on the default virtual
server configuration.

For plain TCP connections, HTTP/2 is now auto-detected by HTTP/2 preface, if
HTTP/2 is enabled in the default virtual server.  If preface is not matched,
HTTP/0.9-1.1 is assumed.

src/http/modules/ngx_http_ssl_module.c

@@ -435,6 +435,9 @@ ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn, const unsigned char **out,
 #if (NGX_HTTP_V2 || NGX_HTTP_V3)
     ngx_http_connection_t   *hc;
 #endif
+#if (NGX_HTTP_V2)
+    ngx_http_v2_srv_conf_t  *h2scf;
+#endif
 #if (NGX_HTTP_V3)
     ngx_http_v3_srv_conf_t  *h3scf;
 #endif
@@ -456,12 +459,6 @@ ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn, const unsigned char **out,
     hc = c->data;
 #endif
 
-#if (NGX_HTTP_V2)
-    if (hc->addr_conf->http2) {
-        srv = (unsigned char *) NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS;
-        srvlen = sizeof(NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS) - 1;
-    } else
-#endif
 #if (NGX_HTTP_V3)
     if (hc->addr_conf->quic) {
 
@@ -488,8 +485,19 @@ ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn, const unsigned char **out,
     } else
 #endif
     {
-        srv = (unsigned char *) NGX_HTTP_ALPN_PROTOS;
-        srvlen = sizeof(NGX_HTTP_ALPN_PROTOS) - 1;
+#if (NGX_HTTP_V2)
+        h2scf = ngx_http_get_module_srv_conf(hc->conf_ctx, ngx_http_v2_module);
+
+        if (h2scf->enable || hc->addr_conf->http2) {
+            srv = (unsigned char *) NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS;
+            srvlen = sizeof(NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS) - 1;
+
+        } else
+#endif
+        {
+            srv = (unsigned char *) NGX_HTTP_ALPN_PROTOS;
+            srvlen = sizeof(NGX_HTTP_ALPN_PROTOS) - 1;
+        }
     }
 
     if (SSL_select_next_proto((unsigned char **) out, outlen, srv, srvlen,

src/http/ngx_http_core_module.c

@@ -4176,6 +4176,11 @@ ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 
         if (ngx_strcmp(value[n].data, "http2") == 0) {
 #if (NGX_HTTP_V2)
+            ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+                               "the \"listen ... http2\" directive "
+                               "is deprecated, use "
+                               "the \"http2\" directive instead");
+
             lsopt.http2 = 1;
             continue;
 #else

src/http/ngx_http_request.c

@@ -318,12 +318,6 @@ ngx_http_init_connection(ngx_connection_t *c)
     rev->handler = ngx_http_wait_request_handler;
     c->write->handler = ngx_http_empty_handler;
 
-#if (NGX_HTTP_V2)
-    if (hc->addr_conf->http2) {
-        rev->handler = ngx_http_v2_init;
-    }
-#endif
-
 #if (NGX_HTTP_V3)
     if (hc->addr_conf->quic) {
         ngx_http_v3_init_stream(c);
@@ -383,6 +377,9 @@ ngx_http_wait_request_handler(ngx_event_t *rev)
     ngx_buf_t                 *b;
     ngx_connection_t          *c;
     ngx_http_connection_t     *hc;
+#if (NGX_HTTP_V2)
+    ngx_http_v2_srv_conf_t    *h2scf;
+#endif
     ngx_http_core_srv_conf_t  *cscf;
 
     c = rev->data;
@@ -429,6 +426,8 @@ ngx_http_wait_request_handler(ngx_event_t *rev)
         b->end = b->last + size;
     }
 
+    size = b->end - b->last;
+
     n = c->recv(c, b->last, size);
 
     if (n == NGX_AGAIN) {
@@ -443,12 +442,16 @@ ngx_http_wait_request_handler(ngx_event_t *rev)
             return;
         }
 
-        /*
-         * We are trying to not hold c->buffer's memory for an idle connection.
-         */
+        if (b->pos == b->last) {
 
-        if (ngx_pfree(c->pool, b->start) == NGX_OK) {
-            b->start = NULL;
+            /*
+             * We are trying to not hold c->buffer's memory for an
+             * idle connection.
+             */
+
+            if (ngx_pfree(c->pool, b->start) == NGX_OK) {
+                b->start = NULL;
+            }
         }
 
         return;
@@ -489,6 +492,29 @@ ngx_http_wait_request_handler(ngx_event_t *rev)
         }
     }
 
+#if (NGX_HTTP_V2)
+
+    h2scf = ngx_http_get_module_srv_conf(hc->conf_ctx, ngx_http_v2_module);
+
+    if (!hc->ssl && (h2scf->enable || hc->addr_conf->http2)) {
+
+        size = ngx_min(sizeof(NGX_HTTP_V2_PREFACE) - 1,
+                       (size_t) (b->last - b->pos));
+
+        if (ngx_memcmp(b->pos, NGX_HTTP_V2_PREFACE, size) == 0) {
+
+            if (size == sizeof(NGX_HTTP_V2_PREFACE) - 1) {
+                ngx_http_v2_init(rev);
+                return;
+            }
+
+            ngx_post_event(rev, &ngx_posted_events);
+            return;
+        }
+    }
+
+#endif
+
     c->log->action = "reading client request line";
 
     ngx_reusable_connection(c, 0);
@@ -808,13 +834,16 @@ ngx_http_ssl_handshake_handler(ngx_connection_t *c)
 #if (NGX_HTTP_V2                                                              \
      && defined TLSEXT_TYPE_application_layer_protocol_negotiation)
         {
-        unsigned int            len;
-        const unsigned char    *data;
-        ngx_http_connection_t  *hc;
+        unsigned int             len;
+        const unsigned char     *data;
+        ngx_http_connection_t   *hc;
+        ngx_http_v2_srv_conf_t  *h2scf;
 
         hc = c->data;
 
-        if (hc->addr_conf->http2) {
+        h2scf = ngx_http_get_module_srv_conf(hc->conf_ctx, ngx_http_v2_module);
+
+        if (h2scf->enable || hc->addr_conf->http2) {
 
             SSL_get0_alpn_selected(c->ssl->connection, &data, &len);
 

src/http/v2/ngx_http_v2.c

@@ -63,8 +63,6 @@ static void ngx_http_v2_handle_connection(ngx_http_v2_connection_t *h2c);
 static void ngx_http_v2_lingering_close(ngx_connection_t *c);
 static void ngx_http_v2_lingering_close_handler(ngx_event_t *rev);
 
-static u_char *ngx_http_v2_state_proxy_protocol(ngx_http_v2_connection_t *h2c,
-    u_char *pos, u_char *end);
 static u_char *ngx_http_v2_state_preface(ngx_http_v2_connection_t *h2c,
     u_char *pos, u_char *end);
 static u_char *ngx_http_v2_state_preface_end(ngx_http_v2_connection_t *h2c,
@@ -232,6 +230,7 @@ static ngx_http_v2_parse_header_t  ngx_http_v2_parse_headers[] = {
 void
 ngx_http_v2_init(ngx_event_t *rev)
 {
+    u_char                    *p, *end;
     ngx_connection_t          *c;
     ngx_pool_cleanup_t        *cln;
     ngx_http_connection_t     *hc;
@@ -314,8 +313,7 @@ ngx_http_v2_init(ngx_event_t *rev)
         return;
     }
 
-    h2c->state.handler = hc->proxy_protocol ? ngx_http_v2_state_proxy_protocol
-                                            : ngx_http_v2_state_preface;
+    h2c->state.handler = ngx_http_v2_state_preface;
 
     ngx_queue_init(&h2c->waiting);
     ngx_queue_init(&h2c->dependencies);
@@ -335,6 +333,23 @@ ngx_http_v2_init(ngx_event_t *rev)
     c->idle = 1;
     ngx_reusable_connection(c, 0);
 
+    if (c->buffer) {
+        p = c->buffer->pos;
+        end = c->buffer->last;
+
+        do {
+            p = h2c->state.handler(h2c, p, end);
+
+            if (p == NULL) {
+                return;
+            }
+
+        } while (p != end);
+
+        h2c->total_bytes += p - c->buffer->pos;
+        c->buffer->pos = p;
+    }
+
     ngx_http_v2_read_handler(rev);
 }
 
@@ -846,32 +861,11 @@ ngx_http_v2_lingering_close_handler(ngx_event_t *rev)
 }
 
 
-static u_char *
-ngx_http_v2_state_proxy_protocol(ngx_http_v2_connection_t *h2c, u_char *pos,
-    u_char *end)
-{
-    ngx_log_t  *log;
-
-    log = h2c->connection->log;
-    log->action = "reading PROXY protocol";
-
-    pos = ngx_proxy_protocol_read(h2c->connection, pos, end);
-
-    log->action = "processing HTTP/2 connection";
-
-    if (pos == NULL) {
-        return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_PROTOCOL_ERROR);
-    }
-
-    return ngx_http_v2_state_preface(h2c, pos, end);
-}
-
-
 static u_char *
 ngx_http_v2_state_preface(ngx_http_v2_connection_t *h2c, u_char *pos,
     u_char *end)
 {
-    static const u_char preface[] = "PRI * HTTP/2.0\r\n";
+    static const u_char preface[] = NGX_HTTP_V2_PREFACE_START;
 
     if ((size_t) (end - pos) < sizeof(preface) - 1) {
         return ngx_http_v2_state_save(h2c, pos, end, ngx_http_v2_state_preface);
@@ -892,7 +886,7 @@ static u_char *
 ngx_http_v2_state_preface_end(ngx_http_v2_connection_t *h2c, u_char *pos,
     u_char *end)
 {
-    static const u_char preface[] = "\r\nSM\r\n\r\n";
+    static const u_char preface[] = NGX_HTTP_V2_PREFACE_END;
 
     if ((size_t) (end - pos) < sizeof(preface) - 1) {
         return ngx_http_v2_state_save(h2c, pos, end,
@@ -3943,10 +3937,22 @@ static void
 ngx_http_v2_run_request(ngx_http_request_t *r)
 {
     ngx_connection_t          *fc;
+    ngx_http_v2_srv_conf_t    *h2scf;
     ngx_http_v2_connection_t  *h2c;
 
     fc = r->connection;
 
+    h2scf = ngx_http_get_module_srv_conf(r, ngx_http_v2_module);
+
+    if (!h2scf->enable && !r->http_connection->addr_conf->http2) {
+        ngx_log_error(NGX_LOG_INFO, fc->log, 0,
+                      "client attempted to request the server name "
+                      "for which the negotiated protocol is disabled");
+
+        ngx_http_finalize_request(r, NGX_HTTP_MISDIRECTED_REQUEST);
+        goto failed;
+    }
+
     if (ngx_http_v2_construct_request_line(r) != NGX_OK) {
         goto failed;
     }

src/http/v2/ngx_http_v2.h

@@ -63,6 +63,16 @@ typedef u_char *(*ngx_http_v2_handler_pt) (ngx_http_v2_connection_t *h2c,
     u_char *pos, u_char *end);
 
 
+typedef struct {
+    ngx_flag_t                       enable;
+    size_t                           pool_size;
+    ngx_uint_t                       concurrent_streams;
+    ngx_uint_t                       concurrent_pushes;
+    size_t                           preread_size;
+    ngx_uint_t                       streams_index_mask;
+} ngx_http_v2_srv_conf_t;
+
+
 typedef struct {
     ngx_str_t                        name;
     ngx_str_t                        value;
@@ -408,9 +418,17 @@ ngx_int_t ngx_http_v2_table_size(ngx_http_v2_connection_t *h2c, size_t size);
 #define NGX_HTTP_V2_USER_AGENT_INDEX      58
 #define NGX_HTTP_V2_VARY_INDEX            59
 
+#define NGX_HTTP_V2_PREFACE_START         "PRI * HTTP/2.0\r\n"
+#define NGX_HTTP_V2_PREFACE_END           "\r\nSM\r\n\r\n"
+#define NGX_HTTP_V2_PREFACE               NGX_HTTP_V2_PREFACE_START           \
+                                          NGX_HTTP_V2_PREFACE_END
+
 
 u_char *ngx_http_v2_string_encode(u_char *dst, u_char *src, size_t len,
     u_char *tmp, ngx_uint_t lower);
 
 
+extern ngx_module_t  ngx_http_v2_module;
+
+
 #endif /* _NGX_HTTP_V2_H_INCLUDED_ */

src/http/v2/ngx_http_v2_module.c

@@ -75,6 +75,13 @@ static ngx_conf_post_t  ngx_http_v2_chunk_size_post =
 
 static ngx_command_t  ngx_http_v2_commands[] = {
 
+    { ngx_string("http2"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_HTTP_SRV_CONF_OFFSET,
+      offsetof(ngx_http_v2_srv_conf_t, enable),
+      NULL },
+
     { ngx_string("http2_recv_buffer_size"),
       NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
       ngx_conf_set_size_slot,
@@ -314,6 +321,8 @@ ngx_http_v2_create_srv_conf(ngx_conf_t *cf)
         return NULL;
     }
 
+    h2scf->enable = NGX_CONF_UNSET;
+
     h2scf->pool_size = NGX_CONF_UNSET_SIZE;
 
     h2scf->concurrent_streams = NGX_CONF_UNSET_UINT;
@@ -333,6 +342,8 @@ ngx_http_v2_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_http_v2_srv_conf_t *prev = parent;
     ngx_http_v2_srv_conf_t *conf = child;
 
+    ngx_conf_merge_value(conf->enable, prev->enable, 0);
+
     ngx_conf_merge_size_value(conf->pool_size, prev->pool_size, 4096);
 
     ngx_conf_merge_uint_value(conf->concurrent_streams,

src/http/v2/ngx_http_v2_module.h

@@ -20,15 +20,6 @@ typedef struct {
 } ngx_http_v2_main_conf_t;
 
 
-typedef struct {
-    size_t                          pool_size;
-    ngx_uint_t                      concurrent_streams;
-    ngx_uint_t                      concurrent_pushes;
-    size_t                          preread_size;
-    ngx_uint_t                      streams_index_mask;
-} ngx_http_v2_srv_conf_t;
-
-
 typedef struct {
     size_t                          chunk_size;
 
@@ -39,7 +30,4 @@ typedef struct {
 } ngx_http_v2_loc_conf_t;
 
 
-extern ngx_module_t  ngx_http_v2_module;
-
-
 #endif /* _NGX_HTTP_V2_MODULE_H_INCLUDED_ */