1 files changed, 131 insertions, 0 deletions
diff --git a/modules/http2/h2_alt_svc.c b/modules/http2/h2_alt_svc.c
new file mode 100644
index 0000000..295a16d
--- /dev/null
+++ b/modules/http2/h2_alt_svc.c
@@ -0,0 +1,131 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <apr_strings.h>
+#include <httpd.h>
+#include <http_core.h>
+#include <http_connection.h>
+#include <http_protocol.h>
+#include <http_log.h>
+
+#include "h2_private.h"
+#include "h2_alt_svc.h"
+#include "h2_ctx.h"
+#include "h2_config.h"
+#include "h2_h2.h"
+#include "h2_util.h"
+
+static int h2_alt_svc_handler(request_rec *r);
+
+void h2_alt_svc_register_hooks(void)
+{
+    ap_hook_post_read_request(h2_alt_svc_handler, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+/**
+ * Parse an Alt-Svc specifier as described in "HTTP Alternative Services"
+ * (https://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-04)
+ * with the following changes:
+ * - do not percent encode token values
+ * - do not use quotation marks
+ */
+h2_alt_svc *h2_alt_svc_parse(const char *s, apr_pool_t *pool)
+{
+    const char *sep = ap_strchr_c(s, '=');
+    if (sep) {
+        const char *alpn = apr_pstrmemdup(pool, s, sep - s);
+        const char *host = NULL;
+        int port = 0;
+        s = sep + 1;
+        sep = ap_strchr_c(s, ':');  /* mandatory : */
+        if (sep) {
+            if (sep != s) {    /* optional host */
+                host = apr_pstrmemdup(pool, s, sep - s);
+            }
+            s = sep + 1;
+            if (*s) {          /* must be a port number */
+                port = (int)apr_atoi64(s);
+                if (port > 0 && port < (0x1 << 16)) {
+                    h2_alt_svc *as = apr_pcalloc(pool, sizeof(*as));
+                    as->alpn = alpn;
+                    as->host = host;
+                    as->port = port;
+                    return as;
+                }
+            }
+        }
+    }
+    return NULL;
+}
+
+#define h2_alt_svc_IDX(list, i) ((h2_alt_svc**)(list)->elts)[i]
+
+static int h2_alt_svc_handler(request_rec *r)
+{
+    const h2_config *cfg;
+    int i;
+    
+    if (r->connection->keepalives > 0) {
+        /* Only announce Alt-Svc on the first response */
+        return DECLINED;
+    }
+    
+    if (h2_ctx_rget(r)) {
+        return DECLINED;
+    }
+    
+    cfg = h2_config_sget(r->server);
+    if (r->hostname && cfg && cfg->alt_svcs && cfg->alt_svcs->nelts > 0) {
+        const char *alt_svc_used = apr_table_get(r->headers_in, "Alt-Svc-Used");
+        if (!alt_svc_used) {
+            /* We have alt-svcs defined and client is not already using
+             * one, announce the services that were configured and match. 
+             * The security of this connection determines if we allow
+             * other host names or ports only.
+             */
+            const char *alt_svc = "";
+            const char *svc_ma = "";
+            int secure = h2_h2_is_tls(r->connection);
+            int ma = h2_config_geti(cfg, H2_CONF_ALT_SVC_MAX_AGE);
+            if (ma >= 0) {
+                svc_ma = apr_psprintf(r->pool, "; ma=%d", ma);
+            }
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(03043)
+                          "h2_alt_svc: announce %s for %s:%d", 
+                          (secure? "secure" : "insecure"), 
+                          r->hostname, (int)r->server->port);
+            for (i = 0; i < cfg->alt_svcs->nelts; ++i) {
+                h2_alt_svc *as = h2_alt_svc_IDX(cfg->alt_svcs, i);
+                const char *ahost = as->host;
+                if (ahost && !apr_strnatcasecmp(ahost, r->hostname)) {
+                    ahost = NULL;
+                }
+                if (secure || !ahost) {
+                    alt_svc = apr_psprintf(r->pool, "%s%s%s=\"%s:%d\"%s", 
+                                           alt_svc,
+                                           (*alt_svc? ", " : ""), as->alpn,
+                                           ahost? ahost : "", as->port,
+                                           svc_ma);
+                }
+            }
+            if (*alt_svc) {
+                apr_table_setn(r->headers_out, "Alt-Svc", alt_svc);
+            }
+        }
+    }
+    
+    return DECLINED;
+}