Multipath TCP patches from BZ 69292

docs/manual/mod/mod_proxy.xml

@@ -1326,6 +1326,10 @@ ProxyPass "/example" "http://backend.example.com" max=20 ttl=120 retry=300
         <td><p>TTL in seconds for how long DNS resolutions of the backend address are cached.
         -1 means until restart of Apache httpd.</p>
     </td></tr>
+    <tr><td><a id="multipathtcp" name="multipathtcp">multipathtcp</a></td>
+        <td>Off</td>
+        <td><p>Enable/disable the use of <a href="https://mptcp.dev">Multipath TCP (MPTCP)</a></p>
+    </td></tr>
 
     </table>
 

docs/manual/mod/mpm_common.xml

@@ -278,6 +278,12 @@ Listen 192.170.2.5:8000
       to the same port.  (If the server is built with IPv4-mapped
       addresses <em>disabled</em>, this is the default behaviour and
       this option has no effect.)</li>
+
+      <li><code>multipathtcp</code>: Enable the use of
+      <a href="https://mptcp.dev">Multipath TCP (MPTCP)</a> for the
+      sockets. Beware that this option is currently limited to Linux
+      only.
+      </li>
     </ul>
 
     <note><title>Error condition</title>

include/ap_listen.h

@@ -44,6 +44,7 @@ typedef apr_status_t (*accept_function)(void **csd, ap_listen_rec *lr, apr_pool_
 #define AP_LISTEN_FREEBIND        (0x0002)
 #define AP_LISTEN_REUSEPORT       (0x0004)
 #define AP_LISTEN_V6ONLY          (0x0008)
+#define AP_LISTEN_MPTCP           (0x0010)
 
 /**
  * @brief Apache's listeners record.

modules/proxy/mod_proxy.c

@@ -356,6 +356,18 @@ static const char *set_worker_param(apr_pool_t *p,
         worker->s->response_field_size = (s ? s : HUGE_STRING_LEN);
         worker->s->response_field_size_set = 1;
     }
+    else if (!strcasecmp(key, "multipathtcp")) {
+#ifdef IPPROTO_MPTCP
+        if (!strcasecmp(val, "On"))
+            worker->s->sock_proto = IPPROTO_MPTCP;
+        else if (!strcasecmp(val, "Off"))
+            worker->s->sock_proto = APR_PROTO_TCP;
+        else
+            return "multipathtcp must be On|Off";
+#else
+        return "multipathtcp is not supported on your platform";
+#endif
+    }
     else {
         if (set_worker_hc_param_f) {
             return set_worker_hc_param_f(p, s, worker, key, val, NULL);

modules/proxy/mod_proxy.h

@@ -497,6 +497,7 @@ typedef struct {
     unsigned int     address_ttl_set:1;
     apr_int32_t      address_ttl;    /* backend address' TTL (seconds) */
     apr_uint32_t     address_expiry; /* backend address' next expiry time */
+    int              sock_proto;     /* The protocol to use to create the socket */
 } proxy_worker_shared;
 
 #define ALIGNED_PROXY_WORKER_SHARED_SIZE (APR_ALIGN_DEFAULT(sizeof(proxy_worker_shared)))

modules/proxy/proxy_util.c

@@ -3858,7 +3858,7 @@ PROXY_DECLARE(int) ap_proxy_connect_backend(const char *proxy_function,
 #endif
         {
             if ((rv = apr_socket_create(&newsock, backend_addr->family,
-                                        SOCK_STREAM, APR_PROTO_TCP,
+                                        SOCK_STREAM, worker->s->sock_proto,
                                         conn->scpool)) != APR_SUCCESS) {
                 loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
                 ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00952)

server/listen.c

@@ -496,6 +496,12 @@ static const char *alloc_listener(process_rec *process, const char *addr,
 
     while (sa) {
         ap_listen_rec *new;
+        int sock_proto = 0;
+
+#ifdef IPPROTO_MPTCP
+        if (flags & AP_LISTEN_MPTCP)
+            sock_proto = IPPROTO_MPTCP;
+#endif
 
         /* this has to survive restarts */
         new = apr_palloc(process->pool, sizeof(ap_listen_rec));
@@ -509,7 +515,7 @@ static const char *alloc_listener(process_rec *process, const char *addr,
         sa = sa->next;
 
         status = apr_socket_create(&new->sd, new->bind_addr->family,
-                                    SOCK_STREAM, 0, process->pool);
+                                    SOCK_STREAM, sock_proto, process->pool);
 
 #if APR_HAVE_IPV6
         /* What could happen is that we got an IPv6 address, but this system
@@ -864,6 +870,7 @@ AP_DECLARE(apr_status_t) ap_duplicate_listeners(apr_pool_t *p, server_rec *s,
             char *hostname;
             apr_port_t port;
             apr_sockaddr_t *sa;
+            int sock_proto = 0;
 #ifdef HAVE_SYSTEMD
             if (use_systemd) {
                 int thesock;
@@ -891,8 +898,12 @@ AP_DECLARE(apr_status_t) ap_duplicate_listeners(apr_pool_t *p, server_rec *s,
                 duplr->bind_addr = sa;
                 duplr->next = NULL;
                 duplr->flags = lr->flags;
+#ifdef IPPROTO_MPTCP
+                if (duplr->flags & AP_LISTEN_MPTCP)
+                    sock_proto = IPPROTO_MPTCP;
+#endif
                 stat = apr_socket_create(&duplr->sd, duplr->bind_addr->family,
-                                         SOCK_STREAM, 0, p);
+                                         SOCK_STREAM, sock_proto, p);
                 if (stat != APR_SUCCESS) {
                     ap_log_perror(APLOG_MARK, APLOG_CRIT, 0, p, APLOGNO(02640)
                                 "ap_duplicate_listeners: for address %pI, "
@@ -1038,6 +1049,13 @@ static const char *parse_listen_flags(apr_pool_t *temp_pool, const char *arg,
             flags |= AP_LISTEN_REUSEPORT;
         else if (ap_cstr_casecmp(token, "v6only") == 0)
             flags |= AP_LISTEN_V6ONLY;
+        else if (ap_cstr_casecmp(token, "multipathtcp") == 0)
+#ifdef IPPROTO_MPTCP
+            flags |= AP_LISTEN_MPTCP;
+#else
+            return apr_psprintf(temp_pool, "Listen option '%s' in '%s' is not supported on this system",
+                                token, arg);
+#endif
         else
             return apr_psprintf(temp_pool, "Unknown Listen option '%s' in '%s'",
                                 token, arg);