make listening socket creation optional for userspace path manager plugins

include/mptcpd/path_manager.h

@@ -126,6 +126,24 @@ MPTCPD_API int mptcpd_pm_add_addr(struct mptcpd_pm *pm,
                                   mptcpd_aid_t id,
                                   mptcpd_token_t token);
 
+/**
+ * @brief Advertise new network address to peers without creating a listener.
+ *
+ * @param[in]     pm    The mptcpd path manager object.
+ * @param[in,out] addr  Local IP address and port to be advertised
+ *                      through the MPTCP protocol @c ADD_ADDR
+ *                      option.  If the port is zero no port will be
+ *                      specified on the underlying protocol level.
+ * @param[in]     id    MPTCP local address ID.
+ * @param[in]     token MPTCP connection token.
+ *
+ * @return @c 0 if operation was successful. -1 or @c errno otherwise.
+ */
+MPTCPD_API int mptcpd_pm_add_addr_no_listener(struct mptcpd_pm *pm,
+                                              struct sockaddr *addr,
+                                              mptcpd_aid_t id,
+                                              mptcpd_token_t token);
+
 /**
  * @brief Stop advertising network address to peers.
  *

include/mptcpd/private/path_manager.h

@@ -150,14 +150,16 @@ struct mptcpd_pm_cmd_ops
          *                      network byte order.
          * @param[in]     id    MPTCP local address ID.
          * @param[in]     token MPTCP connection token.
+         * @param[in]     nolst Don't create listener.
          *
          * @return @c 0 if operation was successful. -1 or @c errno
          *         otherwise.
          */
         int (*add_addr)(struct mptcpd_pm *pm,
                         struct sockaddr *addr,
                         mptcpd_aid_t id,
-                        mptcpd_token_t token);
+                        mptcpd_token_t token,
+                        bool nolst);
 
         /**
          * @brief Stop advertising network address to peers.

lib/path_manager.c

@@ -43,6 +43,31 @@ static bool is_pm_ready(struct mptcpd_pm const *pm, char const *fname)
         return ready;
 }
 
+static int do_pm_add_addr(struct mptcpd_pm *pm,
+                          struct sockaddr *addr,
+                          mptcpd_aid_t address_id,
+                          mptcpd_token_t token,
+                          bool nolst)
+{
+        if (pm == NULL || addr == NULL || address_id == 0)
+                return EINVAL;
+
+        if (!is_pm_ready(pm, __func__))
+                return EAGAIN;
+
+        struct mptcpd_pm_cmd_ops const *const ops =
+                pm->netlink_pm->cmd_ops;
+
+        if (ops == NULL || ops->add_addr == NULL)
+                return ENOTSUP;
+
+        return ops->add_addr(pm,
+                             addr,
+                             address_id,
+                             token,
+                             nolst);
+}
+
 // --------------------------------------------------------------------
 
 bool mptcpd_pm_register_ops(struct mptcpd_pm *pm,
@@ -243,22 +268,15 @@ int mptcpd_pm_add_addr(struct mptcpd_pm *pm,
                        mptcpd_aid_t address_id,
                        mptcpd_token_t token)
 {
-        if (pm == NULL || addr == NULL || address_id == 0)
-                return EINVAL;
-
-        if (!is_pm_ready(pm, __func__))
-                return EAGAIN;
-
-        struct mptcpd_pm_cmd_ops const *const ops =
-                pm->netlink_pm->cmd_ops;
-
-        if (ops == NULL || ops->add_addr == NULL)
-                return ENOTSUP;
+        return do_pm_add_addr(pm, addr, address_id, token, false);
+}
 
-        return ops->add_addr(pm,
-                             addr,
-                             address_id,
-                             token);
+int mptcpd_pm_add_addr_no_listener(struct mptcpd_pm *pm,
+                                   struct sockaddr *addr,
+                                   mptcpd_aid_t address_id,
+                                   mptcpd_token_t token)
+{
+        return do_pm_add_addr(pm, addr, address_id, token, true);
 }
 
 int mptcpd_pm_remove_addr(struct mptcpd_pm *pm,

src/netlink_pm_mptcp_org.c

@@ -155,8 +155,11 @@ static bool append_remote_addr_attr(struct l_genl_msg *msg,
 static int mptcp_org_add_addr(struct mptcpd_pm *pm,
                               struct sockaddr *addr,
                               mptcpd_aid_t id,
-                              mptcpd_token_t token)
+                              mptcpd_token_t token,
+                              bool nolst)
 {
+	(void) nolst;
+
         /*
           Payload:
               Token

src/netlink_pm_upstream.c

@@ -219,20 +219,21 @@ static int send_add_addr(struct mptcpd_pm *pm,
 static int upstream_announce(struct mptcpd_pm *pm,
                              struct sockaddr *addr,
                              mptcpd_aid_t id,
-                             mptcpd_token_t token)
+                             mptcpd_token_t token,
+                             bool nolst)
 {
-        /**
-         * Set up MPTCP listening socket.
-         *
-         * @note An ephemeral port will be assigned to the port in
-         *       @a addr if it is zero.
-         *
-         * @todo This should be optional.
-         */
-        int const r = mptcpd_lm_listen(pm->lm, addr);
+        if (!nolst) {
+                /**
+                 * Set up MPTCP listening socket.
+                 *
+                 * @note An ephemeral port will be assigned to the port in
+                 *       @a addr if it is zero.
+                 */
+                int const r = mptcpd_lm_listen(pm->lm, addr);
 
-        if (r != 0)
-                return r;
+                if (r != 0)
+                        return r;
+        }
 
         /**
          * @todo Add support for the optional network interface index