[SGsAP] Refactor VLR Lookup to Use Socket Pointers Instead of Addresses (#3344)

Updated the VLR (mme_vlr_t) lookup mechanism to identify VLR instances
using socket pointers rather than IP addresses.

Replaced the `mme_vlr_find_by_addr` function with `mme_vlr_find_by_sock` across
relevant modules, including `mme-context.c`, `mme-context.h`, and `mme-sm.c`.

Adjusted memory management for the `addr` field within the VLR structure
to ensure proper allocation and deallocation. Removed address assignments
in `sgsap-sctp.c` for usrsctp and updated logging to reflect the new socket-based
identification.

src/mme/mme-context.c

@@ -2816,6 +2816,8 @@ void mme_vlr_remove(mme_vlr_t *vlr)
 
     ogs_freeaddrinfo(vlr->sa_list);
     ogs_freeaddrinfo(vlr->local_sa_list);
+    if (vlr->addr)
+        ogs_free(vlr->addr);
     if (vlr->option)
         ogs_free(vlr->option);
 
@@ -2840,13 +2842,13 @@ void mme_vlr_close(mme_vlr_t *vlr)
         ogs_sctp_destroy(vlr->sock);
 }
 
-mme_vlr_t *mme_vlr_find_by_addr(const ogs_sockaddr_t *addr)
+mme_vlr_t *mme_vlr_find_by_sock(const ogs_sock_t *sock)
 {
     mme_vlr_t *vlr = NULL;
-    ogs_assert(addr);
+    ogs_assert(sock);
 
     ogs_list_for_each(&self.vlr_list, vlr) {
-        if (ogs_sockaddr_is_equal(vlr->addr, addr) == true)
+        if (vlr->sock == sock)
             return vlr;
     }
 

src/mme/mme-context.h

@@ -219,7 +219,7 @@ typedef struct mme_vlr_s {
     ogs_sockaddr_t  *local_sa_list;   /* VLR SGsAP Socket Local Address List */
 
     ogs_sock_t      *sock;      /* VLR SGsAP Socket */
-    ogs_sockaddr_t  *addr;      /* VLR SGsAP Connected Socket Address */
+    ogs_sockaddr_t  *addr;      /* VLR SGsAP Socket Address */
     ogs_sockopt_t   *option;    /* VLR SGsAP Socket Option */
     ogs_poll_t      *poll;      /* VLR SGsAP Poll */
 } mme_vlr_t;
@@ -946,7 +946,7 @@ mme_vlr_t *mme_vlr_add(
 void mme_vlr_remove(mme_vlr_t *vlr);
 void mme_vlr_remove_all(void);
 void mme_vlr_close(mme_vlr_t *vlr);
-mme_vlr_t *mme_vlr_find_by_addr(const ogs_sockaddr_t *addr);
+mme_vlr_t *mme_vlr_find_by_sock(const ogs_sock_t *sock);
 
 mme_csmap_t *mme_csmap_add(mme_vlr_t *vlr);
 void mme_csmap_remove(mme_csmap_t *csmap);

src/mme/mme-sm.c

@@ -978,12 +978,14 @@ cleanup:
 
         max_num_of_ostreams = e->max_num_of_ostreams;
 
-        vlr = mme_vlr_find_by_addr(addr);
-        ogs_free(addr);
-
+        vlr = mme_vlr_find_by_sock(sock);
         ogs_assert(vlr);
         ogs_assert(OGS_FSM_STATE(&vlr->sm));
 
+        if (vlr->addr)
+            ogs_free(vlr->addr);
+        vlr->addr = addr;
+
         vlr->max_num_of_ostreams =
                 ogs_min(max_num_of_ostreams, vlr->max_num_of_ostreams);
 
@@ -1003,12 +1005,14 @@ cleanup:
         ogs_assert(addr->ogs_sa_family == AF_INET ||
                 addr->ogs_sa_family == AF_INET6);
 
-        vlr = mme_vlr_find_by_addr(addr);
-        ogs_free(addr);
-
+        vlr = mme_vlr_find_by_sock(sock);
         ogs_assert(vlr);
         ogs_assert(OGS_FSM_STATE(&vlr->sm));
 
+        if (vlr->addr)
+            ogs_free(vlr->addr);
+        vlr->addr = addr;
+
         if (OGS_FSM_CHECK(&vlr->sm, sgsap_state_connected)) {
             e->vlr = vlr;
             ogs_fsm_dispatch(&vlr->sm, e);
@@ -1033,12 +1037,14 @@ cleanup:
         ogs_assert(addr->ogs_sa_family == AF_INET ||
                 addr->ogs_sa_family == AF_INET6);
 
-        vlr = mme_vlr_find_by_addr(addr);
-        ogs_free(addr);
-
+        vlr = mme_vlr_find_by_sock(sock);
         ogs_assert(vlr);
         ogs_assert(OGS_FSM_STATE(&vlr->sm));
 
+        if (vlr->addr)
+            ogs_free(vlr->addr);
+        vlr->addr = addr;
+
         e->vlr = vlr;
         ogs_fsm_dispatch(&vlr->sm, e);
 

src/mme/sgsap-sctp.c

@@ -44,33 +44,15 @@ ogs_sock_t *sgsap_client(mme_vlr_t *vlr)
     if (sock) {
         vlr->sock = sock;
 #if HAVE_USRSCTP
-        vlr->addr = vlr->sa_list;
         usrsctp_set_non_blocking((struct socket *)sock, 1);
         usrsctp_set_upcall((struct socket *)sock, usrsctp_recv_handler, NULL);
 #else
-
-/*
- * Originally, the code assigned vlr->addr to the address of sock->remote_addr:
- *   vlr->addr = &sock->remote_addr;
- * However, when using sctp_connectx, it was not easy to set remote_addr.
- * Therefore, at this point, vlr->addr is now assigned to vlr->sa_list,
- * utilizing the initially used address:
- *   vlr->addr = vlr->sa_list;
- *
- * This approach may lead to issues when connecting to multiple addresses,
- * as subsequent addresses cannot be accurately compared using the 'from'
- * parameter in sctp_recvmsg.
- *
- * Since a proper solution is deferred, it is recommended to avoid using
- * sctp_connectx with multiple addresses for the time being.
- */
-        vlr->addr = vlr->sa_list;
         vlr->poll = ogs_pollset_add(ogs_app()->pollset,
                 OGS_POLLIN, sock->fd, lksctp_recv_handler, sock);
         ogs_assert(vlr->poll);
 #endif
         ogs_info("sgsap client() [%s]:%d",
-                OGS_ADDR(vlr->addr, buf), OGS_PORT(vlr->addr));
+                OGS_ADDR(vlr->sa_list, buf), OGS_PORT(vlr->sa_list));
     }
 
     return sock;