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mgcp_network: fix implicit address loopback 

A call agent may send a CRCX to create a connection in LOOPBACK mode but
without specifiying the destination address. In those cases the MGW
should deduct the destination address from the first incoming RTP
packet.

Unfortunately this is currently blocked by an OSMO_ASSERT that checks the
current sa_familiy against the sa_family from the incoming packet. This
makes no sense since the current sa_family is still uninitalized, which
is expected and not an error since the code that follows will initalize
it.

It also makes sense not to access the osmo_sockaddr struct members
individually but rather copy the address as a wohle.

Since the event only happens once and since it is also somewhat special
it makes sense to log the event as well.

Change-Id: I2dbd6f62170a7f62e5287d04a4ee6716b8786c26
Related: OS#5123
This commit is contained in:
Philipp Maier 2021-05-07 22:50:31 +02:00 committed by dexter
parent 427cede4ba
commit 97a9312be8
1 changed files with 14 additions and 6 deletions
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20
src/libosmo-mgcp/mgcp_network.c
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@ -1251,6 +1251,7 @@ int mgcp_dispatch_rtp_bridge_cb(struct msgb *msg)
struct mgcp_conn *conn = conn_src->conn;
struct mgcp_conn *conn_dst;
struct osmo_sockaddr *from_addr = mc->from_addr;
char ipbuf[INET6_ADDRSTRLEN];
/*! NOTE: This callback function implements the endpoint specific
* dispatch behaviour of an rtp bridge/proxy endpoint. It is assumed
@ -1269,19 +1270,22 @@ int mgcp_dispatch_rtp_bridge_cb(struct msgb *msg)
* address data from the UDP packet header to patch the
* outgoing address in connection on the fly */
if (conn->u.rtp.end.rtp_port == 0) {
OSMO_ASSERT(conn->u.rtp.end.addr.u.sa.sa_family == from_addr->u.sa.sa_family);
memcpy(&conn->u.rtp.end.addr, from_addr,
sizeof(conn->u.rtp.end.addr));
switch (from_addr->u.sa.sa_family) {
case AF_INET:
conn->u.rtp.end.addr.u.sin.sin_addr = from_addr->u.sin.sin_addr;
conn->u.rtp.end.rtp_port = from_addr->u.sin.sin_port;
break;
case AF_INET6:
conn->u.rtp.end.addr.u.sin6.sin6_addr = from_addr->u.sin6.sin6_addr;
conn->u.rtp.end.rtp_port = from_addr->u.sin6.sin6_port;
break;
default:
OSMO_ASSERT(false);
}
LOG_CONN_RTP(conn_src, LOGL_NOTICE,
"loopback mode: implicitly using source address (%s:%u) as destination address\n",
osmo_sockaddr_ntop(&from_addr->u.sa, ipbuf),
conn->u.rtp.end.rtp_port);
}
return mgcp_send_rtp(conn_src, msg);
}
@ -1331,6 +1335,7 @@ int mgcp_dispatch_e1_bridge_cb(struct msgb *msg)
struct mgcp_conn_rtp *conn_src = mc->conn_src;
struct mgcp_conn *conn = conn_src->conn;
struct osmo_sockaddr *from_addr = mc->from_addr;
char ipbuf[INET6_ADDRSTRLEN];
/* Check if the connection is in loopback mode, if yes, just send the
* incoming data back to the origin */
@ -1340,19 +1345,22 @@ int mgcp_dispatch_e1_bridge_cb(struct msgb *msg)
* address data from the UDP packet header to patch the
* outgoing address in connection on the fly */
if (conn->u.rtp.end.rtp_port == 0) {
OSMO_ASSERT(conn->u.rtp.end.addr.u.sa.sa_family == from_addr->u.sa.sa_family);
memcpy(&conn->u.rtp.end.addr, from_addr,
sizeof(conn->u.rtp.end.addr));
switch (from_addr->u.sa.sa_family) {
case AF_INET:
conn->u.rtp.end.addr.u.sin.sin_addr = from_addr->u.sin.sin_addr;
conn->u.rtp.end.rtp_port = from_addr->u.sin.sin_port;
break;
case AF_INET6:
conn->u.rtp.end.addr.u.sin6.sin6_addr = from_addr->u.sin6.sin6_addr;
conn->u.rtp.end.rtp_port = from_addr->u.sin6.sin6_port;
break;
default:
OSMO_ASSERT(false);
}
LOG_CONN_RTP(conn_src, LOGL_NOTICE,
"loopback mode: implicitly using source address (%s:%u) as destination address\n",
osmo_sockaddr_ntop(&from_addr->u.sa, ipbuf),
conn->u.rtp.end.rtp_port);
}
return mgcp_send_rtp(conn_src, msg);
}