[sr-dev] [kamailio/kamailio] usrloc keepalive does not work for TLS connections (Issue #3178)
abrezinsky
notifications at github.com
Sat Jul 9 00:58:02 CEST 2022
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### Description
The keepalive (ka*) features of usrloc does not work for TLS connections (and probably TCP). If a TLS connection is registered, the keepalive code attempts to send OPTIONS packets to the endpoint using UDP. Additionally, a TCP/TLS connection is not re-used and the code attempts to create a new one each request.
### Troubleshooting
#### Reproduction
Enable keepalive and register a phone using TLS
#### Log Messages
Kamailio Host: 10.15.5.116
Phone: 10.15.5.117
Phone is registered and seen in the registry
```
kamctl ul show
{
"jsonrpc": "2.0",
"result": {
"Domains": [{
"Domain": {
"Domain": "location",
"Size": 1024,
"AoRs": [{
"Info": {
"AoR": "anonymous",
"HashID": 3819435025,
"Contacts": [{
"Contact": {
"Address": "sips:anonymous at 10.15.5.117:5061",
"Expires": 3531,
"Q": -1,
"Call-ID": "d06e987694afb559",
"CSeq": 521595368,
"User-Agent": "testclient/1.0",
"Received": "[not set]",
"Path": "[not set]",
"State": "CS_NEW",
"Flags": 0,
"CFlags": 0,
"Socket": "tls:10.15.5.116:5061",
"Methods": 7903,
"Ruid": "uloc-62c87f5c-1b6b-2",
"Instance": "<urn:uuid:00000000-0000-1000-8000-0010492e1879>",
"Reg-Id": 0,
"Server-Id": 0,
"Tcpconn-Id": 17,
"Keepalive": 0,
"Last-Keepalive": 1657310753,
"KA-Roundtrip": 0,
"Last-Modified": 1657310753
}
}]
}
}
],
"Stats": {
"Records": 1,
"Max-Slots": 1
}
}
}]
},
"id": 14871
```
When the keepalive code runs it shows the following:
```
Jul 8 14:27:52 localhost kamailio[6976]: 33(7012) DEBUG: usrloc [ul_keepalive.c:112]: ul_ka_urecord(): keepalive for aor: anonymous
Jul 8 14:27:52 localhost kamailio[6976]: 33(7012) DEBUG: usrloc [ul_keepalive.c:235]: ul_ka_urecord(): keepalive request (len: 295) [[
Jul 8 14:27:52 localhost kamailio[6976]: OPTIONS sips:anonymous at 10.15.5.117:5061 SIP/2.0
Jul 8 14:27:52 localhost kamailio[6976]: Via: SIP/2.0/UDP 10.15.5.116:5061;branch=z9hG4bKx.20.1.0
Jul 8 14:27:52 localhost kamailio[6976]: From: <sips:10.15.5.116:5061>;tag=uloc-62c87f5c-1b71-1-e3a7f411-62c88538-cc68d-14.1
Jul 8 14:27:52 localhost kamailio[6976]: To: <sip:anonymous at kamailio.org>
Jul 8 14:27:52 localhost kamailio[6976]: Call-ID: ksrulka-20.1
Jul 8 14:27:52 localhost kamailio[6976]: CSeq: 80 OPTIONS
Jul 8 14:27:52 localhost kamailio[6976]: Content-Length: 0
Jul 8 14:27:52 localhost kamailio[6976]: #015
Jul 8 14:27:52 localhost kamailio[6976]: ]]
Jul 8 14:27:52 localhost kamailio[6976]: 33(7012) ERROR: <core> [core/udp_server.c:597]: udp_send(): sendto(sock, buf: 0x7fffe728ece0, len: 295, 0, dst: (10.15.5.117:5061), tolen: 16) - err: Bad file descriptor (9)
```
### Possible Solutions
There are 2 problems here.
First, the address record does not have a transport defined.
https://github.com/kamailio/kamailio/blob/a466d0b73a66b18419555eca437136f1bcaebff9/src/modules/usrloc/ul_keepalive.c#L164
at this point, `sdst.s` is "sips:anonymous at 10.15.5.117:5061" so parse_uri returns a proto of `UDP`. If you override the value to "sips:anonymous at 10.15.5.117:5061;transport=tls" then the code works as expected. The protocol is detected as TLS and the OPTIONS message generated later has the correct `Via` header.
I'm not sure if the problem is that the address record is missing the transport, or if we need to infer the transport from the socket connection.
The second issue is that the keepalive code doesn't re-use TCP/TLS connections. In the ul_ka_send() function ) all of the socket IDs hardcoded to '0' https://github.com/kamailio/kamailio/blob/a466d0b73a66b18419555eca437136f1bcaebff9/src/modules/usrloc/ul_keepalive.c#L270
This is easily fixable by adding in
```
if(uc->tcpconn_id) {
idst.id = uc->tcpconn_id;
}
```
to `ul_ka_urecord()` and removing all of the `kadst->id=0;` lines from the `ul_ka_send()` function. This works for in-memory during testing. I believe the tcpconn_id field needs to be set in ul_ka_db_records if you're returning it from the DB. I don't have an environment setup to test that.
With those two changes made (hardcoding the transport and fixing the connection id) the keepalives are sent and work as expected:
```
33(19413) DEBUG: usrloc [ul_keepalive.c:112]: ul_ka_urecord(): keepalive for aor: anonymous
33(19413) DEBUG: usrloc [ul_keepalive.c:169]: ul_ka_urecord(): MANUALLY OVERRIDING SDST: sips:anonymous at 10.15.5.117:5061;transport=tls
33(19413) DEBUG: usrloc [ul_keepalive.c:247]: ul_ka_urecord(): keepalive request (len: 288) [[
OPTIONS sips:anonymous at 10.15.5.117:5061 SIP/2.0
Via: SIP/2.0/TLS 10.15.5.116:5061;branch=z9hG4bKx.33.1.0
From: <sips:10.15.5.116:5061>;tag=uloc-62c8af83-4bd9-1-e3a7f411-62c8b37f-f2a22-21.1
To: <sip:anonymous at kamailio.org>
Call-ID: ksrulka-33.1
CSeq: 80 OPTIONS
Content-Length: 0
]]
33(19413) DEBUG: <core> [core/tcp_main.c:1644]: _tcpconn_find(): found connection by id: 1
33(19413) DEBUG: <core> [core/tcp_main.c:2539]: tcpconn_send_put(): found fd in cache (4, 0x7fbaef193db8, 1)
33(19413) DEBUG: <core> [core/tcp_main.c:2761]: tcpconn_do_send(): sending...
33(19413) DEBUG: <core> [core/tcp_main.c:2794]: tcpconn_do_send(): after real write: c= 0x7fbaef193db8 n=317 fd=4
```
I assume that we'd want to re-use a TCP/TLS connection but maybe that needs to be an option (ka_reuse_tcp) if other people are expecting the current behavior of creating a new connection for each new keepalive request.
### Additional Information
```
version: kamailio 5.7.0-dev0 (x86_64/linux) a466d0
flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED
ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: a466d0
compiled on 11:27:35 Jul 8 2022 with gcc 8.3.0
```
* **Operating System**:
Debian Buster
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