<!-- Kamailio Project uses GitHub Issues only for bugs in the code or feature requests. Please use this template only for bug reports.

If you have questions about using Kamailio or related to its configuration file, ask on sr-users mailing list:

* http://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users

If you have questions about developing extensions to Kamailio or its existing C code, ask on sr-dev mailing list:

* http://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-dev

Please try to fill this template as much as possible for any issue. It helps the developers to troubleshoot the issue.

If there is no content to be filled in a section, the entire section can be removed.

You can delete the comments from the template sections when filling.

You can delete next line and everything above before submitting (it is a comment). -->

### Description

<!-- Explain what you did, what you expected to happen, and what actually happened. -->

I found a memory leak which is causing some issues for us in our production. I think I was able to reproduce it and determine that this is happening when we set up an MSRP connection, and that connection is closed due to inactivity (for example when `tcp_connection_lifetime` is triggered).

### Troubleshooting

#### Reproduction

<!-- If the issue can be reproduced, describe how it can be done. -->

In this environment we have a WebRTC SIP client, connected to Kamailio and a second party using SIP, both sending messages each via MSRP protocol. Web Client and SIP client establish a session normally, all fine here, they can communicate. At this point we have this status:

``` sudo netstat -natp | grep 10.22.22 tcp 0 0 10.22.22.21:5060 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10000 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:8080 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10001 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10002 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:8080 10.22.22.1:58508 ESTABLISHED 28640/kamailio tcp 0 0 10.22.22.21:10000 10.22.22.190:32786 ESTABLISHED 28646/kamailio tcp 0 0 10.22.22.21:8080 10.22.22.1:58506 ESTABLISHED 28591/kamailio

TESTER|centos8.4|tester21 [2021-10-06][16:23:57] [/home/vagrant]$ kamcmd -s udp:127.0.0.1:2046 mod.stats core all | grep tcp tcpconn_new(971): 198888 init_tcp(4700): 8192 init_tcp(4694): 32768 init_tcp(4686): 8 init_tcp(4679): 8 init_tcp(4672): 8 init_tcp(4666): 8 init_tcp(4654): 8 ```

In order to trigger this failure much faster, I set `tcp_connection_lifetime=60`. Then we just wait the required seconds to let the TCP connections closed. Then we finish the session, and stop our WebClient registering, so all connections are cleaned up.

``` TESTER|centos8.4|tester21 [2021-10-06][16:28:08] [/home/vagrant]$ sudo netstat -natp | grep 10.22.22 tcp 0 0 10.22.22.21:5060 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10000 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:8080 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10001 0.0.0.0:* LISTEN 28646/kamailio tcp 0 0 10.22.22.21:10002 0.0.0.0:* LISTEN 28646/kamailio TESTER|centos8.4|tester21 [2021-10-06][16:28:20] [/home/vagrant]$ kamcmd -s udp:127.0.0.1:2046 mod.stats core all | grep tcp tcpconn_new(971): 66296 init_tcp(4700): 8192 init_tcp(4694): 32768 init_tcp(4686): 8 init_tcp(4679): 8 init_tcp(4672): 8 init_tcp(4666): 8 init_tcp(4654): 8

```

As you can see there are no connections but there is memory allocated by `tcpconn_new`. I know this is related to the MSRP because we noticed our SIP Web Client is not closing the socket, so we just wait for Kamailio to close it.

#### Debugging Data

<!-- If you got a core dump, use gdb to extract troubleshooting data - full backtrace, local variables and the list of the code at the issue location.

gdb /path/to/kamailio /path/to/corefile bt full info locals list

If you are familiar with gdb, feel free to attach more of what you consider to be relevant. -->

``` (paste your debugging data here) ```

#### Log Messages

<!-- Check the syslog file and if there are relevant log messages printed by Kamailio, add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->

``` 2021-07-25T23:54:41Z ERROR ERROR: <core> [mem/f_malloc.c:415]: fm_search_defrag(): fm_search_defrag(0x7f39a284c000, 66288); Free fragment not found! 2021-07-25T23:54:41Z ERROR ERROR: <core> [mem/f_malloc.c:498]: fm_malloc(): fm_malloc(0x7f39a284c000, 66288) called from core: tcp_main.c: tcpconn_new(957), module: core; Free fragment not found! 2021-07-25T23:54:41Z ERROR ERROR: <core> [tcp_main.c:959]: tcpconn_new(): mem. allocation failure 2021-07-25T23:54:41Z ERROR ERROR: <core> [tcp_main.c:3985]: handle_new_connect(): tcpconn_new failed, closing socket ```

#### SIP Traffic

<!-- If the issue is exposed by processing specific SIP messages, grab them with ngrep or save in a pcap file, then add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->

``` (paste your sip traffic here) ```

### Possible Solutions

<!-- If you found a solution or workaround for the issue, describe it. Ideally, provide a pull request with a fix. -->

### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` version: kamailio 5.1.6 (x86_64/linux) 7d1964 flags: STATS: Off, EXTRA_DEBUG, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, DBG_QM_MALLOC, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES 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: 7d1964 compiled on 13:54:09 Oct 5 2021 with gcc 8.4.1

```

Already tried with the latest stable Kamailio version, with the same issue.

* **Operating System**:

<!-- Details about the operating system, the type: Linux (e.g.,: Debian 8.4, Ubuntu 16.04, CentOS 7.1, ...), MacOS, xBSD, Solaris, ...; Kernel details (output of `lsb_release -a` and `uname -a`) -->

``` Linux tester21 4.18.0-305.17.1.el8_4.x86_64 #1 SMP Wed Sep 8 14:00:07 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

centos 8 ```