### Description All kamailio versions on the 5.7.x train and additionally point release 5.6.5 break early dialog transactions, at least when the following conditions are (cumulatively) met: * topos-redis is enabled (haven't tested other storage backends yet, let me know if needed) * kamailio is multihomed * enable_double_rr is enabled (the default)

### Troubleshooting #### SIP Traffic Here's an exchange demonstrating the problem:

``` kamailio instance ──────────┬──────────────────┬───────── internal external peer 172.30.154.1:5060 185.73.43.241:5060 195.167.21.66:5060 ──────────┬──────────────────┬───────── ──────────┬───────── │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ INVITE (SDP) │ │ │ ──────────────────────────> │ │ │ 100 Trying │ │ │ <────────────────────────── │ │ │ 183 Session Progress (SDP) │ │ │ <────────────────────────── │ │ │ PRACK │ │ │ ──────────────────────────> │ │ │ 200 OK │ │ │ <────────────────────────── │ │ │ UPDATE (SDP) │ UPDATE (SDP) │ │ <─────────────────────────── │ │ ``` Whereas the expected behaviour should be: ``` │ │ UPDATE (SDP) │ | <────────────────────────── │ UPDATE (SDP)│ │ │ <───────── │ │ │

``` This is also exemplified by examining the Via headers as rewritten by kamailio. Not working (>= 5.6.5, 5.7.x): * Inbound Via: `Via: SIP/2.0/UDP 195.167.21.66:5060;branch=z9hG4bKtjlwcpvfh03epe0thhtjhq3qg;Role=3;Hpt=8e58_16` * Oubound Via: `Via: SIP/2.0/UDP 185.73.43.241;branch=z9hG4bK66c4.3453dd9a219858819d528b9da671e39e.0`

Working (5.6.4): * Inbound Via: `Via: SIP/2.0/UDP 195.167.21.66:5060;branch=z9hG4bK8lj1ahz6npz65khd8jkzl1ohh;Role=3;Hpt=8e68_16` * Oubound Via: `Via: SIP/2.0/UDP 172.30.154.1;branch=z9hG4bK4dce.4f5448efd64465fa5dbaf5eef0dc35b7.0` ### Possible Solutions Only solution I have found so far is to downgrade to kamailio 5.6.4 <!-- If you found a solution or workaround for the issue, describe it. Ideally, provide a pull request with a fix. -->

### Additional Information

``` version: kamailio 5.7.4 (x86_64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, MEM_JOIN_FREE, 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: unknown compiled with gcc 10.2.1

``` But I have also tested all 5.7.x versions, which are all affected, as well 5.6.5. * **Operating System**:

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``` Linux host 5.10.0-27-amd64 #1 SMP Debian 5.10.205-2 (2023-12-31) x86_64 GNU/Linux ```