Guard against retransmitting a BYE forever
Review Request #1077 - Created Jan. 18, 2011 and submitted
In the case of an attended transfer (A calls B, A atxfers to C) where A becomes unreachable before replying to Asterisk's BYE, Asterisk can sometimes retransmit the BYE indefinitely. This is because __sip_autodestruct tests p->refer && !ast_test_flag(&p->flags, SIP_ALREADYGONE and will then transmit a BYE. When this BYE times out, it will not ever be marked as ALREADYGONE, so when __sip_autodestruct is called again, we end up starting the cycle over. This patch adds a call to sip_alreadygone(pkt->owner) in retrans_pkt in the case of a BYE that has timed out. This should prevent Asterisk from trying to transmit new BYE messages in the future.
Modified Asterisk to sleep for 2 seconds before sending the transfer NOTIFY to give me time to unplug the network cable from the transfering phone. Registered 3 phones A, B, and C. A calls B, A atxfer to C. I often (but not always) got infinite BYEs. After the patch I did not.