There is a problem in tcp_abort function, when it is used with pcb in
"Active" state. The source port of RST packet sent is set to 0 .
In the previous version of LwIP in tcp_abandon function there was
variable "local_port". It was used to store the local port of pcb before
calling TCP_PCB_REMOVE_ACTIVE, and then it was passed as argument to
tcp_rst instead of pcb->local_port which is set to zero at this moment.
I don't know what was an idea to remove this variable from current
version of LwIP, but from my point of view it doesn't work properly now.