Interface indexes are u8_t internally so cast from sockets int representation to u8_t
This was found with MSVC 2013:
1>lwip\src\api\sockets.c(3190): warning C4242: 'function' : conversion from 'const unsigned int' to 'u8_t', possible loss of data
1>lwip\src\api\sockets.c(3698): warning C4242: 'function' : conversion from 'unsigned int' to 'u8_t', possible loss of data
lwip_itoa would output the number 0 as \0. This fixes the issue by
adding a special check before the normal conversion loop
This was found via shell cmd idxtoname and win32 port. "lo0" should
be returned for index 1
- add a better-documented static function tcp_output_segment_busy
- try to reduce the number of checks
- tcp_rexmit_rto: iterate pcb->unacked only once
- no need to check for ref==1 in tcp_rexmit_fast when tcp_rexmit does
- call tcp_rexmit_fast if dupacks >= 3 (not == 3) and use TF_INFR flag to guard the fast-rexmit case (that way, it's triggered again on the next dupack)
There is already a guard in tcp_output_segment() for a pbuf still being
referenced by the netif driver due to deferred transmission, however the callers
are modifying state even when this gives up.
It seems cleaner to have the callers guard this case and avoid modifying their
state.
tcp_rexmit_rto() might better avoid re-transmission of any segments if any of
the unacked segments are deferred, to avoid loading the link further if it is
struggling to flush its buffered writes. Link level queues can be limited on
some devices and need spares for link management.
- added `altcp_tls_free_config()`.
- added `altcp_tls_context()` function to allow mbedtls parameter tweak.
Since state structure isn't exported, this allow application to get
internal context (port dependent) to tweak it.
- free altcp_pcb when lower error callback called.
- expose `altcp_tcp_setup()` so we can wrap altcp over existing tcp pcb.
- avoid calling tcp_close() with NULL pcb.
- free altcp_pcb struct when error callback called.
According to `mqtt_tcp_err_cb()` in src/apps/mqtt/mqtt.c, altcp socket should
work the same way than raw tcp socket. So freeing altcp_pcb ensure this.
The new functions both take size_t as increment/decrement argument instead of s16_t (which needed to be range-checked before conversion everywhere) - in most places, the direction (increment or decrement) is known anyway, so no need to encode it in a sign bit
