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TCP: fixes backlog limit handling, and allows ephemeral TCP connections (#7096)

* fix backlog limit handling, and allow ephemeral TCP connections
* do not retain empty connections
This commit is contained in:
david gauchard
2020-02-24 07:16:55 +01:00
committed by GitHub
parent 2b640c0189
commit 2d58be744b
3 changed files with 35 additions and 33 deletions

View File

@ -125,12 +125,14 @@ WiFiClient WiFiServer::available(byte* status) {
if (_unclaimed) {
WiFiClient result(_unclaimed);
#if LWIP_VERSION_MAJOR != 1
_unclaimed->acceptPCB();
tcp_backlog_accepted(_unclaimed->getPCB());
// pcb can be null when peer has already closed the connection
if (_unclaimed->getPCB())
// give permission to lwIP to accept one more peer
tcp_backlog_accepted(_unclaimed->getPCB());
#endif
_unclaimed = _unclaimed->next();
result.setNoDelay(getNoDelay());
DEBUGV("WS:av\r\n");
DEBUGV("WS:av status=%d WCav=%d\r\n", result.status(), result.available());
return result;
}
@ -187,9 +189,12 @@ long WiFiServer::_accept(tcp_pcb* apcb, long err) {
(void) err;
DEBUGV("WS:ac\r\n");
// always accept new PCB so incoming data can be stored in our buffers even before
// user calls ::available()
ClientContext* client = new ClientContext(apcb, &WiFiServer::_s_discard, this);
#if LWIP_VERSION_MAJOR == 1
ClientContext* client = new ClientContext(apcb, &WiFiServer::_s_discard, this);
tcp_accepted(_listen_pcb);
#else
@ -198,20 +203,9 @@ long WiFiServer::_accept(tcp_pcb* apcb, long err) {
// http://lwip.100.n7.nabble.com/Problem-re-opening-listening-pbc-tt32484.html#a32494
// https://www.nongnu.org/lwip/2_1_x/group__tcp__raw.html#gaeff14f321d1eecd0431611f382fcd338
// lwip-v2: Tell ClientContext to not accept yet the connection (final 'false' below)
ClientContext* client = new ClientContext(apcb, &WiFiServer::_s_discard, this, false);
// increase lwIP's backlog
tcp_backlog_delayed(apcb);
// Optimization Path:
// when lwip-v1.4 is not allowed anymore,
// - _accept() should not create ClientContext anymore
// - apcb should be stored into some sort of linked list (->_unclaimed)
// (the linked list would store tcp_pcb* instead of ClientContext*)
// (TCP_PCB_EXTARGS might be used for that (lwIP's struct tcp_pcb))
// - on available(), get the pcb back and create the ClientContext
// (this is not done today for better source readability with lwip-1.4 around)
#endif
_unclaimed = slist_append_tail(_unclaimed, client);