From fc13e49d321c16fc65e5c8fcf5d205ce805f7a0e Mon Sep 17 00:00:00 2001 From: Guus Sliepen Date: Sun, 15 Mar 2020 14:55:17 +0100 Subject: [PATCH] Use flightsize instead of cwnd to set ssthresh. --- utcp.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/utcp.c b/utcp.c index b53541d..67d4be3 100644 --- a/utcp.c +++ b/utcp.c @@ -808,27 +808,24 @@ static void retransmit(struct utcp_connection *c) { pkt->hdr.seq = c->snd.una; pkt->hdr.ack = c->rcv.nxt; pkt->hdr.ctl = ACK; - uint32_t len = seqdiff(c->snd.last, c->snd.una); - - if(len > utcp->mtu) { - len = utcp->mtu; - } + uint32_t len = min(seqdiff(c->snd.last, c->snd.una), utcp->mtu); if(fin_wanted(c, c->snd.una + len)) { len--; pkt->hdr.ctl |= FIN; } - c->snd.nxt = c->snd.una + len; - // RFC 5681 slow start after timeout - c->snd.ssthresh = max(c->snd.cwnd / 2, utcp->mtu * 2); // eq. 4 + uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una); + c->snd.ssthresh = max(flightsize / 2, utcp->mtu * 2); // eq. 4 c->snd.cwnd = utcp->mtu; debug_cwnd(c); buffer_copy(&c->sndbuf, pkt->data, 0, len); print_packet(c, "rtrx", pkt, sizeof(pkt->hdr) + len); utcp->send(utcp, pkt, sizeof(pkt->hdr) + len); + + c->snd.nxt = c->snd.una + len; break; case CLOSED: @@ -1467,7 +1464,8 @@ synack: if(c->dupack == 3) { // RFC 5681 fast recovery debug(c, "fast recovery started\n", c->dupack); - c->snd.ssthresh = max(c->snd.cwnd / 2, utcp->mtu * 2); // eq. 4 + uint32_t flightsize = seqdiff(c->snd.nxt, c->snd.una); + c->snd.ssthresh = max(flightsize / 2, utcp->mtu * 2); // eq. 4 c->snd.cwnd = min(c->snd.ssthresh + 3 * utcp->mtu, c->sndbuf.maxsize); if(c->snd.cwnd > c->sndbuf.maxsize) { -- 2.39.2