Always send an ACK back when we receive data from the peer.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index 7e28f9e27e3aef2a7f0937597eabbd5bd3c36f7a..d0e56d2c41e6dd278d1791828ff59375fc5b6391 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -1011,6 +1011,8 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
                ptr += 2;
        }
 
+       bool has_data = len;
+
        // Try to match the packet to an existing connection
 
        struct utcp_connection *c = find_connection(utcp, hdr.dst, hdr.src);
@@ -1105,8 +1107,6 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 
        // It is for an existing connection.
 
-       uint32_t prevrcvnxt = c->rcv.nxt;
-
        // 1. Drop invalid packets.
 
        // 1a. Drop packets that should not happen in our current state.
@@ -1130,7 +1130,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
                break;
        }
 
-       // 1b. Drop packets with a sequence number not in our receive window.
+       // 1b. Discard data that is not in our receive window.
 
        if(is_reliable(c)) {
                bool acceptable;
@@ -1282,7 +1282,6 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
        // 3. Advance snd.una
 
        advanced = seqdiff(hdr.ack, c->snd.una);
-       prevrcvnxt = c->rcv.nxt;
 
        if(advanced) {
                // RTT measurement
@@ -1536,13 +1535,13 @@ skip_ack:
        }
 
        // Now we send something back if:
-       // - we advanced rcv.nxt (ie, we got some data that needs to be ACKed)
+       // - we received data, so we have to send back an ACK
        //   -> sendatleastone = true
        // - or we got an ack, so we should maybe send a bit more data
        //   -> sendatleastone = false
 
        if(is_reliable(c) || hdr.ctl & SYN || hdr.ctl & FIN) {
-               ack(c, len || prevrcvnxt != c->rcv.nxt);
+               ack(c, has_data);
        }
 
        return 0;