Fix handling packets partially overlapping the start of the receive buffer.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index bb29de5824a923a89c3cb28dd110190c199d2d66..0cb68b9da7195495602c1c196c835f2cab46d7b2 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -142,16 +142,12 @@ static int32_t seqdiff(uint32_t a, uint32_t b) {
 
 // Store data into the buffer
 static ssize_t buffer_put_at(struct buffer *buf, size_t offset, const void *data, size_t len) {
-       if(buf->maxsize <= buf->used)
-               return 0;
-
        debug("buffer_put_at %lu %lu %lu\n", (unsigned long)buf->used, (unsigned long)offset, (unsigned long)len);
 
        size_t required = offset + len;
        if(required > buf->maxsize) {
                if(offset >= buf->maxsize)
                        return 0;
-               abort();
                len = buf->maxsize - offset;
                required = buf->maxsize;
        }
@@ -647,8 +643,11 @@ cleanup:
  */
 static void sack_consume(struct utcp_connection *c, size_t len) {
        debug("sack_consume %lu\n", (unsigned long)len);
-       if(len > c->rcvbuf.used)
-               abort();
+       if(len > c->rcvbuf.used) {
+               debug("All SACK entries consumed");
+               c->sacks[0].len = 0;
+               return;
+       }
 
        buffer_get(&c->rcvbuf, NULL, len);
 
@@ -891,14 +890,15 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 
                // cut already accepted front overlapping
                if(rcv_offset < 0) {
-                       acceptable = rcv_offset + len >= 0;
+                       acceptable = len > -rcv_offset;
                        if(acceptable) {
                                data -= rcv_offset;
                                len += rcv_offset;
+                               hdr.seq -= rcv_offset;
                        }
+               } else {
+                       acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
                }
-
-               acceptable = seqdiff(hdr.seq, c->rcv.nxt) >= 0 && seqdiff(hdr.seq, c->rcv.nxt) + len <= c->rcvbuf.maxsize;
        }
 
        if(!acceptable) {
@@ -906,9 +906,8 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
                // Ignore unacceptable RST packets.
                if(hdr.ctl & RST)
                        return 0;
-               // Otherwise, send an ACK back in the hope things improve.
-               ack(c, true);
-               return 0;
+               // Otherwise, continue processing.
+               len = 0;
        }
 
        c->snd.wnd = hdr.wnd; // TODO: move below