[syslinux] [PATCH] tftp: send last ACK correctly

[Роман Донченко]

This patch fixes a couple small bugs in tftp_recvfile:

1) An superfluous ACK is sent if the transfer was terminated abnormally  
(due to a received ERROR or an I/O error).
2) Sending of the last ACK is neither traced nor checked for errors.

diff --git a/tftp/tftp.c b/tftp/tftp.c
index d15da22..5dbaf20 100644
--- a/tftp/tftp.c
+++ b/tftp/tftp.c
@@ -258,16 +258,21 @@ void tftp_recvfile(int fd, const char *name, const  
char *mode)
          size = writeit(file, &dp, n - 4, convert);
          if (size < 0) {
              nak(errno + 100, NULL);
-            break;
+            goto abort;
          }
          amount += size;
      } while (size == SEGSIZE);
-  abort:                       /* ok to ack, since user */
-    ap->th_opcode = htons((u_short) ACK);       /* has seen err msg */
+    /* send last ACK */
+    ap->th_opcode = htons((u_short) ACK);
      ap->th_block = htons((u_short) block);
-    (void)sendto(f, ackbuf, 4, 0, (struct sockaddr *)&peeraddr,
-                 SOCKLEN(&peeraddr));
+    size = 4;
+    if (trace)
+        tpacket("sent", ap, size);
+    if (sendto(f, ackbuf, size, 0, &peeraddr.sa,
+               SOCKLEN(&peeraddr)) != size)
+        perror("tftp: sendto");
      write_behind(file, convert);        /* flush last buffer */
+  abort:
      fclose(file);
      stopclock();
      if (amount > 0)