correctly handle read(2) return value.

fix issue reported by Mikolaj Kucharski.

ok martijn@ deraadt@

diff --git a/lib/libc/asr/res_send_async.c b/lib/libc/asr/res_send_async.c
index f6a8d80..c5cc41f 100644 (file)
--- a/lib/libc/asr/res_send_async.c
+++ b/lib/libc/asr/res_send_async.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: res_send_async.c,v 1.38 2019/01/14 06:49:42 otto Exp $        */
+/*     $OpenBSD: res_send_async.c,v 1.39 2019/09/28 11:21:07 eric Exp $        */
 /*
  * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
  *
@@ -578,10 +578,17 @@ tcp_read(struct asr_query *as)
                pos = (char *)(&as->as.dns.pktlen) + as->as.dns.datalen;
                len = sizeof(as->as.dns.pktlen) - as->as.dns.datalen;
 
+    read_again0:
                n = read(as->as_fd, pos, len);
-               if (n == -1)
+               if (n == -1) {
+                       if (errno == EINTR)
+                               goto read_again0;
                        goto close; /* errno set */
-
+               }
+               if (n == 0) {
+                       errno = ECONNRESET;
+                       goto close;
+               }
                as->as.dns.datalen += n;
                if (as->as.dns.datalen < sizeof(as->as.dns.pktlen))
                        return (1); /* need more data */