[git commit] nslookup: handle replies without RRs
Denys Vlasenko
vda.linux at googlemail.com
Sun Oct 27 16:02:08 UTC 2019
commit: https://git.busybox.net/busybox/commit/?id=8c3b520d4f937b1d1856898dec5f634b12d9cc36
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
Under some circumstances, a DNS reply might contain no resource records,
e.g. when a valid domain is queried that does not have records of the
requested type.
Example with nslookup from BIND dnsutils:
$ nslookup -q=SRV example.org
Server: 10.11.12.13
Address: 10.11.12.13#53
Non-authoritative answer:
*** Can't find example.org: No answer
Currently the busybox nslookup applet simply prints nothing after the
"Non-authoritative answer:" line in the same situation.
This change modifies nslookup to either print "Parse error" or "No answer"
diagnostics, depending on the parse_reply() return value.
function old new delta
send_queries 1676 1711 +35
Signed-off-by: Jo-Philipp Wich <jo at mein.io>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/nslookup.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/networking/nslookup.c b/networking/nslookup.c
index 8adde14b8..a7dd823f0 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -615,9 +615,15 @@ static int send_queries(struct ns *ns)
G.query[qn].name, rcodes[rcode]);
G.exitcode = EXIT_FAILURE;
} else {
- if (parse_reply(reply, recvlen) < 0) {
+ switch (parse_reply(reply, recvlen)) {
+ case -1:
printf("*** Can't find %s: Parse error\n", G.query[qn].name);
G.exitcode = EXIT_FAILURE;
+ break;
+
+ case 0:
+ printf("*** Can't find %s: No answer\n", G.query[qn].name);
+ break;
}
}
bb_putchar('\n');
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