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From adf24e909cda1ae30767d8ca4902eac92781d932 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jo@mein.io>
Date: Thu, 27 Jun 2019 17:27:28 +0200
Subject: [PATCH 1/2] nslookup: handle replies without RRs
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@mein.io>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
(cherry picked from commit 8c3b520d4f937b1d1856898dec5f634b12d9cc36)
---
networking/nslookup.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/networking/nslookup.c b/networking/nslookup.c
index 24e09d4f0..f7fd1d377 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');
--
2.25.0
From 1fc999c00aa6649f17f0879b960427313dac64ae Mon Sep 17 00:00:00 2001
From: Natanael Copa <ncopa@alpinelinux.org>
Date: Tue, 4 Feb 2020 11:04:37 +0000
Subject: [PATCH 2/2] nslookup: fix exitcode with search domains, closes 12541
Return success if there are any valid answer rather than exit with error.
bloatcheck on x86_64:
function old new delta
nslookup_main 917 924 +7
send_queries 2115 2121 +6
.rodata 136606 136609 +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 16/0) Total: 16
bytes
text data bss dec hex filename
839394 14660 2080 856134 d1046 busybox_old
839410 14660 2080 856150 d1056 busybox_unstripped
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
---
networking/nslookup.c | 34 ++++++++++++++++++----------------
1 file changed, 18 insertions(+), 16 deletions(-)
diff --git a/networking/nslookup.c b/networking/nslookup.c
index f7fd1d377..d66b13039 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -265,7 +265,7 @@ struct query {
const char *name;
unsigned qlen;
// unsigned latency;
-// uint8_t rcode;
+ uint8_t rcode;
unsigned char query[512];
// unsigned char reply[512];
};
@@ -320,7 +320,7 @@ struct globals {
struct query *query;
char *search;
smalluint have_search_directive;
- smalluint exitcode;
+ smallint answer;
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
@@ -605,28 +605,31 @@ static int send_queries(struct ns *ns)
/* Process reply */
G.query[qn].qlen = 0; /* flag: "reply received" */
+ G.query[qn].rcode = rcode;
tcur = monotonic_ms();
#if 1
if (option_mask32 & OPT_debug) {
printf("Query #%d completed in %ums:\n", qn, tcur - tstart);
}
if (rcode != 0) {
- printf("** server can't find %s: %s\n",
- G.query[qn].name, rcodes[rcode]);
- G.exitcode = EXIT_FAILURE;
+ printf("** server can't find %s: %s\n\n",
+ G.query[qn].name, rcodes[rcode]);
} else {
switch (parse_reply(reply, recvlen)) {
case -1:
- printf("*** Can't find %s: Parse error\n", G.query[qn].name);
- G.exitcode = EXIT_FAILURE;
+ printf("*** Can't find %s: Parse error\n\n", G.query[qn].name);
+ G.query[qn].rcode = 0x10;
break;
case 0:
- printf("*** Can't find %s: No answer\n", G.query[qn].name);
+ G.query[qn].rcode = 0x20;
+ break;
+ default:
+ bb_putchar('\n');
+ G.answer++;
break;
}
}
- bb_putchar('\n');
n_replies++;
if (n_replies >= G.query_count)
goto ret;
@@ -984,21 +987,20 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
}
err = 0;
- for (rc = 0; rc < G.query_count; rc++) {
- if (G.query[rc].qlen) {
- printf("*** Can't find %s: No answer\n", G.query[rc].name);
- err = 1;
+ for (rc = 0; !G.answer && rc < G.query_count; rc++) {
+ if (G.query[rc].qlen || G.query[rc].rcode == 0x20) {
+ printf("*** Can't find %s: No answer\n\n", G.query[rc].name);
+ } else if (G.query[rc].rcode != 0) {
+ err = EXIT_FAILURE;
}
}
- if (err) /* should this affect exicode too? */
- bb_putchar('\n');
if (ENABLE_FEATURE_CLEAN_UP) {
free(G.server);
free(G.query);
}
- return G.exitcode;
+ return err;
}
#endif
--
2.25.0
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