[git commit] nslookup: process replies immediately, do not store them
Denys Vlasenko
vda.linux at googlemail.com
Sun Apr 15 08:46:44 UTC 2018
commit: https://git.busybox.net/busybox/commit/?id=2cf75b3c8113c59db0bf9290bd0fdfc77cd2237b
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
function old new delta
nslookup_main 1837 2708 +871
parse_reply 852 - -852
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/0 up/down: 871/-852) Total: 19 bytes
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/nslookup.c | 196 ++++++++++++++++++++++++++++----------------------
1 file changed, 110 insertions(+), 86 deletions(-)
diff --git a/networking/nslookup.c b/networking/nslookup.c
index 92e07e8b1..d31801e96 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -264,9 +264,10 @@ struct ns {
struct query {
const char *name;
unsigned qlen, rlen;
- unsigned latency;
- uint8_t rcode;
- unsigned char query[512], reply[512];
+// unsigned latency;
+// uint8_t rcode;
+ unsigned char query[512];
+// unsigned char reply[512];
};
static const struct {
@@ -325,9 +326,14 @@ struct globals {
G.default_timeout = 5; \
} while (0)
-static int
-parse_reply(const unsigned char *msg, size_t len)
+enum {
+ OPT_stats = (1 << 4),
+};
+
+static int parse_reply(const unsigned char *msg, size_t len)
{
+ HEADER *header;
+
ns_msg handle;
ns_rr rr;
int i, n, rdlen;
@@ -335,14 +341,18 @@ parse_reply(const unsigned char *msg, size_t len)
char astr[INET6_ADDRSTRLEN], dname[MAXDNAME];
const unsigned char *cp;
+ header = (HEADER *)msg;
+ if (!header->aa)
+ printf("Non-authoritative answer:\n");
+
if (ns_initparse(msg, len, &handle) != 0) {
- //fprintf(stderr, "Unable to parse reply: %s\n", strerror(errno));
+ //printf("Unable to parse reply: %s\n", strerror(errno));
return -1;
}
for (i = 0; i < ns_msg_count(handle, ns_s_an); i++) {
if (ns_parserr(&handle, ns_s_an, i, &rr) != 0) {
- //fprintf(stderr, "Unable to parse resource record: %s\n", strerror(errno));
+ //printf("Unable to parse resource record: %s\n", strerror(errno));
return -1;
}
@@ -387,7 +397,7 @@ parse_reply(const unsigned char *msg, size_t len)
if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
ns_rr_rdata(rr), dname, sizeof(dname)) < 0
) {
- //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+ //printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
printf(format, ns_rr_name(rr), dname);
@@ -395,14 +405,14 @@ parse_reply(const unsigned char *msg, size_t len)
case ns_t_mx:
if (rdlen < 2) {
- fprintf(stderr, "MX record too short\n");
+ printf("MX record too short\n");
return -1;
}
n = ns_get16(ns_rr_rdata(rr));
if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
ns_rr_rdata(rr) + 2, dname, sizeof(dname)) < 0
) {
- //fprintf(stderr, "Cannot uncompress MX domain: %s\n", strerror(errno));
+ //printf("Cannot uncompress MX domain: %s\n", strerror(errno));
return -1;
}
printf("%s\tmail exchanger = %d %s\n", ns_rr_name(rr), n, dname);
@@ -410,7 +420,7 @@ parse_reply(const unsigned char *msg, size_t len)
case ns_t_txt:
if (rdlen < 1) {
- //fprintf(stderr, "TXT record too short\n");
+ //printf("TXT record too short\n");
return -1;
}
n = *(unsigned char *)ns_rr_rdata(rr);
@@ -433,7 +443,7 @@ parse_reply(const unsigned char *msg, size_t len)
n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
cp, dname, sizeof(dname));
if (n < 0) {
- //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+ //printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
@@ -443,7 +453,7 @@ parse_reply(const unsigned char *msg, size_t len)
n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
cp, dname, sizeof(dname));
if (n < 0) {
- //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+ //printf("Unable to uncompress domain: %s\n", strerror(errno));
return -1;
}
@@ -513,11 +523,13 @@ static char *make_ptr(char resbuf[80], const char *addrstr)
*/
static int send_queries(struct ns *ns, struct query *query, int n_queries)
{
+ unsigned char reply[512];
+ uint8_t rcode;
len_and_sockaddr *local_lsa;
struct pollfd pfd;
int servfail_retry = 0;
int n_replies = 0;
- int save_idx = 0;
+// int save_idx = 0;
unsigned retry_interval;
unsigned timeout = G.default_timeout * 1000;
unsigned tstart, tsent, tcur;
@@ -564,18 +576,34 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
goto next;
- recvlen = read(pfd.fd, query[save_idx].reply, sizeof(query[0].reply));
+ recvlen = read(pfd.fd, reply, sizeof(reply));
+ if (recvlen < 0) {
+ bb_perror_msg("read");
+ next:
+ tcur = monotonic_ms();
+ continue;
+ }
- /* Error/non-identifiable packet */
+ if (ns->replies++ == 0) {
+ printf("Server:\t\t%s\n", ns->name);
+ printf("Address:\t%s\n\n",
+ auto_string(xmalloc_sockaddr2dotted(&ns->lsa->u.sa))
+ );
+ /* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
+ /* Should we do the same? */
+ }
+
+ /* Non-identifiable packet */
if (recvlen < 4) {
dbg("read is too short:%d\n", recvlen);
goto next;
}
/* Find which query this answer goes with, if any */
- qn = save_idx;
+// qn = save_idx;
+ qn = 0;
for (;;) {
- if (memcmp(query[save_idx].reply, query[qn].query, 2) == 0) {
+ if (memcmp(reply, query[qn].query, 2) == 0) {
dbg("response matches query %u\n", qn);
break;
}
@@ -590,38 +618,42 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
goto next;
}
- ns->replies++;
-
- query[qn].rcode = query[save_idx].reply[3] & 15;
- dbg("query %u rcode:%s\n", qn, rcodes[query[qn].rcode]);
+ rcode = reply[3] & 0x0f;
+ dbg("query %u rcode:%s\n", qn, rcodes[rcode]);
- /* Only accept positive or negative responses;
- * retry immediately on server failure, and ignore
- * all other codes such as refusal.
- */
- switch (query[qn].rcode) {
- case 0:
- case 3:
- break;
- case 2:
+ /* Retry immediately on SERVFAIL */
+ if (rcode == 2) {
+ ns->failures++;
if (servfail_retry) {
servfail_retry--;
- ns->failures++;
write(pfd.fd, query[qn].query, query[qn].qlen);
dbg("query %u resent\n", qn);
+ goto next;
}
- /* fall through */
- default:
- next:
- tcur = monotonic_ms();
- continue;
}
- /* Store answer */
- n_replies++;
+ /* Process reply */
query[qn].rlen = recvlen;
tcur = monotonic_ms();
+#if 1
+ if (option_mask32 & OPT_stats) {
+ printf("Query #%d completed in %ums:\n", qn, tcur - tstart);
+ }
+ if (rcode != 0) {
+ printf("** server can't find %s: %s\n",
+ query[qn].name, rcodes[rcode]);
+ } else {
+ if (parse_reply(reply, recvlen) < 0)
+ printf("*** Can't find %s: Parse error\n", query[qn].name);
+ }
+ bb_putchar('\n');
+ n_replies++;
+ if (n_replies >= n_queries)
+ goto ret;
+#else
+//used to store replies and process them later
query[qn].latency = tcur - tstart;
+ n_replies++;
if (qn != save_idx) {
/* "wrong" receive buffer, move to correct one */
memcpy(query[qn].reply, query[save_idx].reply, recvlen);
@@ -635,6 +667,7 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
if (!query[save_idx].rlen)
break; /* this one is empty */
}
+#endif
} /* while() */
ret:
@@ -718,11 +751,9 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
llist_t *type_strings;
int n_queries;
unsigned types;
- int rc;
int opts;
- enum {
- OPT_stats = (1 << 4),
- };
+ int rc;
+ int err;
INIT_G();
@@ -827,61 +858,54 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
add_ns("127.0.0.1");
}
- for (rc = 0; rc < G.serv_count; rc++) {
- int c = send_queries(&G.server[rc], queries, n_queries);
- if (c > 0)
+ for (rc = 0; rc < G.serv_count;) {
+ int c;
+
+ c = send_queries(&G.server[rc], queries, n_queries);
+ if (c > 0) {
+ /* more than zero replies received */
+ if (opts & OPT_stats) {
+ printf("Replies:\t%d\n", G.server[rc].replies);
+ printf("Failures:\t%d\n\n", G.server[rc].failures);
+ }
break;
+//FIXME: we "break" even though some queries may still be not answered, and other servers may know them?
+ }
/* c = 0: timed out waiting for replies */
/* c < 0: error (message already printed) */
rc++;
if (rc >= G.serv_count) {
- fprintf(stderr,
- ";; connection timed out; no servers could be reached\n\n");
+//
+// NB: bind-utils-9.11.3 behavior (all to stdout, not stderr):
+//
+// $ nslookup gmail.com 8.8.8.8
+// ;; connection timed out; no servers could be reached
+//
+// $ nslookup -s gmail.com 8.8.8.8; echo EXITCODE:$?
+// <~10 sec>
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+// <~10 sec>
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+// <~10 sec>
+// ;; connection timed out; no servers could be reached
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+// <empty line>
+// EXITCODE:1
+// $ _
+ printf(";; connection timed out; no servers could be reached\n\n");
return EXIT_FAILURE;
}
}
- printf("Server:\t\t%s\n", G.server[rc].name);
- printf("Address:\t%s\n", xmalloc_sockaddr2dotted(&G.server[rc].lsa->u.sa));
- /* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
- /* Should we do the same? */
-
- if (opts & OPT_stats) {
- printf("Replies:\t%d\n", G.server[rc].replies);
- printf("Failures:\t%d\n", G.server[rc].failures);
- }
- printf("\n");
-
+ err = 0;
for (rc = 0; rc < n_queries; rc++) {
- int c;
-
- if (opts & OPT_stats) {
- printf("Query #%d completed in %ums:\n", rc, queries[rc].latency);
- }
-
- if (queries[rc].rcode != 0) {
- printf("** server can't find %s: %s\n", queries[rc].name,
- rcodes[queries[rc].rcode]);
- continue;
- }
-
- c = 0;
- if (queries[rc].rlen) {
- HEADER *header;
-
- header = (HEADER *)queries[rc].reply;
- if (!header->aa)
- printf("Non-authoritative answer:\n");
- c = parse_reply(queries[rc].reply, queries[rc].rlen);
- }
-
- if (c == 0)
+ if (queries[rc].rlen == 0) {
printf("*** Can't find %s: No answer\n", queries[rc].name);
- else if (c < 0)
- printf("*** Can't find %s: Parse error\n", queries[rc].name);
-
- bb_putchar('\n');
+ err = 1;
+ }
}
+ if (err)
+ bb_putchar('\n'); /* should this affect exicode too? */
if (ENABLE_FEATURE_CLEAN_UP) {
free(ns);
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