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nslookup: shrink send_queries()

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function                                             old     new   delta
rcodes                                                68      64      -4
nslookup_main                                       2007    1880    -127
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-131)           Total: -131 bytes
   text	   data	    bss	    dec	    hex	filename
 926735	    555	   5740	 933030	  e3ca6	busybox_old
 926525	    555	   5740	 932820	  e3bd4	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-04-14 22:53:39 +02:00
parent db93b21ec9
commit 71e016d806
1 changed files with 131 additions and 126 deletions
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257
networking/nslookup.c
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@ -263,10 +263,10 @@ struct ns {
struct query { struct query {
const char *name; const char *name;
size_t qlen, rlen; unsigned qlen, rlen;
unsigned latency;
uint8_t rcode;
unsigned char query[512], reply[512]; unsigned char query[512], reply[512];
unsigned long latency;
int rcode;
}; };
static const struct { static const struct {
@ -288,23 +288,22 @@ static const struct {
}; };
static const char *const rcodes[] = { static const char *const rcodes[] = {
"NOERROR", "NOERROR", // 0
"FORMERR", "FORMERR", // 1
"SERVFAIL", "SERVFAIL", // 2
"NXDOMAIN", "NXDOMAIN", // 3
"NOTIMP", "NOTIMP", // 4
"REFUSED", "REFUSED", // 5
"YXDOMAIN", "YXDOMAIN", // 6
"YXRRSET", "YXRRSET", // 7
"NXRRSET", "NXRRSET", // 8
"NOTAUTH", "NOTAUTH", // 9
"NOTZONE", "NOTZONE", // 10
"RESERVED11", "11", // 11 not assigned
"RESERVED12", "12", // 12 not assigned
"RESERVED13", "13", // 13 not assigned
"RESERVED14", "14", // 14 not assigned
"RESERVED15", "15", // 15 not assigned
"BADVERS"
}; };
#if ENABLE_FEATURE_IPV6 #if ENABLE_FEATURE_IPV6
@ -518,131 +517,136 @@ static char *make_ptr(char resbuf[80], const char *addrstr)
/* /*
* Function logic borrowed & modified from musl libc, res_msend.c * Function logic borrowed & modified from musl libc, res_msend.c
* n_queries is always > 0.
*/ */
static int send_queries(struct ns *ns, struct query *queries, int n_queries) static int send_queries(struct ns *ns, struct query *query, int n_queries)
{ {
len_and_sockaddr *local_lsa;
struct pollfd pfd; struct pollfd pfd;
int servfail_retry = 0; int servfail_retry = 0;
int n_replies = 0; int n_replies = 0;
int next_query = 0; int save_idx = 0;
unsigned retry_interval; unsigned retry_interval;
unsigned timeout = G.default_timeout * 1000; unsigned timeout = G.default_timeout * 1000;
unsigned t0, t1, t2; unsigned tstart, tsent, tcur;
pfd.fd = -1;
pfd.events = POLLIN; pfd.events = POLLIN;
pfd.fd = xsocket_type(&local_lsa, ns->lsa->u.sa.sa_family, SOCK_DGRAM);
/*
* local_lsa has "null" address and port 0 now.
* bind() ensures we have a *particular port* selected by kernel
* and remembered in fd, thus later recv(fd)
* receives only packets sent to this port.
*/
xbind(pfd.fd, &local_lsa->u.sa, local_lsa->len);
free(local_lsa);
/* Make read/writes know the destination */
xconnect(pfd.fd, &ns->lsa->u.sa, ns->lsa->len);
ndelay_on(pfd.fd);
retry_interval = timeout / G.default_retry; retry_interval = timeout / G.default_retry;
t0 = t2 = monotonic_ms(); tstart = tcur = monotonic_ms();
t1 = t2 - retry_interval; goto send;
for (; t2 - t0 < timeout; t2 = monotonic_ms()) { while (tcur - tstart < timeout) {
if (t2 - t1 >= retry_interval) { int qn;
int qn; int recvlen;
if (tcur - tsent >= retry_interval) {
send:
for (qn = 0; qn < n_queries; qn++) { for (qn = 0; qn < n_queries; qn++) {
if (queries[qn].rlen) if (query[qn].rlen)
continue; continue;
if (pfd.fd < 0) { if (write(pfd.fd, query[qn].query, query[qn].qlen) < 0) {
len_and_sockaddr *local_lsa;
pfd.fd = xsocket_type(&local_lsa, ns->lsa->u.sa.sa_family, SOCK_DGRAM);
/*
* local_lsa has "null" address and port 0 now.
* bind() ensures we have a *particular port* selected by kernel
* and remembered in fd, thus later recv(fd)
* receives only packets sent to this port.
*/
xbind(pfd.fd, &local_lsa->u.sa, local_lsa->len);
free(local_lsa);
/* Make read/writes know the destination */
xconnect(pfd.fd, &ns->lsa->u.sa, ns->lsa->len);
ndelay_on(pfd.fd);
}
if (write(pfd.fd, queries[qn].query, queries[qn].qlen) < 0) {
bb_perror_msg("write to '%s'", ns->name); bb_perror_msg("write to '%s'", ns->name);
close(pfd.fd); n_replies = -1; /* "no go, try next server" */
return -1; /* "no go, try next server" */ goto ret;
} }
dbg("query %u sent\n", qn);
} }
tsent = tcur;
t1 = t2;
servfail_retry = 2 * n_queries; servfail_retry = 2 * n_queries;
} }
poll_more:
/* Wait for a response, or until time to retry */ /* Wait for a response, or until time to retry */
if (poll(&pfd, 1, t1 + retry_interval - t2) <= 0) if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
continue; goto next;
while (1) { recvlen = read(pfd.fd, query[save_idx].reply, sizeof(query[0].reply));
int qn;
int recvlen;
recvlen = read(pfd.fd, /* Error/non-identifiable packet */
queries[next_query].reply, if (recvlen < 4) {
sizeof(queries[next_query].reply) dbg("read is too short:%d\n", recvlen);
); goto next;
/* read error */
if (recvlen < 0)
break;
/* Ignore non-identifiable packets */
if (recvlen < 4)
goto poll_more;
/* Find which query this answer goes with, if any */
for (qn = next_query; qn < n_queries; qn++)
if (memcmp(queries[next_query].reply, queries[qn].query, 2) == 0)
break;
if (qn >= n_queries || queries[qn].rlen)
goto poll_more;
queries[qn].rcode = queries[next_query].reply[3] & 15;
queries[qn].latency = monotonic_ms() - t0;
ns->replies++;
/* Only accept positive or negative responses;
* retry immediately on server failure, and ignore
* all other codes such as refusal. */
switch (queries[qn].rcode) {
case 0:
case 3:
break;
case 2:
if (servfail_retry && servfail_retry--) {
ns->failures++;
write(pfd.fd, queries[qn].query, queries[qn].qlen);
}
/* fall through */
default:
continue;
}
/* Store answer */
n_replies++;
queries[qn].rlen = recvlen;
if (qn == next_query) {
while (next_query < n_queries) {
if (!queries[next_query].rlen)
break;
next_query++;
}
} else {
memcpy(queries[qn].reply, queries[next_query].reply, recvlen);
}
if (next_query >= n_queries)
goto ret;
} }
}
/* Find which query this answer goes with, if any */
qn = save_idx;
for (;;) {
if (memcmp(query[save_idx].reply, query[qn].query, 2) == 0) {
dbg("response matches query %u\n", qn);
break;
}
if (++qn >= n_queries) {
dbg("response does not match any query\n");
goto next;
}
}
if (query[qn].rlen) {
dbg("dropped duplicate response to query %u\n", qn);
goto next;
}
ns->replies++;
query[qn].rcode = query[save_idx].reply[3] & 15;
dbg("query %u rcode:%s\n", qn, rcodes[query[qn].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:
if (servfail_retry) {
servfail_retry--;
ns->failures++;
write(pfd.fd, query[qn].query, query[qn].qlen);
dbg("query %u resent\n", qn);
}
/* fall through */
default:
next:
tcur = monotonic_ms();
continue;
}
/* Store answer */
n_replies++;
query[qn].rlen = recvlen;
tcur = monotonic_ms();
query[qn].latency = tcur - tstart;
if (qn != save_idx) {
/* "wrong" receive buffer, move to correct one */
memcpy(query[qn].reply, query[save_idx].reply, recvlen);
continue;
}
/* query[0..save_idx] have replies, move to next one, if exists */
for (;;) {
save_idx++;
if (save_idx >= n_queries)
goto ret; /* all are full: we have all results */
if (!query[save_idx].rlen)
break; /* this one is empty */
}
} /* while() */
ret: ret:
if (pfd.fd >= 0) close(pfd.fd);
close(pfd.fd);
return n_replies; return n_replies;
} }
@ -791,12 +795,13 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
n_queries = 0; n_queries = 0;
queries = NULL; queries = NULL;
do { do {
/* No explicit type given, guess query type.
* If we can convert the domain argument into a ptr (means that
* inet_pton() could read it) we assume a PTR request, else
* we issue A+AAAA queries and switch to an output format
* mimicking the one of the traditional nslookup applet. */
if (types == 0) { if (types == 0) {
/* No explicit type given, guess query type.
* If we can convert the domain argument into a ptr (means that
* inet_pton() could read it) we assume a PTR request, else
* we issue A+AAAA queries and switch to an output format
* mimicking the one of the traditional nslookup applet.
*/
char *ptr; char *ptr;
char buf80[80]; char buf80[80];