nslookup: shrink send_queries()

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

View File

@ -263,10 +263,10 @@ struct ns {
struct query {
const char *name;
size_t qlen, rlen;
unsigned qlen, rlen;
unsigned latency;
uint8_t rcode;
unsigned char query[512], reply[512];
unsigned long latency;
int rcode;
};
static const struct {
@ -288,23 +288,22 @@ static const struct {
};
static const char *const rcodes[] = {
"NOERROR",
"FORMERR",
"SERVFAIL",
"NXDOMAIN",
"NOTIMP",
"REFUSED",
"YXDOMAIN",
"YXRRSET",
"NXRRSET",
"NOTAUTH",
"NOTZONE",
"RESERVED11",
"RESERVED12",
"RESERVED13",
"RESERVED14",
"RESERVED15",
"BADVERS"
"NOERROR", // 0
"FORMERR", // 1
"SERVFAIL", // 2
"NXDOMAIN", // 3
"NOTIMP", // 4
"REFUSED", // 5
"YXDOMAIN", // 6
"YXRRSET", // 7
"NXRRSET", // 8
"NOTAUTH", // 9
"NOTZONE", // 10
"11", // 11 not assigned
"12", // 12 not assigned
"13", // 13 not assigned
"14", // 14 not assigned
"15", // 15 not assigned
};
#if ENABLE_FEATURE_IPV6
@ -518,32 +517,20 @@ static char *make_ptr(char resbuf[80], const char *addrstr)
/*
* 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;
int servfail_retry = 0;
int n_replies = 0;
int next_query = 0;
int save_idx = 0;
unsigned retry_interval;
unsigned timeout = G.default_timeout * 1000;
unsigned t0, t1, t2;
unsigned tstart, tsent, tcur;
pfd.fd = -1;
pfd.events = POLLIN;
retry_interval = timeout / G.default_retry;
t0 = t2 = monotonic_ms();
t1 = t2 - retry_interval;
for (; t2 - t0 < timeout; t2 = monotonic_ms()) {
if (t2 - t1 >= retry_interval) {
int qn;
for (qn = 0; qn < n_queries; qn++) {
if (queries[qn].rlen)
continue;
if (pfd.fd < 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.
@ -556,92 +543,109 @@ static int send_queries(struct ns *ns, struct query *queries, int n_queries)
/* 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);
close(pfd.fd);
return -1; /* "no go, try next server" */
}
}
t1 = t2;
servfail_retry = 2 * n_queries;
}
poll_more:
/* Wait for a response, or until time to retry */
if (poll(&pfd, 1, t1 + retry_interval - t2) <= 0)
continue;
retry_interval = timeout / G.default_retry;
tstart = tcur = monotonic_ms();
goto send;
while (1) {
while (tcur - tstart < timeout) {
int qn;
int recvlen;
recvlen = read(pfd.fd,
queries[next_query].reply,
sizeof(queries[next_query].reply)
);
if (tcur - tsent >= retry_interval) {
send:
for (qn = 0; qn < n_queries; qn++) {
if (query[qn].rlen)
continue;
if (write(pfd.fd, query[qn].query, query[qn].qlen) < 0) {
bb_perror_msg("write to '%s'", ns->name);
n_replies = -1; /* "no go, try next server" */
goto ret;
}
dbg("query %u sent\n", qn);
}
tsent = tcur;
servfail_retry = 2 * n_queries;
}
/* read error */
if (recvlen < 0)
break;
/* Wait for a response, or until time to retry */
if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
goto next;
/* Ignore non-identifiable packets */
if (recvlen < 4)
goto poll_more;
recvlen = read(pfd.fd, query[save_idx].reply, sizeof(query[0].reply));
/* Error/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 */
for (qn = next_query; qn < n_queries; qn++)
if (memcmp(queries[next_query].reply, queries[qn].query, 2) == 0)
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 (qn >= n_queries || queries[qn].rlen)
goto poll_more;
queries[qn].rcode = queries[next_query].reply[3] & 15;
queries[qn].latency = monotonic_ms() - t0;
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 (queries[qn].rcode) {
* all other codes such as refusal.
*/
switch (query[qn].rcode) {
case 0:
case 3:
break;
case 2:
if (servfail_retry && servfail_retry--) {
if (servfail_retry) {
servfail_retry--;
ns->failures++;
write(pfd.fd, queries[qn].query, queries[qn].qlen);
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() */
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;
}
}
ret:
if (pfd.fd >= 0)
close(pfd.fd);
return n_replies;
@ -791,12 +795,13 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
n_queries = 0;
queries = NULL;
do {
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. */
if (types == 0) {
* mimicking the one of the traditional nslookup applet.
*/
char *ptr;
char buf80[80];