generic-library/bionic
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Adding a timeout to tcp dns lookup connects.

Browse Source 
TCP isn't supported on some dns servers, which makes the old code
hang forever.

NOT adding a stopship to remove debugging stuff - it was too painful
(14s timeout on failed tcp dns lookups) so we decided not to bother people.

bug:5766949
Change-Id: I381c20c3e11b8e994438d4f7c58ef643cd36554e
This commit is contained in:
Robert Greenwalt 2012-01-11 10:04:48 -08:00
parent 94963af28e
commit ecd0e95a02
1 changed files with 168 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

194
libc/netbsd/resolv/res_send.c
View File

@ -99,6 +99,7 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef ANDROID_CHANGES
#include "resolv_private.h"
@ -109,6 +110,7 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <isc/eventlib.h>
@ -117,6 +119,8 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
# include <resolv_cache.h>
#endif
#include "logd.h"
#ifndef DE_CONST
#define DE_CONST(c,v) v = ((c) ? \
strchr((const void *)(c), *(const char *)(const void *)(c)) : NULL)
@ -130,6 +134,7 @@ __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");
#include "res_private.h"
#define EXT(res) ((res)->_u._ext)
#define DBG 0
static const int highestFD = FD_SETSIZE - 1;
@ -152,7 +157,10 @@ static int pselect(int, void *, void *, void *,
const sigset_t *);
#endif
void res_pquery(const res_state, const u_char *, int, FILE *);
static int connect_with_timeout(int sock, const struct sockaddr *nsap,
socklen_t salen, int sec);
static int retrying_select(const int sock, fd_set *readset, fd_set *writeset,
const struct timespec *finish);
/* BIONIC-BEGIN: implement source port randomization */
typedef union {
@ -521,16 +529,23 @@ res_nsend(res_state statp,
Dprint(((statp->options & RES_DEBUG) &&
getnameinfo(nsap, (socklen_t)nsaplen, abuf, sizeof(abuf),
NULL, 0, niflags) == 0),
(stdout, ";; Querying server (# %d) address = %s\n",
ns + 1, abuf));
NULL, 0, niflags) == 0),
(stdout, ";; Querying server (# %d) address = %s\n",
ns + 1, abuf));
if (v_circuit) {
/* Use VC; at most one attempt per server. */
try = statp->retry;
n = send_vc(statp, buf, buflen, ans, anssiz, &terrno,
ns);
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
"used send_vc %d\n", n);
}
if (n < 0)
goto fail;
if (n == 0)
@ -538,12 +553,26 @@ res_nsend(res_state statp,
resplen = n;
} else {
/* Use datagrams. */
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
"using send_dg\n");
}
n = send_dg(statp, buf, buflen, ans, anssiz, &terrno,
ns, &v_circuit, &gotsomewhere);
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
"used send_dg %d\n",n);
}
if (n < 0)
goto fail;
if (n == 0)
goto next_ns;
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
"time=%d, %d\n",time(NULL), time(NULL)%2);
}
if (v_circuit)
goto same_ns;
resplen = n;
@ -668,6 +697,23 @@ get_nsaddr(statp, n)
}
}
static int get_timeout(const res_state statp, const int ns)
{
int timeout = (statp->retrans << ns);
if (ns > 0) {
timeout /= statp->nscount;
}
if (timeout <= 0) {
timeout = 1;
}
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
"using timeout of %d sec\n", timeout);
}
return timeout;
}
static int
send_vc(res_state statp,
const u_char *buf, int buflen, u_char *ans, int anssiz,
@ -683,6 +729,10 @@ send_vc(res_state statp,
u_char *cp;
void *tmp;
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc", "using send_vc\n");
}
nsap = get_nsaddr(statp, (size_t)ns);
nsaplen = get_salen(nsap);
@ -735,7 +785,8 @@ send_vc(res_state statp,
res_nclose(statp);
return (0);
}
if (connect(statp->_vcsock, nsap, (socklen_t)nsaplen) < 0) {
if (connect_with_timeout(statp->_vcsock, nsap, (socklen_t)nsaplen,
get_timeout(statp, ns)) < 0) {
*terrno = errno;
Aerror(statp, stderr, "connect/vc", errno, nsap,
nsaplen);
@ -859,6 +910,111 @@ send_vc(res_state statp,
return (resplen);
}
/* return -1 on error (errno set), 0 on success */
static int
connect_with_timeout(int sock, const struct sockaddr *nsap, socklen_t salen, int sec)
{
int res, origflags;
fd_set rset, wset;
struct timespec now, timeout, finish;
origflags = fcntl(sock, F_GETFL, 0);
fcntl(sock, F_SETFL, origflags | O_NONBLOCK);
res = connect(sock, nsap, salen);
if (res < 0 && errno != EINPROGRESS) {
res = -1;
goto done;
}
if (res != 0) {
now = evNowTime();
timeout = evConsTime((long)sec, 0L);
finish = evAddTime(now, timeout);
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
" %d send_vc\n", sock);
}
res = retrying_select(sock, &rset, &wset, &finish);
if (res <= 0) {
res = -1;
}
}
done:
fcntl(sock, F_SETFL, origflags);
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
" %d connect_with_timeout returning %s\n", sock, res);
}
return res;
}
static int
retrying_select(const int sock, fd_set *readset, fd_set *writeset, const struct timespec *finish)
{
struct timespec now, timeout;
int n, error;
socklen_t len;
retry:
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc", " %d retying_select\n", sock);
}
now = evNowTime();
if (readset) {
FD_ZERO(readset);
FD_SET(sock, readset);
}
if (writeset) {
FD_ZERO(writeset);
FD_SET(sock, writeset);
}
if (evCmpTime(*finish, now) > 0)
timeout = evSubTime(*finish, now);
else
timeout = evConsTime(0L, 0L);
n = pselect(sock + 1, readset, writeset, NULL, &timeout, NULL);
if (n == 0) {
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, " libc",
" %d retrying_select timeout\n", sock);
}
errno = ETIMEDOUT;
return 0;
}
if (n < 0) {
if (errno == EINTR)
goto retry;
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
" %d retrying_select got error %d\n",sock, n);
}
return n;
}
if ((readset && FD_ISSET(sock, readset)) || (writeset && FD_ISSET(sock, writeset))) {
len = sizeof(error);
if (getsockopt(sock, SOL_SOCKET, SO_ERROR, &error, &len) < 0 || error) {
errno = error;
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
" %d retrying_select dot error2 %d\n", sock, errno);
}
return -1;
}
}
if (DBG) {
__libc_android_log_print(ANDROID_LOG_DEBUG, "libc",
" %d retrying_select returning %d for %d\n",sock, n);
}
return n;
}
static int
send_dg(res_state statp,
const u_char *buf, int buflen, u_char *ans, int anssiz,
@ -944,33 +1100,19 @@ send_dg(res_state statp,
/*
* Wait for reply.
*/
seconds = (statp->retrans << ns);
if (ns > 0)
seconds /= statp->nscount;
if (seconds <= 0)
seconds = 1;
seconds = get_timeout(statp, ns);
now = evNowTime();
timeout = evConsTime((long)seconds, 0L);
finish = evAddTime(now, timeout);
goto nonow;
wait:
now = evNowTime();
nonow:
FD_ZERO(&dsmask);
FD_SET(s, &dsmask);
if (evCmpTime(finish, now) > 0)
timeout = evSubTime(finish, now);
else
timeout = evConsTime(0L, 0L);
n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);
retry:
n = retrying_select(s, &dsmask, NULL, &finish);
if (n == 0) {
Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
*gotsomewhere = 1;
return (0);
}
if (n < 0) {
if (errno == EINTR)
goto wait;
Perror(statp, stderr, "select", errno);
res_nclose(statp);
return (0);
@ -1006,7 +1148,7 @@ send_dg(res_state statp,
(statp->pfcode & RES_PRF_REPLY),
(stdout, ";; old answer:\n"),
ans, (resplen > anssiz) ? anssiz : resplen);
goto wait;
goto retry;
}
if (!(statp->options & RES_INSECURE1) &&
!res_ourserver_p(statp, (struct sockaddr *)(void *)&from)) {
@ -1019,7 +1161,7 @@ send_dg(res_state statp,
(statp->pfcode & RES_PRF_REPLY),
(stdout, ";; not our server:\n"),
ans, (resplen > anssiz) ? anssiz : resplen);
goto wait;
goto retry;
}
#ifdef RES_USE_EDNS0
if (anhp->rcode == FORMERR && (statp->options & RES_USE_EDNS0) != 0U) {
@ -1049,7 +1191,7 @@ send_dg(res_state statp,
(statp->pfcode & RES_PRF_REPLY),
(stdout, ";; wrong query name:\n"),
ans, (resplen > anssiz) ? anssiz : resplen);
goto wait;
goto retry;;
}
if (anhp->rcode == SERVFAIL ||
anhp->rcode == NOTIMP ||