ossp-pkg/adns/adns_event.c
1.6
/*
* event.c
* - event loop core
* - TCP connection management
* - user-visible check/wait and event-loop-related functions
*/
/*
* This file is
* Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
*
* It is part of adns, which is
* Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
* Copyright (C) 1999-2000 Tony Finch <dot@dotat.at>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "adns_internal.h"
/* TCP connection management. */
static void tcp_close(adns_state ads) {
int serv;
serv= ads->tcpserver;
close(ads->tcpsocket);
ads->tcpsocket= -1;
ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
}
void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
int serv;
adns_query qu;
assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
serv= ads->tcpserver;
if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
if (ads->tcpstate == server_connecting) {
/* Counts as a retry for all the queries waiting for TCP. */
for (qu= ads->tcpw.head; qu; qu= qu->next)
qu->retries++;
}
tcp_close(ads);
ads->tcpstate= server_broken;
ads->tcpserver= (serv+1)%ads->nservers;
}
static void tcp_connected(adns_state ads, struct timeval now) {
adns_query qu, nqu;
adns__debug(ads,ads->tcpserver,0,"TCP connected");
ads->tcpstate= server_ok;
for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
nqu= qu->next;
assert(qu->state == query_tcpw);
adns__querysend_tcp(qu,now);
}
}
void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
int r, fd, tries;
struct sockaddr_in addr;
struct protoent *proto;
for (tries=0; tries<ads->nservers; tries++) {
switch (ads->tcpstate) {
case server_connecting:
case server_ok:
case server_broken:
return;
case server_disconnected:
break;
default:
abort();
}
assert(!ads->tcpsend.used);
assert(!ads->tcprecv.used);
assert(!ads->tcprecv_skip);
proto= getprotobyname("tcp");
if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
if (fd<0) {
adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
return;
}
r= adns__setnonblock(ads,fd);
if (r) {
adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
close(fd);
return;
}
memset(&addr,0,sizeof(addr));
addr.sin_family= AF_INET;
addr.sin_port= htons(DNS_PORT);
addr.sin_addr= ads->servers[ads->tcpserver].addr;
r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
ads->tcpsocket= fd;
ads->tcpstate= server_connecting;
if (r==0) { tcp_connected(ads,now); return; }
if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
ads->tcptimeout= now;
_adns_timevaladd(&ads->tcptimeout,TCPCONNMS);
return;
}
adns__tcp_broken(ads,"connect",strerror(errno));
ads->tcpstate= server_disconnected;
}
}
/* Timeout handling functions. */
void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
struct timeval *tv_buf) {
const struct timeval *now;
int r;
now= *now_io;
if (now) return;
r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
adns_globalsystemfailure(ads);
return;
}
static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
struct timeval *rbuf;
if (!tv_io) return;
rbuf= *tv_io;
if (!rbuf) { *tv_io= rbuf= tvbuf; }
timerclear(rbuf);
}
static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
struct timeval maxto) {
struct timeval *rbuf;
if (!tv_io) return;
rbuf= *tv_io;
if (!rbuf) {
*tvbuf= maxto; *tv_io= tvbuf;
} else {
if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
}
/*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
}
static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
struct timeval now, struct timeval maxtime) {
/* tv_io may be 0 */
ldiv_t dr;
/*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
if (!tv_io) return;
maxtime.tv_sec -= (now.tv_sec+2);
maxtime.tv_usec -= (now.tv_usec-2000000);
dr= ldiv(maxtime.tv_usec,1000000);
maxtime.tv_sec += dr.quot;
maxtime.tv_usec -= dr.quot*1000000;
if (maxtime.tv_sec<0) timerclear(&maxtime);
inter_maxto(tv_io,tvbuf,maxtime);
}
static void timeouts_queue(adns_state ads, int act,
struct timeval **tv_io, struct timeval *tvbuf,
struct timeval now, struct query_queue *queue) {
adns_query qu, nqu;
for (qu= queue->head; qu; qu= nqu) {
nqu= qu->next;
if (!timercmp(&now,&qu->timeout,>)) {
inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
} else {
if (!act) { inter_immed(tv_io,tvbuf); return; }
ADNS_LIST_UNLINK(*queue,qu);
if (qu->state != query_tosend) {
adns__query_fail(qu,adns_s_timeout);
} else {
adns__query_send(qu,now);
}
nqu= queue->head;
}
}
}
static void tcp_events(adns_state ads, int act,
struct timeval **tv_io, struct timeval *tvbuf,
struct timeval now) {
adns_query qu, nqu;
for (;;) {
switch (ads->tcpstate) {
case server_broken:
if (!act) { inter_immed(tv_io,tvbuf); return; }
for (qu= ads->tcpw.head; qu; qu= nqu) {
nqu= qu->next;
assert(qu->state == query_tcpw);
if (qu->retries > ads->nservers) {
ADNS_LIST_UNLINK(ads->tcpw,qu);
adns__query_fail(qu,adns_s_allservfail);
}
}
ads->tcpstate= server_disconnected;
case server_disconnected: /* fall through */
if (!ads->tcpw.head) return;
if (!act) { inter_immed(tv_io,tvbuf); return; }
adns__tcp_tryconnect(ads,now);
break;
case server_ok:
if (ads->tcpw.head) return;
if (!ads->tcptimeout.tv_sec) {
assert(!ads->tcptimeout.tv_usec);
ads->tcptimeout= now;
_adns_timevaladd(&ads->tcptimeout,TCPIDLEMS);
}
case server_connecting: /* fall through */
if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
return;
} {
/* TCP timeout has happened */
switch (ads->tcpstate) {
case server_connecting: /* failed to connect */
adns__tcp_broken(ads,"unable to make connection","timed out");
break;
case server_ok: /* idle timeout */
tcp_close(ads);
ads->tcpstate= server_disconnected;
return;
default:
abort();
}
}
break;
default:
abort();
}
}
return;
}
void adns__timeouts(adns_state ads, int act,
struct timeval **tv_io, struct timeval *tvbuf,
struct timeval now) {
timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
tcp_events(ads,act,tv_io,tvbuf,now);
}
void adns_firsttimeout(adns_state ads,
struct timeval **tv_io, struct timeval *tvbuf,
struct timeval now) {
adns__consistency(ads,0,cc_entex);
adns__timeouts(ads, 0, tv_io,tvbuf, now);
adns__consistency(ads,0,cc_entex);
}
void adns_processtimeouts(adns_state ads, const struct timeval *now) {
struct timeval tv_buf;
adns__consistency(ads,0,cc_entex);
adns__must_gettimeofday(ads,&now,&tv_buf);
if (now) adns__timeouts(ads, 1, 0,0, *now);
adns__consistency(ads,0,cc_entex);
}
/* fd handling functions. These are the top-level of the real work of
* reception and often transmission.
*/
int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
/* Returns the number of entries filled in. Always zeroes revents. */
assert(MAX_POLLFDS==2);
pollfds_buf[0].fd= ads->udpsocket;
pollfds_buf[0].events= POLLIN;
pollfds_buf[0].revents= 0;
switch (ads->tcpstate) {
case server_disconnected:
case server_broken:
return 1;
case server_connecting:
pollfds_buf[1].events= POLLOUT;
break;
case server_ok:
pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
break;
default:
abort();
}
pollfds_buf[1].fd= ads->tcpsocket;
return 2;
}
int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
int want, dgramlen, r, udpaddrlen, serv, old_skip;
byte udpbuf[DNS_MAXUDP];
struct sockaddr_in udpaddr;
adns__consistency(ads,0,cc_entex);
switch (ads->tcpstate) {
case server_disconnected:
case server_broken:
case server_connecting:
break;
case server_ok:
if (fd != ads->tcpsocket) break;
assert(!ads->tcprecv_skip);
do {
if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
ads->tcprecv.buf[ads->tcprecv_skip+1]);
if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
old_skip= ads->tcprecv_skip;
ads->tcprecv_skip += 2+dgramlen;
adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
dgramlen, ads->tcpserver, 1,*now);
continue;
} else {
want= 2+dgramlen;
}
} else {
want= 2;
}
ads->tcprecv.used -= ads->tcprecv_skip;
memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
ads->tcprecv_skip= 0;
if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
assert(ads->tcprecv.used <= ads->tcprecv.avail);
if (ads->tcprecv.used == ads->tcprecv.avail) continue;
r= read(ads->tcpsocket,
ads->tcprecv.buf+ads->tcprecv.used,
ads->tcprecv.avail-ads->tcprecv.used);
if (r>0) {
ads->tcprecv.used+= r;
} else {
if (r) {
if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
if (errno==EINTR) continue;
if (errno_resources(errno)) { r= errno; goto xit; }
}
adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
}
} while (ads->tcpstate == server_ok);
r= 0; goto xit;
default:
abort();
}
if (fd == ads->udpsocket) {
for (;;) {
udpaddrlen= sizeof(udpaddr);
r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
(struct sockaddr*)&udpaddr,&udpaddrlen);
if (r<0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
if (errno == EINTR) continue;
if (errno_resources(errno)) { r= errno; goto xit; }
adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
r= 0; goto xit;
}
if (udpaddrlen != sizeof(udpaddr)) {
adns__diag(ads,-1,0,"datagram received with wrong address length %d"
" (expected %lu)", udpaddrlen,
(unsigned long)sizeof(udpaddr));
continue;
}
if (udpaddr.sin_family != AF_INET) {
adns__diag(ads,-1,0,"datagram received with wrong protocol family"
" %u (expected %u)",udpaddr.sin_family,AF_INET);
continue;
}
if (ntohs(udpaddr.sin_port) != DNS_PORT) {
adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
ntohs(udpaddr.sin_port),DNS_PORT);
continue;
}
for (serv= 0;
serv < ads->nservers &&
ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
serv++);
if (serv >= ads->nservers) {
adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
inet_ntoa(udpaddr.sin_addr));
continue;
}
adns__procdgram(ads,udpbuf,r,serv,0,*now);
}
}
r= 0;
xit:
adns__consistency(ads,0,cc_entex);
return r;
}
int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
int r;
adns__consistency(ads,0,cc_entex);
switch (ads->tcpstate) {
case server_disconnected:
case server_broken:
break;
case server_connecting:
if (fd != ads->tcpsocket) break;
assert(ads->tcprecv.used==0);
assert(ads->tcprecv_skip==0);
for (;;) {
if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
tcp_connected(ads,*now);
r= 0; goto xit;
}
if (r>0) {
adns__tcp_broken(ads,"connect/read","sent data before first request");
r= 0; goto xit;
}
if (errno==EINTR) continue;
if (errno_resources(errno)) { r= errno; goto xit; }
adns__tcp_broken(ads,"connect/read",strerror(errno));
r= 0; goto xit;
} /* not reached */
case server_ok:
if (fd != ads->tcpsocket) break;
while (ads->tcpsend.used) {
adns__sigpipe_protect(ads);
r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
adns__sigpipe_unprotect(ads);
if (r<0) {
if (errno==EINTR) continue;
if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
if (errno_resources(errno)) { r= errno; goto xit; }
adns__tcp_broken(ads,"write",strerror(errno));
r= 0; goto xit;
} else if (r>0) {
ads->tcpsend.used -= r;
memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
}
}
r= 0;
goto xit;
default:
abort();
}
r= 0;
xit:
adns__consistency(ads,0,cc_entex);
return r;
}
int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
adns__consistency(ads,0,cc_entex);
switch (ads->tcpstate) {
case server_disconnected:
case server_broken:
break;
case server_connecting:
case server_ok:
if (fd != ads->tcpsocket) break;
adns__tcp_broken(ads,"poll/select","exceptional condition detected");
break;
default:
abort();
}
adns__consistency(ads,0,cc_entex);
return 0;
}
static void fd_event(adns_state ads, int fd,
int revent, int pollflag,
int maxfd, const fd_set *fds,
int (*func)(adns_state, int fd, const struct timeval *now),
struct timeval now, int *r_r) {
int r;
if (!(revent & pollflag)) return;
if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
r= func(ads,fd,&now);
if (r) {
if (r_r) {
*r_r= r;
} else {
adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
adns_globalsystemfailure(ads);
}
}
}
void adns__fdevents(adns_state ads,
const struct pollfd *pollfds, int npollfds,
int maxfd, const fd_set *readfds,
const fd_set *writefds, const fd_set *exceptfds,
struct timeval now, int *r_r) {
int i, fd, revents;
for (i=0; i<npollfds; i++) {
fd= pollfds[i].fd;
if (fd >= maxfd) maxfd= fd+1;
revents= pollfds[i].revents;
fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
}
}
/* Wrappers for select(2). */
void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
fd_set *writefds_io, fd_set *exceptfds_io,
struct timeval **tv_mod, struct timeval *tv_tobuf,
const struct timeval *now) {
struct timeval tv_nowbuf;
struct pollfd pollfds[MAX_POLLFDS];
int i, fd, maxfd, npollfds;
adns__consistency(ads,0,cc_entex);
if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
/* The caller is planning to sleep. */
adns__must_gettimeofday(ads,&now,&tv_nowbuf);
if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
}
npollfds= adns__pollfds(ads,pollfds);
maxfd= *maxfd_io;
for (i=0; i<npollfds; i++) {
fd= pollfds[i].fd;
if (fd >= maxfd) maxfd= fd+1;
if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
}
*maxfd_io= maxfd;
xit:
adns__consistency(ads,0,cc_entex);
}
void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
const fd_set *writefds, const fd_set *exceptfds,
const struct timeval *now) {
struct timeval tv_buf;
struct pollfd pollfds[MAX_POLLFDS];
int npollfds, i;
adns__consistency(ads,0,cc_entex);
adns__must_gettimeofday(ads,&now,&tv_buf);
if (!now) goto xit;
adns_processtimeouts(ads,now);
npollfds= adns__pollfds(ads,pollfds);
for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
adns__fdevents(ads,
pollfds,npollfds,
maxfd,readfds,writefds,exceptfds,
*now, 0);
xit:
adns__consistency(ads,0,cc_entex);
}
/* General helpful functions. */
void adns_globalsystemfailure(adns_state ads) {
adns__consistency(ads,0,cc_entex);
while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
switch (ads->tcpstate) {
case server_connecting:
case server_ok:
adns__tcp_broken(ads,0,0);
break;
case server_disconnected:
case server_broken:
break;
default:
abort();
}
adns__consistency(ads,0,cc_entex);
}
int adns_processany(adns_state ads) {
int r, i;
struct timeval now;
struct pollfd pollfds[MAX_POLLFDS];
int npollfds;
adns__consistency(ads,0,cc_entex);
r= gettimeofday(&now,0);
if (!r) adns_processtimeouts(ads,&now);
/* We just use adns__fdevents to loop over the fd's trying them.
* This seems more sensible than calling select, since we're most
* likely just to want to do a read on one or two fds anyway.
*/
npollfds= adns__pollfds(ads,pollfds);
for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
adns__fdevents(ads,
pollfds,npollfds,
0,0,0,0,
now,&r);
adns__consistency(ads,0,cc_entex);
return 0;
}
void adns__autosys(adns_state ads, struct timeval now) {
if (ads->iflags & adns_if_noautosys) return;
adns_processany(ads);
}
int adns__internal_check(adns_state ads,
adns_query *query_io,
adns_answer **answer,
void **context_r) {
adns_query qu;
qu= *query_io;
if (!qu) {
if (ads->output.head) {
qu= ads->output.head;
} else if (ads->udpw.head || ads->tcpw.head) {
return EAGAIN;
} else {
return ESRCH;
}
} else {
if (qu->id>=0) return EAGAIN;
}
ADNS_LIST_UNLINK(ads->output,qu);
*answer= qu->answer;
if (context_r) *context_r= qu->ctx.ext;
*query_io= qu;
free(qu);
return 0;
}
int adns_wait(adns_state ads,
adns_query *query_io,
adns_answer **answer_r,
void **context_r) {
int r, maxfd, rsel;
fd_set readfds, writefds, exceptfds;
struct timeval tvbuf, *tvp;
adns__consistency(ads,*query_io,cc_entex);
for (;;) {
r= adns__internal_check(ads,query_io,answer_r,context_r);
if (r != EAGAIN) break;
maxfd= 0; tvp= 0;
FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
assert(tvp);
rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
if (rsel==-1) {
if (errno == EINTR) {
if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
} else {
adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
adns_globalsystemfailure(ads);
}
} else {
assert(rsel >= 0);
adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
}
}
adns__consistency(ads,0,cc_entex);
return r;
}
int adns_check(adns_state ads,
adns_query *query_io,
adns_answer **answer_r,
void **context_r) {
struct timeval now;
int r;
adns__consistency(ads,*query_io,cc_entex);
r= gettimeofday(&now,0);
if (!r) adns__autosys(ads,now);
r= adns__internal_check(ads,query_io,answer_r,context_r);
adns__consistency(ads,0,cc_entex);
return r;
}
