diff options
Diffstat (limited to 'src/event.c')
| -rw-r--r-- | src/event.c | 732 |
1 files changed, 732 insertions, 0 deletions
diff --git a/src/event.c b/src/event.c new file mode 100644 index 0000000..3dd927b --- /dev/null +++ b/src/event.c @@ -0,0 +1,732 @@ +/* + * event.c + * - event loop core + * - TCP connection management + * - user-visible check/wait and event-loop-related functions + */ +/* + * This file is part of adns, which is + * Copyright (C) 1997-2000,2003,2006,2014 Ian Jackson + * Copyright (C) 2014 Mark Wooding + * Copyright (C) 1999-2000,2003,2006 Tony Finch + * Copyright (C) 1991 Massachusetts Institute of Technology + * (See the file INSTALL for full details.) + * + * 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 3, 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. + */ + +#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 "internal.h" +#include "tvarith.h" + +/* TCP connection management. */ + +static void tcp_close(adns_state ads) { + 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); + } +} + +static void tcp_broken_events(adns_state ads) { + adns_query qu, nqu; + + assert(ads->tcpstate == server_broken); + for (qu= ads->tcpw.head; qu; qu= nqu) { + nqu= qu->next; + assert(qu->state == query_tcpw); + if (qu->retries > ads->nservers) { + LIST_UNLINK(ads->tcpw,qu); + adns__query_fail(qu,adns_s_allservfail); + } + } + ads->tcpstate= server_disconnected; +} + +void adns__tcp_tryconnect(adns_state ads, struct timeval now) { + int r, fd, tries; + adns_rr_addr *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; + } + addr = &ads->servers[ads->tcpserver]; + fd= socket(addr->addr.sa.sa_family, 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; + } + r= connect(fd,&addr->addr.sa,addr->len); + ads->tcpsocket= fd; + ads->tcpstate= server_connecting; + if (r==0) { tcp_connected(ads,now); return; } + if (errno == EWOULDBLOCK || errno == EINPROGRESS) { + ads->tcptimeout= now; + timevaladd(&ads->tcptimeout,TCPCONNMS); + return; + } + adns__tcp_broken(ads,"connect",strerror(errno)); + tcp_broken_events(ads); + } +} + +/* 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; } + 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) { + for (;;) { + switch (ads->tcpstate) { + case server_broken: + if (!act) { inter_immed(tv_io,tvbuf); return; } + tcp_broken_events(ads); + 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; + 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__returning(ads,0); +} + +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__returning(ads,0); +} + +/* 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. */ + int nwanted=0; +#define ADD_POLLFD(wantfd, wantevents) do{ \ + pollfds_buf[nwanted].fd= (wantfd); \ + pollfds_buf[nwanted].events= (wantevents); \ + pollfds_buf[nwanted].revents= 0; \ + nwanted++; \ + }while(0) + + int i; + + assert(MAX_POLLFDS == MAXUDP + 1); + + for (i=0; i<ads->nudpsockets; i++) + ADD_POLLFD(ads->udpsockets[i].fd, POLLIN); + + switch (ads->tcpstate) { + case server_disconnected: + case server_broken: + break; + case server_connecting: + ADD_POLLFD(ads->tcpsocket, POLLOUT); + break; + case server_ok: + ADD_POLLFD(ads->tcpsocket, + ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI); + break; + default: + abort(); + } + assert(nwanted<=MAX_POLLFDS); +#undef ADD_POLLFD + return nwanted; +} + +int adns_processreadable(adns_state ads, int fd, const struct timeval *now) { + int want, dgramlen, r, i, udpaddrlen, serv, old_skip; + byte udpbuf[DNS_MAXUDP]; + char addrbuf[ADNS_ADDR2TEXT_BUFLEN]; + struct udpsocket *udp; + adns_sockaddr 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(); + } + for (i=0; i<ads->nudpsockets; i++) { + udp= &ads->udpsockets[i]; + if (fd != udp->fd) continue; + for (;;) { + udpaddrlen= sizeof(udpaddr); + r= recvfrom(fd,udpbuf,sizeof(udpbuf),0, &udpaddr.sa,&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; + } + for (serv= 0; + serv < ads->nservers && + !adns__sockaddrs_equal(&udpaddr.sa, + &ads->servers[serv].addr.sa); + serv++); + if (serv >= ads->nservers) { + adns__warn(ads,-1,0,"datagram received from unknown nameserver %s", + adns__sockaddr_ntoa(&udpaddr.sa, addrbuf)); + continue; + } + adns__procdgram(ads,udpbuf,r,serv,0,*now); + } + break; + } + r= 0; +xit: + adns__returning(ads,0); + 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__returning(ads,0); + 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__returning(ads,0); + 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; +#define EV(pollfl,fds,how) \ + fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r) + EV( POLLIN, readfds, readable ); + EV( POLLOUT, writefds, writeable ); + EV( POLLPRI, exceptfds, exceptional ); +#undef EV + } +} + +/* 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__returning(ads,0); +} + +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__returning(ads,0); +} + +/* 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__returning(ads,0); +} + +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__returning(ads,0); + 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; + } + 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__returning(ads,0); + 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__returning(ads,0); + return r; +} |