diff options
Diffstat (limited to 'ares_process.c')
-rw-r--r-- | ares_process.c | 263 |
1 files changed, 149 insertions, 114 deletions
diff --git a/ares_process.c b/ares_process.c index e5efa5f..bbeca5e 100644 --- a/ares_process.c +++ b/ares_process.c @@ -1,6 +1,6 @@ /* Copyright 1998 by the Massachusetts Institute of Technology. - * Copyright (C) 2004-2010 by Daniel Stenberg + * Copyright (C) 2004-2013 by Daniel Stenberg * * Permission to use, copy, modify, and distribute this * software and its documentation for any purpose and without @@ -17,9 +17,6 @@ #include "ares_setup.h" -#ifdef HAVE_SYS_SOCKET_H -# include <sys/socket.h> -#endif #ifdef HAVE_SYS_UIO_H # include <sys/uio.h> #endif @@ -41,16 +38,9 @@ # include <arpa/nameser_compat.h> #endif -#ifdef HAVE_SYS_TIME_H -# include <sys/time.h> -#endif - #ifdef HAVE_STRINGS_H # include <strings.h> #endif -#ifdef HAVE_UNISTD_H -# include <unistd.h> -#endif #ifdef HAVE_SYS_IOCTL_H # include <sys/ioctl.h> #endif @@ -59,10 +49,7 @@ #endif #include <assert.h> -#include <string.h> -#include <stdlib.h> #include <fcntl.h> -#include <time.h> #include "ares.h" #include "ares_dns.h" @@ -268,7 +255,7 @@ static void write_tcp_data(ares_channel channel, if (wcount < 0) { if (!try_again(SOCKERRNO)) - handle_error(channel, i, now); + handle_error(channel, i, now); continue; } @@ -284,7 +271,7 @@ static void write_tcp_data(ares_channel channel, if (scount < 0) { if (!try_again(SOCKERRNO)) - handle_error(channel, i, now); + handle_error(channel, i, now); continue; } @@ -356,11 +343,11 @@ static void read_tcp_data(ares_channel channel, fd_set *read_fds, } if(read_fds) - /* If there's an error and we close this socket, then open - * another with the same fd to talk to another server, then we - * don't want to think that it was the new socket that was - * ready. This is not disastrous, but is likely to result in - * extra system calls and confusion. */ + /* If there's an error and we close this socket, then open another + * with the same fd to talk to another server, then we don't want to + * think that it was the new socket that was ready. This is not + * disastrous, but is likely to result in extra system calls and + * confusion. */ FD_CLR(server->tcp_socket, read_fds); if (server->tcp_lenbuf_pos != 2) @@ -374,7 +361,7 @@ static void read_tcp_data(ares_channel channel, fd_set *read_fds, if (count <= 0) { if (!(count == -1 && try_again(SOCKERRNO))) - handle_error(channel, i, now); + handle_error(channel, i, now); continue; } @@ -401,7 +388,7 @@ static void read_tcp_data(ares_channel channel, fd_set *read_fds, if (count <= 0) { if (!(count == -1 && try_again(SOCKERRNO))) - handle_error(channel, i, now); + handle_error(channel, i, now); continue; } @@ -430,7 +417,7 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, struct server_state *server; int i; ssize_t count; - unsigned char buf[PACKETSZ + 1]; + unsigned char buf[MAXENDSSZ + 1]; #ifdef HAVE_RECVFROM ares_socklen_t fromlen; union { @@ -472,25 +459,31 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds, /* To reduce event loop overhead, read and process as many * packets as we can. */ do { + if (server->udp_socket == ARES_SOCKET_BAD) + count = 0; + + else { #ifdef HAVE_RECVFROM - if (server->addr.family == AF_INET) - fromlen = sizeof(from.sa4); - else - fromlen = sizeof(from.sa6); - count = (ssize_t)recvfrom(server->udp_socket, (void *)buf, sizeof(buf), - 0, &from.sa, &fromlen); + if (server->addr.family == AF_INET) + fromlen = sizeof(from.sa4); + else + fromlen = sizeof(from.sa6); + count = (ssize_t)recvfrom(server->udp_socket, (void *)buf, + sizeof(buf), 0, &from.sa, &fromlen); #else - count = sread(server->udp_socket, buf, sizeof(buf)); + count = sread(server->udp_socket, buf, sizeof(buf)); #endif + } + if (count == -1 && try_again(SOCKERRNO)) continue; else if (count <= 0) handle_error(channel, i, now); #ifdef HAVE_RECVFROM else if (!same_address(&from.sa, &server->addr)) - /* The address the response comes from does not match - * the address we sent the request to. Someone may be - * attempting to perform a cache poisoning attack. */ + /* The address the response comes from does not match the address we + * sent the request to. Someone may be attempting to perform a cache + * poisoning attack. */ break; #endif else @@ -507,11 +500,10 @@ static void process_timeouts(ares_channel channel, struct timeval *now) struct list_node* list_head; struct list_node* list_node; - /* Process all the timeouts that have fired since the last time we - * processed timeouts. If things are going well, then we'll have - * hundreds/thousands of queries that fall into future buckets, and - * only a handful of requests that fall into the "now" bucket, so - * this should be quite quick. + /* Process all the timeouts that have fired since the last time we processed + * timeouts. If things are going well, then we'll have hundreds/thousands of + * queries that fall into future buckets, and only a handful of requests + * that fall into the "now" bucket, so this should be quite quick. */ for (t = channel->last_timeout_processed; t <= now->tv_sec; t++) { @@ -536,7 +528,7 @@ static void process_answer(ares_channel channel, unsigned char *abuf, int alen, int whichserver, int tcp, struct timeval *now) { - int tc, rcode; + int tc, rcode, packetsz; unsigned short id; struct query *query; struct list_node* list_head; @@ -553,11 +545,10 @@ static void process_answer(ares_channel channel, unsigned char *abuf, rcode = DNS_HEADER_RCODE(abuf); /* Find the query corresponding to this packet. The queries are - * hashed/bucketed by query id, so this lookup should be quick. - * Note that both the query id and the questions must be the same; - * when the query id wraps around we can have multiple outstanding - * queries with the same query id, so we need to check both the id and - * question. + * hashed/bucketed by query id, so this lookup should be quick. Note that + * both the query id and the questions must be the same; when the query id + * wraps around we can have multiple outstanding queries with the same query + * id, so we need to check both the id and question. */ query = NULL; list_head = &(channel->queries_by_qid[id % ARES_QID_TABLE_SIZE]); @@ -574,11 +565,34 @@ static void process_answer(ares_channel channel, unsigned char *abuf, if (!query) return; + packetsz = PACKETSZ; + /* If we use EDNS and server answers with one of these RCODES, the protocol + * extension is not understood by the responder. We must retry the query + * without EDNS enabled. + */ + if (channel->flags & ARES_FLAG_EDNS) + { + packetsz = channel->ednspsz; + if (rcode == NOTIMP || rcode == FORMERR || rcode == SERVFAIL) + { + int qlen = alen - EDNSFIXEDSZ; + channel->flags ^= ARES_FLAG_EDNS; + query->tcplen -= EDNSFIXEDSZ; + query->qlen -= EDNSFIXEDSZ; + query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff); + query->tcpbuf[1] = (unsigned char)(qlen & 0xff); + DNS_HEADER_SET_ARCOUNT(query->tcpbuf + 2, 0); + query->tcpbuf = realloc(query->tcpbuf, query->tcplen); + ares__send_query(channel, query, now); + return; + } + } + /* If we got a truncated UDP packet and are not ignoring truncation, * don't accept the packet, and switch the query to TCP if we hadn't * done so already. */ - if ((tc || alen > PACKETSZ) && !tcp && !(channel->flags & ARES_FLAG_IGNTC)) + if ((tc || alen > packetsz) && !tcp && !(channel->flags & ARES_FLAG_IGNTC)) { if (!query->using_tcp) { @@ -591,8 +605,8 @@ static void process_answer(ares_channel channel, unsigned char *abuf, /* Limit alen to PACKETSZ if we aren't using TCP (only relevant if we * are ignoring truncation. */ - if (alen > PACKETSZ && !tcp) - alen = PACKETSZ; + if (alen > packetsz && !tcp) + alen = packetsz; /* If we aren't passing through all error packets, discard packets * with SERVFAIL, NOTIMP, or REFUSED response codes. @@ -626,6 +640,31 @@ static void process_broken_connections(ares_channel channel, } } +/* Swap the contents of two lists */ +static void swap_lists(struct list_node* head_a, + struct list_node* head_b) +{ + int is_a_empty = ares__is_list_empty(head_a); + int is_b_empty = ares__is_list_empty(head_b); + struct list_node old_a = *head_a; + struct list_node old_b = *head_b; + + if (is_a_empty) { + ares__init_list_head(head_b); + } else { + *head_b = old_a; + old_a.next->prev = head_b; + old_a.prev->next = head_b; + } + if (is_b_empty) { + ares__init_list_head(head_a); + } else { + *head_a = old_b; + old_b.next->prev = head_a; + old_b.prev->next = head_a; + } +} + static void handle_error(ares_channel channel, int whichserver, struct timeval *now) { @@ -639,15 +678,14 @@ static void handle_error(ares_channel channel, int whichserver, /* Reset communications with this server. */ ares__close_sockets(channel, server); - /* Tell all queries talking to this server to move on and not try - * this server again. We steal the current list of queries that were - * in-flight to this server, since when we call next_server this can - * cause the queries to be re-sent to this server, which will - * re-insert these queries in that same server->queries_to_server - * list. + /* Tell all queries talking to this server to move on and not try this + * server again. We steal the current list of queries that were in-flight to + * this server, since when we call next_server this can cause the queries to + * be re-sent to this server, which will re-insert these queries in that + * same server->queries_to_server list. */ ares__init_list_head(&list_head); - ares__swap_lists(&list_head, &(server->queries_to_server)); + swap_lists(&list_head, &(server->queries_to_server)); for (list_node = list_head.next; list_node != &list_head; ) { query = list_node->data; @@ -663,14 +701,15 @@ static void handle_error(ares_channel channel, int whichserver, } static void skip_server(ares_channel channel, struct query *query, - int whichserver) { - /* The given server gave us problems with this query, so if we have - * the luxury of using other servers, then let's skip the - * potentially broken server and just use the others. If we only - * have one server and we need to retry then we should just go ahead - * and re-use that server, since it's our only hope; perhaps we - * just got unlucky, and retrying will work (eg, the server timed - * out our TCP connection just as we were sending another request). + int whichserver) +{ + /* The given server gave us problems with this query, so if we have the + * luxury of using other servers, then let's skip the potentially broken + * server and just use the others. If we only have one server and we need to + * retry then we should just go ahead and re-use that server, since it's our + * only hope; perhaps we just got unlucky, and retrying will work (eg, the + * server timed out our TCP connection just as we were sending another + * request). */ if (channel->nservers > 1) { @@ -693,11 +732,10 @@ static void next_server(ares_channel channel, struct query *query, query->server = (query->server + 1) % channel->nservers; server = &channel->servers[query->server]; - /* We don't want to use this server if (1) we decided this - * connection is broken, and thus about to be closed, (2) - * we've decided to skip this server because of earlier - * errors we encountered, or (3) we already sent this query - * over this exact connection. + /* We don't want to use this server if (1) we decided this connection is + * broken, and thus about to be closed, (2) we've decided to skip this + * server because of earlier errors we encountered, or (3) we already + * sent this query over this exact connection. */ if (!server->is_broken && !query->server_info[query->server].skip_server && @@ -709,11 +747,11 @@ static void next_server(ares_channel channel, struct query *query, return; } - /* You might think that with TCP we only need one try. However, - * even when using TCP, servers can time-out our connection just - * as we're sending a request, or close our connection because - * they die, or never send us a reply because they get wedged or - * tickle a bug that drops our request. + /* You might think that with TCP we only need one try. However, even + * when using TCP, servers can time-out our connection just as we're + * sending a request, or close our connection because they die, or never + * send us a reply because they get wedged or tickle a bug that drops + * our request. */ } @@ -749,11 +787,11 @@ void ares__send_query(ares_channel channel, struct query *query, end_query(channel, query, ARES_ENOMEM, NULL, 0); return; } - /* To make the common case fast, we avoid copies by using the - * query's tcpbuf for as long as the query is alive. In the rare - * case where the query ends while it's queued for transmission, - * then we give the sendreq its own copy of the request packet - * and put it in sendreq->data_storage. + /* To make the common case fast, we avoid copies by using the query's + * tcpbuf for as long as the query is alive. In the rare case where the + * query ends while it's queued for transmission, then we give the + * sendreq its own copy of the request packet and put it in + * sendreq->data_storage. */ sendreq->data_storage = NULL; sendreq->data = query->tcpbuf; @@ -837,30 +875,29 @@ static int setsocknonblock(ares_socket_t sockfd, /* operate on this */ #elif defined(HAVE_IOCTL_FIONBIO) /* older unix versions */ - int flags; - flags = nonblock; + int flags = nonblock ? 1 : 0; return ioctl(sockfd, FIONBIO, &flags); #elif defined(HAVE_IOCTLSOCKET_FIONBIO) #ifdef WATT32 - char flags; + char flags = nonblock ? 1 : 0; #else /* Windows */ - unsigned long flags; + unsigned long flags = nonblock ? 1UL : 0UL; #endif - flags = nonblock; return ioctlsocket(sockfd, FIONBIO, &flags); #elif defined(HAVE_IOCTLSOCKET_CAMEL_FIONBIO) /* Amiga */ - return IoctlSocket(sockfd, FIONBIO, (long)nonblock); + long flags = nonblock ? 1L : 0L; + return IoctlSocket(sockfd, FIONBIO, flags); #elif defined(HAVE_SETSOCKOPT_SO_NONBLOCK) /* BeOS */ - long b = nonblock ? 1 : 0; + long b = nonblock ? 1L : 0L; return setsockopt(sockfd, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b)); #else @@ -917,10 +954,12 @@ static int configure_socket(ares_socket_t s, int family, ares_channel channel) } } else if (family == AF_INET6) { - if (memcmp(channel->local_ip6, &ares_in6addr_any, sizeof(channel->local_ip6)) != 0) { + if (memcmp(channel->local_ip6, &ares_in6addr_any, + sizeof(channel->local_ip6)) != 0) { memset(&local.sa6, 0, sizeof(local.sa6)); local.sa6.sin6_family = AF_INET6; - memcpy(&local.sa6.sin6_addr, channel->local_ip6, sizeof(channel->local_ip6)); + memcpy(&local.sa6.sin6_addr, channel->local_ip6, + sizeof(channel->local_ip6)); if (bind(s, &local.sa, sizeof(local.sa6)) < 0) return -1; } @@ -947,7 +986,7 @@ static int open_tcp_socket(ares_channel channel, struct server_state *server) salen = sizeof(saddr.sa4); memset(sa, 0, salen); saddr.sa4.sin_family = AF_INET; - saddr.sa4.sin_port = (unsigned short)(channel->tcp_port & 0xffff); + saddr.sa4.sin_port = aresx_sitous(channel->tcp_port); memcpy(&saddr.sa4.sin_addr, &server->addr.addrV4, sizeof(server->addr.addrV4)); break; @@ -956,7 +995,7 @@ static int open_tcp_socket(ares_channel channel, struct server_state *server) salen = sizeof(saddr.sa6); memset(sa, 0, salen); saddr.sa6.sin6_family = AF_INET6; - saddr.sa6.sin6_port = (unsigned short)(channel->tcp_port & 0xffff); + saddr.sa6.sin6_port = aresx_sitous(channel->tcp_port); memcpy(&saddr.sa6.sin6_addr, &server->addr.addrV6, sizeof(server->addr.addrV6)); break; @@ -1039,7 +1078,7 @@ static int open_udp_socket(ares_channel channel, struct server_state *server) salen = sizeof(saddr.sa4); memset(sa, 0, salen); saddr.sa4.sin_family = AF_INET; - saddr.sa4.sin_port = (unsigned short)(channel->udp_port & 0xffff); + saddr.sa4.sin_port = aresx_sitous(channel->udp_port); memcpy(&saddr.sa4.sin_addr, &server->addr.addrV4, sizeof(server->addr.addrV4)); break; @@ -1048,7 +1087,7 @@ static int open_udp_socket(ares_channel channel, struct server_state *server) salen = sizeof(saddr.sa6); memset(sa, 0, salen); saddr.sa6.sin6_family = AF_INET6; - saddr.sa6.sin6_port = (unsigned short)(channel->udp_port & 0xffff); + saddr.sa6.sin6_port = aresx_sitous(channel->udp_port); memcpy(&saddr.sa6.sin6_addr, &server->addr.addrV6, sizeof(server->addr.addrV6)); break; @@ -1223,19 +1262,17 @@ static void end_query (ares_channel channel, struct query *query, int status, assert(sendreq->data_storage == NULL); if (status == ARES_SUCCESS) { - /* We got a reply for this query, but this queued - * sendreq points into this soon-to-be-gone query's - * tcpbuf. Probably this means we timed out and queued - * the query for retransmission, then received a - * response before actually retransmitting. This is - * perfectly fine, so we want to keep the connection - * running smoothly if we can. But in the worst case - * we may have sent only some prefix of the query, - * with some suffix of the query left to send. Also, - * the buffer may be queued on multiple queues. To - * prevent dangling pointers to the query's tcpbuf and - * handle these cases, we just give such sendreqs - * their own copy of the query packet. + /* We got a reply for this query, but this queued sendreq + * points into this soon-to-be-gone query's tcpbuf. Probably + * this means we timed out and queued the query for + * retransmission, then received a response before actually + * retransmitting. This is perfectly fine, so we want to keep + * the connection running smoothly if we can. But in the worst + * case we may have sent only some prefix of the query, with + * some suffix of the query left to send. Also, the buffer may + * be queued on multiple queues. To prevent dangling pointers + * to the query's tcpbuf and handle these cases, we just give + * such sendreqs their own copy of the query packet. */ sendreq->data_storage = malloc(sendreq->len); if (sendreq->data_storage != NULL) @@ -1246,14 +1283,12 @@ static void end_query (ares_channel channel, struct query *query, int status, } if ((status != ARES_SUCCESS) || (sendreq->data_storage == NULL)) { - /* We encountered an error (probably a timeout, - * suggesting the DNS server we're talking to is - * probably unreachable, wedged, or severely - * overloaded) or we couldn't copy the request, so - * mark the connection as broken. When we get to - * process_broken_connections() we'll close the - * connection and try to re-send requests to another - * server. + /* We encountered an error (probably a timeout, suggesting the + * DNS server we're talking to is probably unreachable, + * wedged, or severely overloaded) or we couldn't copy the + * request, so mark the connection as broken. When we get to + * process_broken_connections() we'll close the connection and + * try to re-send requests to another server. */ server->is_broken = 1; /* Just to be paranoid, zero out this sendreq... */ @@ -1267,8 +1302,8 @@ static void end_query (ares_channel channel, struct query *query, int status, query->callback(query->arg, status, query->timeouts, abuf, alen); ares__free_query(query); - /* Simple cleanup policy: if no queries are remaining, close all - * network sockets unless STAYOPEN is set. + /* Simple cleanup policy: if no queries are remaining, close all network + * sockets unless STAYOPEN is set. */ if (!(channel->flags & ARES_FLAG_STAYOPEN) && ares__is_list_empty(&(channel->all_queries))) |