diff options
Diffstat (limited to 'ares_send.c')
-rw-r--r-- | ares_send.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/ares_send.c b/ares_send.c new file mode 100644 index 0000000..37b0704 --- /dev/null +++ b/ares_send.c @@ -0,0 +1,134 @@ + +/* Copyright 1998 by the Massachusetts Institute of Technology. + * + * Permission to use, copy, modify, and distribute this + * software and its documentation for any purpose and without + * fee is hereby granted, provided that the above copyright + * notice appear in all copies and that both that copyright + * notice and this permission notice appear in supporting + * documentation, and that the name of M.I.T. not be used in + * advertising or publicity pertaining to distribution of the + * software without specific, written prior permission. + * M.I.T. makes no representations about the suitability of + * this software for any purpose. It is provided "as is" + * without express or implied warranty. + */ + +#include "ares_setup.h" + +#ifdef HAVE_SYS_SOCKET_H +# include <sys/socket.h> +#endif +#ifdef HAVE_NETINET_IN_H +# include <netinet/in.h> +#endif +#ifdef HAVE_ARPA_NAMESER_H +# include <arpa/nameser.h> +#else +# include "nameser.h" +#endif +#ifdef HAVE_ARPA_NAMESER_COMPAT_H +# include <arpa/nameser_compat.h> +#endif + +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include "ares.h" +#include "ares_dns.h" +#include "ares_private.h" + +void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen, + ares_callback callback, void *arg) +{ + struct query *query; + int i; + struct timeval now; + + /* Verify that the query is at least long enough to hold the header. */ + if (qlen < HFIXEDSZ || qlen >= (1 << 16)) + { + callback(arg, ARES_EBADQUERY, 0, NULL, 0); + return; + } + + /* Allocate space for query and allocated fields. */ + query = malloc(sizeof(struct query)); + if (!query) + { + callback(arg, ARES_ENOMEM, 0, NULL, 0); + return; + } + query->tcpbuf = malloc(qlen + 2); + if (!query->tcpbuf) + { + free(query); + callback(arg, ARES_ENOMEM, 0, NULL, 0); + return; + } + query->server_info = malloc(channel->nservers * + sizeof(query->server_info[0])); + if (!query->server_info) + { + free(query->tcpbuf); + free(query); + callback(arg, ARES_ENOMEM, 0, NULL, 0); + return; + } + + /* Compute the query ID. Start with no timeout. */ + query->qid = (unsigned short)DNS_HEADER_QID(qbuf); + query->timeout.tv_sec = 0; + query->timeout.tv_usec = 0; + + /* Form the TCP query buffer by prepending qlen (as two + * network-order bytes) to qbuf. + */ + query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff); + query->tcpbuf[1] = (unsigned char)(qlen & 0xff); + memcpy(query->tcpbuf + 2, qbuf, qlen); + query->tcplen = qlen + 2; + + /* Fill in query arguments. */ + query->qbuf = query->tcpbuf + 2; + query->qlen = qlen; + query->callback = callback; + query->arg = arg; + + /* Initialize query status. */ + query->try_count = 0; + + /* Choose the server to send the query to. If rotation is enabled, keep track + * of the next server we want to use. */ + query->server = channel->last_server; + if (channel->rotate == 1) + channel->last_server = (channel->last_server + 1) % channel->nservers; + + for (i = 0; i < channel->nservers; i++) + { + query->server_info[i].skip_server = 0; + query->server_info[i].tcp_connection_generation = 0; + } + query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > PACKETSZ; + query->error_status = ARES_ECONNREFUSED; + query->timeouts = 0; + + /* Initialize our list nodes. */ + ares__init_list_node(&(query->queries_by_qid), query); + ares__init_list_node(&(query->queries_by_timeout), query); + ares__init_list_node(&(query->queries_to_server), query); + ares__init_list_node(&(query->all_queries), query); + + /* Chain the query into the list of all queries. */ + ares__insert_in_list(&(query->all_queries), &(channel->all_queries)); + /* Keep track of queries bucketed by qid, so we can process DNS + * responses quickly. + */ + ares__insert_in_list( + &(query->queries_by_qid), + &(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE])); + + /* Perform the first query action. */ + now = ares__tvnow(); + ares__send_query(channel, query, &now); +} |