/* $Id: ares_query.c,v 1.21 2009-11-02 11:55:53 yangtse Exp $ */ /* 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 "ares.h" #include "ares_dns.h" #include "ares_private.h" struct qquery { ares_callback callback; void *arg; }; static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen); void ares__rc4(rc4_key* key, unsigned char *buffer_ptr, int buffer_len) { unsigned char x; unsigned char y; unsigned char* state; unsigned char xorIndex; short counter; x = key->x; y = key->y; state = &key->state[0]; for(counter = 0; counter < buffer_len; counter ++) { x = (unsigned char)((x + 1) % 256); y = (unsigned char)((state[x] + y) % 256); ARES_SWAP_BYTE(&state[x], &state[y]); xorIndex = (unsigned char)((state[x] + state[y]) % 256); buffer_ptr[counter] = (unsigned char)(buffer_ptr[counter]^state[xorIndex]); } key->x = x; key->y = y; } static struct query* find_query_by_id(ares_channel channel, unsigned short id) { unsigned short qid; struct list_node* list_head; struct list_node* list_node; DNS_HEADER_SET_QID(((unsigned char*)&qid), id); /* Find the query corresponding to this packet. */ list_head = &(channel->queries_by_qid[qid % ARES_QID_TABLE_SIZE]); for (list_node = list_head->next; list_node != list_head; list_node = list_node->next) { struct query *q = list_node->data; if (q->qid == qid) return q; } return NULL; } /* a unique query id is generated using an rc4 key. Since the id may already be used by a running query (as infrequent as it may be), a lookup is performed per id generation. In practice this search should happen only once per newly generated id */ static unsigned short generate_unique_id(ares_channel channel) { unsigned short id; do { id = ares__generate_new_id(&channel->id_key); } while (find_query_by_id(channel, id)); return (unsigned short)id; } void ares_query(ares_channel channel, const char *name, int dnsclass, int type, ares_callback callback, void *arg) { struct qquery *qquery; unsigned char *qbuf; int qlen, rd, status; /* Compose the query. */ rd = !(channel->flags & ARES_FLAG_NORECURSE); status = ares_mkquery(name, dnsclass, type, channel->next_id, rd, &qbuf, &qlen); if (status != ARES_SUCCESS) { if (qbuf != NULL) free(qbuf); callback(arg, status, 0, NULL, 0); return; } channel->next_id = generate_unique_id(channel); /* Allocate and fill in the query structure. */ qquery = malloc(sizeof(struct qquery)); if (!qquery) { ares_free_string(qbuf); callback(arg, ARES_ENOMEM, 0, NULL, 0); return; } qquery->callback = callback; qquery->arg = arg; /* Send it off. qcallback will be called when we get an answer. */ ares_send(channel, qbuf, qlen, qcallback, qquery); ares_free_string(qbuf); } static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen) { struct qquery *qquery = (struct qquery *) arg; unsigned int ancount; int rcode; if (status != ARES_SUCCESS) qquery->callback(qquery->arg, status, timeouts, abuf, alen); else { /* Pull the response code and answer count from the packet. */ rcode = DNS_HEADER_RCODE(abuf); ancount = DNS_HEADER_ANCOUNT(abuf); /* Convert errors. */ switch (rcode) { case NOERROR: status = (ancount > 0) ? ARES_SUCCESS : ARES_ENODATA; break; case FORMERR: status = ARES_EFORMERR; break; case SERVFAIL: status = ARES_ESERVFAIL; break; case NXDOMAIN: status = ARES_ENOTFOUND; break; case NOTIMP: status = ARES_ENOTIMP; break; case REFUSED: status = ARES_EREFUSED; break; } qquery->callback(qquery->arg, status, timeouts, abuf, alen); } free(qquery); }