1 2 /* Copyright 1998 by the Massachusetts Institute of Technology. 3 * Copyright (C) 2009 by Jakub Hrozek <jhrozek (at) redhat.com> 4 * 5 * Permission to use, copy, modify, and distribute this 6 * software and its documentation for any purpose and without 7 * fee is hereby granted, provided that the above copyright 8 * notice appear in all copies and that both that copyright 9 * notice and this permission notice appear in supporting 10 * documentation, and that the name of M.I.T. not be used in 11 * advertising or publicity pertaining to distribution of the 12 * software without specific, written prior permission. 13 * M.I.T. makes no representations about the suitability of 14 * this software for any purpose. It is provided "as is" 15 * without express or implied warranty. 16 */ 17 18 #include "ares_setup.h" 19 20 #ifdef HAVE_SYS_SOCKET_H 21 # include <sys/socket.h> 22 #endif 23 #ifdef HAVE_NETINET_IN_H 24 # include <netinet/in.h> 25 #endif 26 #ifdef HAVE_NETDB_H 27 # include <netdb.h> 28 #endif 29 #ifdef HAVE_ARPA_INET_H 30 # include <arpa/inet.h> 31 #endif 32 #ifdef HAVE_ARPA_NAMESER_H 33 # include <arpa/nameser.h> 34 #else 35 # include "nameser.h" 36 #endif 37 #ifdef HAVE_ARPA_NAMESER_COMPAT_H 38 # include <arpa/nameser_compat.h> 39 #endif 40 41 #include <stdlib.h> 42 #include <string.h> 43 #include "ares.h" 44 #include "ares_dns.h" 45 #include "ares_data.h" 46 #include "ares_private.h" 47 48 /* AIX portability check */ 49 #ifndef T_SRV 50 # define T_SRV 33 /* server selection */ 51 #endif 52 53 int 54 ares_parse_srv_reply (const unsigned char *abuf, int alen, 55 struct ares_srv_reply **srv_out) 56 { 57 unsigned int qdcount, ancount, i; 58 const unsigned char *aptr, *vptr; 59 int status, rr_type, rr_class, rr_len; 60 long len; 61 char *hostname = NULL, *rr_name = NULL; 62 struct ares_srv_reply *srv_head = NULL; 63 struct ares_srv_reply *srv_last = NULL; 64 struct ares_srv_reply *srv_curr; 65 66 /* Set *srv_out to NULL for all failure cases. */ 67 *srv_out = NULL; 68 69 /* Give up if abuf doesn't have room for a header. */ 70 if (alen < HFIXEDSZ) 71 return ARES_EBADRESP; 72 73 /* Fetch the question and answer count from the header. */ 74 qdcount = DNS_HEADER_QDCOUNT (abuf); 75 ancount = DNS_HEADER_ANCOUNT (abuf); 76 if (qdcount != 1) 77 return ARES_EBADRESP; 78 if (ancount == 0) 79 return ARES_ENODATA; 80 81 /* Expand the name from the question, and skip past the question. */ 82 aptr = abuf + HFIXEDSZ; 83 status = ares_expand_name (aptr, abuf, alen, &hostname, &len); 84 if (status != ARES_SUCCESS) 85 return status; 86 87 if (aptr + len + QFIXEDSZ > abuf + alen) 88 { 89 free (hostname); 90 return ARES_EBADRESP; 91 } 92 aptr += len + QFIXEDSZ; 93 94 /* Examine each answer resource record (RR) in turn. */ 95 for (i = 0; i < ancount; i++) 96 { 97 /* Decode the RR up to the data field. */ 98 status = ares_expand_name (aptr, abuf, alen, &rr_name, &len); 99 if (status != ARES_SUCCESS) 100 { 101 break; 102 } 103 aptr += len; 104 if (aptr + RRFIXEDSZ > abuf + alen) 105 { 106 status = ARES_EBADRESP; 107 break; 108 } 109 rr_type = DNS_RR_TYPE (aptr); 110 rr_class = DNS_RR_CLASS (aptr); 111 rr_len = DNS_RR_LEN (aptr); 112 aptr += RRFIXEDSZ; 113 114 /* Check if we are really looking at a SRV record */ 115 if (rr_class == C_IN && rr_type == T_SRV) 116 { 117 /* parse the SRV record itself */ 118 if (rr_len < 6) 119 { 120 status = ARES_EBADRESP; 121 break; 122 } 123 124 /* Allocate storage for this SRV answer appending it to the list */ 125 srv_curr = ares_malloc_data(ARES_DATATYPE_SRV_REPLY); 126 if (!srv_curr) 127 { 128 status = ARES_ENOMEM; 129 break; 130 } 131 if (srv_last) 132 { 133 srv_last->next = srv_curr; 134 } 135 else 136 { 137 srv_head = srv_curr; 138 } 139 srv_last = srv_curr; 140 141 vptr = aptr; 142 srv_curr->priority = DNS__16BIT(vptr); 143 vptr += sizeof(unsigned short); 144 srv_curr->weight = DNS__16BIT(vptr); 145 vptr += sizeof(unsigned short); 146 srv_curr->port = DNS__16BIT(vptr); 147 vptr += sizeof(unsigned short); 148 149 status = ares_expand_name (vptr, abuf, alen, &srv_curr->host, &len); 150 if (status != ARES_SUCCESS) 151 break; 152 } 153 154 /* Don't lose memory in the next iteration */ 155 free (rr_name); 156 rr_name = NULL; 157 158 /* Move on to the next record */ 159 aptr += rr_len; 160 } 161 162 if (hostname) 163 free (hostname); 164 if (rr_name) 165 free (rr_name); 166 167 /* clean up on error */ 168 if (status != ARES_SUCCESS) 169 { 170 if (srv_head) 171 ares_free_data (srv_head); 172 return status; 173 } 174 175 /* everything looks fine, return the data */ 176 *srv_out = srv_head; 177 178 return ARES_SUCCESS; 179 } 180
