yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | |
| 2 | /* Copyright 1998 by the Massachusetts Institute of Technology. |
| 3 | * Copyright (C) 2009 by Jakub Hrozek <jhrozek@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_NETINET_IN_H |
| 21 | # include <netinet/in.h> |
| 22 | #endif |
| 23 | #ifdef HAVE_NETDB_H |
| 24 | # include <netdb.h> |
| 25 | #endif |
| 26 | #ifdef HAVE_ARPA_INET_H |
| 27 | # include <arpa/inet.h> |
| 28 | #endif |
| 29 | #ifdef HAVE_ARPA_NAMESER_H |
| 30 | # include <arpa/nameser.h> |
| 31 | #else |
| 32 | # include "nameser.h" |
| 33 | #endif |
| 34 | #ifdef HAVE_ARPA_NAMESER_COMPAT_H |
| 35 | # include <arpa/nameser_compat.h> |
| 36 | #endif |
| 37 | |
| 38 | #include "ares.h" |
| 39 | #include "ares_dns.h" |
| 40 | #include "ares_data.h" |
| 41 | #include "ares_private.h" |
| 42 | |
| 43 | /* AIX portability check */ |
| 44 | #ifndef T_SRV |
| 45 | # define T_SRV 33 /* server selection */ |
| 46 | #endif |
| 47 | |
| 48 | int |
| 49 | ares_parse_srv_reply (const unsigned char *abuf, int alen, |
| 50 | struct ares_srv_reply **srv_out) |
| 51 | { |
| 52 | unsigned int qdcount, ancount, i; |
| 53 | const unsigned char *aptr, *vptr; |
| 54 | int status, rr_type, rr_class, rr_len; |
| 55 | long len; |
| 56 | char *hostname = NULL, *rr_name = NULL; |
| 57 | struct ares_srv_reply *srv_head = NULL; |
| 58 | struct ares_srv_reply *srv_last = NULL; |
| 59 | struct ares_srv_reply *srv_curr; |
| 60 | |
| 61 | /* Set *srv_out to NULL for all failure cases. */ |
| 62 | *srv_out = NULL; |
| 63 | |
| 64 | /* Give up if abuf doesn't have room for a header. */ |
| 65 | if (alen < HFIXEDSZ) |
| 66 | return ARES_EBADRESP; |
| 67 | |
| 68 | /* Fetch the question and answer count from the header. */ |
| 69 | qdcount = DNS_HEADER_QDCOUNT (abuf); |
| 70 | ancount = DNS_HEADER_ANCOUNT (abuf); |
| 71 | if (qdcount != 1) |
| 72 | return ARES_EBADRESP; |
| 73 | if (ancount == 0) |
| 74 | return ARES_ENODATA; |
| 75 | |
| 76 | /* Expand the name from the question, and skip past the question. */ |
| 77 | aptr = abuf + HFIXEDSZ; |
| 78 | status = ares_expand_name (aptr, abuf, alen, &hostname, &len); |
| 79 | if (status != ARES_SUCCESS) |
| 80 | return status; |
| 81 | |
| 82 | if (aptr + len + QFIXEDSZ > abuf + alen) |
| 83 | { |
| 84 | ares_free (hostname); |
| 85 | return ARES_EBADRESP; |
| 86 | } |
| 87 | aptr += len + QFIXEDSZ; |
| 88 | |
| 89 | /* Examine each answer resource record (RR) in turn. */ |
| 90 | for (i = 0; i < ancount; i++) |
| 91 | { |
| 92 | /* Decode the RR up to the data field. */ |
| 93 | status = ares_expand_name (aptr, abuf, alen, &rr_name, &len); |
| 94 | if (status != ARES_SUCCESS) |
| 95 | { |
| 96 | break; |
| 97 | } |
| 98 | aptr += len; |
| 99 | if (aptr + RRFIXEDSZ > abuf + alen) |
| 100 | { |
| 101 | status = ARES_EBADRESP; |
| 102 | break; |
| 103 | } |
| 104 | rr_type = DNS_RR_TYPE (aptr); |
| 105 | rr_class = DNS_RR_CLASS (aptr); |
| 106 | rr_len = DNS_RR_LEN (aptr); |
| 107 | aptr += RRFIXEDSZ; |
| 108 | if (aptr + rr_len > abuf + alen) |
| 109 | { |
| 110 | status = ARES_EBADRESP; |
| 111 | break; |
| 112 | } |
| 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 | ares_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 | ares_free (hostname); |
| 164 | if (rr_name) |
| 165 | ares_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 | } |