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| 1 | + |
| 2 | +/* Copyright 2020 by <danny.sonnenschein@platynum.ch> |
| 3 | + * |
| 4 | + * Permission to use, copy, modify, and distribute this |
| 5 | + * software and its documentation for any purpose and without |
| 6 | + * fee is hereby granted, provided that the above copyright |
| 7 | + * notice appear in all copies and that both that copyright |
| 8 | + * notice and this permission notice appear in supporting |
| 9 | + * documentation, and that the name of M.I.T. not be used in |
| 10 | + * advertising or publicity pertaining to distribution of the |
| 11 | + * software without specific, written prior permission. |
| 12 | + * M.I.T. makes no representations about the suitability of |
| 13 | + * this software for any purpose. It is provided "as is" |
| 14 | + * without express or implied warranty. |
| 15 | + */ |
| 16 | + |
| 17 | +#include "ares_setup.h" |
| 18 | + |
| 19 | +#ifdef HAVE_NETINET_IN_H |
| 20 | +# include <netinet/in.h> |
| 21 | +#endif |
| 22 | +#ifdef HAVE_NETDB_H |
| 23 | +# include <netdb.h> |
| 24 | +#endif |
| 25 | +#ifdef HAVE_ARPA_INET_H |
| 26 | +# include <arpa/inet.h> |
| 27 | +#endif |
| 28 | +#ifdef HAVE_ARPA_NAMESER_H |
| 29 | +# include <arpa/nameser.h> |
| 30 | +#else |
| 31 | +# include "nameser.h" |
| 32 | +#endif |
| 33 | +#ifdef HAVE_ARPA_NAMESER_COMPAT_H |
| 34 | +# include <arpa/nameser_compat.h> |
| 35 | +#endif |
| 36 | + |
| 37 | +#ifdef HAVE_STRINGS_H |
| 38 | +# include <strings.h> |
| 39 | +#endif |
| 40 | + |
| 41 | +#include "ares.h" |
| 42 | +#include "ares_dns.h" |
| 43 | +#include "ares_data.h" |
| 44 | +#include "ares_private.h" |
| 45 | + |
| 46 | +#ifndef T_CAA |
| 47 | +# define T_CAA 257 /* Certification Authority Authorization */ |
| 48 | +#endif |
| 49 | + |
| 50 | +int |
| 51 | +ares_parse_caa_reply (const unsigned char *abuf, int alen, |
| 52 | + struct ares_caa_reply **caa_out) |
| 53 | +{ |
| 54 | + unsigned int qdcount, ancount, i; |
| 55 | + const unsigned char *aptr; |
| 56 | + const unsigned char *strptr; |
| 57 | + int status, rr_type, rr_class, rr_len; |
| 58 | + long len; |
| 59 | + char *hostname = NULL, *rr_name = NULL; |
| 60 | + struct ares_caa_reply *caa_head = NULL; |
| 61 | + struct ares_caa_reply *caa_last = NULL; |
| 62 | + struct ares_caa_reply *caa_curr; |
| 63 | + |
| 64 | + /* Set *caa_out to NULL for all failure cases. */ |
| 65 | + *caa_out = NULL; |
| 66 | + |
| 67 | + /* Give up if abuf doesn't have room for a header. */ |
| 68 | + if (alen < HFIXEDSZ) |
| 69 | + return ARES_EBADRESP; |
| 70 | + |
| 71 | + /* Fetch the question and answer count from the header. */ |
| 72 | + qdcount = DNS_HEADER_QDCOUNT (abuf); |
| 73 | + ancount = DNS_HEADER_ANCOUNT (abuf); |
| 74 | + if (qdcount != 1) |
| 75 | + return ARES_EBADRESP; |
| 76 | + if (ancount == 0) |
| 77 | + return ARES_ENODATA; |
| 78 | + |
| 79 | + /* Expand the name from the question, and skip past the question. */ |
| 80 | + aptr = abuf + HFIXEDSZ; |
| 81 | + status = ares_expand_name (aptr, abuf, alen, &hostname, &len); |
| 82 | + if (status != ARES_SUCCESS) |
| 83 | + return status; |
| 84 | + |
| 85 | + if (aptr + len + QFIXEDSZ > abuf + alen) |
| 86 | + { |
| 87 | + ares_free (hostname); |
| 88 | + return ARES_EBADRESP; |
| 89 | + } |
| 90 | + aptr += len + QFIXEDSZ; |
| 91 | + |
| 92 | + /* Examine each answer resource record (RR) in turn. */ |
| 93 | + for (i = 0; i < ancount; i++) |
| 94 | + { |
| 95 | + /* Decode the RR up to the data field. */ |
| 96 | + status = ares_expand_name (aptr, abuf, alen, &rr_name, &len); |
| 97 | + if (status != ARES_SUCCESS) |
| 98 | + { |
| 99 | + break; |
| 100 | + } |
| 101 | + aptr += len; |
| 102 | + if (aptr + RRFIXEDSZ > abuf + alen) |
| 103 | + { |
| 104 | + status = ARES_EBADRESP; |
| 105 | + break; |
| 106 | + } |
| 107 | + rr_type = DNS_RR_TYPE (aptr); |
| 108 | + rr_class = DNS_RR_CLASS (aptr); |
| 109 | + rr_len = DNS_RR_LEN (aptr); |
| 110 | + aptr += RRFIXEDSZ; |
| 111 | + if (aptr + rr_len > abuf + alen) |
| 112 | + { |
| 113 | + status = ARES_EBADRESP; |
| 114 | + break; |
| 115 | + } |
| 116 | + |
| 117 | + /* Check if we are really looking at a CAA record */ |
| 118 | + if ((rr_class == C_IN || rr_class == C_CHAOS) && rr_type == T_CAA) |
| 119 | + { |
| 120 | + strptr = aptr; |
| 121 | + |
| 122 | + /* Allocate storage for this CAA answer appending it to the list */ |
| 123 | + caa_curr = ares_malloc_data(ARES_DATATYPE_CAA_REPLY); |
| 124 | + if (!caa_curr) |
| 125 | + { |
| 126 | + status = ARES_ENOMEM; |
| 127 | + break; |
| 128 | + } |
| 129 | + if (caa_last) |
| 130 | + { |
| 131 | + caa_last->next = caa_curr; |
| 132 | + } |
| 133 | + else |
| 134 | + { |
| 135 | + caa_head = caa_curr; |
| 136 | + } |
| 137 | + caa_last = caa_curr; |
| 138 | + if (rr_len < 2) |
| 139 | + { |
| 140 | + status = ARES_EBADRESP; |
| 141 | + break; |
| 142 | + } |
| 143 | + caa_curr->critical = (int)*strptr++; |
| 144 | + caa_curr->plength = (int)*strptr++; |
| 145 | + if (caa_curr->plength <= 0 || (int)caa_curr->plength >= rr_len - 2) |
| 146 | + { |
| 147 | + status = ARES_EBADRESP; |
| 148 | + break; |
| 149 | + } |
| 150 | + caa_curr->property = ares_malloc (caa_curr->plength + 1/* Including null byte */); |
| 151 | + if (caa_curr->property == NULL) |
| 152 | + { |
| 153 | + status = ARES_ENOMEM; |
| 154 | + break; |
| 155 | + } |
| 156 | + memcpy ((char *) caa_curr->property, strptr, caa_curr->plength); |
| 157 | + /* Make sure we NULL-terminate */ |
| 158 | + caa_curr->property[caa_curr->plength] = 0; |
| 159 | + strptr += caa_curr->plength; |
| 160 | + |
| 161 | + caa_curr->length = rr_len - caa_curr->plength - 2; |
| 162 | + if (caa_curr->length <= 0) |
| 163 | + { |
| 164 | + status = ARES_EBADRESP; |
| 165 | + break; |
| 166 | + } |
| 167 | + caa_curr->value = ares_malloc (caa_curr->length + 1/* Including null byte */); |
| 168 | + if (caa_curr->value == NULL) |
| 169 | + { |
| 170 | + status = ARES_ENOMEM; |
| 171 | + break; |
| 172 | + } |
| 173 | + memcpy ((char *) caa_curr->value, strptr, caa_curr->length); |
| 174 | + /* Make sure we NULL-terminate */ |
| 175 | + caa_curr->value[caa_curr->length] = 0; |
| 176 | + } |
| 177 | + |
| 178 | + /* Propagate any failures */ |
| 179 | + if (status != ARES_SUCCESS) |
| 180 | + { |
| 181 | + break; |
| 182 | + } |
| 183 | + |
| 184 | + /* Don't lose memory in the next iteration */ |
| 185 | + ares_free (rr_name); |
| 186 | + rr_name = NULL; |
| 187 | + |
| 188 | + /* Move on to the next record */ |
| 189 | + aptr += rr_len; |
| 190 | + } |
| 191 | + |
| 192 | + if (hostname) |
| 193 | + ares_free (hostname); |
| 194 | + if (rr_name) |
| 195 | + ares_free (rr_name); |
| 196 | + |
| 197 | + /* clean up on error */ |
| 198 | + if (status != ARES_SUCCESS) |
| 199 | + { |
| 200 | + if (caa_head) |
| 201 | + ares_free_data (caa_head); |
| 202 | + return status; |
| 203 | + } |
| 204 | + |
| 205 | + /* everything looks fine, return the data */ |
| 206 | + *caa_out = caa_head; |
| 207 | + |
| 208 | + return ARES_SUCCESS; |
| 209 | +} |
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