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12471842 PL |
1 | /* |
2 | * This file is part of PowerDNS or dnsdist. | |
3 | * Copyright -- PowerDNS.COM B.V. and its contributors | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of version 2 of the GNU General Public License as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * In addition, for the avoidance of any doubt, permission is granted to | |
10 | * link this program with OpenSSL and to (re)distribute the binaries | |
11 | * produced as the result of such linking. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
21 | */ | |
5c3b5e7f RG |
22 | #include "dns.hh" |
23 | #include "ednsoptions.hh" | |
24 | #include "iputils.hh" | |
25 | ||
26 | /* extract a specific EDNS0 option from a pointer on the beginning rdLen of the OPT RR */ | |
27 | int getEDNSOption(char* optRR, const size_t len, uint16_t wantedOption, char ** optionValue, size_t * optionValueSize) | |
28 | { | |
29 | assert(optRR != NULL); | |
30 | assert(optionValue != NULL); | |
31 | assert(optionValueSize != NULL); | |
32 | size_t pos = 0; | |
33 | if (len < DNS_RDLENGTH_SIZE) | |
34 | return EINVAL; | |
35 | ||
36 | const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
37 | size_t rdPos = 0; | |
38 | pos += DNS_RDLENGTH_SIZE; | |
39 | if ((pos + rdLen) > len) { | |
40 | return EINVAL; | |
41 | } | |
42 | ||
43 | while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) && | |
44 | rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) { | |
45 | const uint16_t optionCode = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
46 | pos += EDNS_OPTION_CODE_SIZE; | |
47 | rdPos += EDNS_OPTION_CODE_SIZE; | |
48 | const uint16_t optionLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
49 | pos += EDNS_OPTION_LENGTH_SIZE; | |
50 | rdPos += EDNS_OPTION_LENGTH_SIZE; | |
51 | if (optionLen > (rdLen - rdPos) || optionLen > (len - pos)) | |
52 | return EINVAL; | |
53 | ||
54 | if (optionCode == wantedOption) { | |
55 | *optionValue = optRR + pos - (EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE); | |
56 | *optionValueSize = optionLen + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE; | |
57 | return 0; | |
58 | } | |
59 | else { | |
60 | /* skip this option */ | |
61 | pos += optionLen; | |
62 | rdPos += optionLen; | |
63 | } | |
64 | } | |
65 | ||
66 | return ENOENT; | |
67 | } | |
68 | ||
00b8cadc RG |
69 | /* extract all EDNS0 options from a pointer on the beginning rdLen of the OPT RR */ |
70 | int getEDNSOptions(const char* optRR, const size_t len, std::map<uint16_t, EDNSOptionView>& options) | |
71 | { | |
72 | assert(optRR != NULL); | |
73 | size_t pos = 0; | |
74 | if (len < DNS_RDLENGTH_SIZE) | |
75 | return EINVAL; | |
76 | ||
77 | const uint16_t rdLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
78 | size_t rdPos = 0; | |
79 | pos += DNS_RDLENGTH_SIZE; | |
80 | if ((pos + rdLen) > len) { | |
81 | return EINVAL; | |
82 | } | |
83 | ||
84 | while(len >= (pos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE) && | |
85 | rdLen >= (rdPos + EDNS_OPTION_CODE_SIZE + EDNS_OPTION_LENGTH_SIZE)) { | |
86 | const uint16_t optionCode = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
87 | pos += EDNS_OPTION_CODE_SIZE; | |
88 | rdPos += EDNS_OPTION_CODE_SIZE; | |
89 | const uint16_t optionLen = (((unsigned char) optRR[pos]) * 256) + ((unsigned char) optRR[pos+1]); | |
90 | pos += EDNS_OPTION_LENGTH_SIZE; | |
91 | rdPos += EDNS_OPTION_LENGTH_SIZE; | |
92 | if (optionLen > (rdLen - rdPos) || optionLen > (len - pos)) | |
93 | return EINVAL; | |
94 | ||
95 | EDNSOptionView view; | |
96 | view.content = optRR + pos; | |
97 | view.size = optionLen; | |
98 | options[optionCode] = view; | |
99 | ||
100 | /* skip this option */ | |
101 | pos += optionLen; | |
102 | rdPos += optionLen; | |
103 | } | |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
5c3b5e7f RG |
108 | void generateEDNSOption(uint16_t optionCode, const std::string& payload, std::string& res) |
109 | { | |
110 | const uint16_t ednsOptionCode = htons(optionCode); | |
111 | const uint16_t payloadLen = htons(payload.length()); | |
112 | res.append((const char *) &ednsOptionCode, sizeof ednsOptionCode); | |
113 | res.append((const char *) &payloadLen, sizeof payloadLen); | |
114 | res.append(payload); | |
115 | } |