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420a0d19 CE |
1 | /* |
2 | * PDKIM - a RFC4871 (DKIM) implementation | |
3 | * | |
4 | * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net> | |
2813c06e | 5 | * Copyright (c) 2016 - 2017 Jeremy Harris |
420a0d19 CE |
6 | * |
7 | * http://duncanthrax.net/pdkim/ | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation; either version 2 of the License, or | |
12 | * (at your option) any later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU General Public License along | |
20 | * with this program; if not, write to the Free Software Foundation, Inc., | |
21 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
22 | */ | |
2813c06e CE |
23 | #ifndef PDKIM_H |
24 | #define PDKIM_H | |
420a0d19 | 25 | |
2813c06e CE |
26 | #include "../blob.h" |
27 | #include "../hash.h" | |
420a0d19 CE |
28 | |
29 | /* -------------------------------------------------------------------------- */ | |
30 | /* Length of the preallocated buffer for the "answer" from the dns/txt | |
31 | callback function. This should match the maximum RDLENGTH from DNS. */ | |
32 | #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16) | |
33 | ||
34 | /* -------------------------------------------------------------------------- */ | |
35 | /* Function success / error codes */ | |
36 | #define PDKIM_OK 0 | |
37 | #define PDKIM_FAIL -1 | |
420a0d19 CE |
38 | #define PDKIM_ERR_RSA_PRIVKEY -101 |
39 | #define PDKIM_ERR_RSA_SIGNING -102 | |
40 | #define PDKIM_ERR_LONG_LINE -103 | |
41 | #define PDKIM_ERR_BUFFER_TOO_SMALL -104 | |
2813c06e CE |
42 | #define PDKIM_SIGN_PRIVKEY_WRAP -105 |
43 | #define PDKIM_SIGN_PRIVKEY_B64D -106 | |
420a0d19 CE |
44 | |
45 | /* -------------------------------------------------------------------------- */ | |
46 | /* Main/Extended verification status */ | |
47 | #define PDKIM_VERIFY_NONE 0 | |
48 | #define PDKIM_VERIFY_INVALID 1 | |
49 | #define PDKIM_VERIFY_FAIL 2 | |
50 | #define PDKIM_VERIFY_PASS 3 | |
51 | ||
2813c06e CE |
52 | #define PDKIM_VERIFY_FAIL_BODY 1 |
53 | #define PDKIM_VERIFY_FAIL_MESSAGE 2 | |
54 | #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3 | |
55 | #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 4 | |
56 | #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 5 | |
57 | #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 6 | |
58 | #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 7 | |
59 | #define PDKIM_VERIFY_INVALID_DKIM_VERSION 8 | |
420a0d19 CE |
60 | |
61 | /* -------------------------------------------------------------------------- */ | |
62 | /* Some parameter values */ | |
63 | #define PDKIM_QUERYMETHOD_DNS_TXT 0 | |
64 | ||
65 | #define PDKIM_ALGO_RSA_SHA256 0 | |
66 | #define PDKIM_ALGO_RSA_SHA1 1 | |
67 | ||
68 | #define PDKIM_CANON_SIMPLE 0 | |
69 | #define PDKIM_CANON_RELAXED 1 | |
70 | ||
71 | #define PDKIM_HASH_SHA256 0 | |
72 | #define PDKIM_HASH_SHA1 1 | |
73 | ||
74 | #define PDKIM_KEYTYPE_RSA 0 | |
75 | ||
76 | /* -------------------------------------------------------------------------- */ | |
77 | /* Some required forward declarations, please ignore */ | |
78 | typedef struct pdkim_stringlist pdkim_stringlist; | |
79 | typedef struct pdkim_str pdkim_str; | |
80 | typedef struct sha1_context sha1_context; | |
81 | typedef struct sha2_context sha2_context; | |
82 | #define HAVE_SHA1_CONTEXT | |
83 | #define HAVE_SHA2_CONTEXT | |
84 | ||
85 | /* -------------------------------------------------------------------------- */ | |
86 | /* Some concessions towards Redmond */ | |
87 | #ifdef WINDOWS | |
88 | #define snprintf _snprintf | |
89 | #define strcasecmp _stricmp | |
90 | #define strncasecmp _strnicmp | |
91 | #define DLLEXPORT __declspec(dllexport) | |
92 | #else | |
93 | #define DLLEXPORT | |
94 | #endif | |
95 | ||
96 | ||
97 | /* -------------------------------------------------------------------------- */ | |
98 | /* Public key as (usually) fetched from DNS */ | |
99 | typedef struct pdkim_pubkey { | |
2813c06e CE |
100 | uschar *version; /* v= */ |
101 | uschar *granularity; /* g= */ | |
420a0d19 | 102 | |
2813c06e CE |
103 | #ifdef notdef |
104 | uschar *hashes; /* h= */ | |
105 | uschar *keytype; /* k= */ | |
106 | #endif | |
107 | uschar *srvtype; /* s= */ | |
108 | uschar *notes; /* n= */ | |
420a0d19 | 109 | |
2813c06e | 110 | blob key; /* p= */ |
420a0d19 CE |
111 | int testing; /* t=y */ |
112 | int no_subdomaining; /* t=s */ | |
113 | } pdkim_pubkey; | |
114 | ||
115 | /* -------------------------------------------------------------------------- */ | |
116 | /* Signature as it appears in a DKIM-Signature header */ | |
117 | typedef struct pdkim_signature { | |
118 | ||
119 | /* Bits stored in a DKIM signature header --------------------------- */ | |
120 | ||
121 | /* (v=) The version, as an integer. Currently, always "1" */ | |
122 | int version; | |
123 | ||
124 | /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256 | |
125 | or PDKIM_ALGO_RSA_SHA1 */ | |
126 | int algo; | |
127 | ||
128 | /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE | |
129 | or PDKIM_CANON_RELAXED */ | |
130 | int canon_headers; | |
131 | ||
132 | /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE | |
133 | or PDKIM_CANON_RELAXED */ | |
134 | int canon_body; | |
135 | ||
136 | /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT | |
137 | is specified */ | |
138 | int querymethod; | |
139 | ||
140 | /* (s=) The selector string as given in the signature */ | |
2813c06e | 141 | uschar *selector; |
420a0d19 CE |
142 | |
143 | /* (d=) The domain as given in the signature */ | |
2813c06e | 144 | uschar *domain; |
420a0d19 CE |
145 | |
146 | /* (i=) The identity as given in the signature */ | |
2813c06e | 147 | uschar *identity; |
420a0d19 CE |
148 | |
149 | /* (t=) Timestamp of signature creation */ | |
150 | unsigned long created; | |
151 | ||
152 | /* (x=) Timestamp of expiry of signature */ | |
153 | unsigned long expires; | |
154 | ||
155 | /* (l=) Amount of hashed body bytes (after canonicalization). Default | |
156 | is -1. Note: a value of 0 means that the body is unsigned! */ | |
157 | long bodylength; | |
158 | ||
159 | /* (h=) Colon-separated list of header names that are included in the | |
160 | signature */ | |
2813c06e | 161 | uschar *headernames; |
420a0d19 CE |
162 | |
163 | /* (z=) */ | |
2813c06e | 164 | uschar *copiedheaders; |
420a0d19 CE |
165 | |
166 | /* (b=) Raw signature data, along with its length in bytes */ | |
2813c06e | 167 | blob sighash; |
420a0d19 CE |
168 | |
169 | /* (bh=) Raw body hash data, along with its length in bytes */ | |
2813c06e | 170 | blob bodyhash; |
420a0d19 CE |
171 | |
172 | /* Folded DKIM-Signature: header. Singing only, NULL for verifying. | |
173 | Ready for insertion into the message. Note: Folded using CRLFTB, | |
174 | but final line terminator is NOT included. Note2: This buffer is | |
175 | free()d when you call pdkim_free_ctx(). */ | |
2813c06e | 176 | uschar *signature_header; |
420a0d19 CE |
177 | |
178 | /* The main verification status. Verification only. One of: | |
179 | ||
180 | PDKIM_VERIFY_NONE Verification was not attempted. This status | |
181 | should not appear. | |
182 | ||
183 | PDKIM_VERIFY_INVALID There was an error while trying to verify | |
184 | the signature. A more precise description | |
185 | is available in verify_ext_status. | |
186 | ||
187 | PDKIM_VERIFY_FAIL Verification failed because either the body | |
188 | hash did not match, or the signature verification | |
189 | failed. This means the message was modified. | |
190 | Check verify_ext_status for the exact reason. | |
191 | ||
192 | PDKIM_VERIFY_PASS Verification succeeded. | |
193 | */ | |
194 | int verify_status; | |
195 | ||
196 | /* Extended verification status. Verification only. Depending on the value | |
197 | of verify_status, it can contain: | |
198 | ||
199 | For verify_status == PDKIM_VERIFY_INVALID: | |
200 | ||
201 | PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE | |
202 | Unable to retrieve a public key container. | |
203 | ||
204 | PDKIM_VERIFY_INVALID_BUFFER_SIZE | |
205 | Either the DNS name constructed to retrieve the public key record | |
206 | does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved | |
207 | record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes. | |
208 | ||
209 | PDKIM_VERIFY_INVALID_PUBKEY_PARSING | |
210 | (Syntax) error while parsing the retrieved public key record. | |
211 | ||
212 | ||
213 | For verify_status == PDKIM_VERIFY_FAIL: | |
214 | ||
215 | PDKIM_VERIFY_FAIL_BODY | |
216 | The calculated body hash does not match the advertised body hash | |
217 | from the bh= tag of the signature. | |
218 | ||
219 | PDKIM_VERIFY_FAIL_MESSAGE | |
220 | RSA verification of the signature (b= tag) failed. | |
221 | */ | |
222 | int verify_ext_status; | |
223 | ||
224 | /* Pointer to a public key record that was used to verify the signature. | |
225 | See pdkim_pubkey declaration above for more information. | |
226 | Caution: is NULL if signing or if no record was retrieved. */ | |
227 | pdkim_pubkey *pubkey; | |
228 | ||
229 | /* Pointer to the next pdkim_signature signature. NULL if signing or if | |
230 | this is the last signature. */ | |
231 | void *next; | |
232 | ||
233 | /* Properties below this point are used internally only ------------- */ | |
234 | ||
235 | /* Per-signature helper variables ----------------------------------- */ | |
2813c06e CE |
236 | hctx body_hash_ctx; |
237 | ||
420a0d19 CE |
238 | unsigned long signed_body_bytes; /* How many body bytes we hashed */ |
239 | pdkim_stringlist *headers; /* Raw headers included in the sig */ | |
240 | /* Signing specific ------------------------------------------------- */ | |
2813c06e CE |
241 | uschar * rsa_privkey; /* Private RSA key */ |
242 | uschar * sign_headers; /* To-be-signed header names */ | |
243 | uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */ | |
420a0d19 CE |
244 | } pdkim_signature; |
245 | ||
246 | ||
247 | /* -------------------------------------------------------------------------- */ | |
248 | /* Context to keep state between all operations. */ | |
420a0d19 CE |
249 | typedef struct pdkim_ctx { |
250 | ||
2813c06e CE |
251 | #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */ |
252 | #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */ | |
253 | #define PDKIM_SEEN_CR BIT(2) | |
254 | #define PDKIM_SEEN_LF BIT(3) | |
255 | #define PDKIM_PAST_HDRS BIT(4) | |
256 | #define PDKIM_SEEN_EOD BIT(5) | |
257 | unsigned flags; | |
420a0d19 CE |
258 | |
259 | /* One (signing) or several chained (verification) signatures */ | |
260 | pdkim_signature *sig; | |
261 | ||
262 | /* Callback for dns/txt query method (verification only) */ | |
263 | int(*dns_txt_callback)(char *, char *); | |
264 | ||
265 | /* Coder's little helpers */ | |
2813c06e CE |
266 | uschar *cur_header; |
267 | int cur_header_size; | |
268 | int cur_header_len; | |
420a0d19 CE |
269 | char *linebuf; |
270 | int linebuf_offset; | |
420a0d19 CE |
271 | int num_buffered_crlf; |
272 | int num_headers; | |
273 | pdkim_stringlist *headers; /* Raw headers for verification */ | |
420a0d19 CE |
274 | } pdkim_ctx; |
275 | ||
276 | ||
277 | /* -------------------------------------------------------------------------- */ | |
278 | /* API functions. Please see the sample code in sample/test_sign.c and | |
279 | sample/test_verify.c for documentation. | |
280 | */ | |
281 | ||
282 | #ifdef __cplusplus | |
283 | extern "C" { | |
284 | #endif | |
285 | ||
2813c06e CE |
286 | void pdkim_init (void); |
287 | ||
420a0d19 | 288 | DLLEXPORT |
2813c06e CE |
289 | pdkim_ctx *pdkim_init_sign (char *, char *, char *, int, |
290 | BOOL, int(*)(char *, char *)); | |
420a0d19 CE |
291 | |
292 | DLLEXPORT | |
2813c06e | 293 | pdkim_ctx *pdkim_init_verify (int(*)(char *, char *), BOOL); |
420a0d19 CE |
294 | |
295 | DLLEXPORT | |
296 | int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int, | |
2813c06e | 297 | long, |
420a0d19 CE |
298 | unsigned long, |
299 | unsigned long); | |
300 | ||
301 | DLLEXPORT | |
302 | int pdkim_feed (pdkim_ctx *, char *, int); | |
303 | DLLEXPORT | |
304 | int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **); | |
305 | ||
306 | DLLEXPORT | |
307 | void pdkim_free_ctx (pdkim_ctx *); | |
308 | ||
2813c06e CE |
309 | |
310 | const char * pdkim_errstr(int); | |
420a0d19 CE |
311 | |
312 | #ifdef __cplusplus | |
313 | } | |
314 | #endif | |
2813c06e CE |
315 | |
316 | #endif |