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420a0d19 CE |
1 | /* |
2 | * PDKIM - a RFC4871 (DKIM) implementation | |
3 | * | |
4 | * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net> | |
2ea97746 | 5 | * Copyright (c) 2016 - 2018 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 | */ | |
2ea97746 CE |
23 | #ifndef PDKIM_H |
24 | #define PDKIM_H | |
420a0d19 | 25 | |
2ea97746 CE |
26 | #include "../blob.h" |
27 | #include "../hash.h" | |
28 | ||
29 | #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\ | |
30 | "Message-ID:To:Cc:MIME-Version:Content-Type:"\ | |
31 | "Content-Transfer-Encoding:Content-ID:"\ | |
32 | "Content-Description:Resent-Date:Resent-From:"\ | |
33 | "Resent-Sender:Resent-To:Resent-Cc:"\ | |
34 | "Resent-Message-ID:In-Reply-To:References:"\ | |
35 | "List-Id:List-Help:List-Unsubscribe:"\ | |
36 | "List-Subscribe:List-Post:List-Owner:List-Archive" | |
420a0d19 CE |
37 | |
38 | /* -------------------------------------------------------------------------- */ | |
39 | /* Length of the preallocated buffer for the "answer" from the dns/txt | |
40 | callback function. This should match the maximum RDLENGTH from DNS. */ | |
41 | #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16) | |
42 | ||
43 | /* -------------------------------------------------------------------------- */ | |
44 | /* Function success / error codes */ | |
45 | #define PDKIM_OK 0 | |
46 | #define PDKIM_FAIL -1 | |
420a0d19 CE |
47 | #define PDKIM_ERR_RSA_PRIVKEY -101 |
48 | #define PDKIM_ERR_RSA_SIGNING -102 | |
49 | #define PDKIM_ERR_LONG_LINE -103 | |
50 | #define PDKIM_ERR_BUFFER_TOO_SMALL -104 | |
2ea97746 CE |
51 | #define PDKIM_ERR_EXCESS_SIGS -105 |
52 | #define PDKIM_SIGN_PRIVKEY_WRAP -106 | |
53 | #define PDKIM_SIGN_PRIVKEY_B64D -107 | |
420a0d19 CE |
54 | |
55 | /* -------------------------------------------------------------------------- */ | |
56 | /* Main/Extended verification status */ | |
57 | #define PDKIM_VERIFY_NONE 0 | |
58 | #define PDKIM_VERIFY_INVALID 1 | |
59 | #define PDKIM_VERIFY_FAIL 2 | |
60 | #define PDKIM_VERIFY_PASS 3 | |
2ea97746 CE |
61 | #define PDKIM_VERIFY_POLICY BIT(31) |
62 | ||
63 | #define PDKIM_VERIFY_FAIL_BODY 1 | |
64 | #define PDKIM_VERIFY_FAIL_MESSAGE 2 | |
65 | #define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH 3 | |
66 | #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 4 | |
67 | #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 5 | |
68 | #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 6 | |
69 | #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 7 | |
70 | #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 8 | |
71 | #define PDKIM_VERIFY_INVALID_DKIM_VERSION 9 | |
420a0d19 CE |
72 | |
73 | /* -------------------------------------------------------------------------- */ | |
74 | /* Some parameter values */ | |
75 | #define PDKIM_QUERYMETHOD_DNS_TXT 0 | |
76 | ||
2ea97746 CE |
77 | /*#define PDKIM_ALGO_RSA_SHA256 0 */ |
78 | /*#define PDKIM_ALGO_RSA_SHA1 1 */ | |
420a0d19 CE |
79 | |
80 | #define PDKIM_CANON_SIMPLE 0 | |
81 | #define PDKIM_CANON_RELAXED 1 | |
82 | ||
420a0d19 CE |
83 | /* -------------------------------------------------------------------------- */ |
84 | /* Some required forward declarations, please ignore */ | |
85 | typedef struct pdkim_stringlist pdkim_stringlist; | |
86 | typedef struct pdkim_str pdkim_str; | |
87 | typedef struct sha1_context sha1_context; | |
88 | typedef struct sha2_context sha2_context; | |
89 | #define HAVE_SHA1_CONTEXT | |
90 | #define HAVE_SHA2_CONTEXT | |
91 | ||
92 | /* -------------------------------------------------------------------------- */ | |
93 | /* Some concessions towards Redmond */ | |
94 | #ifdef WINDOWS | |
95 | #define snprintf _snprintf | |
96 | #define strcasecmp _stricmp | |
97 | #define strncasecmp _strnicmp | |
98 | #define DLLEXPORT __declspec(dllexport) | |
99 | #else | |
100 | #define DLLEXPORT | |
101 | #endif | |
102 | ||
103 | ||
104 | /* -------------------------------------------------------------------------- */ | |
105 | /* Public key as (usually) fetched from DNS */ | |
106 | typedef struct pdkim_pubkey { | |
2ea97746 CE |
107 | const uschar * version; /* v= */ |
108 | const uschar *granularity; /* g= */ | |
420a0d19 | 109 | |
2ea97746 CE |
110 | const uschar * hashes; /* h= */ |
111 | const uschar * keytype; /* k= */ | |
112 | const uschar * srvtype; /* s= */ | |
113 | uschar *notes; /* n= */ | |
420a0d19 | 114 | |
2ea97746 | 115 | blob key; /* p= */ |
420a0d19 CE |
116 | int testing; /* t=y */ |
117 | int no_subdomaining; /* t=s */ | |
118 | } pdkim_pubkey; | |
119 | ||
2ea97746 CE |
120 | /* -------------------------------------------------------------------------- */ |
121 | /* Body-hash to be calculated */ | |
122 | typedef struct pdkim_bodyhash { | |
123 | struct pdkim_bodyhash * next; | |
124 | int hashtype; | |
125 | int canon_method; | |
126 | long bodylength; | |
127 | ||
128 | hctx body_hash_ctx; | |
129 | unsigned long signed_body_bytes; /* done so far */ | |
130 | int num_buffered_blanklines; | |
131 | ||
132 | blob bh; /* completed hash */ | |
133 | } pdkim_bodyhash; | |
134 | ||
420a0d19 CE |
135 | /* -------------------------------------------------------------------------- */ |
136 | /* Signature as it appears in a DKIM-Signature header */ | |
137 | typedef struct pdkim_signature { | |
2ea97746 | 138 | struct pdkim_signature * next; |
420a0d19 CE |
139 | |
140 | /* Bits stored in a DKIM signature header --------------------------- */ | |
141 | ||
142 | /* (v=) The version, as an integer. Currently, always "1" */ | |
143 | int version; | |
144 | ||
2ea97746 CE |
145 | /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256 */ |
146 | int keytype; /* pdkim_keytypes index */ | |
147 | int hashtype; /* pdkim_hashes index */ | |
420a0d19 CE |
148 | |
149 | /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE | |
150 | or PDKIM_CANON_RELAXED */ | |
151 | int canon_headers; | |
152 | ||
153 | /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE | |
154 | or PDKIM_CANON_RELAXED */ | |
155 | int canon_body; | |
156 | ||
157 | /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT | |
158 | is specified */ | |
159 | int querymethod; | |
160 | ||
161 | /* (s=) The selector string as given in the signature */ | |
2ea97746 | 162 | uschar *selector; |
420a0d19 CE |
163 | |
164 | /* (d=) The domain as given in the signature */ | |
2ea97746 | 165 | uschar *domain; |
420a0d19 CE |
166 | |
167 | /* (i=) The identity as given in the signature */ | |
2ea97746 | 168 | uschar *identity; |
420a0d19 CE |
169 | |
170 | /* (t=) Timestamp of signature creation */ | |
171 | unsigned long created; | |
172 | ||
173 | /* (x=) Timestamp of expiry of signature */ | |
174 | unsigned long expires; | |
175 | ||
176 | /* (l=) Amount of hashed body bytes (after canonicalization). Default | |
177 | is -1. Note: a value of 0 means that the body is unsigned! */ | |
178 | long bodylength; | |
179 | ||
180 | /* (h=) Colon-separated list of header names that are included in the | |
181 | signature */ | |
2ea97746 | 182 | uschar *headernames; |
420a0d19 CE |
183 | |
184 | /* (z=) */ | |
2ea97746 | 185 | uschar *copiedheaders; |
420a0d19 CE |
186 | |
187 | /* (b=) Raw signature data, along with its length in bytes */ | |
2ea97746 | 188 | blob sighash; |
420a0d19 CE |
189 | |
190 | /* (bh=) Raw body hash data, along with its length in bytes */ | |
2ea97746 | 191 | blob bodyhash; |
420a0d19 | 192 | |
2ea97746 | 193 | /* Folded DKIM-Signature: header. Signing only, NULL for verifying. |
420a0d19 CE |
194 | Ready for insertion into the message. Note: Folded using CRLFTB, |
195 | but final line terminator is NOT included. Note2: This buffer is | |
196 | free()d when you call pdkim_free_ctx(). */ | |
2ea97746 | 197 | uschar *signature_header; |
420a0d19 CE |
198 | |
199 | /* The main verification status. Verification only. One of: | |
200 | ||
201 | PDKIM_VERIFY_NONE Verification was not attempted. This status | |
202 | should not appear. | |
203 | ||
204 | PDKIM_VERIFY_INVALID There was an error while trying to verify | |
205 | the signature. A more precise description | |
206 | is available in verify_ext_status. | |
207 | ||
208 | PDKIM_VERIFY_FAIL Verification failed because either the body | |
209 | hash did not match, or the signature verification | |
210 | failed. This means the message was modified. | |
211 | Check verify_ext_status for the exact reason. | |
212 | ||
213 | PDKIM_VERIFY_PASS Verification succeeded. | |
214 | */ | |
215 | int verify_status; | |
216 | ||
217 | /* Extended verification status. Verification only. Depending on the value | |
218 | of verify_status, it can contain: | |
219 | ||
220 | For verify_status == PDKIM_VERIFY_INVALID: | |
221 | ||
222 | PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE | |
223 | Unable to retrieve a public key container. | |
224 | ||
225 | PDKIM_VERIFY_INVALID_BUFFER_SIZE | |
226 | Either the DNS name constructed to retrieve the public key record | |
227 | does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved | |
228 | record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes. | |
229 | ||
230 | PDKIM_VERIFY_INVALID_PUBKEY_PARSING | |
231 | (Syntax) error while parsing the retrieved public key record. | |
232 | ||
233 | ||
234 | For verify_status == PDKIM_VERIFY_FAIL: | |
235 | ||
236 | PDKIM_VERIFY_FAIL_BODY | |
237 | The calculated body hash does not match the advertised body hash | |
238 | from the bh= tag of the signature. | |
239 | ||
240 | PDKIM_VERIFY_FAIL_MESSAGE | |
241 | RSA verification of the signature (b= tag) failed. | |
242 | */ | |
243 | int verify_ext_status; | |
244 | ||
245 | /* Pointer to a public key record that was used to verify the signature. | |
246 | See pdkim_pubkey declaration above for more information. | |
247 | Caution: is NULL if signing or if no record was retrieved. */ | |
248 | pdkim_pubkey *pubkey; | |
249 | ||
420a0d19 CE |
250 | /* Properties below this point are used internally only ------------- */ |
251 | ||
252 | /* Per-signature helper variables ----------------------------------- */ | |
2ea97746 CE |
253 | pdkim_bodyhash *calc_body_hash; /* hash to be / being calculated */ |
254 | ||
255 | pdkim_stringlist *headers; /* Raw headers included in the sig */ | |
256 | ||
420a0d19 | 257 | /* Signing specific ------------------------------------------------- */ |
2ea97746 CE |
258 | uschar * privkey; /* Private key */ |
259 | uschar * sign_headers; /* To-be-signed header names */ | |
260 | uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */ | |
420a0d19 CE |
261 | } pdkim_signature; |
262 | ||
263 | ||
264 | /* -------------------------------------------------------------------------- */ | |
265 | /* Context to keep state between all operations. */ | |
420a0d19 CE |
266 | typedef struct pdkim_ctx { |
267 | ||
2ea97746 CE |
268 | #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */ |
269 | #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */ | |
270 | #define PDKIM_SEEN_CR BIT(2) | |
271 | #define PDKIM_SEEN_LF BIT(3) | |
272 | #define PDKIM_PAST_HDRS BIT(4) | |
273 | #define PDKIM_SEEN_EOD BIT(5) | |
274 | unsigned flags; | |
420a0d19 CE |
275 | |
276 | /* One (signing) or several chained (verification) signatures */ | |
277 | pdkim_signature *sig; | |
278 | ||
2ea97746 CE |
279 | /* One (signing) or several chained (verification) bodyhashes */ |
280 | pdkim_bodyhash *bodyhash; | |
281 | ||
420a0d19 | 282 | /* Callback for dns/txt query method (verification only) */ |
2ea97746 | 283 | uschar * (*dns_txt_callback)(uschar *); |
420a0d19 CE |
284 | |
285 | /* Coder's little helpers */ | |
2ea97746 CE |
286 | gstring *cur_header; |
287 | uschar *linebuf; | |
420a0d19 | 288 | int linebuf_offset; |
420a0d19 CE |
289 | int num_headers; |
290 | pdkim_stringlist *headers; /* Raw headers for verification */ | |
2ea97746 | 291 | } pdkim_ctx; |
420a0d19 | 292 | |
420a0d19 | 293 | |
2ea97746 CE |
294 | /******************************************************************************/ |
295 | ||
296 | typedef struct { | |
297 | const uschar * dkim_hashname; | |
298 | hashmethod exim_hashmethod; | |
299 | } pdkim_hashtype; | |
300 | extern const pdkim_hashtype pdkim_hashes[]; | |
301 | ||
302 | /******************************************************************************/ | |
420a0d19 CE |
303 | |
304 | ||
305 | /* -------------------------------------------------------------------------- */ | |
306 | /* API functions. Please see the sample code in sample/test_sign.c and | |
307 | sample/test_verify.c for documentation. | |
308 | */ | |
309 | ||
310 | #ifdef __cplusplus | |
311 | extern "C" { | |
312 | #endif | |
313 | ||
2ea97746 CE |
314 | void pdkim_init (void); |
315 | ||
316 | void pdkim_init_context (pdkim_ctx *, BOOL, uschar * (*)(uschar *)); | |
317 | ||
420a0d19 | 318 | DLLEXPORT |
2ea97746 CE |
319 | pdkim_signature *pdkim_init_sign (pdkim_ctx *, |
320 | uschar *, uschar *, uschar *, uschar *, | |
321 | const uschar **); | |
420a0d19 CE |
322 | |
323 | DLLEXPORT | |
2ea97746 | 324 | pdkim_ctx *pdkim_init_verify (uschar * (*)(uschar *), BOOL); |
420a0d19 CE |
325 | |
326 | DLLEXPORT | |
2ea97746 CE |
327 | void pdkim_set_optional (pdkim_signature *, char *, char *,int, int, |
328 | long, | |
420a0d19 CE |
329 | unsigned long, |
330 | unsigned long); | |
331 | ||
2ea97746 CE |
332 | int pdkim_hashname_to_hashtype(const uschar *, unsigned); |
333 | void pdkim_cstring_to_canons(const uschar *, unsigned, int *, int *); | |
334 | pdkim_bodyhash *pdkim_set_bodyhash(pdkim_ctx *, int, int, long); | |
335 | pdkim_bodyhash *pdkim_set_sig_bodyhash(pdkim_ctx *, pdkim_signature *); | |
336 | ||
420a0d19 | 337 | DLLEXPORT |
2ea97746 | 338 | int pdkim_feed (pdkim_ctx *, uschar *, int); |
420a0d19 | 339 | DLLEXPORT |
2ea97746 | 340 | int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **); |
420a0d19 CE |
341 | |
342 | DLLEXPORT | |
343 | void pdkim_free_ctx (pdkim_ctx *); | |
344 | ||
2ea97746 CE |
345 | |
346 | const uschar * pdkim_errstr(int); | |
347 | ||
348 | extern uschar * pdkim_encode_base64(blob *); | |
349 | extern void pdkim_decode_base64(const uschar *, blob *); | |
350 | extern void pdkim_hexprint(const uschar *, int); | |
351 | extern void pdkim_quoteprint(const uschar *, int); | |
352 | extern pdkim_pubkey * pdkim_parse_pubkey_record(const uschar *); | |
353 | extern uschar * pdkim_relax_header_n(const uschar *, int, BOOL); | |
354 | extern uschar * pdkim_relax_header(const uschar *, BOOL); | |
355 | extern uschar * dkim_sig_to_a_tag(const pdkim_signature *); | |
420a0d19 CE |
356 | |
357 | #ifdef __cplusplus | |
358 | } | |
359 | #endif | |
2ea97746 CE |
360 | |
361 | #endif |