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[exim.git] / src / src / pdkim / pdkim.h
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1/*
2 * PDKIM - a RFC4871 (DKIM) implementation
3 *
c4ceed07 4 * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net>
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5 *
6 * http://duncanthrax.net/pdkim/
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
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 along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21 */
22
80a47a2c 23/* -------------------------------------------------------------------------- */
80a47a2c 24/* Length of the preallocated buffer for the "answer" from the dns/txt
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25 callback function. This should match the maximum RDLENGTH from DNS. */
26#define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16)
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27
28/* -------------------------------------------------------------------------- */
29/* Function success / error codes */
30#define PDKIM_OK 0
31#define PDKIM_FAIL -1
32#define PDKIM_ERR_OOM -100
33#define PDKIM_ERR_RSA_PRIVKEY -101
34#define PDKIM_ERR_RSA_SIGNING -102
35#define PDKIM_ERR_LONG_LINE -103
36#define PDKIM_ERR_BUFFER_TOO_SMALL -104
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37#define PDKIM_SIGN_PRIVKEY_WRAP -105
38#define PDKIM_SIGN_PRIVKEY_B64D -106
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39
40/* -------------------------------------------------------------------------- */
41/* Main/Extended verification status */
42#define PDKIM_VERIFY_NONE 0
43#define PDKIM_VERIFY_INVALID 1
44#define PDKIM_VERIFY_FAIL 2
45#define PDKIM_VERIFY_PASS 3
46
47#define PDKIM_VERIFY_FAIL_BODY 1
48#define PDKIM_VERIFY_FAIL_MESSAGE 2
49#define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
50#define PDKIM_VERIFY_INVALID_BUFFER_SIZE 4
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51#define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 5
52#define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 6
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53
54/* -------------------------------------------------------------------------- */
55/* Some parameter values */
56#define PDKIM_QUERYMETHOD_DNS_TXT 0
57
58#define PDKIM_ALGO_RSA_SHA256 0
59#define PDKIM_ALGO_RSA_SHA1 1
60
61#define PDKIM_CANON_SIMPLE 0
62#define PDKIM_CANON_RELAXED 1
63
64#define PDKIM_HASH_SHA256 0
65#define PDKIM_HASH_SHA1 1
66
67#define PDKIM_KEYTYPE_RSA 0
68
69/* -------------------------------------------------------------------------- */
70/* Some required forward declarations, please ignore */
71typedef struct pdkim_stringlist pdkim_stringlist;
72typedef struct pdkim_str pdkim_str;
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73typedef struct sha1_context sha1_context;
74typedef struct sha2_context sha2_context;
75#define HAVE_SHA1_CONTEXT
76#define HAVE_SHA2_CONTEXT
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77
78/* -------------------------------------------------------------------------- */
79/* Some concessions towards Redmond */
80#ifdef WINDOWS
81#define snprintf _snprintf
82#define strcasecmp _stricmp
83#define strncasecmp _strnicmp
84#define DLLEXPORT __declspec(dllexport)
85#else
86#define DLLEXPORT
87#endif
88
89
90/* -------------------------------------------------------------------------- */
91/* Public key as (usually) fetched from DNS */
92typedef struct pdkim_pubkey {
93 char *version; /* v= */
94 char *granularity; /* g= */
95
96 char *hashes; /* h= */
97 char *keytype; /* k= */
98 char *srvtype; /* s= */
99 char *notes; /* n= */
100
101 char *key; /* p= */
102 int key_len;
103
104 int testing; /* t=y */
105 int no_subdomaining; /* t=s */
106} pdkim_pubkey;
107
108/* -------------------------------------------------------------------------- */
109/* Signature as it appears in a DKIM-Signature header */
110typedef struct pdkim_signature {
111
112 /* Bits stored in a DKIM signature header --------------------------- */
113
114 /* (v=) The version, as an integer. Currently, always "1" */
115 int version;
116
117 /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
118 or PDKIM_ALGO_RSA_SHA1 */
119 int algo;
120
121 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
122 or PDKIM_CANON_RELAXED */
123 int canon_headers;
124
125 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
126 or PDKIM_CANON_RELAXED */
127 int canon_body;
128
129 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
130 is specified */
131 int querymethod;
132
133 /* (s=) The selector string as given in the signature */
134 char *selector;
135
136 /* (d=) The domain as given in the signature */
137 char *domain;
138
139 /* (i=) The identity as given in the signature */
140 char *identity;
141
142 /* (t=) Timestamp of signature creation */
143 unsigned long created;
144
145 /* (x=) Timestamp of expiry of signature */
146 unsigned long expires;
147
148 /* (l=) Amount of hashed body bytes (after canonicalization). Default
149 is -1. Note: a value of 0 means that the body is unsigned! */
150 long bodylength;
151
152 /* (h=) Colon-separated list of header names that are included in the
153 signature */
154 char *headernames;
155
156 /* (z=) */
157 char *copiedheaders;
158
159 /* (b=) Raw signature data, along with its length in bytes */
160 char *sigdata;
161 int sigdata_len;
162
163 /* (bh=) Raw body hash data, along with its length in bytes */
164 char *bodyhash;
165 int bodyhash_len;
166
167 /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
168 Ready for insertion into the message. Note: Folded using CRLFTB,
169 but final line terminator is NOT included. Note2: This buffer is
170 free()d when you call pdkim_free_ctx(). */
171 char *signature_header;
172
173 /* The main verification status. Verification only. One of:
174
175 PDKIM_VERIFY_NONE Verification was not attempted. This status
176 should not appear.
177
178 PDKIM_VERIFY_INVALID There was an error while trying to verify
179 the signature. A more precise description
180 is available in verify_ext_status.
181
182 PDKIM_VERIFY_FAIL Verification failed because either the body
183 hash did not match, or the signature verification
184 failed. This means the message was modified.
185 Check verify_ext_status for the exact reason.
186
187 PDKIM_VERIFY_PASS Verification succeeded.
188 */
189 int verify_status;
190
191 /* Extended verification status. Verification only. Depending on the value
192 of verify_status, it can contain:
193
194 For verify_status == PDKIM_VERIFY_INVALID:
195
196 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
197 Unable to retrieve a public key container.
198
199 PDKIM_VERIFY_INVALID_BUFFER_SIZE
200 Either the DNS name constructed to retrieve the public key record
201 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
202 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
203
204 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
205 (Syntax) error while parsing the retrieved public key record.
206
207
208 For verify_status == PDKIM_VERIFY_FAIL:
209
210 PDKIM_VERIFY_FAIL_BODY
211 The calculated body hash does not match the advertised body hash
212 from the bh= tag of the signature.
213
214 PDKIM_VERIFY_FAIL_MESSAGE
215 RSA verification of the signature (b= tag) failed.
216 */
217 int verify_ext_status;
218
219 /* Pointer to a public key record that was used to verify the signature.
220 See pdkim_pubkey declaration above for more information.
221 Caution: is NULL if signing or if no record was retrieved. */
222 pdkim_pubkey *pubkey;
223
224 /* Pointer to the next pdkim_signature signature. NULL if signing or if
225 this is the last signature. */
226 void *next;
227
228 /* Properties below this point are used internally only ------------- */
229
230 /* Per-signature helper variables ----------------------------------- */
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231#ifdef SHA_OPENSSL
232 SHA_CTX sha1_body; /* SHA1 block */
233 SHA256_CTX sha2_body; /* SHA256 block */
234#elif defined(SHA_GNUTLS)
f444c2c7 235 gnutls_hash_hd_t sha_body; /* Either SHA1 or SHA256 block */
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236#elif defined(SHA_POLARSSL)
237 sha1_context *sha1_body; /* SHA1 block */
238 sha2_context *sha2_body; /* SHA256 block */
f444c2c7 239#endif
80a47a2c 240 unsigned long signed_body_bytes; /* How many body bytes we hashed */
cb224393 241 pdkim_stringlist *headers; /* Raw headers included in the sig */
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242 /* Signing specific ------------------------------------------------- */
243 char *rsa_privkey; /* Private RSA key */
244 char *sign_headers; /* To-be-signed header names */
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245 char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
246} pdkim_signature;
247
248
249/* -------------------------------------------------------------------------- */
250/* Context to keep state between all operations. */
251#define PDKIM_MODE_SIGN 0
252#define PDKIM_MODE_VERIFY 1
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253typedef struct pdkim_ctx {
254
255 /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
256 int mode;
257
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258 /* One (signing) or several chained (verification) signatures */
259 pdkim_signature *sig;
260
261 /* Callback for dns/txt query method (verification only) */
262 int(*dns_txt_callback)(char *, char *);
263
264 /* Coder's little helpers */
265 pdkim_str *cur_header;
266 char *linebuf;
267 int linebuf_offset;
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268 BOOL seen_lf;
269 BOOL seen_eod;
270 BOOL past_headers;
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271 int num_buffered_crlf;
272 int num_headers;
37f8b554 273 pdkim_stringlist *headers; /* Raw headers for verification */
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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
283extern "C" {
284#endif
285
286DLLEXPORT
f444c2c7 287pdkim_ctx *pdkim_init_sign (char *, char *, char *, int);
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288
289DLLEXPORT
0d04a285 290pdkim_ctx *pdkim_init_verify (int(*)(char *, char *));
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291
292DLLEXPORT
293int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
f444c2c7 294 long,
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295 unsigned long,
296 unsigned long);
297
298DLLEXPORT
299int pdkim_feed (pdkim_ctx *, char *, int);
300DLLEXPORT
301int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **);
302
303DLLEXPORT
304void pdkim_free_ctx (pdkim_ctx *);
305
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306#ifdef __cplusplus
307}
308#endif