src/src/pdkim/pdkim.h

   1 /*
   2  *  PDKIM - a RFC4871 (DKIM) implementation
   3  *
   4  *  Copyright (C) 2009 - 2012  Tom Kistner <tom@duncanthrax.net>
   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
  23 #ifdef USE_GNUTLS
  24 # include <gnutls/gnutls.h>
  25 # include <gnutls/crypto.h>
  26 #else
  27 # include <openssl/sha.h>
  28 #endif
  29
  30 /* -------------------------------------------------------------------------- */
  31 /* Length of the preallocated buffer for the "answer" from the dns/txt
  32    callback function. This should match the maximum RDLENGTH from DNS. */
  33 #define PDKIM_DNS_TXT_MAX_RECLEN    (1 << 16)
  34
  35 /* -------------------------------------------------------------------------- */
  36 /* Function success / error codes */
  37 #define PDKIM_OK                      0
  38 #define PDKIM_FAIL                   -1
  39 #define PDKIM_ERR_OOM              -100
  40 #define PDKIM_ERR_RSA_PRIVKEY      -101
  41 #define PDKIM_ERR_RSA_SIGNING      -102
  42 #define PDKIM_ERR_LONG_LINE        -103
  43 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
  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
  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_PARSING     5
  57
  58 /* -------------------------------------------------------------------------- */
  59 /* Some parameter values */
  60 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  61
  62 #define PDKIM_ALGO_RSA_SHA256     0
  63 #define PDKIM_ALGO_RSA_SHA1       1
  64
  65 #define PDKIM_CANON_SIMPLE        0
  66 #define PDKIM_CANON_RELAXED       1
  67
  68 #define PDKIM_HASH_SHA256         0
  69 #define PDKIM_HASH_SHA1           1
  70
  71 #define PDKIM_KEYTYPE_RSA         0
  72
  73 /* -------------------------------------------------------------------------- */
  74 /* Some required forward declarations, please ignore */
  75 typedef struct pdkim_stringlist pdkim_stringlist;
  76 typedef struct pdkim_str pdkim_str;
  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 */
  92 typedef 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 */
 110 typedef 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 ----------------------------------- */
 231 #ifdef USE_GNUTLS
 232   gnutls_hash_hd_t sha_body; /* Either SHA1 or SHA256 block             */
 233 #else
 234   SHA_CTX      sha1_body;    /* SHA1 block                              */
 235   SHA256_CTX   sha2_body;    /* SHA256 block                            */
 236 #endif
 237   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 238   pdkim_stringlist *headers;       /* Raw headers included in the sig   */
 239   /* Signing specific ------------------------------------------------- */
 240   char *rsa_privkey;     /* Private RSA key                             */
 241   char *sign_headers;    /* To-be-signed header names                   */
 242   char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 243 } pdkim_signature;
 244
 245
 246 /* -------------------------------------------------------------------------- */
 247 /* Context to keep state between all operations. */
 248 #define PDKIM_MODE_SIGN     0
 249 #define PDKIM_MODE_VERIFY   1
 250 typedef struct pdkim_ctx {
 251
 252   /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
 253   int mode;
 254
 255   /* One (signing) or several chained (verification) signatures */
 256   pdkim_signature *sig;
 257
 258   /* Callback for dns/txt query method (verification only) */
 259   int(*dns_txt_callback)(char *, char *);
 260
 261   /* Coder's little helpers */
 262   pdkim_str *cur_header;
 263   char      *linebuf;
 264   int        linebuf_offset;
 265   BOOL       seen_lf;
 266   BOOL       seen_eod;
 267   BOOL       past_headers;
 268   int        num_buffered_crlf;
 269   int        num_headers;
 270   pdkim_stringlist *headers; /* Raw headers for verification         */
 271 } pdkim_ctx;
 272
 273
 274 /* -------------------------------------------------------------------------- */
 275 /* API functions. Please see the sample code in sample/test_sign.c and
 276    sample/test_verify.c for documentation.
 277 */
 278
 279 #ifdef __cplusplus
 280 extern "C" {
 281 #endif
 282
 283 DLLEXPORT
 284 pdkim_ctx *pdkim_init_sign    (char *, char *, char *, int);
 285
 286 DLLEXPORT
 287 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *));
 288
 289 DLLEXPORT
 290 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 291                                long,
 292                                unsigned long,
 293                                unsigned long);
 294
 295 DLLEXPORT
 296 int        pdkim_feed         (pdkim_ctx *, char *, int);
 297 DLLEXPORT
 298 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 299
 300 DLLEXPORT
 301 void       pdkim_free_ctx     (pdkim_ctx *);
 302
 303 #ifdef __cplusplus
 304 }
 305 #endif