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 /* -------------------------------------------------------------------------- */
  24 /* Length of the preallocated buffer for the "answer" from the dns/txt
  25    callback function. This should match the maximum RDLENGTH from DNS. */
  26 #define PDKIM_DNS_TXT_MAX_RECLEN    (1 << 16)
  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
  37
  38 /* -------------------------------------------------------------------------- */
  39 /* Main/Extended verification status */
  40 #define PDKIM_VERIFY_NONE      0
  41 #define PDKIM_VERIFY_INVALID   1
  42 #define PDKIM_VERIFY_FAIL      2
  43 #define PDKIM_VERIFY_PASS      3
  44
  45 #define PDKIM_VERIFY_FAIL_BODY                  1
  46 #define PDKIM_VERIFY_FAIL_MESSAGE               2
  47 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
  48 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE        4
  49 #define PDKIM_VERIFY_INVALID_PUBKEY_PARSING     5
  50
  51 /* -------------------------------------------------------------------------- */
  52 /* Some parameter values */
  53 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  54
  55 #define PDKIM_ALGO_RSA_SHA256     0
  56 #define PDKIM_ALGO_RSA_SHA1       1
  57
  58 #define PDKIM_CANON_SIMPLE        0
  59 #define PDKIM_CANON_RELAXED       1
  60
  61 #define PDKIM_HASH_SHA256         0
  62 #define PDKIM_HASH_SHA1           1
  63
  64 #define PDKIM_KEYTYPE_RSA         0
  65
  66 /* -------------------------------------------------------------------------- */
  67 /* Some required forward declarations, please ignore */
  68 typedef struct pdkim_stringlist pdkim_stringlist;
  69 typedef struct pdkim_str pdkim_str;
  70 typedef struct sha1_context sha1_context;
  71 typedef struct sha2_context sha2_context;
  72 #define HAVE_SHA1_CONTEXT
  73 #define HAVE_SHA2_CONTEXT
  74
  75 /* -------------------------------------------------------------------------- */
  76 /* Some concessions towards Redmond */
  77 #ifdef WINDOWS
  78 #define snprintf _snprintf
  79 #define strcasecmp _stricmp
  80 #define strncasecmp _strnicmp
  81 #define DLLEXPORT __declspec(dllexport)
  82 #else
  83 #define DLLEXPORT
  84 #endif
  85
  86
  87 /* -------------------------------------------------------------------------- */
  88 /* Public key as (usually) fetched from DNS */
  89 typedef struct pdkim_pubkey {
  90   char *version;                  /* v=  */
  91   char *granularity;              /* g=  */
  92
  93   char *hashes;                   /* h=  */
  94   char *keytype;                  /* k=  */
  95   char *srvtype;                  /* s=  */
  96   char *notes;                    /* n=  */
  97
  98   char *key;                      /* p=  */
  99   int   key_len;
 100
 101   int   testing;                  /* t=y */
 102   int   no_subdomaining;          /* t=s */
 103 } pdkim_pubkey;
 104
 105 /* -------------------------------------------------------------------------- */
 106 /* Signature as it appears in a DKIM-Signature header */
 107 typedef struct pdkim_signature {
 108
 109   /* Bits stored in a DKIM signature header --------------------------- */
 110
 111   /* (v=) The version, as an integer. Currently, always "1" */
 112   int version;
 113
 114   /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
 115      or PDKIM_ALGO_RSA_SHA1 */
 116   int algo;
 117
 118   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 119      or PDKIM_CANON_RELAXED */
 120   int canon_headers;
 121
 122   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 123      or PDKIM_CANON_RELAXED */
 124   int canon_body;
 125
 126   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 127      is specified */
 128   int querymethod;
 129
 130   /* (s=) The selector string as given in the signature */
 131   char *selector;
 132
 133   /* (d=) The domain as given in the signature */
 134   char *domain;
 135
 136   /* (i=) The identity as given in the signature */
 137   char *identity;
 138
 139   /* (t=) Timestamp of signature creation */
 140   unsigned long created;
 141
 142   /* (x=) Timestamp of expiry of signature */
 143   unsigned long expires;
 144
 145   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 146      is -1. Note: a value of 0 means that the body is unsigned! */
 147   long bodylength;
 148
 149   /* (h=) Colon-separated list of header names that are included in the
 150      signature */
 151   char *headernames;
 152
 153   /* (z=) */
 154   char *copiedheaders;
 155
 156   /* (b=) Raw signature data, along with its length in bytes */
 157   char *sigdata;
 158   int   sigdata_len;
 159
 160   /* (bh=) Raw body hash data, along with its length in bytes */
 161   char *bodyhash;
 162   int   bodyhash_len;
 163
 164   /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
 165      Ready for insertion into the message. Note: Folded using CRLFTB,
 166      but final line terminator is NOT included. Note2: This buffer is
 167      free()d when you call pdkim_free_ctx(). */
 168   char *signature_header;
 169
 170   /* The main verification status. Verification only. One of:
 171
 172      PDKIM_VERIFY_NONE      Verification was not attempted. This status
 173                             should not appear.
 174
 175      PDKIM_VERIFY_INVALID   There was an error while trying to verify
 176                             the signature. A more precise description
 177                             is available in verify_ext_status.
 178
 179      PDKIM_VERIFY_FAIL      Verification failed because either the body
 180                             hash did not match, or the signature verification
 181                             failed. This means the message was modified.
 182                             Check verify_ext_status for the exact reason.
 183
 184      PDKIM_VERIFY_PASS      Verification succeeded.
 185   */
 186   int verify_status;
 187
 188   /* Extended verification status. Verification only. Depending on the value
 189      of verify_status, it can contain:
 190
 191      For verify_status == PDKIM_VERIFY_INVALID:
 192
 193         PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
 194           Unable to retrieve a public key container.
 195
 196         PDKIM_VERIFY_INVALID_BUFFER_SIZE
 197           Either the DNS name constructed to retrieve the public key record
 198           does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
 199           record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
 200
 201         PDKIM_VERIFY_INVALID_PUBKEY_PARSING
 202           (Syntax) error while parsing the retrieved public key record.
 203
 204
 205      For verify_status == PDKIM_VERIFY_FAIL:
 206
 207         PDKIM_VERIFY_FAIL_BODY
 208           The calculated body hash does not match the advertised body hash
 209           from the bh= tag of the signature.
 210
 211         PDKIM_VERIFY_FAIL_MESSAGE
 212           RSA verification of the signature (b= tag) failed.
 213   */
 214   int verify_ext_status;
 215
 216   /* Pointer to a public key record that was used to verify the signature.
 217      See pdkim_pubkey declaration above for more information.
 218      Caution: is NULL if signing or if no record was retrieved. */
 219   pdkim_pubkey *pubkey;
 220
 221   /* Pointer to the next pdkim_signature signature. NULL if signing or if
 222      this is the last signature. */
 223   void *next;
 224
 225   /* Properties below this point are used internally only ------------- */
 226
 227   /* Per-signature helper variables ----------------------------------- */
 228   sha1_context *sha1_body; /* SHA1 block                                */
 229   sha2_context *sha2_body; /* SHA256 block                              */
 230   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 231   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 232   /* Signing specific ------------------------------------------------- */
 233   char *rsa_privkey;     /* Private RSA key                             */
 234   char *sign_headers;    /* To-be-signed header names                   */
 235   char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 236 } pdkim_signature;
 237
 238
 239 /* -------------------------------------------------------------------------- */
 240 /* Context to keep state between all operations. */
 241 #define PDKIM_MODE_SIGN     0
 242 #define PDKIM_MODE_VERIFY   1
 243 typedef struct pdkim_ctx {
 244
 245   /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
 246   int mode;
 247
 248   /* One (signing) or several chained (verification) signatures */
 249   pdkim_signature *sig;
 250
 251   /* Callback for dns/txt query method (verification only) */
 252   int(*dns_txt_callback)(char *, char *);
 253
 254   /* Coder's little helpers */
 255   pdkim_str *cur_header;
 256   char      *linebuf;
 257   int        linebuf_offset;
 258   BOOL       seen_lf;
 259   BOOL       seen_eod;
 260   BOOL       past_headers;
 261   int        num_buffered_crlf;
 262   int        num_headers;
 263   pdkim_stringlist *headers; /* Raw headers for verification         */
 264 } pdkim_ctx;
 265
 266
 267 /* -------------------------------------------------------------------------- */
 268 /* API functions. Please see the sample code in sample/test_sign.c and
 269    sample/test_verify.c for documentation.
 270 */
 271
 272 #ifdef __cplusplus
 273 extern "C" {
 274 #endif
 275
 276 DLLEXPORT
 277 pdkim_ctx *pdkim_init_sign    (char *, char *, char *);
 278
 279 DLLEXPORT
 280 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *));
 281
 282 DLLEXPORT
 283 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 284                                long, int,
 285                                unsigned long,
 286                                unsigned long);
 287
 288 DLLEXPORT
 289 int        pdkim_feed         (pdkim_ctx *, char *, int);
 290 DLLEXPORT
 291 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 292
 293 DLLEXPORT
 294 void       pdkim_free_ctx     (pdkim_ctx *);
 295
 296 #ifdef __cplusplus
 297 }
 298 #endif