src/src/pdkim/pdkim.h

   1 /*
   2  *  PDKIM - a RFC4871 (DKIM) implementation
   3  *
   4  *  Copyright (C) 2009 - 2012  Tom Kistner <tom@duncanthrax.net>
   5  *  Copyright (c) Jeremy Harris 2016
   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  */
  23 #ifndef PDKIM_H
  24 #define PDKIM_H
  25
  26 #include "blob.h"
  27 #include "hash.h"
  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
  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
  42 #define PDKIM_SIGN_PRIVKEY_WRAP    -105
  43 #define PDKIM_SIGN_PRIVKEY_B64D    -106
  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_DNSRECORD   5
  57 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT      6
  58
  59 /* -------------------------------------------------------------------------- */
  60 /* Some parameter values */
  61 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  62
  63 #define PDKIM_ALGO_RSA_SHA256     0
  64 #define PDKIM_ALGO_RSA_SHA1       1
  65
  66 #define PDKIM_CANON_SIMPLE        0
  67 #define PDKIM_CANON_RELAXED       1
  68
  69 #define PDKIM_HASH_SHA256         0
  70 #define PDKIM_HASH_SHA1           1
  71
  72 #define PDKIM_KEYTYPE_RSA         0
  73
  74 /* -------------------------------------------------------------------------- */
  75 /* Some required forward declarations, please ignore */
  76 typedef struct pdkim_stringlist pdkim_stringlist;
  77 typedef struct pdkim_str pdkim_str;
  78 typedef struct sha1_context sha1_context;
  79 typedef struct sha2_context sha2_context;
  80 #define HAVE_SHA1_CONTEXT
  81 #define HAVE_SHA2_CONTEXT
  82
  83 /* -------------------------------------------------------------------------- */
  84 /* Some concessions towards Redmond */
  85 #ifdef WINDOWS
  86 #define snprintf _snprintf
  87 #define strcasecmp _stricmp
  88 #define strncasecmp _strnicmp
  89 #define DLLEXPORT __declspec(dllexport)
  90 #else
  91 #define DLLEXPORT
  92 #endif
  93
  94
  95 /* -------------------------------------------------------------------------- */
  96 /* Public key as (usually) fetched from DNS */
  97 typedef struct pdkim_pubkey {
  98   uschar *version;                /* v=  */
  99   uschar *granularity;            /* g=  */
 100
 101   uschar *hashes;                 /* h=  */
 102   uschar *keytype;                /* k=  */
 103   uschar *srvtype;                /* s=  */
 104   uschar *notes;                  /* n=  */
 105
 106   blob  key;                      /* p=  */
 107
 108   int   testing;                  /* t=y */
 109   int   no_subdomaining;          /* t=s */
 110 } pdkim_pubkey;
 111
 112 /* -------------------------------------------------------------------------- */
 113 /* Signature as it appears in a DKIM-Signature header */
 114 typedef struct pdkim_signature {
 115
 116   /* Bits stored in a DKIM signature header --------------------------- */
 117
 118   /* (v=) The version, as an integer. Currently, always "1" */
 119   int version;
 120
 121   /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
 122      or PDKIM_ALGO_RSA_SHA1 */
 123   int algo;
 124
 125   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 126      or PDKIM_CANON_RELAXED */
 127   int canon_headers;
 128
 129   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 130      or PDKIM_CANON_RELAXED */
 131   int canon_body;
 132
 133   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 134      is specified */
 135   int querymethod;
 136
 137   /* (s=) The selector string as given in the signature */
 138   uschar *selector;
 139
 140   /* (d=) The domain as given in the signature */
 141   uschar *domain;
 142
 143   /* (i=) The identity as given in the signature */
 144   uschar *identity;
 145
 146   /* (t=) Timestamp of signature creation */
 147   unsigned long created;
 148
 149   /* (x=) Timestamp of expiry of signature */
 150   unsigned long expires;
 151
 152   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 153      is -1. Note: a value of 0 means that the body is unsigned! */
 154   long bodylength;
 155
 156   /* (h=) Colon-separated list of header names that are included in the
 157      signature */
 158   uschar *headernames;
 159
 160   /* (z=) */
 161   uschar *copiedheaders;
 162
 163   /* (b=) Raw signature data, along with its length in bytes */
 164   blob sigdata;
 165
 166   /* (bh=) Raw body hash data, along with its length in bytes */
 167   blob bodyhash;
 168
 169   /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
 170      Ready for insertion into the message. Note: Folded using CRLFTB,
 171      but final line terminator is NOT included. Note2: This buffer is
 172      free()d when you call pdkim_free_ctx(). */
 173   uschar *signature_header;
 174
 175   /* The main verification status. Verification only. One of:
 176
 177      PDKIM_VERIFY_NONE      Verification was not attempted. This status
 178                             should not appear.
 179
 180      PDKIM_VERIFY_INVALID   There was an error while trying to verify
 181                             the signature. A more precise description
 182                             is available in verify_ext_status.
 183
 184      PDKIM_VERIFY_FAIL      Verification failed because either the body
 185                             hash did not match, or the signature verification
 186                             failed. This means the message was modified.
 187                             Check verify_ext_status for the exact reason.
 188
 189      PDKIM_VERIFY_PASS      Verification succeeded.
 190   */
 191   int verify_status;
 192
 193   /* Extended verification status. Verification only. Depending on the value
 194      of verify_status, it can contain:
 195
 196      For verify_status == PDKIM_VERIFY_INVALID:
 197
 198         PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
 199           Unable to retrieve a public key container.
 200
 201         PDKIM_VERIFY_INVALID_BUFFER_SIZE
 202           Either the DNS name constructed to retrieve the public key record
 203           does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
 204           record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
 205
 206         PDKIM_VERIFY_INVALID_PUBKEY_PARSING
 207           (Syntax) error while parsing the retrieved public key record.
 208
 209
 210      For verify_status == PDKIM_VERIFY_FAIL:
 211
 212         PDKIM_VERIFY_FAIL_BODY
 213           The calculated body hash does not match the advertised body hash
 214           from the bh= tag of the signature.
 215
 216         PDKIM_VERIFY_FAIL_MESSAGE
 217           RSA verification of the signature (b= tag) failed.
 218   */
 219   int verify_ext_status;
 220
 221   /* Pointer to a public key record that was used to verify the signature.
 222      See pdkim_pubkey declaration above for more information.
 223      Caution: is NULL if signing or if no record was retrieved. */
 224   pdkim_pubkey *pubkey;
 225
 226   /* Pointer to the next pdkim_signature signature. NULL if signing or if
 227      this is the last signature. */
 228   void *next;
 229
 230   /* Properties below this point are used internally only ------------- */
 231
 232   /* Per-signature helper variables ----------------------------------- */
 233   hctx         body_hash;
 234
 235   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 236   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 237   /* Signing specific ------------------------------------------------- */
 238   uschar * rsa_privkey;     /* Private RSA key                             */
 239   uschar * sign_headers;    /* To-be-signed header names                   */
 240   uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 241 } pdkim_signature;
 242
 243
 244 /* -------------------------------------------------------------------------- */
 245 /* Context to keep state between all operations. */
 246 #define PDKIM_MODE_SIGN     0
 247 #define PDKIM_MODE_VERIFY   1
 248 typedef struct pdkim_ctx {
 249
 250   /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
 251   int mode;
 252
 253   /* One (signing) or several chained (verification) signatures */
 254   pdkim_signature *sig;
 255
 256   /* Callback for dns/txt query method (verification only) */
 257   int(*dns_txt_callback)(char *, char *);
 258
 259   /* Coder's little helpers */
 260   uschar    *cur_header;
 261   int        cur_header_size;
 262   int        cur_header_len;
 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 void       pdkim_init         (void);
 284
 285 DLLEXPORT
 286 pdkim_ctx *pdkim_init_sign    (char *, char *, char *, int);
 287
 288 DLLEXPORT
 289 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *));
 290
 291 DLLEXPORT
 292 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 293                                long,
 294                                unsigned long,
 295                                unsigned long);
 296
 297 DLLEXPORT
 298 int        pdkim_feed         (pdkim_ctx *, char *, int);
 299 DLLEXPORT
 300 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 301
 302 DLLEXPORT
 303 void       pdkim_free_ctx     (pdkim_ctx *);
 304
 305 #ifdef __cplusplus
 306 }
 307 #endif
 308
 309 #endif