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) 2016 - 2017  Jeremy Harris
   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_FAIL_SIG_ALGO_MISMATCH       3
  55 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE   4
  56 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE          5
  57 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD     6
  58 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT        7
  59 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR      8
  60 #define PDKIM_VERIFY_INVALID_DKIM_VERSION         9
  61
  62 /* -------------------------------------------------------------------------- */
  63 /* Some parameter values */
  64 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  65
  66 #define PDKIM_ALGO_RSA_SHA256     0
  67 #define PDKIM_ALGO_RSA_SHA1       1
  68
  69 #define PDKIM_CANON_SIMPLE        0
  70 #define PDKIM_CANON_RELAXED       1
  71
  72 #define PDKIM_HASH_SHA256         0
  73 #define PDKIM_HASH_SHA1           1
  74
  75 #define PDKIM_KEYTYPE_RSA         0
  76
  77 /* -------------------------------------------------------------------------- */
  78 /* Some required forward declarations, please ignore */
  79 typedef struct pdkim_stringlist pdkim_stringlist;
  80 typedef struct pdkim_str pdkim_str;
  81 typedef struct sha1_context sha1_context;
  82 typedef struct sha2_context sha2_context;
  83 #define HAVE_SHA1_CONTEXT
  84 #define HAVE_SHA2_CONTEXT
  85
  86 /* -------------------------------------------------------------------------- */
  87 /* Some concessions towards Redmond */
  88 #ifdef WINDOWS
  89 #define snprintf _snprintf
  90 #define strcasecmp _stricmp
  91 #define strncasecmp _strnicmp
  92 #define DLLEXPORT __declspec(dllexport)
  93 #else
  94 #define DLLEXPORT
  95 #endif
  96
  97
  98 /* -------------------------------------------------------------------------- */
  99 /* Public key as (usually) fetched from DNS */
 100 typedef struct pdkim_pubkey {
 101   uschar *version;                /* v=  */
 102   uschar *granularity;            /* g=  */
 103
 104   uschar *hashes;                 /* h=  */
 105 #ifdef notdef
 106   uschar *keytype;                /* k=  */
 107 #endif
 108   uschar *srvtype;                /* s=  */
 109   uschar *notes;                  /* n=  */
 110
 111   blob  key;                      /* p=  */
 112   int   testing;                  /* t=y */
 113   int   no_subdomaining;          /* t=s */
 114 } pdkim_pubkey;
 115
 116 /* -------------------------------------------------------------------------- */
 117 /* Signature as it appears in a DKIM-Signature header */
 118 typedef struct pdkim_signature {
 119
 120   /* Bits stored in a DKIM signature header --------------------------- */
 121
 122   /* (v=) The version, as an integer. Currently, always "1" */
 123   int version;
 124
 125   /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
 126      or PDKIM_ALGO_RSA_SHA1 */
 127   int algo;
 128
 129   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 130      or PDKIM_CANON_RELAXED */
 131   int canon_headers;
 132
 133   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 134      or PDKIM_CANON_RELAXED */
 135   int canon_body;
 136
 137   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 138      is specified */
 139   int querymethod;
 140
 141   /* (s=) The selector string as given in the signature */
 142   uschar *selector;
 143
 144   /* (d=) The domain as given in the signature */
 145   uschar *domain;
 146
 147   /* (i=) The identity as given in the signature */
 148   uschar *identity;
 149
 150   /* (t=) Timestamp of signature creation */
 151   unsigned long created;
 152
 153   /* (x=) Timestamp of expiry of signature */
 154   unsigned long expires;
 155
 156   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 157      is -1. Note: a value of 0 means that the body is unsigned! */
 158   long bodylength;
 159
 160   /* (h=) Colon-separated list of header names that are included in the
 161      signature */
 162   uschar *headernames;
 163
 164   /* (z=) */
 165   uschar *copiedheaders;
 166
 167   /* (b=) Raw signature data, along with its length in bytes */
 168   blob sighash;
 169
 170   /* (bh=) Raw body hash data, along with its length in bytes */
 171   blob bodyhash;
 172
 173   /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
 174      Ready for insertion into the message. Note: Folded using CRLFTB,
 175      but final line terminator is NOT included. Note2: This buffer is
 176      free()d when you call pdkim_free_ctx(). */
 177   uschar *signature_header;
 178
 179   /* The main verification status. Verification only. One of:
 180
 181      PDKIM_VERIFY_NONE      Verification was not attempted. This status
 182                             should not appear.
 183
 184      PDKIM_VERIFY_INVALID   There was an error while trying to verify
 185                             the signature. A more precise description
 186                             is available in verify_ext_status.
 187
 188      PDKIM_VERIFY_FAIL      Verification failed because either the body
 189                             hash did not match, or the signature verification
 190                             failed. This means the message was modified.
 191                             Check verify_ext_status for the exact reason.
 192
 193      PDKIM_VERIFY_PASS      Verification succeeded.
 194   */
 195   int verify_status;
 196
 197   /* Extended verification status. Verification only. Depending on the value
 198      of verify_status, it can contain:
 199
 200      For verify_status == PDKIM_VERIFY_INVALID:
 201
 202         PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
 203           Unable to retrieve a public key container.
 204
 205         PDKIM_VERIFY_INVALID_BUFFER_SIZE
 206           Either the DNS name constructed to retrieve the public key record
 207           does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
 208           record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
 209
 210         PDKIM_VERIFY_INVALID_PUBKEY_PARSING
 211           (Syntax) error while parsing the retrieved public key record.
 212
 213
 214      For verify_status == PDKIM_VERIFY_FAIL:
 215
 216         PDKIM_VERIFY_FAIL_BODY
 217           The calculated body hash does not match the advertised body hash
 218           from the bh= tag of the signature.
 219
 220         PDKIM_VERIFY_FAIL_MESSAGE
 221           RSA verification of the signature (b= tag) failed.
 222   */
 223   int verify_ext_status;
 224
 225   /* Pointer to a public key record that was used to verify the signature.
 226      See pdkim_pubkey declaration above for more information.
 227      Caution: is NULL if signing or if no record was retrieved. */
 228   pdkim_pubkey *pubkey;
 229
 230   /* Pointer to the next pdkim_signature signature. NULL if signing or if
 231      this is the last signature. */
 232   void *next;
 233
 234   /* Properties below this point are used internally only ------------- */
 235
 236   /* Per-signature helper variables ----------------------------------- */
 237   hctx         body_hash_ctx;
 238
 239   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 240   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 241   /* Signing specific ------------------------------------------------- */
 242   uschar * rsa_privkey;     /* Private RSA key                             */
 243   uschar * sign_headers;    /* To-be-signed header names                   */
 244   uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 245 } pdkim_signature;
 246
 247
 248 /* -------------------------------------------------------------------------- */
 249 /* Context to keep state between all operations. */
 250 typedef struct pdkim_ctx {
 251
 252 #define PDKIM_MODE_SIGN   BIT(0)        /* if unset, mode==verify */
 253 #define PDKIM_DOT_TERM    BIT(1)        /* dot termination and unstuffing */
 254 #define PDKIM_SEEN_CR     BIT(2)
 255 #define PDKIM_SEEN_LF     BIT(3)
 256 #define PDKIM_PAST_HDRS   BIT(4)
 257 #define PDKIM_SEEN_EOD    BIT(5)
 258   unsigned   flags;
 259
 260   /* One (signing) or several chained (verification) signatures */
 261   pdkim_signature *sig;
 262
 263   /* Callback for dns/txt query method (verification only) */
 264   int(*dns_txt_callback)(char *, char *);
 265
 266   /* Coder's little helpers */
 267   uschar    *cur_header;
 268   int        cur_header_size;
 269   int        cur_header_len;
 270   char      *linebuf;
 271   int        linebuf_offset;
 272   int        num_buffered_crlf;
 273   int        num_headers;
 274   pdkim_stringlist *headers; /* Raw headers for verification         */
 275 } pdkim_ctx;
 276
 277
 278 /* -------------------------------------------------------------------------- */
 279 /* API functions. Please see the sample code in sample/test_sign.c and
 280    sample/test_verify.c for documentation.
 281 */
 282
 283 #ifdef __cplusplus
 284 extern "C" {
 285 #endif
 286
 287 void       pdkim_init         (void);
 288
 289 DLLEXPORT
 290 pdkim_ctx *pdkim_init_sign    (char *, char *, char *, int,
 291                               BOOL, int(*)(char *, char *), const uschar **);
 292
 293 DLLEXPORT
 294 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *), BOOL);
 295
 296 DLLEXPORT
 297 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 298                                long,
 299                                unsigned long,
 300                                unsigned long);
 301
 302 DLLEXPORT
 303 int        pdkim_feed         (pdkim_ctx *, uschar *, int);
 304 DLLEXPORT
 305 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **, const uschar **);
 306
 307 DLLEXPORT
 308 void       pdkim_free_ctx     (pdkim_ctx *);
 309
 310
 311 const uschar *  pdkim_errstr(int);
 312
 313 #ifdef __cplusplus
 314 }
 315 #endif
 316
 317 #endif