/* * PDKIM - a RFC4871 (DKIM) implementation * * Copyright (C) 2009 - 2012 Tom Kistner * * http://duncanthrax.net/pdkim/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ /* -------------------------------------------------------------------------- */ /* Debugging. This can also be enabled/disabled at run-time. I recommend to leave it defined. */ #define PDKIM_DEBUG /* -------------------------------------------------------------------------- */ /* Length of the preallocated buffer for the "answer" from the dns/txt callback function. This should match the maximum RDLENGTH from DNS. */ #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16) /* -------------------------------------------------------------------------- */ /* Function success / error codes */ #define PDKIM_OK 0 #define PDKIM_FAIL -1 #define PDKIM_ERR_OOM -100 #define PDKIM_ERR_RSA_PRIVKEY -101 #define PDKIM_ERR_RSA_SIGNING -102 #define PDKIM_ERR_LONG_LINE -103 #define PDKIM_ERR_BUFFER_TOO_SMALL -104 /* -------------------------------------------------------------------------- */ /* Main/Extended verification status */ #define PDKIM_VERIFY_NONE 0 #define PDKIM_VERIFY_INVALID 1 #define PDKIM_VERIFY_FAIL 2 #define PDKIM_VERIFY_PASS 3 #define PDKIM_VERIFY_FAIL_BODY 1 #define PDKIM_VERIFY_FAIL_MESSAGE 2 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 4 #define PDKIM_VERIFY_INVALID_PUBKEY_PARSING 5 /* -------------------------------------------------------------------------- */ /* Some parameter values */ #define PDKIM_QUERYMETHOD_DNS_TXT 0 #define PDKIM_ALGO_RSA_SHA256 0 #define PDKIM_ALGO_RSA_SHA1 1 #define PDKIM_CANON_SIMPLE 0 #define PDKIM_CANON_RELAXED 1 #define PDKIM_HASH_SHA256 0 #define PDKIM_HASH_SHA1 1 #define PDKIM_KEYTYPE_RSA 0 /* -------------------------------------------------------------------------- */ /* Some required forward declarations, please ignore */ typedef struct pdkim_stringlist pdkim_stringlist; typedef struct pdkim_str pdkim_str; typedef struct sha1_context sha1_context; typedef struct sha2_context sha2_context; #define HAVE_SHA1_CONTEXT #define HAVE_SHA2_CONTEXT /* -------------------------------------------------------------------------- */ /* Some concessions towards Redmond */ #ifdef WINDOWS #define snprintf _snprintf #define strcasecmp _stricmp #define strncasecmp _strnicmp #define DLLEXPORT __declspec(dllexport) #else #define DLLEXPORT #endif /* -------------------------------------------------------------------------- */ /* Public key as (usually) fetched from DNS */ typedef struct pdkim_pubkey { char *version; /* v= */ char *granularity; /* g= */ char *hashes; /* h= */ char *keytype; /* k= */ char *srvtype; /* s= */ char *notes; /* n= */ char *key; /* p= */ int key_len; int testing; /* t=y */ int no_subdomaining; /* t=s */ } pdkim_pubkey; /* -------------------------------------------------------------------------- */ /* Signature as it appears in a DKIM-Signature header */ typedef struct pdkim_signature { /* Bits stored in a DKIM signature header --------------------------- */ /* (v=) The version, as an integer. Currently, always "1" */ int version; /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256 or PDKIM_ALGO_RSA_SHA1 */ int algo; /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE or PDKIM_CANON_RELAXED */ int canon_headers; /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE or PDKIM_CANON_RELAXED */ int canon_body; /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT is specified */ int querymethod; /* (s=) The selector string as given in the signature */ char *selector; /* (d=) The domain as given in the signature */ char *domain; /* (i=) The identity as given in the signature */ char *identity; /* (t=) Timestamp of signature creation */ unsigned long created; /* (x=) Timestamp of expiry of signature */ unsigned long expires; /* (l=) Amount of hashed body bytes (after canonicalization). Default is -1. Note: a value of 0 means that the body is unsigned! */ long bodylength; /* (h=) Colon-separated list of header names that are included in the signature */ char *headernames; /* (z=) */ char *copiedheaders; /* (b=) Raw signature data, along with its length in bytes */ char *sigdata; int sigdata_len; /* (bh=) Raw body hash data, along with its length in bytes */ char *bodyhash; int bodyhash_len; /* Folded DKIM-Signature: header. Singing only, NULL for verifying. Ready for insertion into the message. Note: Folded using CRLFTB, but final line terminator is NOT included. Note2: This buffer is free()d when you call pdkim_free_ctx(). */ char *signature_header; /* The main verification status. Verification only. One of: PDKIM_VERIFY_NONE Verification was not attempted. This status should not appear. PDKIM_VERIFY_INVALID There was an error while trying to verify the signature. A more precise description is available in verify_ext_status. PDKIM_VERIFY_FAIL Verification failed because either the body hash did not match, or the signature verification failed. This means the message was modified. Check verify_ext_status for the exact reason. PDKIM_VERIFY_PASS Verification succeeded. */ int verify_status; /* Extended verification status. Verification only. Depending on the value of verify_status, it can contain: For verify_status == PDKIM_VERIFY_INVALID: PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE Unable to retrieve a public key container. PDKIM_VERIFY_INVALID_BUFFER_SIZE Either the DNS name constructed to retrieve the public key record does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes. PDKIM_VERIFY_INVALID_PUBKEY_PARSING (Syntax) error while parsing the retrieved public key record. For verify_status == PDKIM_VERIFY_FAIL: PDKIM_VERIFY_FAIL_BODY The calculated body hash does not match the advertised body hash from the bh= tag of the signature. PDKIM_VERIFY_FAIL_MESSAGE RSA verification of the signature (b= tag) failed. */ int verify_ext_status; /* Pointer to a public key record that was used to verify the signature. See pdkim_pubkey declaration above for more information. Caution: is NULL if signing or if no record was retrieved. */ pdkim_pubkey *pubkey; /* Pointer to the next pdkim_signature signature. NULL if signing or if this is the last signature. */ void *next; /* Properties below this point are used internally only ------------- */ /* Per-signature helper variables ----------------------------------- */ sha1_context *sha1_body; /* SHA1 block */ sha2_context *sha2_body; /* SHA256 block */ unsigned long signed_body_bytes; /* How many body bytes we hashed */ pdkim_stringlist *headers; /* Raw headers included in the sig */ /* Signing specific ------------------------------------------------- */ char *rsa_privkey; /* Private RSA key */ char *sign_headers; /* To-be-signed header names */ char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */ } pdkim_signature; /* -------------------------------------------------------------------------- */ /* Context to keep state between all operations. */ #define PDKIM_MODE_SIGN 0 #define PDKIM_MODE_VERIFY 1 #define PDKIM_INPUT_NORMAL 0 #define PDKIM_INPUT_SMTP 1 typedef struct pdkim_ctx { /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */ int mode; /* PDKIM_INPUT_SMTP or PDKIM_INPUT_NORMAL */ int input_mode; /* One (signing) or several chained (verification) signatures */ pdkim_signature *sig; /* Callback for dns/txt query method (verification only) */ int(*dns_txt_callback)(char *, char *); /* Coder's little helpers */ pdkim_str *cur_header; char *linebuf; int linebuf_offset; int seen_lf; int seen_eod; int past_headers; int num_buffered_crlf; int num_headers; pdkim_stringlist *headers; /* Raw headers for verification */ #ifdef PDKIM_DEBUG /* A FILE pointer. When not NULL, debug output will be generated and sent to this stream */ FILE *debug_stream; #endif } pdkim_ctx; /* -------------------------------------------------------------------------- */ /* API functions. Please see the sample code in sample/test_sign.c and sample/test_verify.c for documentation. */ #ifdef __cplusplus extern "C" { #endif DLLEXPORT pdkim_ctx *pdkim_init_sign (int, char *, char *, char *); DLLEXPORT pdkim_ctx *pdkim_init_verify (int, int(*)(char *, char *)); DLLEXPORT int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int, long, int, unsigned long, unsigned long); DLLEXPORT int pdkim_feed (pdkim_ctx *, char *, int); DLLEXPORT int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **); DLLEXPORT void pdkim_free_ctx (pdkim_ctx *); #ifdef PDKIM_DEBUG DLLEXPORT void pdkim_set_debug_stream(pdkim_ctx *, FILE *); #endif #ifdef __cplusplus } #endif