2 * PDKIM - a RFC4871 (DKIM) implementation
4 * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net>
5 * Copyright (C) 2016 Jeremy Harris <jgh@exim.org>
7 * http://duncanthrax.net/pdkim/
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.
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.
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.
27 #ifndef DISABLE_DKIM /* entire file */
30 # error Need SUPPORT_TLS for DKIM
33 #include "crypt_ver.h"
36 # include <openssl/rsa.h>
37 # include <openssl/ssl.h>
38 # include <openssl/err.h>
39 #elif defined(RSA_GNUTLS)
40 # include <gnutls/gnutls.h>
41 # include <gnutls/x509.h>
47 #define PDKIM_SIGNATURE_VERSION "1"
48 #define PDKIM_PUB_RECORD_VERSION US "DKIM1"
50 #define PDKIM_MAX_HEADER_LEN 65536
51 #define PDKIM_MAX_HEADERS 512
52 #define PDKIM_MAX_BODY_LINE_LEN 16384
53 #define PDKIM_DNS_TXT_MAX_NAMELEN 1024
54 #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
55 "Message-ID:To:Cc:MIME-Version:Content-Type:"\
56 "Content-Transfer-Encoding:Content-ID:"\
57 "Content-Description:Resent-Date:Resent-From:"\
58 "Resent-Sender:Resent-To:Resent-Cc:"\
59 "Resent-Message-ID:In-Reply-To:References:"\
60 "List-Id:List-Help:List-Unsubscribe:"\
61 "List-Subscribe:List-Post:List-Owner:List-Archive"
63 /* -------------------------------------------------------------------------- */
64 struct pdkim_stringlist {
70 /* -------------------------------------------------------------------------- */
71 /* A bunch of list constants */
72 const uschar * pdkim_querymethods[] = {
76 const uschar * pdkim_algos[] = {
81 const uschar * pdkim_canons[] = {
86 const uschar * pdkim_hashes[] = {
91 const uschar * pdkim_keytypes[] = {
96 typedef struct pdkim_combined_canon_entry {
100 } pdkim_combined_canon_entry;
102 pdkim_combined_canon_entry pdkim_combined_canons[] = {
103 { US"simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
104 { US"simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED },
105 { US"relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
106 { US"relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED },
107 { US"simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
108 { US"relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
113 /* -------------------------------------------------------------------------- */
116 pdkim_verify_status_str(int status)
120 case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE";
121 case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID";
122 case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL";
123 case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS";
124 default: return "PDKIM_VERIFY_UNKNOWN";
129 pdkim_verify_ext_status_str(int ext_status)
133 case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY";
134 case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE";
135 case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE";
136 case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE";
137 case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD";
138 case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT";
139 case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR";
140 case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION";
141 default: return "PDKIM_VERIFY_UNKNOWN";
146 pdkim_errstr(int status)
150 case PDKIM_OK: return "OK";
151 case PDKIM_FAIL: return "FAIL";
152 case PDKIM_ERR_RSA_PRIVKEY: return "RSA_PRIVKEY";
153 case PDKIM_ERR_RSA_SIGNING: return "RSA SIGNING";
154 case PDKIM_ERR_LONG_LINE: return "RSA_LONG_LINE";
155 case PDKIM_ERR_BUFFER_TOO_SMALL: return "BUFFER_TOO_SMALL";
156 case PDKIM_SIGN_PRIVKEY_WRAP: return "PRIVKEY_WRAP";
157 case PDKIM_SIGN_PRIVKEY_B64D: return "PRIVKEY_B64D";
158 default: return "(unknown)";
163 /* -------------------------------------------------------------------------- */
164 /* Print debugging functions */
166 pdkim_quoteprint(const uschar *data, int len)
169 for (i = 0; i < len; i++)
171 const int c = data[i];
174 case ' ' : debug_printf("{SP}"); break;
175 case '\t': debug_printf("{TB}"); break;
176 case '\r': debug_printf("{CR}"); break;
177 case '\n': debug_printf("{LF}"); break;
178 case '{' : debug_printf("{BO}"); break;
179 case '}' : debug_printf("{BC}"); break;
181 if ( (c < 32) || (c > 127) )
182 debug_printf("{%02x}", c);
184 debug_printf("%c", c);
192 pdkim_hexprint(const uschar *data, int len)
195 for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
201 static pdkim_stringlist *
202 pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
204 pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist));
206 memset(new_entry, 0, sizeof(pdkim_stringlist));
207 new_entry->value = string_copy(str);
208 if (base) new_entry->next = base;
214 /* Trim whitespace fore & aft */
217 pdkim_strtrim(uschar * str)
221 while (*p == '\t' || *p == ' ') p++; /* skip whitespace */
222 while (*p) {*q = *p; q++; p++;} /* dump the leading whitespace */
224 while (q != str && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) )
225 { /* dump trailing whitespace */
233 /* -------------------------------------------------------------------------- */
236 pdkim_free_ctx(pdkim_ctx *ctx)
241 /* -------------------------------------------------------------------------- */
242 /* Matches the name of the passed raw "header" against
243 the passed colon-separated "tick", and invalidates
244 the entry in tick. Returns OK or fail-code */
245 /*XXX might be safer done using a pdkim_stringlist for "tick" */
248 header_name_match(const uschar * header, uschar * tick)
254 uschar * hcolon = Ustrchr(header, ':'); /* Get header name */
257 return PDKIM_FAIL; /* This isn't a header */
259 /* if we had strncmpic() we wouldn't need this copy */
260 hname = string_copyn(header, hcolon-header);
262 /* Copy tick-off list locally, so we can punch zeroes into it */
263 p = lcopy = string_copy(tick);
265 for (q = Ustrchr(p, ':'); q; q = Ustrchr(p, ':'))
268 if (strcmpic(p, hname) == 0)
274 if (strcmpic(p, hname) == 0)
280 /* Invalidate header name instance in tick-off list */
286 /* -------------------------------------------------------------------------- */
287 /* Performs "relaxed" canonicalization of a header. */
290 pdkim_relax_header(const uschar * header, int crlf)
292 BOOL past_field_name = FALSE;
293 BOOL seen_wsp = FALSE;
295 uschar * relaxed = store_get(Ustrlen(header)+3);
296 uschar * q = relaxed;
298 for (p = header; *p; p++)
302 if (c == '\r' || c == '\n')
304 if (c == '\t' || c == ' ')
308 c = ' '; /* Turns WSP into SP */
312 if (!past_field_name && c == ':')
314 if (seen_wsp) q--; /* This removes WSP before the colon */
315 seen_wsp = TRUE; /* This removes WSP after the colon */
316 past_field_name = TRUE;
321 /* Lowercase header name */
322 if (!past_field_name) c = tolower(c);
326 if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */
328 if (crlf) { *q++ = '\r'; *q++ = '\n'; }
334 /* -------------------------------------------------------------------------- */
335 #define PDKIM_QP_ERROR_DECODE -1
338 pdkim_decode_qp_char(uschar *qp_p, int *c)
340 uschar *initial_pos = qp_p;
342 /* Advance one char */
345 /* Check for two hex digits and decode them */
346 if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
348 /* Do hex conversion */
349 *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) << 4;
350 *c |= isdigit(qp_p[1]) ? qp_p[1] - '0' : toupper(qp_p[1]) - 'A' + 10;
354 /* Illegal char here */
355 *c = PDKIM_QP_ERROR_DECODE;
360 /* -------------------------------------------------------------------------- */
363 pdkim_decode_qp(uschar * str)
368 uschar * n = store_get(Ustrlen(str)+1);
376 p = pdkim_decode_qp_char(p, &nchar);
392 /* -------------------------------------------------------------------------- */
395 pdkim_decode_base64(uschar *str, blob * b)
398 dlen = b64decode(str, &b->data);
399 if (dlen < 0) b->data = NULL;
404 pdkim_encode_base64(blob * b)
406 return b64encode(b->data, b->len);
410 /* -------------------------------------------------------------------------- */
411 #define PDKIM_HDR_LIMBO 0
412 #define PDKIM_HDR_TAG 1
413 #define PDKIM_HDR_VALUE 2
415 static pdkim_signature *
416 pdkim_parse_sig_header(pdkim_ctx *ctx, uschar * raw_hdr)
418 pdkim_signature *sig ;
420 uschar * cur_tag = NULL; int ts = 0, tl = 0;
421 uschar * cur_val = NULL; int vs = 0, vl = 0;
422 BOOL past_hname = FALSE;
423 BOOL in_b_val = FALSE;
424 int where = PDKIM_HDR_LIMBO;
427 sig = store_get(sizeof(pdkim_signature));
428 memset(sig, 0, sizeof(pdkim_signature));
429 sig->bodylength = -1;
431 /* Set so invalid/missing data error display is accurate */
435 q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1);
437 for (p = raw_hdr; ; p++)
442 if (c == '\r' || c == '\n')
445 /* Fast-forward through header name */
448 if (c == ':') past_hname = TRUE;
452 if (where == PDKIM_HDR_LIMBO)
454 /* In limbo, just wait for a tag-char to appear */
455 if (!(c >= 'a' && c <= 'z'))
458 where = PDKIM_HDR_TAG;
461 if (where == PDKIM_HDR_TAG)
463 if (c >= 'a' && c <= 'z')
464 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
469 if (Ustrcmp(cur_tag, "b") == 0)
474 where = PDKIM_HDR_VALUE;
479 if (where == PDKIM_HDR_VALUE)
481 if (c == '\r' || c == '\n' || c == ' ' || c == '\t')
484 if (c == ';' || c == '\0')
489 pdkim_strtrim(cur_val);
491 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
496 if (cur_tag[1] == 'h')
497 pdkim_decode_base64(cur_val, &sig->bodyhash);
499 pdkim_decode_base64(cur_val, &sig->sigdata);
502 /* We only support version 1, and that is currently the
503 only version there is. */
505 Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
508 for (i = 0; pdkim_algos[i]; i++)
509 if (Ustrcmp(cur_val, pdkim_algos[i]) == 0)
516 for (i = 0; pdkim_combined_canons[i].str; i++)
517 if (Ustrcmp(cur_val, pdkim_combined_canons[i].str) == 0)
519 sig->canon_headers = pdkim_combined_canons[i].canon_headers;
520 sig->canon_body = pdkim_combined_canons[i].canon_body;
525 for (i = 0; pdkim_querymethods[i]; i++)
526 if (Ustrcmp(cur_val, pdkim_querymethods[i]) == 0)
528 sig->querymethod = i;
533 sig->selector = string_copy(cur_val); break;
535 sig->domain = string_copy(cur_val); break;
537 sig->identity = pdkim_decode_qp(cur_val); break;
539 sig->created = strtoul(CS cur_val, NULL, 10); break;
541 sig->expires = strtoul(CS cur_val, NULL, 10); break;
543 sig->bodylength = strtol(CS cur_val, NULL, 10); break;
545 sig->headernames = string_copy(cur_val); break;
547 sig->copiedheaders = pdkim_decode_qp(cur_val); break;
549 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
556 where = PDKIM_HDR_LIMBO;
559 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
571 /* Chomp raw header. The final newline must not be added to the signature. */
572 while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n'))
578 "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
579 pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val));
581 "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sigdata.len*8);
583 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
586 exim_sha_init(&sig->body_hash, sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
591 /* -------------------------------------------------------------------------- */
593 static pdkim_pubkey *
594 pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record)
598 uschar * cur_tag = NULL; int ts = 0, tl = 0;
599 uschar * cur_val = NULL; int vs = 0, vl = 0;
600 int where = PDKIM_HDR_LIMBO;
602 pub = store_get(sizeof(pdkim_pubkey));
603 memset(pub, 0, sizeof(pdkim_pubkey));
605 for (p = raw_record; ; p++)
610 if (c == '\r' || c == '\n')
613 if (where == PDKIM_HDR_LIMBO)
615 /* In limbo, just wait for a tag-char to appear */
616 if (!(c >= 'a' && c <= 'z'))
619 where = PDKIM_HDR_TAG;
622 if (where == PDKIM_HDR_TAG)
624 if (c >= 'a' && c <= 'z')
625 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
630 where = PDKIM_HDR_VALUE;
635 if (where == PDKIM_HDR_VALUE)
637 if (c == ';' || c == '\0')
642 pdkim_strtrim(cur_val);
643 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
648 /* This tag isn't evaluated because:
649 - We only support version DKIM1.
650 - Which is the default for this value (set below)
651 - Other versions are currently not specified. */
655 pub->hashes = string_copy(cur_val); break;
657 pub->granularity = string_copy(cur_val); break;
659 pub->notes = pdkim_decode_qp(cur_val); break;
661 pdkim_decode_base64(US cur_val, &pub->key);
664 pub->srvtype = string_copy(cur_val); break;
666 if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1;
667 if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1;
670 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
676 where = PDKIM_HDR_LIMBO;
679 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
683 if (c == '\0') break;
686 /* Set fallback defaults */
687 if (!pub->version ) pub->version = string_copy(PDKIM_PUB_RECORD_VERSION);
688 if (!pub->granularity) pub->granularity = string_copy(US"*");
689 if (!pub->keytype ) pub->keytype = string_copy(US"rsa");
690 if (!pub->srvtype ) pub->srvtype = string_copy(US"*");
700 /* -------------------------------------------------------------------------- */
703 pdkim_update_bodyhash(pdkim_ctx *ctx, const char *data, int len)
705 pdkim_signature *sig = ctx->sig;
706 /* Cache relaxed version of data */
707 uschar *relaxed_data = NULL;
710 /* Traverse all signatures, updating their hashes. */
713 /* Defaults to simple canon (no further treatment necessary) */
714 const uschar *canon_data = CUS data;
717 if (sig->canon_body == PDKIM_CANON_RELAXED)
719 /* Relax the line if not done already */
722 BOOL seen_wsp = FALSE;
726 relaxed_data = store_get(len+1);
728 for (p = data; *p; p++)
733 if (q > 0 && relaxed_data[q-1] == ' ')
736 else if (c == '\t' || c == ' ')
738 c = ' '; /* Turns WSP into SP */
745 relaxed_data[q++] = c;
747 relaxed_data[q] = '\0';
750 canon_data = relaxed_data;
751 canon_len = relaxed_len;
754 /* Make sure we don't exceed the to-be-signed body length */
755 if ( sig->bodylength >= 0
756 && sig->signed_body_bytes + (unsigned long)canon_len > sig->bodylength
758 canon_len = sig->bodylength - sig->signed_body_bytes;
762 exim_sha_update(&sig->body_hash, CUS canon_data, canon_len);
763 sig->signed_body_bytes += canon_len;
764 DEBUG(D_acl) pdkim_quoteprint(canon_data, canon_len);
770 if (relaxed_data) store_reset(relaxed_data);
775 /* -------------------------------------------------------------------------- */
778 pdkim_finish_bodyhash(pdkim_ctx *ctx)
780 pdkim_signature *sig;
782 /* Traverse all signatures */
783 for (sig = ctx->sig; sig; sig = sig->next)
784 { /* Finish hashes */
787 exim_sha_finish(&sig->body_hash, &bh);
791 debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
792 "PDKIM [%s] bh computed: ",
793 sig->domain, sig->signed_body_bytes, sig->domain);
794 pdkim_hexprint(CUS bh.data, bh.len);
797 /* SIGNING -------------------------------------------------------------- */
798 if (ctx->mode == PDKIM_MODE_SIGN)
802 /* If bodylength limit is set, and we have received less bytes
803 than the requested amount, effectively remove the limit tag. */
804 if (sig->signed_body_bytes < sig->bodylength)
805 sig->bodylength = -1;
808 /* VERIFICATION --------------------------------------------------------- */
811 /* Compare bodyhash */
812 if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
814 DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
820 debug_printf("PDKIM [%s] bh signature: ", sig->domain);
821 pdkim_hexprint(sig->bodyhash.data,
822 exim_sha_hashlen(&sig->body_hash));
823 debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
825 sig->verify_status = PDKIM_VERIFY_FAIL;
826 sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
834 /* -------------------------------------------------------------------------- */
835 /* Callback from pdkim_feed below for processing complete body lines */
838 pdkim_bodyline_complete(pdkim_ctx *ctx)
840 char *p = ctx->linebuf;
841 int n = ctx->linebuf_offset;
842 pdkim_signature *sig = ctx->sig; /*XXX assumes only one sig */
844 /* Ignore extra data if we've seen the end-of-data marker */
845 if (ctx->seen_eod) goto BAIL;
847 /* We've always got one extra byte to stuff a zero ... */
848 ctx->linebuf[ctx->linebuf_offset] = '\0';
850 /* Terminate on EOD marker */
851 if (memcmp(p, ".\r\n", 3) == 0)
853 /* In simple body mode, if any empty lines were buffered,
854 replace with one. rfc 4871 3.4.3 */
855 /*XXX checking the signed-body-bytes is a gross hack; I think
856 it indicates that all linebreaks should be buffered, including
857 the one terminating a text line */
858 if ( sig && sig->canon_body == PDKIM_CANON_SIMPLE
859 && sig->signed_body_bytes == 0
860 && ctx->num_buffered_crlf > 0
862 pdkim_update_bodyhash(ctx, "\r\n", 2);
864 ctx->seen_eod = TRUE;
868 if (memcmp(p, "..", 2) == 0)
874 /* Empty lines need to be buffered until we find a non-empty line */
875 if (memcmp(p, "\r\n", 2) == 0)
877 ctx->num_buffered_crlf++;
881 if (sig && sig->canon_body == PDKIM_CANON_RELAXED)
883 /* Lines with just spaces need to be buffered too */
885 while (memcmp(check, "\r\n", 2) != 0)
889 if (c != '\t' && c != ' ')
894 ctx->num_buffered_crlf++;
899 /* At this point, we have a non-empty line, so release the buffered ones. */
900 while (ctx->num_buffered_crlf)
902 pdkim_update_bodyhash(ctx, "\r\n", 2);
903 ctx->num_buffered_crlf--;
906 pdkim_update_bodyhash(ctx, p, n);
909 ctx->linebuf_offset = 0;
914 /* -------------------------------------------------------------------------- */
915 /* Callback from pdkim_feed below for processing complete headers */
916 #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
919 pdkim_header_complete(pdkim_ctx *ctx)
921 /* Special case: The last header can have an extra \r appended */
922 if ( (ctx->cur_header_len > 1) &&
923 (ctx->cur_header[(ctx->cur_header_len)-1] == '\r') )
924 --ctx->cur_header_len;
925 ctx->cur_header[ctx->cur_header_len] = '\0';
928 if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
930 /* SIGNING -------------------------------------------------------------- */
931 if (ctx->mode == PDKIM_MODE_SIGN)
933 pdkim_signature *sig;
935 for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */
937 /* Add header to the signed headers list (in reverse order) */
938 sig->headers = pdkim_prepend_stringlist(sig->headers,
942 /* VERIFICATION ----------------------------------------------------------- */
943 /* DKIM-Signature: headers are added to the verification list */
944 if (ctx->mode == PDKIM_MODE_VERIFY)
946 if (strncasecmp(CCS ctx->cur_header,
947 DKIM_SIGNATURE_HEADERNAME,
948 Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
950 pdkim_signature *new_sig;
952 /* Create and chain new signature block */
953 DEBUG(D_acl) debug_printf(
954 "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
956 if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header)))
958 pdkim_signature *last_sig = ctx->sig;
963 while (last_sig->next) last_sig = last_sig->next;
964 last_sig->next = new_sig;
968 DEBUG(D_acl) debug_printf(
969 "Error while parsing signature header\n"
970 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
973 /* every other header is stored for signature verification */
975 ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
979 *ctx->cur_header = '\0';
980 ctx->cur_header_len = 0; /* leave buffer for reuse */
986 /* -------------------------------------------------------------------------- */
987 #define HEADER_BUFFER_FRAG_SIZE 256
990 pdkim_feed(pdkim_ctx *ctx, char *data, int len)
994 for (p = 0; p<len; p++)
998 if (ctx->past_headers)
1000 /* Processing body byte */
1001 ctx->linebuf[ctx->linebuf_offset++] = c;
1004 int rc = pdkim_bodyline_complete(ctx); /* End of line */
1005 if (rc != PDKIM_OK) return rc;
1007 if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1))
1008 return PDKIM_ERR_LONG_LINE;
1012 /* Processing header byte */
1019 int rc = pdkim_header_complete(ctx); /* Seen last header line */
1020 if (rc != PDKIM_OK) return rc;
1022 ctx->past_headers = TRUE;
1024 DEBUG(D_acl) debug_printf(
1025 "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>\n");
1029 ctx->seen_lf = TRUE;
1031 else if (ctx->seen_lf)
1033 if (!(c == '\t' || c == ' '))
1035 int rc = pdkim_header_complete(ctx); /* End of header */
1036 if (rc != PDKIM_OK) return rc;
1038 ctx->seen_lf = FALSE;
1042 if (ctx->cur_header_len < PDKIM_MAX_HEADER_LEN)
1043 ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size,
1044 &ctx->cur_header_len, CUS &data[p], 1);
1052 /* Extend a grwong header with a continuation-linebreak */
1054 pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col)
1057 return string_catn(str, size, ptr, US"\r\n\t", 3);
1063 * RFC 5322 specifies that header line length SHOULD be no more than 78
1067 * returns uschar * (not nul-terminated)
1069 * col: this int holds and receives column number (octets since last '\n')
1070 * str: partial string to append to
1071 * size: current buffer size for str
1072 * ptr: current tail-pointer for str
1073 * pad: padding, split line or space after before or after eg: ";"
1074 * intro: - must join to payload eg "h=", usually the tag name
1075 * payload: eg base64 data - long data can be split arbitrarily.
1077 * this code doesn't fold the header in some of the places that RFC4871
1078 * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
1079 * pairs and inside long values. it also always spaces or breaks after the
1082 * no guarantees are made for output given out-of range input. like tag
1083 * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
1087 pdkim_headcat(int * col, uschar * str, int * size, int * ptr,
1088 const uschar * pad, const uschar * intro, const uschar * payload)
1096 str = pdkim_hdr_cont(str, size, ptr, col);
1097 str = string_catn(str, size, ptr, pad, l);
1101 l = (pad?1:0) + (intro?Ustrlen(intro):0);
1104 { /*can't fit intro - start a new line to make room.*/
1105 str = pdkim_hdr_cont(str, size, ptr, col);
1106 l = intro?Ustrlen(intro):0;
1109 l += payload ? Ustrlen(payload):0 ;
1112 { /* this fragment will not fit on a single line */
1115 str = string_catn(str, size, ptr, US" ", 1);
1117 pad = NULL; /* only want this once */
1123 size_t sl = Ustrlen(intro);
1125 str = string_catn(str, size, ptr, intro, sl);
1128 intro = NULL; /* only want this once */
1133 size_t sl = Ustrlen(payload);
1134 size_t chomp = *col+sl < 77 ? sl : 78-*col;
1136 str = string_catn(str, size, ptr, payload, chomp);
1142 /* the while precondition tells us it didn't fit. */
1143 str = pdkim_hdr_cont(str, size, ptr, col);
1148 str = pdkim_hdr_cont(str, size, ptr, col);
1154 str = string_catn(str, size, ptr, US" ", 1);
1161 size_t sl = Ustrlen(intro);
1163 str = string_catn(str, size, ptr, intro, sl);
1171 size_t sl = Ustrlen(payload);
1173 str = string_catn(str, size, ptr, payload, sl);
1181 /* -------------------------------------------------------------------------- */
1184 pdkim_create_header(pdkim_signature *sig, BOOL final)
1189 uschar * hdr; int hdr_size = 0, hdr_len = 0;
1190 uschar * canon_all; int can_size = 0, can_len = 0;
1192 canon_all = string_cat (NULL, &can_size, &can_len,
1193 pdkim_canons[sig->canon_headers]);
1194 canon_all = string_catn(canon_all, &can_size, &can_len, US"/", 1);
1195 canon_all = string_cat (canon_all, &can_size, &can_len,
1196 pdkim_canons[sig->canon_body]);
1197 canon_all[can_len] = '\0';
1199 hdr = string_cat(NULL, &hdr_size, &hdr_len,
1200 US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
1203 /* Required and static bits */
1204 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=",
1205 pdkim_algos[sig->algo]);
1206 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=",
1207 pdkim_querymethods[sig->querymethod]);
1208 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"c=",
1210 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=",
1212 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
1215 /* list of header names can be split between items. */
1217 uschar * n = string_copy(sig->headernames);
1218 uschar * i = US"h=";
1223 uschar * c = Ustrchr(n, ':');
1228 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":");
1230 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n);
1241 base64_bh = pdkim_encode_base64(&sig->bodyhash);
1242 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh);
1246 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"i=", sig->identity);
1248 if (sig->created > 0)
1252 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
1253 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf);
1256 if (sig->expires > 0)
1260 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
1261 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf);
1264 if (sig->bodylength >= 0)
1268 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
1269 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf);
1272 /* Preliminary or final version? */
1273 base64_b = final ? pdkim_encode_base64(&sig->sigdata) : US"";
1274 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"b=", base64_b);
1276 /* add trailing semicolon: I'm not sure if this is actually needed */
1277 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, US";", US"");
1279 hdr[hdr_len] = '\0';
1284 /* -------------------------------------------------------------------------- */
1287 pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures)
1289 pdkim_signature *sig = ctx->sig;
1290 uschar * headernames = NULL; /* Collected signed header names */
1293 /* Check if we must still flush a (partial) header. If that is the
1294 case, the message has no body, and we must compute a body hash
1295 out of '<CR><LF>' */
1296 if (ctx->cur_header && ctx->cur_header_len)
1298 int rc = pdkim_header_complete(ctx);
1299 if (rc != PDKIM_OK) return rc;
1300 pdkim_update_bodyhash(ctx, "\r\n", 2);
1303 DEBUG(D_acl) debug_printf(
1304 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1306 /* Build (and/or evaluate) body hash */
1307 pdkim_finish_bodyhash(ctx);
1311 BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1;
1316 int hdata_alloc = 0;
1321 exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256);
1323 DEBUG(D_acl) debug_printf(
1324 "PDKIM >> Hashed header data, canonicalized, in sequence >>>>>>>>>>>>>>\n");
1326 /* SIGNING ---------------------------------------------------------------- */
1327 /* When signing, walk through our header list and add them to the hash. As we
1328 go, construct a list of the header's names to use for the h= parameter.
1329 Then append to that list any remaining header names for which there was no
1332 if (ctx->mode == PDKIM_MODE_SIGN)
1334 pdkim_stringlist *p;
1339 for (p = sig->headers; p; p = p->next)
1340 if (header_name_match(p->value, sig->sign_headers) == PDKIM_OK)
1343 /* Collect header names (Note: colon presence is guaranteed here) */
1344 uschar * q = Ustrchr(p->value, ':');
1346 headernames = string_catn(headernames, &hs, &hl,
1347 p->value, (q - US p->value) + (p->next ? 1 : 0));
1349 rh = sig->canon_headers == PDKIM_CANON_RELAXED
1350 ? pdkim_relax_header(p->value, 1) /* cook header for relaxed canon */
1351 : string_copy(CUS p->value); /* just copy it for simple canon */
1353 /* Feed header to the hash algorithm */
1354 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1356 /* Remember headers block for signing (when the library cannot do incremental) */
1357 (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh);
1359 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1362 l = sig->sign_headers;
1363 while((s = string_nextinlist(&l, &sep, NULL, 0)))
1365 { /*SSS string_append_listele() */
1366 if (hl > 0 && headernames[hl-1] != ':')
1367 headernames = string_catn(headernames, &hs, &hl, US":", 1);
1369 headernames = string_cat(headernames, &hs, &hl, s);
1371 headernames[hl] = '\0';
1373 /* Copy headernames to signature struct */
1374 sig->headernames = headernames;
1375 headernames = NULL, hs = hl = 0;
1377 /* Create signature header with b= omitted */
1378 sig_hdr = pdkim_create_header(sig, FALSE);
1381 /* VERIFICATION ----------------------------------------------------------- */
1382 /* When verifying, walk through the header name list in the h= parameter and
1383 add the headers to the hash in that order. */
1386 uschar * b = string_copy(sig->headernames);
1389 pdkim_stringlist * hdrs;
1392 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1397 if ((q = Ustrchr(p, ':')))
1400 /*XXX walk the list of headers in same order as received. */
1401 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1403 && strncasecmp(hdrs->value, CS p, Ustrlen(p)) == 0
1404 && (hdrs->value)[Ustrlen(p)] == ':'
1407 uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
1408 ? pdkim_relax_header(hdrs->value, 1) /* cook header for relaxed canon */
1409 : string_copy(CUS hdrs->value); /* just copy it for simple canon */
1411 /* Feed header to the hash algorithm */
1412 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1414 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1423 sig_hdr = string_copy(sig->rawsig_no_b_val);
1426 DEBUG(D_acl) debug_printf(
1427 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1429 /* Relax header if necessary */
1430 if (sig->canon_headers == PDKIM_CANON_RELAXED)
1431 sig_hdr = pdkim_relax_header(sig_hdr, 0);
1436 "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
1437 pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
1439 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1442 /* Finalize header hash */
1443 exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
1444 exim_sha_finish(&hhash_ctx, &hhash);
1448 debug_printf("PDKIM [%s] hh computed: ", sig->domain);
1449 pdkim_hexprint(hhash.data, hhash.len);
1452 /* Remember headers block for signing (when the library cannot do incremental) */
1453 if (ctx->mode == PDKIM_MODE_SIGN)
1454 (void) exim_rsa_data_append(&hdata, &hdata_alloc, US sig_hdr);
1456 /* SIGNING ---------------------------------------------------------------- */
1457 if (ctx->mode == PDKIM_MODE_SIGN)
1460 const uschar * errstr;
1462 /* Import private key */
1463 if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
1465 DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr);
1466 return PDKIM_ERR_RSA_PRIVKEY;
1469 /* Do signing. With OpenSSL we are signing the hash of headers just
1470 calculated, with GnuTLS we have to sign an entire block of headers
1471 (due to available interfaces) and it recalculates the hash internally. */
1473 #if defined(RSA_OPENSSL) || defined(RSA_GCRYPT)
1477 if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata)))
1479 DEBUG(D_acl) debug_printf("signing: %s\n", errstr);
1480 return PDKIM_ERR_RSA_SIGNING;
1485 debug_printf( "PDKIM [%s] b computed: ", sig->domain);
1486 pdkim_hexprint(sig->sigdata.data, sig->sigdata.len);
1489 sig->signature_header = pdkim_create_header(sig, TRUE);
1492 /* VERIFICATION ----------------------------------------------------------- */
1496 const uschar * errstr;
1498 uschar *dns_txt_name, *dns_txt_reply;
1500 /* Make sure we have all required signature tags */
1501 if (!( sig->domain && *sig->domain
1502 && sig->selector && *sig->selector
1503 && sig->headernames && *sig->headernames
1504 && sig->bodyhash.data
1505 && sig->sigdata.data
1510 sig->verify_status = PDKIM_VERIFY_INVALID;
1511 sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
1513 DEBUG(D_acl) debug_printf(
1514 " Error in DKIM-Signature header: tags missing or invalid\n"
1515 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1519 /* Make sure sig uses supported DKIM version (only v1) */
1520 if (sig->version != 1)
1522 sig->verify_status = PDKIM_VERIFY_INVALID;
1523 sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
1525 DEBUG(D_acl) debug_printf(
1526 " Error in DKIM-Signature header: unsupported DKIM version\n"
1527 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1531 /* Fetch public key for signing domain, from DNS */
1533 dns_txt_name = string_sprintf("%s._domainkey.%s.",
1534 sig->selector, sig->domain);
1536 dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN);
1537 memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN);
1539 if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK
1540 || dns_txt_reply[0] == '\0')
1542 sig->verify_status = PDKIM_VERIFY_INVALID;
1543 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
1550 "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
1552 pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
1555 if (!(sig->pubkey = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)))
1557 sig->verify_status = PDKIM_VERIFY_INVALID;
1558 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
1560 DEBUG(D_acl) debug_printf(
1561 " Error while parsing public key record\n"
1562 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1566 DEBUG(D_acl) debug_printf(
1567 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1569 /* Import public key */
1570 if ((errstr = exim_rsa_verify_init(&sig->pubkey->key, &vctx)))
1572 DEBUG(D_acl) debug_printf("verify_init: %s\n", errstr);
1573 sig->verify_status = PDKIM_VERIFY_INVALID;
1574 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
1578 /* Check the signature */
1579 if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata)))
1581 DEBUG(D_acl) debug_printf("headers verify: %s\n", errstr);
1582 sig->verify_status = PDKIM_VERIFY_FAIL;
1583 sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE;
1588 /* We have a winner! (if bodydhash was correct earlier) */
1589 if (sig->verify_status == PDKIM_VERIFY_NONE)
1590 sig->verify_status = PDKIM_VERIFY_PASS;
1596 debug_printf("PDKIM [%s] signature status: %s",
1597 sig->domain, pdkim_verify_status_str(sig->verify_status));
1598 if (sig->verify_ext_status > 0)
1599 debug_printf(" (%s)\n",
1600 pdkim_verify_ext_status_str(sig->verify_ext_status));
1609 /* If requested, set return pointer to signature(s) */
1610 if (return_signatures)
1611 *return_signatures = ctx->sig;
1617 /* -------------------------------------------------------------------------- */
1619 DLLEXPORT pdkim_ctx *
1620 pdkim_init_verify(int(*dns_txt_callback)(char *, char *))
1624 ctx = store_get(sizeof(pdkim_ctx));
1625 memset(ctx, 0, sizeof(pdkim_ctx));
1627 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1628 ctx->mode = PDKIM_MODE_VERIFY;
1629 ctx->dns_txt_callback = dns_txt_callback;
1635 /* -------------------------------------------------------------------------- */
1637 DLLEXPORT pdkim_ctx *
1638 pdkim_init_sign(char *domain, char *selector, char *rsa_privkey, int algo)
1641 pdkim_signature *sig;
1643 if (!domain || !selector || !rsa_privkey)
1646 ctx = store_get(sizeof(pdkim_ctx));
1647 memset(ctx, 0, sizeof(pdkim_ctx));
1649 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1651 sig = store_get(sizeof(pdkim_signature));
1652 memset(sig, 0, sizeof(pdkim_signature));
1654 sig->bodylength = -1;
1656 ctx->mode = PDKIM_MODE_SIGN;
1659 sig->domain = string_copy(US domain);
1660 sig->selector = string_copy(US selector);
1661 sig->rsa_privkey = string_copy(US rsa_privkey);
1664 exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
1669 /* -------------------------------------------------------------------------- */
1672 pdkim_set_optional(pdkim_ctx *ctx,
1678 unsigned long created,
1679 unsigned long expires)
1681 pdkim_signature * sig = ctx->sig;
1684 sig->identity = string_copy(US identity);
1686 sig->sign_headers = string_copy(sign_headers
1687 ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
1689 sig->canon_headers = canon_headers;
1690 sig->canon_body = canon_body;
1691 sig->bodylength = bodylength;
1692 sig->created = created;
1693 sig->expires = expires;
1707 #endif /*DISABLE_DKIM*/