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);
774 /* -------------------------------------------------------------------------- */
777 pdkim_finish_bodyhash(pdkim_ctx *ctx)
779 pdkim_signature *sig;
781 /* Traverse all signatures */
782 for (sig = ctx->sig; sig; sig = sig->next)
783 { /* Finish hashes */
786 exim_sha_finish(&sig->body_hash, &bh);
790 debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
791 "PDKIM [%s] bh computed: ",
792 sig->domain, sig->signed_body_bytes, sig->domain);
793 pdkim_hexprint(CUS bh.data, bh.len);
796 /* SIGNING -------------------------------------------------------------- */
797 if (ctx->mode == PDKIM_MODE_SIGN)
801 /* If bodylength limit is set, and we have received less bytes
802 than the requested amount, effectively remove the limit tag. */
803 if (sig->signed_body_bytes < sig->bodylength)
804 sig->bodylength = -1;
807 /* VERIFICATION --------------------------------------------------------- */
810 /* Compare bodyhash */
811 if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
813 DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
819 debug_printf("PDKIM [%s] bh signature: ", sig->domain);
820 pdkim_hexprint(sig->bodyhash.data,
821 exim_sha_hashlen(&sig->body_hash));
822 debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
824 sig->verify_status = PDKIM_VERIFY_FAIL;
825 sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
833 /* -------------------------------------------------------------------------- */
834 /* Callback from pdkim_feed below for processing complete body lines */
837 pdkim_bodyline_complete(pdkim_ctx *ctx)
839 char *p = ctx->linebuf;
840 int n = ctx->linebuf_offset;
841 pdkim_signature *sig = ctx->sig; /*XXX assumes only one sig */
843 /* Ignore extra data if we've seen the end-of-data marker */
844 if (ctx->seen_eod) goto BAIL;
846 /* We've always got one extra byte to stuff a zero ... */
847 ctx->linebuf[ctx->linebuf_offset] = '\0';
849 /* Terminate on EOD marker */
850 if (memcmp(p, ".\r\n", 3) == 0)
852 /* In simple body mode, if any empty lines were buffered,
853 replace with one. rfc 4871 3.4.3 */
854 /*XXX checking the signed-body-bytes is a gross hack; I think
855 it indicates that all linebreaks should be buffered, including
856 the one terminating a text line */
857 if ( sig && sig->canon_body == PDKIM_CANON_SIMPLE
858 && sig->signed_body_bytes == 0
859 && ctx->num_buffered_crlf > 0
861 pdkim_update_bodyhash(ctx, "\r\n", 2);
863 ctx->seen_eod = TRUE;
867 if (memcmp(p, "..", 2) == 0)
873 /* Empty lines need to be buffered until we find a non-empty line */
874 if (memcmp(p, "\r\n", 2) == 0)
876 ctx->num_buffered_crlf++;
880 if (sig && sig->canon_body == PDKIM_CANON_RELAXED)
882 /* Lines with just spaces need to be buffered too */
884 while (memcmp(check, "\r\n", 2) != 0)
888 if (c != '\t' && c != ' ')
893 ctx->num_buffered_crlf++;
898 /* At this point, we have a non-empty line, so release the buffered ones. */
899 while (ctx->num_buffered_crlf)
901 pdkim_update_bodyhash(ctx, "\r\n", 2);
902 ctx->num_buffered_crlf--;
905 pdkim_update_bodyhash(ctx, p, n);
908 ctx->linebuf_offset = 0;
913 /* -------------------------------------------------------------------------- */
914 /* Callback from pdkim_feed below for processing complete headers */
915 #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
918 pdkim_header_complete(pdkim_ctx *ctx)
920 /* Special case: The last header can have an extra \r appended */
921 if ( (ctx->cur_header_len > 1) &&
922 (ctx->cur_header[(ctx->cur_header_len)-1] == '\r') )
923 --ctx->cur_header_len;
924 ctx->cur_header[ctx->cur_header_len] = '\0';
927 if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
929 /* SIGNING -------------------------------------------------------------- */
930 if (ctx->mode == PDKIM_MODE_SIGN)
932 pdkim_signature *sig;
934 for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */
936 /* Add header to the signed headers list (in reverse order) */
937 sig->headers = pdkim_prepend_stringlist(sig->headers,
941 /* VERIFICATION ----------------------------------------------------------- */
942 /* DKIM-Signature: headers are added to the verification list */
943 if (ctx->mode == PDKIM_MODE_VERIFY)
945 if (strncasecmp(CCS ctx->cur_header,
946 DKIM_SIGNATURE_HEADERNAME,
947 Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
949 pdkim_signature *new_sig;
951 /* Create and chain new signature block */
952 DEBUG(D_acl) debug_printf(
953 "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
955 if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header)))
957 pdkim_signature *last_sig = ctx->sig;
962 while (last_sig->next) last_sig = last_sig->next;
963 last_sig->next = new_sig;
967 DEBUG(D_acl) debug_printf(
968 "Error while parsing signature header\n"
969 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
972 /* every other header is stored for signature verification */
974 ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
978 *ctx->cur_header = '\0';
979 ctx->cur_header_len = 0; /* leave buffer for reuse */
985 /* -------------------------------------------------------------------------- */
986 #define HEADER_BUFFER_FRAG_SIZE 256
989 pdkim_feed(pdkim_ctx *ctx, char *data, int len)
993 for (p = 0; p<len; p++)
997 if (ctx->past_headers)
999 /* Processing body byte */
1000 ctx->linebuf[ctx->linebuf_offset++] = c;
1003 int rc = pdkim_bodyline_complete(ctx); /* End of line */
1004 if (rc != PDKIM_OK) return rc;
1006 if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1))
1007 return PDKIM_ERR_LONG_LINE;
1011 /* Processing header byte */
1018 int rc = pdkim_header_complete(ctx); /* Seen last header line */
1019 if (rc != PDKIM_OK) return rc;
1021 ctx->past_headers = TRUE;
1023 DEBUG(D_acl) debug_printf(
1024 "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>\n");
1028 ctx->seen_lf = TRUE;
1030 else if (ctx->seen_lf)
1032 if (!(c == '\t' || c == ' '))
1034 int rc = pdkim_header_complete(ctx); /* End of header */
1035 if (rc != PDKIM_OK) return rc;
1037 ctx->seen_lf = FALSE;
1041 if (ctx->cur_header_len < PDKIM_MAX_HEADER_LEN)
1042 ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size,
1043 &ctx->cur_header_len, CUS &data[p], 1);
1051 /* Extend a grwong header with a continuation-linebreak */
1053 pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col)
1056 return string_catn(str, size, ptr, US"\r\n\t", 3);
1062 * RFC 5322 specifies that header line length SHOULD be no more than 78
1066 * returns uschar * (not nul-terminated)
1068 * col: this int holds and receives column number (octets since last '\n')
1069 * str: partial string to append to
1070 * size: current buffer size for str
1071 * ptr: current tail-pointer for str
1072 * pad: padding, split line or space after before or after eg: ";"
1073 * intro: - must join to payload eg "h=", usually the tag name
1074 * payload: eg base64 data - long data can be split arbitrarily.
1076 * this code doesn't fold the header in some of the places that RFC4871
1077 * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
1078 * pairs and inside long values. it also always spaces or breaks after the
1081 * no guarantees are made for output given out-of range input. like tag
1082 * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
1086 pdkim_headcat(int * col, uschar * str, int * size, int * ptr,
1087 const uschar * pad, const uschar * intro, const uschar * payload)
1095 str = pdkim_hdr_cont(str, size, ptr, col);
1096 str = string_catn(str, size, ptr, pad, l);
1100 l = (pad?1:0) + (intro?Ustrlen(intro):0);
1103 { /*can't fit intro - start a new line to make room.*/
1104 str = pdkim_hdr_cont(str, size, ptr, col);
1105 l = intro?Ustrlen(intro):0;
1108 l += payload ? Ustrlen(payload):0 ;
1111 { /* this fragment will not fit on a single line */
1114 str = string_catn(str, size, ptr, US" ", 1);
1116 pad = NULL; /* only want this once */
1122 size_t sl = Ustrlen(intro);
1124 str = string_catn(str, size, ptr, intro, sl);
1127 intro = NULL; /* only want this once */
1132 size_t sl = Ustrlen(payload);
1133 size_t chomp = *col+sl < 77 ? sl : 78-*col;
1135 str = string_catn(str, size, ptr, payload, chomp);
1141 /* the while precondition tells us it didn't fit. */
1142 str = pdkim_hdr_cont(str, size, ptr, col);
1147 str = pdkim_hdr_cont(str, size, ptr, col);
1153 str = string_catn(str, size, ptr, US" ", 1);
1160 size_t sl = Ustrlen(intro);
1162 str = string_catn(str, size, ptr, intro, sl);
1170 size_t sl = Ustrlen(payload);
1172 str = string_catn(str, size, ptr, payload, sl);
1180 /* -------------------------------------------------------------------------- */
1183 pdkim_create_header(pdkim_signature *sig, BOOL final)
1188 uschar * hdr; int hdr_size = 0, hdr_len = 0;
1189 uschar * canon_all; int can_size = 0, can_len = 0;
1191 canon_all = string_cat (NULL, &can_size, &can_len,
1192 pdkim_canons[sig->canon_headers]);
1193 canon_all = string_catn(canon_all, &can_size, &can_len, US"/", 1);
1194 canon_all = string_cat (canon_all, &can_size, &can_len,
1195 pdkim_canons[sig->canon_body]);
1196 canon_all[can_len] = '\0';
1198 hdr = string_cat(NULL, &hdr_size, &hdr_len,
1199 US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
1202 /* Required and static bits */
1203 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=",
1204 pdkim_algos[sig->algo]);
1205 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=",
1206 pdkim_querymethods[sig->querymethod]);
1207 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"c=",
1209 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=",
1211 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
1214 /* list of header names can be split between items. */
1216 uschar * n = string_copy(sig->headernames);
1217 uschar * i = US"h=";
1222 uschar * c = Ustrchr(n, ':');
1227 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":");
1229 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n);
1240 base64_bh = pdkim_encode_base64(&sig->bodyhash);
1241 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh);
1245 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"i=", sig->identity);
1247 if (sig->created > 0)
1251 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
1252 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf);
1255 if (sig->expires > 0)
1259 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
1260 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf);
1263 if (sig->bodylength >= 0)
1267 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
1268 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf);
1271 /* Preliminary or final version? */
1272 base64_b = final ? pdkim_encode_base64(&sig->sigdata) : US"";
1273 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"b=", base64_b);
1275 /* add trailing semicolon: I'm not sure if this is actually needed */
1276 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, US";", US"");
1278 hdr[hdr_len] = '\0';
1283 /* -------------------------------------------------------------------------- */
1286 pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures)
1288 pdkim_signature *sig = ctx->sig;
1289 uschar * headernames = NULL; /* Collected signed header names */
1292 /* Check if we must still flush a (partial) header. If that is the
1293 case, the message has no body, and we must compute a body hash
1294 out of '<CR><LF>' */
1295 if (ctx->cur_header && ctx->cur_header_len)
1297 int rc = pdkim_header_complete(ctx);
1298 if (rc != PDKIM_OK) return rc;
1299 pdkim_update_bodyhash(ctx, "\r\n", 2);
1302 DEBUG(D_acl) debug_printf(
1303 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1305 /* Build (and/or evaluate) body hash */
1306 pdkim_finish_bodyhash(ctx);
1310 BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1;
1315 int hdata_alloc = 0;
1320 exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256);
1322 DEBUG(D_acl) debug_printf(
1323 "PDKIM >> Hashed header data, canonicalized, in sequence >>>>>>>>>>>>>>\n");
1325 /* SIGNING ---------------------------------------------------------------- */
1326 /* When signing, walk through our header list and add them to the hash. As we
1327 go, construct a list of the header's names to use for the h= parameter.
1328 Then append to that list any remaining header names for which there was no
1331 if (ctx->mode == PDKIM_MODE_SIGN)
1333 pdkim_stringlist *p;
1338 for (p = sig->headers; p; p = p->next)
1339 if (header_name_match(p->value, sig->sign_headers) == PDKIM_OK)
1342 /* Collect header names (Note: colon presence is guaranteed here) */
1343 uschar * q = Ustrchr(p->value, ':');
1345 headernames = string_catn(headernames, &hs, &hl,
1346 p->value, (q - US p->value) + (p->next ? 1 : 0));
1348 rh = sig->canon_headers == PDKIM_CANON_RELAXED
1349 ? pdkim_relax_header(p->value, 1) /* cook header for relaxed canon */
1350 : string_copy(CUS p->value); /* just copy it for simple canon */
1352 /* Feed header to the hash algorithm */
1353 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1355 /* Remember headers block for signing (when the library cannot do incremental) */
1356 (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh);
1358 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1361 l = sig->sign_headers;
1362 while((s = string_nextinlist(&l, &sep, NULL, 0)))
1364 { /*SSS string_append_listele() */
1365 if (hl > 0 && headernames[hl-1] != ':')
1366 headernames = string_catn(headernames, &hs, &hl, US":", 1);
1368 headernames = string_cat(headernames, &hs, &hl, s);
1370 headernames[hl] = '\0';
1372 /* Copy headernames to signature struct */
1373 sig->headernames = headernames;
1374 headernames = NULL, hs = hl = 0;
1376 /* Create signature header with b= omitted */
1377 sig_hdr = pdkim_create_header(sig, FALSE);
1380 /* VERIFICATION ----------------------------------------------------------- */
1381 /* When verifying, walk through the header name list in the h= parameter and
1382 add the headers to the hash in that order. */
1385 uschar * b = string_copy(sig->headernames);
1388 pdkim_stringlist * hdrs;
1391 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1396 if ((q = Ustrchr(p, ':')))
1399 /*XXX walk the list of headers in same order as received. */
1400 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1402 && strncasecmp(hdrs->value, CS p, Ustrlen(p)) == 0
1403 && (hdrs->value)[Ustrlen(p)] == ':'
1406 uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
1407 ? pdkim_relax_header(hdrs->value, 1) /* cook header for relaxed canon */
1408 : string_copy(CUS hdrs->value); /* just copy it for simple canon */
1410 /* Feed header to the hash algorithm */
1411 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1413 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1422 sig_hdr = string_copy(sig->rawsig_no_b_val);
1425 DEBUG(D_acl) debug_printf(
1426 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1428 /* Relax header if necessary */
1429 if (sig->canon_headers == PDKIM_CANON_RELAXED)
1430 sig_hdr = pdkim_relax_header(sig_hdr, 0);
1435 "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
1436 pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
1438 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1441 /* Finalize header hash */
1442 exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
1443 exim_sha_finish(&hhash_ctx, &hhash);
1447 debug_printf("PDKIM [%s] hh computed: ", sig->domain);
1448 pdkim_hexprint(hhash.data, hhash.len);
1451 /* Remember headers block for signing (when the library cannot do incremental) */
1452 if (ctx->mode == PDKIM_MODE_SIGN)
1453 (void) exim_rsa_data_append(&hdata, &hdata_alloc, US sig_hdr);
1455 /* SIGNING ---------------------------------------------------------------- */
1456 if (ctx->mode == PDKIM_MODE_SIGN)
1459 const uschar * errstr;
1461 /* Import private key */
1462 if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
1464 DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr);
1465 return PDKIM_ERR_RSA_PRIVKEY;
1468 /* Do signing. With OpenSSL we are signing the hash of headers just
1469 calculated, with GnuTLS we have to sign an entire block of headers
1470 (due to available interfaces) and it recalculates the hash internally. */
1472 #if defined(RSA_OPENSSL) || defined(RSA_GCRYPT)
1476 if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata)))
1478 DEBUG(D_acl) debug_printf("signing: %s\n", errstr);
1479 return PDKIM_ERR_RSA_SIGNING;
1484 debug_printf( "PDKIM [%s] b computed: ", sig->domain);
1485 pdkim_hexprint(sig->sigdata.data, sig->sigdata.len);
1488 sig->signature_header = pdkim_create_header(sig, TRUE);
1491 /* VERIFICATION ----------------------------------------------------------- */
1495 const uschar * errstr;
1497 uschar *dns_txt_name, *dns_txt_reply;
1499 /* Make sure we have all required signature tags */
1500 if (!( sig->domain && *sig->domain
1501 && sig->selector && *sig->selector
1502 && sig->headernames && *sig->headernames
1503 && sig->bodyhash.data
1504 && sig->sigdata.data
1509 sig->verify_status = PDKIM_VERIFY_INVALID;
1510 sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
1512 DEBUG(D_acl) debug_printf(
1513 " Error in DKIM-Signature header: tags missing or invalid\n"
1514 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1518 /* Make sure sig uses supported DKIM version (only v1) */
1519 if (sig->version != 1)
1521 sig->verify_status = PDKIM_VERIFY_INVALID;
1522 sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
1524 DEBUG(D_acl) debug_printf(
1525 " Error in DKIM-Signature header: unsupported DKIM version\n"
1526 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1530 /* Fetch public key for signing domain, from DNS */
1532 dns_txt_name = string_sprintf("%s._domainkey.%s.",
1533 sig->selector, sig->domain);
1535 dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN);
1536 memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN);
1538 if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK
1539 || dns_txt_reply[0] == '\0')
1541 sig->verify_status = PDKIM_VERIFY_INVALID;
1542 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
1549 "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
1551 pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
1554 if (!(sig->pubkey = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)))
1556 sig->verify_status = PDKIM_VERIFY_INVALID;
1557 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
1559 DEBUG(D_acl) debug_printf(
1560 " Error while parsing public key record\n"
1561 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1565 DEBUG(D_acl) debug_printf(
1566 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1568 /* Import public key */
1569 if ((errstr = exim_rsa_verify_init(&sig->pubkey->key, &vctx)))
1571 DEBUG(D_acl) debug_printf("verify_init: %s\n", errstr);
1572 sig->verify_status = PDKIM_VERIFY_INVALID;
1573 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
1577 /* Check the signature */
1578 if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata)))
1580 DEBUG(D_acl) debug_printf("headers verify: %s\n", errstr);
1581 sig->verify_status = PDKIM_VERIFY_FAIL;
1582 sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE;
1587 /* We have a winner! (if bodydhash was correct earlier) */
1588 if (sig->verify_status == PDKIM_VERIFY_NONE)
1589 sig->verify_status = PDKIM_VERIFY_PASS;
1595 debug_printf("PDKIM [%s] signature status: %s",
1596 sig->domain, pdkim_verify_status_str(sig->verify_status));
1597 if (sig->verify_ext_status > 0)
1598 debug_printf(" (%s)\n",
1599 pdkim_verify_ext_status_str(sig->verify_ext_status));
1608 /* If requested, set return pointer to signature(s) */
1609 if (return_signatures)
1610 *return_signatures = ctx->sig;
1616 /* -------------------------------------------------------------------------- */
1618 DLLEXPORT pdkim_ctx *
1619 pdkim_init_verify(int(*dns_txt_callback)(char *, char *))
1623 ctx = store_get(sizeof(pdkim_ctx));
1624 memset(ctx, 0, sizeof(pdkim_ctx));
1626 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1627 ctx->mode = PDKIM_MODE_VERIFY;
1628 ctx->dns_txt_callback = dns_txt_callback;
1634 /* -------------------------------------------------------------------------- */
1636 DLLEXPORT pdkim_ctx *
1637 pdkim_init_sign(char *domain, char *selector, char *rsa_privkey, int algo)
1640 pdkim_signature *sig;
1642 if (!domain || !selector || !rsa_privkey)
1645 ctx = store_get(sizeof(pdkim_ctx));
1646 memset(ctx, 0, sizeof(pdkim_ctx));
1648 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1650 sig = store_get(sizeof(pdkim_signature));
1651 memset(sig, 0, sizeof(pdkim_signature));
1653 sig->bodylength = -1;
1655 ctx->mode = PDKIM_MODE_SIGN;
1658 sig->domain = string_copy(US domain);
1659 sig->selector = string_copy(US selector);
1660 sig->rsa_privkey = string_copy(US rsa_privkey);
1663 exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
1668 /* -------------------------------------------------------------------------- */
1671 pdkim_set_optional(pdkim_ctx *ctx,
1677 unsigned long created,
1678 unsigned long expires)
1680 pdkim_signature * sig = ctx->sig;
1683 sig->identity = string_copy(US identity);
1685 sig->sign_headers = string_copy(sign_headers
1686 ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
1688 sig->canon_headers = canon_headers;
1689 sig->canon_body = canon_body;
1690 sig->bodylength = bodylength;
1691 sig->created = created;
1692 sig->expires = expires;
1706 #endif /*DISABLE_DKIM*/