+/*
+ * PDKIM - a RFC4871 (DKIM) implementation
+ *
+ * Copyright (c) The Exim Maintainers 2021 - 2024
+ * Copyright (C) 2016 - 2020 Jeremy Harris <jgh@exim.org>
+ * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net>
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * 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.
+ */
+
+#include "../exim.h"
+
+
+#ifndef DISABLE_DKIM /* entire file */
+
+#ifdef DISABLE_TLS
+# error Must not DISABLE_TLS, for DKIM
+#endif
+
+#include "crypt_ver.h"
+
+#ifdef SIGN_OPENSSL
+# include <openssl/rsa.h>
+# include <openssl/ssl.h>
+# include <openssl/err.h>
+#elif defined(SIGN_GNUTLS)
+# include <gnutls/gnutls.h>
+# include <gnutls/x509.h>
+#endif
+
+#include "pdkim.h"
+#include "signing.h"
+
+#define PDKIM_SIGNATURE_VERSION "1"
+#define PDKIM_PUB_RECORD_VERSION US "DKIM1"
+
+#define PDKIM_MAX_HEADER_LEN 65536
+#define PDKIM_MAX_HEADERS 512
+#define PDKIM_MAX_BODY_LINE_LEN 16384
+#define PDKIM_DNS_TXT_MAX_NAMELEN 1024
+
+/* -------------------------------------------------------------------------- */
+struct pdkim_stringlist {
+ uschar * value;
+ int tag;
+ void * next;
+};
+
+/* -------------------------------------------------------------------------- */
+/* A bunch of list constants */
+const uschar * pdkim_querymethods[] = {
+ US"dns/txt",
+ NULL
+};
+const uschar * pdkim_canons[] = {
+ US"simple",
+ US"relaxed",
+ NULL
+};
+
+const pdkim_hashtype pdkim_hashes[] = {
+ { US"sha1", HASH_SHA1 },
+ { US"sha256", HASH_SHA2_256 },
+ { US"sha512", HASH_SHA2_512 }
+};
+
+const uschar * pdkim_keytypes[] = {
+ [KEYTYPE_RSA] = US"rsa",
+#ifdef SIGN_HAVE_ED25519
+ [KEYTYPE_ED25519] = US"ed25519", /* Works for 3.6.0 GnuTLS, OpenSSL 1.1.1 */
+#endif
+
+#ifdef notyet_EC_dkim_extensions /* https://tools.ietf.org/html/draft-srose-dkim-ecc-00 */
+ US"eccp256",
+ US"eccp348",
+ US"ed448",
+#endif
+};
+
+typedef struct pdkim_combined_canon_entry {
+ const uschar * str;
+ int canon_headers;
+ int canon_body;
+} pdkim_combined_canon_entry;
+
+pdkim_combined_canon_entry pdkim_combined_canons[] = {
+ { US"simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
+ { US"simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED },
+ { US"relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
+ { US"relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED },
+ { US"simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
+ { US"relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
+ { NULL, 0, 0 }
+};
+
+
+static const blob lineending = {.data = US"\r\n", .len = 2};
+
+/* -------------------------------------------------------------------------- */
+uschar *
+dkim_sig_to_a_tag(const pdkim_signature * sig)
+{
+if ( sig->keytype < 0 || sig->keytype > nelem(pdkim_keytypes)
+ || sig->hashtype < 0 || sig->hashtype > nelem(pdkim_hashes))
+ return US"err";
+return string_sprintf("%s-%s",
+ pdkim_keytypes[sig->keytype], pdkim_hashes[sig->hashtype].dkim_hashname);
+}
+
+
+static int
+pdkim_keyname_to_keytype(const uschar * s)
+{
+for (int i = 0; i < nelem(pdkim_keytypes); i++)
+ if (Ustrcmp(s, pdkim_keytypes[i]) == 0) return i;
+return -1;
+}
+
+int
+pdkim_hashname_to_hashtype(const uschar * s, unsigned len)
+{
+if (!len) len = Ustrlen(s);
+for (int i = 0; i < nelem(pdkim_hashes); i++)
+ if (Ustrncmp(s, pdkim_hashes[i].dkim_hashname, len) == 0)
+ return i;
+return -1;
+}
+
+void
+pdkim_cstring_to_canons(const uschar * s, unsigned len,
+ int * canon_head, int * canon_body)
+{
+if (!len) len = Ustrlen(s);
+for (int i = 0; pdkim_combined_canons[i].str; i++)
+ if ( Ustrncmp(s, pdkim_combined_canons[i].str, len) == 0
+ && len == Ustrlen(pdkim_combined_canons[i].str))
+ {
+ *canon_head = pdkim_combined_canons[i].canon_headers;
+ *canon_body = pdkim_combined_canons[i].canon_body;
+ break;
+ }
+}
+
+
+
+const char *
+pdkim_verify_status_str(int status)
+{
+switch(status)
+ {
+ case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE";
+ case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID";
+ case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL";
+ case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS";
+ default: return "PDKIM_VERIFY_UNKNOWN";
+ }
+}
+
+const char *
+pdkim_verify_ext_status_str(int ext_status)
+{
+switch(ext_status)
+ {
+ case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY";
+ case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE";
+ case PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH: return "PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH";
+ case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE";
+ case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE";
+ case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD";
+ case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT";
+ case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE: return "PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE";
+ case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR";
+ case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION";
+ default: return "PDKIM_VERIFY_UNKNOWN";
+ }
+}
+
+const uschar *
+pdkim_errstr(int status)
+{
+switch(status)
+ {
+ case PDKIM_OK: return US"OK";
+ case PDKIM_FAIL: return US"FAIL";
+ case PDKIM_ERR_RSA_PRIVKEY: return US"PRIVKEY";
+ case PDKIM_ERR_RSA_SIGNING: return US"SIGNING";
+ case PDKIM_ERR_LONG_LINE: return US"LONG_LINE";
+ case PDKIM_ERR_BUFFER_TOO_SMALL: return US"BUFFER_TOO_SMALL";
+ case PDKIM_ERR_EXCESS_SIGS: return US"EXCESS_SIGS";
+ case PDKIM_SIGN_PRIVKEY_WRAP: return US"PRIVKEY_WRAP";
+ case PDKIM_SIGN_PRIVKEY_B64D: return US"PRIVKEY_B64D";
+ default: return US"(unknown)";
+ }
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+
+static pdkim_stringlist *
+pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
+{
+pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist), GET_UNTAINTED);
+
+memset(new_entry, 0, sizeof(pdkim_stringlist));
+new_entry->value = string_copy(str);
+if (base) new_entry->next = base;
+return new_entry;
+}
+
+
+
+/* Trim whitespace fore & aft */
+
+static void
+pdkim_strtrim(gstring * str)
+{
+uschar * p = str->s;
+uschar * q;
+
+while (*p == '\t' || *p == ' ') /* dump the leading whitespace */
+ { str->size--; str->ptr--; str->s++; }
+
+while ( str->ptr > 0
+ && ((q = str->s + str->ptr - 1), (*q == '\t' || *q == ' '))
+ )
+ str->ptr--; /* dump trailing whitespace */
+
+(void) string_from_gstring(str);
+}
+
+
+
+/* -------------------------------------------------------------------------- */
+
+DLLEXPORT void
+pdkim_free_ctx(pdkim_ctx *ctx)
+{
+}
+
+
+/* -------------------------------------------------------------------------- */
+/* Matches the name of the passed raw "header" against
+ the passed colon-separated "tick", and invalidates
+ the entry in tick. Entries can be prefixed for multi- or over-signing,
+ in which case do not invalidate.
+
+ Returns OK for a match, or fail-code
+*/
+
+static int
+header_name_match(const uschar * header, uschar * tick)
+{
+const uschar * ticklist = tick;
+int sep = ':';
+BOOL multisign;
+uschar * hname, * p, * ele;
+uschar * hcolon = Ustrchr(header, ':'); /* Get header name */
+
+if (!hcolon)
+ return PDKIM_FAIL; /* This isn't a header */
+
+/* if we had strncmpic() we wouldn't need this copy */
+hname = string_copyn(header, hcolon-header);
+
+while (p = US ticklist, ele = string_nextinlist(&ticklist, &sep, NULL, 0))
+ {
+ switch (*ele)
+ {
+ case '=': case '+': multisign = TRUE; ele++; break;
+ default: multisign = FALSE; break;
+ }
+
+ if (strcmpic(ele, hname) == 0)
+ {
+ if (!multisign)
+ *p = '_'; /* Invalidate this header name instance in tick-off list */
+ return PDKIM_OK;
+ }
+ }
+return PDKIM_FAIL;
+}
+
+
+/* -------------------------------------------------------------------------- */
+/* Module API */
+/* Performs "relaxed" canonicalization of a header. */
+
+uschar *
+pdkim_relax_header_n(const uschar * header, int len, BOOL append_crlf)
+{
+BOOL past_field_name = FALSE;
+BOOL seen_wsp = FALSE;
+uschar * relaxed = store_get(len+3, GET_TAINTED);
+uschar * q = relaxed;
+
+for (const uschar * p = header; p - header < len; p++)
+ {
+ uschar c = *p;
+
+ if (c == '\r' || c == '\n') /* Ignore CR & LF */
+ continue;
+ if (c == '\t' || c == ' ')
+ {
+ if (seen_wsp)
+ continue;
+ c = ' '; /* Turns WSP into SP */
+ seen_wsp = TRUE;
+ }
+ else
+ if (!past_field_name && c == ':')
+ {
+ if (seen_wsp) q--; /* This removes WSP immediately before the colon */
+ seen_wsp = TRUE; /* This removes WSP immediately after the colon */
+ past_field_name = TRUE;
+ }
+ else
+ seen_wsp = FALSE;
+
+ /* Lowercase header name */
+ if (!past_field_name) c = tolower(c);
+ *q++ = c;
+ }
+
+if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */
+
+if (append_crlf) { *q++ = '\r'; *q++ = '\n'; }
+*q = '\0';
+return relaxed;
+}
+
+
+uschar *
+pdkim_relax_header(const uschar * header, BOOL append_crlf)
+{
+return pdkim_relax_header_n(header, Ustrlen(header), append_crlf);
+}
+
+
+/* -------------------------------------------------------------------------- */
+#define PDKIM_QP_ERROR_DECODE -1
+
+static const uschar *
+pdkim_decode_qp_char(const uschar *qp_p, int *c)
+{
+const uschar *initial_pos = qp_p;
+
+/* Advance one char */
+qp_p++;
+
+/* Check for two hex digits and decode them */
+if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
+ {
+ /* Do hex conversion */
+ *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) << 4;
+ *c |= isdigit(qp_p[1]) ? qp_p[1] - '0' : toupper(qp_p[1]) - 'A' + 10;
+ return qp_p + 2;
+ }
+
+/* Illegal char here */
+*c = PDKIM_QP_ERROR_DECODE;
+return initial_pos;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+static uschar *
+pdkim_decode_qp(const uschar * str)
+{
+int nchar = 0;
+uschar * q;
+const uschar * p = str;
+uschar * n = store_get(Ustrlen(str)+1, GET_TAINTED);
+
+*n = '\0';
+q = n;
+while (*p)
+ {
+ if (*p == '=')
+ {
+ p = pdkim_decode_qp_char(p, &nchar);
+ if (nchar >= 0)
+ {
+ *q++ = nchar;
+ continue;
+ }
+ }
+ else
+ *q++ = *p;
+ p++;
+ }
+*q = '\0';
+return n;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+void
+pdkim_decode_base64(const uschar * str, blob * b)
+{
+int dlen = b64decode(str, &b->data, str);
+if (dlen < 0) b->data = NULL;
+b->len = dlen;
+}
+
+uschar *
+pdkim_encode_base64(blob * b)
+{
+return b64encode(b->data, b->len);
+}
+
+
+/* -------------------------------------------------------------------------- */
+#define PDKIM_HDR_LIMBO 0
+#define PDKIM_HDR_TAG 1
+#define PDKIM_HDR_VALUE 2
+
+static pdkim_signature *
+pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr)
+{
+pdkim_signature * sig = store_get(sizeof(pdkim_signature), GET_UNTAINTED);
+uschar * q;
+gstring * cur_tag = NULL, * cur_val = NULL;
+BOOL past_hname = FALSE, in_b_val = FALSE;
+int where = PDKIM_HDR_LIMBO;
+
+memset(sig, 0, sizeof(pdkim_signature));
+sig->bodylength = -1;
+
+/* Set so invalid/missing data error display is accurate */
+sig->version = 0;
+sig->keytype = -1;
+sig->hashtype = -1;
+
+q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1, GET_TAINTED);
+
+for (uschar * p = raw_hdr; ; p++)
+ {
+ char c = *p;
+
+ /* Ignore FWS */
+ if (c == '\r' || c == '\n')
+ goto NEXT_CHAR;
+
+ /* Fast-forward through header name */
+ if (!past_hname)
+ {
+ if (c == ':') past_hname = TRUE;
+ goto NEXT_CHAR;
+ }
+
+ if (where == PDKIM_HDR_LIMBO)
+ {
+ /* In limbo, just wait for a tag-char to appear */
+ if (!(c >= 'a' && c <= 'z'))
+ goto NEXT_CHAR;
+
+ where = PDKIM_HDR_TAG;
+ }
+
+ if (where == PDKIM_HDR_TAG)
+ if (c == '=')
+ {
+ if (Ustrcmp(string_from_gstring(cur_tag), "b") == 0)
+ {
+ *q++ = '=';
+ in_b_val = TRUE;
+ }
+ where = PDKIM_HDR_VALUE;
+ goto NEXT_CHAR;
+ }
+ else if (!isspace(c))
+ cur_tag = string_catn(cur_tag, p, 1);
+
+ if (where == PDKIM_HDR_VALUE)
+ {
+ if (c == '\r' || c == '\n' || c == ' ' || c == '\t')
+ goto NEXT_CHAR;
+
+ if (c == ';' || c == '\0')
+ {
+ /* We must have both tag and value, and tags must be one char except
+ for the possibility of "bh". */
+
+ if ( cur_tag && cur_val
+ && (cur_tag->ptr == 1 || *cur_tag->s == 'b')
+ )
+ {
+ (void) string_from_gstring(cur_val);
+ pdkim_strtrim(cur_val);
+
+ DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag->s, cur_val->s);
+
+ switch (*cur_tag->s)
+ {
+ case 'b': /* sig-data or body-hash */
+ switch (cur_tag->s[1])
+ {
+ case '\0': pdkim_decode_base64(cur_val->s, &sig->sighash); break;
+ case 'h': if (cur_tag->ptr != 2) goto bad_tag;
+ pdkim_decode_base64(cur_val->s, &sig->bodyhash);
+ break;
+ default: goto bad_tag;
+ }
+ break;
+ case 'v': /* version */
+ /* We only support version 1, and that is currently the
+ only version there is. */
+ sig->version =
+ Ustrcmp(cur_val->s, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
+ break;
+ case 'a': /* algorithm */
+ {
+ const uschar * list = cur_val->s;
+ int sep = '-';
+ uschar * elem;
+
+ if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+ sig->keytype = pdkim_keyname_to_keytype(elem);
+ if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+ for (int i = 0; i < nelem(pdkim_hashes); i++)
+ if (Ustrcmp(elem, pdkim_hashes[i].dkim_hashname) == 0)
+ { sig->hashtype = i; break; }
+ }
+ break;
+
+ case 'c': /* canonicalization */
+ pdkim_cstring_to_canons(cur_val->s, 0,
+ &sig->canon_headers, &sig->canon_body);
+ break;
+ case 'q': /* Query method (for pubkey)*/
+ for (int i = 0; pdkim_querymethods[i]; i++)
+ if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0)
+ {
+ sig->querymethod = i; /* we never actually use this */
+ break;
+ }
+ break;
+ case 's': /* Selector */
+ sig->selector = string_copy_from_gstring(cur_val); break;
+ case 'd': /* SDID */
+ sig->domain = string_copy_from_gstring(cur_val); break;
+ case 'i': /* AUID */
+ sig->identity = pdkim_decode_qp(cur_val->s); break;
+ case 't': /* Timestamp */
+ sig->created = strtoul(CS cur_val->s, NULL, 10); break;
+ case 'x': /* Expiration */
+ sig->expires = strtoul(CS cur_val->s, NULL, 10); break;
+ case 'l': /* Body length count */
+ sig->bodylength = strtol(CS cur_val->s, NULL, 10); break;
+ case 'h': /* signed header fields */
+ sig->headernames = string_copy_from_gstring(cur_val); break;
+ case 'z': /* Copied headfields */
+ sig->copiedheaders = pdkim_decode_qp(cur_val->s); break;
+/*XXX draft-ietf-dcrup-dkim-crypto-05 would need 'p' tag support
+for rsafp signatures. But later discussion is dropping those. */
+ default:
+ goto bad_tag;
+ }
+ }
+ else
+bad_tag: DEBUG(D_acl) debug_printf(" Unknown tag encountered: %Y\n", cur_tag);
+
+ cur_tag = cur_val = NULL;
+ in_b_val = FALSE;
+ where = PDKIM_HDR_LIMBO;
+ }
+ else
+ cur_val = string_catn(cur_val, p, 1);
+ }
+
+NEXT_CHAR:
+ if (c == '\0')
+ break;
+
+ if (!in_b_val)
+ *q++ = c;
+ }
+
+if (sig->keytype < 0 || sig->hashtype < 0) /* Cannot verify this signature */
+ return NULL;
+
+*q = '\0';
+/* Chomp raw header. The final newline must not be added to the signature. */
+while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n'))
+ *q = '\0';
+
+DEBUG(D_acl)
+ {
+ debug_printf(
+ "DKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+ debug_printf("%Z\n", US sig->rawsig_no_b_val);
+ debug_printf(
+ "DKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8);
+ debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ }
+
+if (!pdkim_set_sig_bodyhash(ctx, sig))
+ return NULL;
+
+return sig;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+pdkim_pubkey *
+pdkim_parse_pubkey_record(const uschar * raw_record)
+{
+pdkim_pubkey * pub = store_get(sizeof(pdkim_pubkey), GET_TAINTED);
+
+memset(pub, 0, sizeof(pdkim_pubkey));
+
+for (const uschar * ele = raw_record, * tspec, * end, * val; *ele; ele = end)
+ {
+ Uskip_whitespace(&ele);
+ end = Ustrchrnul(ele, ';');
+ tspec = string_copyn(ele, end - ele);
+ if (*end) end++; /* skip the ; */
+
+ if ((val = Ustrchr(tspec, '=')))
+ {
+ int taglen = val++ - tspec;
+
+ DEBUG(D_acl) debug_printf(" %.*s=%s\n", taglen, tspec, val);
+ while (taglen > 1 && isspace(tspec[taglen-1]))
+ taglen--; /* Ignore whitespace before = */
+ Uskip_whitespace(&val); /* Ignore whitespace after = */
+ if (isspace(val[ Ustrlen(val)-1 ]))
+ { /* Ignore whitespace after value */
+ gstring * g = string_cat(NULL, val);
+ while (isspace(gstring_last_char(g)))
+ gstring_trim(g, 1);
+ val = string_from_gstring(g);
+ }
+
+ if (taglen == 1) switch (tspec[0])
+ {
+ case 'v': pub->version = val; break;
+ case 'h': pub->hashes = val; break;
+ case 'k': pub->keytype = val; break;
+ case 'g': pub->granularity = val; break;
+ case 'n': pub->notes = pdkim_decode_qp(val); break;
+ case 'p': pdkim_decode_base64(val, &pub->key); break;
+ case 's': pub->srvtype = val; break;
+ case 't': if (Ustrchr(val, 'y')) pub->testing = 1;
+ if (Ustrchr(val, 's')) pub->no_subdomaining = 1;
+ break;
+ default: goto bad_tag;
+ }
+ else
+bad_tag:
+ DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
+ }
+ }
+
+/* Set fallback defaults */
+if (!pub->version)
+ pub->version = string_copy(PDKIM_PUB_RECORD_VERSION);
+else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0)
+ {
+ DEBUG(D_acl) debug_printf(" Bad v= field\n");
+ return NULL;
+ }
+
+if (!pub->granularity) pub->granularity = US"*";
+if (!pub->keytype ) pub->keytype = US"rsa";
+if (!pub->srvtype ) pub->srvtype = US"*";
+
+/* p= is required */
+if (pub->key.data)
+ return pub;
+
+DEBUG(D_acl) debug_printf(" Missing p= field\n");
+return NULL;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+/* Update one bodyhash with some additional data.
+If we have to relax the data for this sig, return our copy of it. */
+
+static blob *
+pdkim_update_ctx_bodyhash(pdkim_bodyhash * b, const blob * orig_data, blob * relaxed_data)
+{
+const blob * canon_data = orig_data;
+size_t left;
+
+/* Defaults to simple canon (no further treatment necessary) */
+
+if (b->canon_method == PDKIM_CANON_RELAXED)
+ {
+ /* Relax the line if not done already */
+ if (!relaxed_data)
+ {
+ BOOL seen_wsp = FALSE;
+ int q = 0;
+
+ /* We want to be able to free this else we allocate
+ for the entire message which could be many MB. Since
+ we don't know what allocations the SHA routines might
+ do, not safe to use store_get()/store_reset(). */
+
+ relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1);
+ relaxed_data->data = US (relaxed_data+1);
+
+ for (const uschar * p = orig_data->data, * r = p + orig_data->len; p < r; p++)
+ {
+ char c = *p;
+ if (c == '\r')
+ {
+ if (q > 0 && relaxed_data->data[q-1] == ' ')
+ q--;
+ }
+ else if (c == '\t' || c == ' ')
+ {
+ c = ' '; /* Turns WSP into SP */
+ if (seen_wsp)
+ continue;
+ seen_wsp = TRUE;
+ }
+ else
+ seen_wsp = FALSE;
+ relaxed_data->data[q++] = c;
+ }
+ relaxed_data->data[q] = '\0';
+ relaxed_data->len = q;
+ }
+ canon_data = relaxed_data;
+ }
+
+/* Make sure we don't exceed the to-be-signed body length */
+left = canon_data->len;
+if ( b->bodylength >= 0
+ && left > (unsigned long)b->bodylength - b->signed_body_bytes
+ )
+ left = (unsigned long)b->bodylength - b->signed_body_bytes;
+
+if (left > 0)
+ {
+ exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, left);
+ b->signed_body_bytes += left;
+ DEBUG(D_acl) debug_printf("%.*Z\n", left, canon_data->data);
+ }
+
+return relaxed_data;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+static void
+pdkim_finish_bodyhash(pdkim_ctx * ctx)
+{
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) /* Finish hashes */
+ {
+ DEBUG(D_acl) debug_printf("DKIM: finish bodyhash %s/%s/%ld len %ld\n",
+ pdkim_hashes[b->hashtype].dkim_hashname, pdkim_canons[b->canon_method],
+ b->bodylength, b->signed_body_bytes);
+ exim_sha_finish(&b->body_hash_ctx, &b->bh);
+ }
+
+/* Traverse all signatures */
+for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
+ {
+ pdkim_bodyhash * b = sig->calc_body_hash;
+
+ DEBUG(D_acl)
+ {
+ debug_printf("DKIM [%s]%s Body bytes (%s) hashed: %lu\n"
+ "DKIM [%s]%s Body %s computed: ",
+ sig->domain, sig->selector, pdkim_canons[b->canon_method], b->signed_body_bytes,
+ sig->domain, sig->selector, pdkim_hashes[b->hashtype].dkim_hashname);
+ debug_printf("%.*H\n", b->bh.len, CUS b->bh.data);
+ }
+
+ /* SIGNING -------------------------------------------------------------- */
+ if (ctx->flags & PDKIM_MODE_SIGN)
+ {
+ /* If bodylength limit is set, and we have received less bytes
+ than the requested amount, effectively remove the limit tag. */
+ if (b->signed_body_bytes < sig->bodylength)
+ sig->bodylength = -1;
+ }
+
+ else
+ /* VERIFICATION --------------------------------------------------------- */
+ /* Be careful that the header sig included a bodyash */
+
+ if (sig->bodyhash.data && sig->bodyhash.len == b->bh.len
+ && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0)
+ {
+ DEBUG(D_acl) debug_printf("DKIM [%s] Body hash compared OK\n", sig->domain);
+ }
+ else
+ {
+ DEBUG(D_acl)
+ {
+ debug_printf("DKIM [%s] Body hash signature from headers: ", sig->domain);
+ debug_printf("%.*H\n", sig->bodyhash.len, sig->bodyhash.data);
+ debug_printf("DKIM [%s] Body hash did NOT verify\n", sig->domain);
+ }
+ sig->verify_status = PDKIM_VERIFY_FAIL;
+ sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
+ }
+ }
+}
+
+
+
+static void
+pdkim_body_complete(pdkim_ctx * ctx)
+{
+/* In simple body mode, if any empty lines were buffered,
+replace with one. rfc 4871 3.4.3 */
+/*XXX checking the signed-body-bytes is a gross hack; I think
+it indicates that all linebreaks should be buffered, including
+the one terminating a text line */
+
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
+ if ( b->canon_method == PDKIM_CANON_SIMPLE
+ && b->signed_body_bytes == 0
+ && b->num_buffered_blanklines > 0
+ )
+ (void) pdkim_update_ctx_bodyhash(b, &lineending, NULL);
+
+ctx->flags |= PDKIM_SEEN_EOD;
+ctx->linebuf_offset = 0;
+}
+
+
+
+/* -------------------------------------------------------------------------- */
+/* Call from pdkim_feed below for processing complete body lines */
+/* NOTE: the line is not NUL-terminated; but we have a count */
+
+static void
+pdkim_bodyline_complete(pdkim_ctx * ctx)
+{
+blob line = {.data = ctx->linebuf, .len = ctx->linebuf_offset};
+blob * rnl = NULL;
+blob * rline = NULL;
+
+/* Ignore extra data if we've seen the end-of-data marker */
+if (ctx->flags & PDKIM_SEEN_EOD) goto all_skip;
+
+/* We've always got one extra byte to stuff a zero ... */
+ctx->linebuf[line.len] = '\0';
+
+/* Terminate on EOD marker */
+if (ctx->flags & PDKIM_DOT_TERM)
+ {
+ if (memcmp(line.data, ".\r\n", 3) == 0)
+ { pdkim_body_complete(ctx); return; }
+
+ /* Unstuff dots */
+ if (memcmp(line.data, "..", 2) == 0)
+ { line.data++; line.len--; }
+ }
+
+/* Empty lines need to be buffered until we find a non-empty line */
+if (memcmp(line.data, "\r\n", 2) == 0)
+ {
+ for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
+ b->num_buffered_blanklines++;
+ goto all_skip;
+ }
+
+/* Process line for each bodyhash separately */
+for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
+ {
+ if (b->canon_method == PDKIM_CANON_RELAXED)
+ {
+ /* Lines with just spaces need to be buffered too */
+ uschar * cp = line.data;
+ char c;
+
+ while ((c = *cp))
+ {
+ if (c == '\r' && cp[1] == '\n') break;
+ if (c != ' ' && c != '\t') goto hash_process;
+ cp++;
+ }
+
+ b->num_buffered_blanklines++;
+ goto hash_skip;
+ }
+
+hash_process:
+ /* At this point, we have a non-empty line, so release the buffered ones. */
+
+ while (b->num_buffered_blanklines)
+ {
+ rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl);
+ b->num_buffered_blanklines--;
+ }
+
+ rline = pdkim_update_ctx_bodyhash(b, &line, rline);
+hash_skip: ;
+ }
+
+if (rnl) store_free(rnl);
+if (rline) store_free(rline);
+
+all_skip:
+
+ctx->linebuf_offset = 0;
+return;
+}
+
+
+/* -------------------------------------------------------------------------- */
+/* Callback from pdkim_feed below for processing complete headers */
+#define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
+
+static int
+pdkim_header_complete(pdkim_ctx * ctx)
+{
+if (ctx->cur_header->ptr > 1)
+ gstring_trim_trailing(ctx->cur_header, '\r');
+(void) string_from_gstring(ctx->cur_header);
+
+#ifdef EXPERIMENTAL_ARC
+/* Feed the header line to ARC processing */
+(void) arc_header_feed(ctx->cur_header, !(ctx->flags & PDKIM_MODE_SIGN));
+#endif
+
+if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
+
+/* SIGNING -------------------------------------------------------------- */
+if (ctx->flags & PDKIM_MODE_SIGN)
+ for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */
+
+ /* Add header to the signed headers list (in reverse order) */
+ sig->headers = pdkim_prepend_stringlist(sig->headers, ctx->cur_header->s);
+
+/* VERIFICATION ----------------------------------------------------------- */
+/* DKIM-Signature: headers are added to the verification list */
+else
+ {
+#ifdef notdef
+ DEBUG(D_acl) debug_printf("DKIM >> raw hdr: %.*Z\n",
+ ctx->cur_head->ptr, CUS ctx->cur_header->s);
+#endif
+ if (strncasecmp(CCS ctx->cur_header->s,
+ DKIM_SIGNATURE_HEADERNAME,
+ Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
+ {
+ pdkim_signature * sig, * last_sig;
+ /* Create and chain new signature block. We could error-check for all
+ required tags here, but prefer to create the internal sig and expicitly
+ fail verification of it later. */
+
+ DEBUG(D_acl) debug_printf(
+ "DKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+
+ sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s);
+
+ if (!(last_sig = ctx->sig))
+ ctx->sig = sig;
+ else
+ {
+ while (last_sig->next) last_sig = last_sig->next;
+ last_sig->next = sig;
+ }
+
+ if (dkim_collect_input && --dkim_collect_input == 0)
+ {
+ ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s);
+ ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0';
+ return PDKIM_ERR_EXCESS_SIGS;
+ }
+ }
+
+ /* all headers are stored for signature verification */
+ ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s);
+ }
+
+BAIL:
+ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0'; /* leave buffer for reuse */
+return PDKIM_OK;
+}
+
+
+
+/* -------------------------------------------------------------------------- */
+#define HEADER_BUFFER_FRAG_SIZE 256
+
+DLLEXPORT int
+pdkim_feed(pdkim_ctx * ctx, const uschar * data, unsigned len)
+{
+/* Alternate EOD signal, used in non-dotstuffing mode */
+if (!data)
+ pdkim_body_complete(ctx);
+
+else for (unsigned p = 0; p < len; p++)
+ {
+ uschar c = data[p];
+ int rc;
+
+ if (ctx->flags & PDKIM_PAST_HDRS)
+ {
+ if (c == '\n' && !(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */
+ {
+ ctx->linebuf[ctx->linebuf_offset++] = '\r';
+ if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1)
+ return PDKIM_ERR_LONG_LINE;
+ }
+
+ /* Processing body byte */
+ ctx->linebuf[ctx->linebuf_offset++] = c;
+ if (c == '\r')
+ ctx->flags |= PDKIM_SEEN_CR;
+ else if (c == '\n')
+ {
+ ctx->flags &= ~PDKIM_SEEN_CR;
+ pdkim_bodyline_complete(ctx);
+ }
+
+ if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1)
+ return PDKIM_ERR_LONG_LINE;
+ }
+ else
+ {
+ /* Processing header byte */
+ if (c == '\r')
+ ctx->flags |= PDKIM_SEEN_CR;
+ else if (c == '\n')
+ {
+ if (!(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */
+ ctx->cur_header = string_catn(ctx->cur_header, CUS "\r", 1);
+
+ if (ctx->flags & PDKIM_SEEN_LF) /* Seen last header line */
+ {
+ if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK)
+ return rc;
+
+ ctx->flags = (ctx->flags & ~(PDKIM_SEEN_LF|PDKIM_SEEN_CR)) | PDKIM_PAST_HDRS;
+ DEBUG(D_acl) debug_printf(
+ "DKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+ continue;
+ }
+ else
+ ctx->flags = (ctx->flags & ~PDKIM_SEEN_CR) | PDKIM_SEEN_LF;
+ }
+ else if (ctx->flags & PDKIM_SEEN_LF)
+ {
+ if (!(c == '\t' || c == ' ')) /* End of header */
+ if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK)
+ return rc;
+ ctx->flags &= ~PDKIM_SEEN_LF;
+ }
+
+ if (!ctx->cur_header || ctx->cur_header->ptr < PDKIM_MAX_HEADER_LEN)
+ ctx->cur_header = string_catn(ctx->cur_header, CUS &data[p], 1);
+ }
+ }
+return PDKIM_OK;
+}
+
+
+
+/* Extend a growing header with a continuation-linebreak */
+static gstring *
+pdkim_hdr_cont(gstring * str, int * col)
+{
+*col = 1;
+return string_catn(str, US"\r\n\t", 3);
+}
+
+
+
+/*
+ * RFC 5322 specifies that header line length SHOULD be no more than 78
+ * pdkim_headcat
+ *
+ * Returns gstring (not nul-terminated) appending to one supplied
+ *
+ * col: this int holds and receives column number (octets since last '\n')
+ * str: partial string to append to
+ * pad: padding, split line or space after before or after eg: ";".
+ * Only the initial charater is used.
+ * intro: - must join to payload eg "h=", usually the tag name
+ * payload: eg base64 data - long data can be split arbitrarily.
+ *
+ * this code doesn't fold the header in some of the places that RFC4871
+ * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
+ * pairs and inside long values. it also always spaces or breaks after the
+ * "pad"
+ *
+ * No guarantees are made for output given out-of range input. like tag
+ * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
+ */
+
+static gstring *
+pdkim_headcat(int * col, gstring * str,
+ const uschar * pad, const uschar * intro, const uschar * payload)
+{
+int len, chomp, padded = 0;
+
+/* If we can fit at least the pad at the end of current line, do it now.
+Otherwise, wrap if there is a pad. */
+
+if (pad)
+ if (*col + 1 <= 78)
+ {
+ str = string_catn(str, pad, 1);
+ (*col)++;
+ pad = NULL;
+ padded = 1;
+ }
+ else
+ str = pdkim_hdr_cont(str, col);
+
+/* Special case: if the whole addition does not fit at the end of the current
+line, but could fit on a new line, wrap to give it its full, dedicated line. */
+
+len = (pad ? 2 : padded)
+ + (intro ? Ustrlen(intro) : 0)
+ + (payload ? Ustrlen(payload) : 0);
+if (len <= 77 && *col+len > 78)
+ {
+ str = pdkim_hdr_cont(str, col);
+ padded = 0;
+ }
+
+/* Either we already dealt with the pad or we know there is room */
+
+if (pad)
+ {
+ str = string_catn(str, pad, 1);
+ str = string_catn(str, US" ", 1);
+ *col += 2;
+ }
+else if (padded && *col < 78)
+ {
+ str = string_catn(str, US" ", 1);
+ (*col)++;
+ }
+
+/* Call recursively with intro as payload: it gets the same, special treatment
+(that is, not split if < 78). */
+
+if (intro)
+ str = pdkim_headcat(col, str, NULL, NULL, intro);
+
+if (payload)
+ for (len = Ustrlen(payload); len; len -= chomp)
+ {
+ if (*col >= 78)
+ str = pdkim_hdr_cont(str, col);
+ chomp = *col+len > 78 ? 78 - *col : len;
+ str = string_catn(str, payload, chomp);
+ *col += chomp;
+ payload += chomp;
+ }
+
+return str;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+/* Signing: create signature header
+*/
+static uschar *
+pdkim_create_header(pdkim_signature * sig, BOOL final)
+{
+uschar * base64_bh;
+uschar * base64_b;
+int col = 0;
+gstring * hdr;
+gstring * canon_all;
+
+canon_all = string_cat (NULL, pdkim_canons[sig->canon_headers]);
+canon_all = string_catn(canon_all, US"/", 1);
+canon_all = string_cat (canon_all, pdkim_canons[sig->canon_body]);
+(void) string_from_gstring(canon_all);
+
+hdr = string_cat(NULL, US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
+col = hdr->ptr;
+
+/* Required and static bits */
+hdr = pdkim_headcat(&col, hdr, US";", US"a=", dkim_sig_to_a_tag(sig));
+hdr = pdkim_headcat(&col, hdr, US";", US"q=", pdkim_querymethods[sig->querymethod]);
+hdr = pdkim_headcat(&col, hdr, US";", US"c=", canon_all->s);
+hdr = pdkim_headcat(&col, hdr, US";", US"d=", sig->domain);
+hdr = pdkim_headcat(&col, hdr, US";", US"s=", sig->selector);
+
+/* list of header names can be split between items. */
+ {
+ uschar * n = string_copy(sig->headernames);
+ uschar * i = US"h=";
+ uschar * s = US";";
+
+ while (*n)
+ {
+ uschar * c = Ustrchr(n, ':');
+
+ if (c) *c ='\0';
+
+ if (!i)
+ hdr = pdkim_headcat(&col, hdr, NULL, NULL, US":");
+
+ hdr = pdkim_headcat(&col, hdr, s, i, n);
+
+ if (!c)
+ break;
+
+ n = c+1;
+ s = NULL;
+ i = NULL;
+ }
+ }
+
+base64_bh = pdkim_encode_base64(&sig->calc_body_hash->bh);
+hdr = pdkim_headcat(&col, hdr, US";", US"bh=", base64_bh);
+
+/* Optional bits */
+if (sig->identity)
+ hdr = pdkim_headcat(&col, hdr, US";", US"i=", sig->identity);
+
+if (sig->created > 0)
+ {
+ uschar minibuf[21];
+
+ snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
+ hdr = pdkim_headcat(&col, hdr, US";", US"t=", minibuf);
+}
+
+if (sig->expires > 0)
+ {
+ uschar minibuf[21];
+
+ snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
+ hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf);
+ }
+
+if (sig->bodylength >= 0)
+ {
+ uschar minibuf[21];
+
+ snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
+ hdr = pdkim_headcat(&col, hdr, US";", US"l=", minibuf);
+ }
+
+/* Preliminary or final version? */
+if (final)
+ {
+ base64_b = pdkim_encode_base64(&sig->sighash);
+ hdr = pdkim_headcat(&col, hdr, US";", US"b=", base64_b);
+
+ /* add trailing semicolon: I'm not sure if this is actually needed */
+ hdr = pdkim_headcat(&col, hdr, NULL, US";", US"");
+ }
+else
+ {
+ /* To satisfy the rule "all surrounding whitespace [...] deleted"
+ ( RFC 6376 section 3.7 ) we ensure there is no whitespace here. Otherwise
+ the headcat routine could insert a linebreak which the relaxer would reduce
+ to a single space preceding the terminating semicolon, resulting in an
+ incorrect header-hash. */
+ hdr = pdkim_headcat(&col, hdr, US";", US"b=;", US"");
+ }
+
+return string_from_gstring(hdr);
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+/* According to draft-ietf-dcrup-dkim-crypto-07 "keys are 256 bits" (referring
+to DNS, hence the pubkey). Check for more than 32 bytes; if so assume the
+alternate possible representation (still) being discussed: a
+SubjectPublickeyInfo wrapped key - and drop all but the trailing 32-bytes (it
+should be a DER, with exactly 12 leading bytes - but we could accept a BER also,
+which could be any size). We still rely on the crypto library for checking for
+undersize.
+
+When the RFC is published this should be re-addressed. */
+
+static void
+check_bare_ed25519_pubkey(pdkim_pubkey * p)
+{
+int excess = p->key.len - 32;
+if (excess > 0)
+ {
+ DEBUG(D_acl)
+ debug_printf("DKIM: unexpected pubkey len %lu\n", (unsigned long) p->key.len);
+ p->key.data += excess; p->key.len = 32;
+ }
+}
+
+
+static pdkim_pubkey *
+pdkim_key_from_dns(pdkim_ctx * ctx, pdkim_signature * sig, ev_ctx * vctx,
+ const uschar ** errstr)
+{
+uschar * dns_txt_name, * dns_txt_reply;
+pdkim_pubkey * p;
+
+/* Fetch public key for signing domain, from DNS */
+
+dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain);
+
+if ( !(dns_txt_reply = ctx->dns_txt_callback(dns_txt_name))
+ || dns_txt_reply[0] == '\0'
+ )
+ {
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
+ return NULL;
+ }
+
+DEBUG(D_acl)
+ {
+ debug_printf(
+ "DKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
+ " %s\n"
+ " Raw record: %Z\n",
+ dns_txt_name,
+ CUS dns_txt_reply);
+ }
+
+if ( !(p = pdkim_parse_pubkey_record(CUS dns_txt_reply))
+ || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0)
+ )
+ {
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
+
+ DEBUG(D_acl)
+ {
+ if (p)
+ debug_printf(" Invalid public key service type '%s'\n", p->srvtype);
+ else
+ debug_printf(" Error while parsing public key record\n");
+ debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ }
+ return NULL;
+ }
+
+DEBUG(D_acl) debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+
+/* Import public key */
+
+/* Normally we use the signature a= tag to tell us the pubkey format.
+When signing under debug we do a test-import of the pubkey, and at that
+time we do not have a signature so we must interpret the pubkey k= tag
+instead. Assume writing on the sig is ok in that case. */
+
+if (sig->keytype < 0)
+ if ((sig->keytype = pdkim_keyname_to_keytype(p->keytype)) < 0)
+ {
+ DEBUG(D_acl) debug_printf("verify_init: unhandled keytype %s\n", p->keytype);
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
+ return NULL;
+ }
+
+if (sig->keytype == KEYTYPE_ED25519)
+ check_bare_ed25519_pubkey(p);
+
+if ((*errstr = exim_dkim_verify_init(&p->key,
+ sig->keytype == KEYTYPE_ED25519 ? KEYFMT_ED25519_BARE : KEYFMT_DER,
+ vctx, &sig->keybits)))
+ {
+ DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr);
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
+ return NULL;
+ }
+
+vctx->keytype = sig->keytype;
+return p;
+}
+
+
+/* -------------------------------------------------------------------------- */
+/* Sort and filter the sigs developed from the message */
+
+static pdkim_signature *
+sort_sig_methods(pdkim_signature * siglist)
+{
+pdkim_signature * yield, ** ss;
+const uschar * prefs;
+uschar * ele;
+int sep;
+
+if (!siglist) return NULL;
+
+/* first select in order of hashtypes */
+DEBUG(D_acl) debug_printf("DKIM: dkim_verify_hashes '%s'\n", dkim_verify_hashes);
+for (prefs = dkim_verify_hashes, sep = 0, yield = NULL, ss = &yield;
+ ele = string_nextinlist(&prefs, &sep, NULL, 0); )
+ {
+ int i = pdkim_hashname_to_hashtype(CUS ele, 0);
+ for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s;
+ s = next)
+ {
+ next = s->next;
+ if (s->hashtype == i)
+ { *prev = next; s->next = NULL; *ss = s; ss = &s->next; }
+ else
+ prev = &s->next;
+ }
+ }
+
+/* then in order of keytypes */
+siglist = yield;
+DEBUG(D_acl) debug_printf("DKIM: dkim_verify_keytypes '%s'\n", dkim_verify_keytypes);
+for (prefs = dkim_verify_keytypes, sep = 0, yield = NULL, ss = &yield;
+ ele = string_nextinlist(&prefs, &sep, NULL, 0); )
+ {
+ int i = pdkim_keyname_to_keytype(CUS ele);
+ for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s;
+ s = next)
+ {
+ next = s->next;
+ if (s->keytype == i)
+ { *prev = next; s->next = NULL; *ss = s; ss = &s->next; }
+ else
+ prev = &s->next;
+ }
+ }
+
+DEBUG(D_acl) for (pdkim_signature * s = yield; s; s = s->next)
+ debug_printf(" retain d=%s s=%s a=%s\n",
+ s->domain, s->selector, dkim_sig_to_a_tag(s));
+return yield;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+DLLEXPORT int
+pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures,
+ const uschar ** err)
+{
+BOOL verify_pass = FALSE;
+
+/* Check if we must still flush a (partial) header. If that is the
+ case, the message has no body, and we must compute a body hash
+ out of '<CR><LF>' */
+if (ctx->cur_header && ctx->cur_header->ptr > 0)
+ {
+ blob * rnl = NULL;
+ int rc;
+
+ if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK)
+ return rc;
+
+ for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
+ rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl);
+ if (rnl) store_free(rnl);
+ }
+else
+ DEBUG(D_acl) debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+
+/* Build (and/or evaluate) body hash. Do this even if no DKIM sigs, in case we
+have a hash to do for ARC. */
+
+pdkim_finish_bodyhash(ctx);
+
+/* Sort and filter the recived signatures */
+
+if (!(ctx->flags & PDKIM_MODE_SIGN))
+ ctx->sig = sort_sig_methods(ctx->sig);
+
+if (!ctx->sig)
+ {
+ DEBUG(D_acl) debug_printf("DKIM: no signatures\n");
+ *return_signatures = NULL;
+ return PDKIM_OK;
+ }
+
+for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
+ {
+ hctx hhash_ctx;
+ uschar * sig_hdr = US"";
+ blob hhash;
+ gstring * hdata = NULL;
+ es_ctx sctx;
+
+ if ( !(ctx->flags & PDKIM_MODE_SIGN)
+ && sig->verify_status == PDKIM_VERIFY_FAIL)
+ {
+ DEBUG(D_acl)
+ debug_printf("DKIM: [%s] abandoning this signature\n", sig->domain);
+ continue;
+ }
+
+ /*XXX The hash of the headers is needed for GCrypt (for which we can do RSA
+ signing only, as it happens) and for either GnuTLS and OpenSSL when we are
+ signing with EC (specifically, Ed25519). The former is because the GCrypt
+ signing operation is pure (does not do its own hash) so we must hash. The
+ latter is because we (stupidly, but this is what the IETF draft is saying)
+ must hash with the declared hash method, then pass the result to the library
+ hash-and-sign routine (because that's all the libraries are providing. And
+ we're stuck with whatever that hidden hash method is, too). We may as well
+ do this hash incrementally.
+ We don't need the hash we're calculating here for the GnuTLS and OpenSSL
+ cases of RSA signing, since those library routines can do hash-and-sign.
+
+ Some time in the future we could easily avoid doing the hash here for those
+ cases (which will be common for a long while. We could also change from
+ the current copy-all-the-headers-into-one-block, then call the hash-and-sign
+ implementation - to a proper incremental one. Unfortunately, GnuTLS just
+ cannot do incremental - either signing or verification. Unsure about GCrypt.
+ */
+
+ /*XXX The header hash is also used (so far) by the verify operation */
+
+ if (!exim_sha_init(&hhash_ctx, pdkim_hashes[sig->hashtype].exim_hashmethod))
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "DKIM: hash setup error, possibly nonhandled hashtype");
+ break;
+ }
+
+ if (ctx->flags & PDKIM_MODE_SIGN)
+ DEBUG(D_acl) debug_printf(
+ "DKIM >> Headers to be signed: >>>>>>>>>>>>\n"
+ " %s\n",
+ sig->sign_headers);
+
+ DEBUG(D_acl) debug_printf(
+ "DKIM >> Header data for hash, canonicalized (%-7s), in sequence >>\n",
+ pdkim_canons[sig->canon_headers]);
+
+
+ /* SIGNING ---------------------------------------------------------------- */
+ /* When signing, walk through our header list and add them to the hash. As we
+ go, construct a list of the header's names to use for the h= parameter.
+ Then append to that list any remaining header names for which there was no
+ header to sign. */
+
+ if (ctx->flags & PDKIM_MODE_SIGN)
+ {
+ gstring * g = NULL;
+ const uschar * l;
+ uschar * s;
+ int sep = 0;
+
+ /* Import private key, including the keytype which we need for building
+ the signature header */
+
+ if ((*err = exim_dkim_signing_init(CUS sig->privkey, &sctx)))
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "signing_init: %s", *err);
+ return PDKIM_ERR_RSA_PRIVKEY;
+ }
+ sig->keytype = sctx.keytype;
+
+ sig->headernames = NULL; /* Collected signed header names */
+ for (pdkim_stringlist * p = sig->headers; p; p = p->next)
+ {
+ uschar * rh = p->value;
+
+ if (header_name_match(rh, sig->sign_headers) == PDKIM_OK)
+ {
+ /* Collect header names (Note: colon presence is guaranteed here) */
+ g = string_append_listele_n(g, ':', rh, Ustrchr(rh, ':') - rh);
+
+ if (sig->canon_headers == PDKIM_CANON_RELAXED)
+ rh = pdkim_relax_header(rh, TRUE); /* cook header for relaxed canon */
+
+ /* Feed header to the hash algorithm */
+ exim_sha_update_string(&hhash_ctx, CUS rh);
+
+ /* Remember headers block for signing (when the library cannot do incremental) */
+ /*XXX we could avoid doing this for all but the GnuTLS/RSA case */
+ hdata = exim_dkim_data_append(hdata, rh);
+
+ DEBUG(D_acl) debug_printf("%Z\n", rh);
+ }
+ }
+
+ /* Any headers we wanted to sign but were not present must also be listed.
+ Ignore elements that have been ticked-off or are marked as never-oversign. */
+
+ l = sig->sign_headers;
+ while((s = string_nextinlist(&l, &sep, NULL, 0)))
+ {
+ if (*s == '+') /* skip oversigning marker */
+ s++;
+ if (*s != '_' && *s != '=')
+ g = string_append_listele(g, ':', s);
+ }
+ sig->headernames = string_from_gstring(g);
+
+ /* Create signature header with b= omitted */
+ sig_hdr = pdkim_create_header(sig, FALSE);
+ }
+
+ /* VERIFICATION ----------------------------------------------------------- */
+ /* When verifying, walk through the header name list in the h= parameter and
+ add the headers to the hash in that order. */
+ else
+ {
+ uschar * p = sig->headernames;
+ uschar * q;
+
+ if (p)
+ {
+ /* clear tags */
+ for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
+ hdrs->tag = 0;
+
+ p = string_copy(p);
+ while(1)
+ {
+ if ((q = Ustrchr(p, ':')))
+ *q = '\0';
+
+ /*XXX walk the list of headers in same order as received. */
+ for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
+ if ( hdrs->tag == 0
+ && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0
+ && (hdrs->value)[Ustrlen(p)] == ':'
+ )
+ {
+ /* cook header for relaxed canon, or just copy it for simple */
+
+ uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
+ ? pdkim_relax_header(hdrs->value, TRUE)
+ : string_copy(CUS hdrs->value);
+
+ /* Feed header to the hash algorithm */
+ exim_sha_update_string(&hhash_ctx, CUS rh);
+
+ DEBUG(D_acl) debug_printf("%Z\n", rh);
+ hdrs->tag = 1;
+ break;
+ }
+
+ if (!q) break;
+ p = q+1;
+ }
+
+ sig_hdr = string_copy(sig->rawsig_no_b_val);
+ }
+ }
+
+ DEBUG(D_acl) debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+
+ DEBUG(D_acl)
+ {
+ debug_printf(
+ "DKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n");
+ debug_printf("%Z\n", CUS sig_hdr);
+ debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ }
+
+ /* Relax header if necessary */
+ if (sig->canon_headers == PDKIM_CANON_RELAXED)
+ sig_hdr = pdkim_relax_header(sig_hdr, FALSE);
+
+ DEBUG(D_acl)
+ {
+ debug_printf("DKIM >> Signed DKIM-Signature header, canonicalized (%-7s) >>>>>>>\n",
+ pdkim_canons[sig->canon_headers]);
+ debug_printf("%Z\n", CUS sig_hdr);
+ debug_printf(
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ }
+
+ /* Finalize header hash */
+ exim_sha_update_string(&hhash_ctx, CUS sig_hdr);
+ exim_sha_finish(&hhash_ctx, &hhash);
+
+ DEBUG(D_acl)
+ {
+ debug_printf("DKIM [%s] Header %s computed: ",
+ sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname);
+ debug_printf("%.*H\n", hhash.len, hhash.data);
+ }
+
+ /* Remember headers block for signing (when the signing library cannot do
+ incremental) */
+ if (ctx->flags & PDKIM_MODE_SIGN)
+ hdata = exim_dkim_data_append(hdata, US sig_hdr);
+
+ /* SIGNING ---------------------------------------------------------------- */
+ if (ctx->flags & PDKIM_MODE_SIGN)
+ {
+ hashmethod hm = sig->keytype == KEYTYPE_ED25519
+#if defined(SIGN_OPENSSL)
+ ? HASH_NULL
+#else
+ ? HASH_SHA2_512
+#endif
+ : pdkim_hashes[sig->hashtype].exim_hashmethod;
+
+#ifdef SIGN_HAVE_ED25519
+ /* For GCrypt, and for EC, we pass the hash-of-headers to the signing
+ routine. For anything else we just pass the headers. */
+
+ if (sig->keytype != KEYTYPE_ED25519)
+#endif
+ {
+ hhash.data = hdata->s;
+ hhash.len = hdata->ptr;
+ }
+
+ if ((*err = exim_dkim_sign(&sctx, hm, &hhash, &sig->sighash)))
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "signing: %s", *err);
+ return PDKIM_ERR_RSA_SIGNING;
+ }
+
+ DEBUG(D_acl)
+ {
+ debug_printf( "DKIM [%s] b computed: ", sig->domain);
+ debug_printf("%.*H\n", sig->sighash.len, sig->sighash.data);
+ }
+
+ sig->signature_header = pdkim_create_header(sig, TRUE);
+ }
+
+ /* VERIFICATION ----------------------------------------------------------- */
+ else
+ {
+ ev_ctx vctx;
+ hashmethod hm;
+
+ /* Make sure we have all required signature tags */
+ if (!( sig->domain && *sig->domain
+ && sig->selector && *sig->selector
+ && sig->headernames && *sig->headernames
+ && sig->bodyhash.data
+ && sig->sighash.data
+ && sig->keytype >= 0
+ && sig->hashtype >= 0
+ && sig->version
+ ) )
+ {
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
+
+ DEBUG(D_acl) debug_printf(
+ " Error in DKIM-Signature header: tags missing or invalid (%s)\n"
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n",
+ !(sig->domain && *sig->domain) ? "d="
+ : !(sig->selector && *sig->selector) ? "s="
+ : !(sig->headernames && *sig->headernames) ? "h="
+ : !sig->bodyhash.data ? "bh="
+ : !sig->sighash.data ? "b="
+ : sig->keytype < 0 || sig->hashtype < 0 ? "a="
+ : "v="
+ );
+ goto NEXT_VERIFY;
+ }
+
+ /* Make sure sig uses supported DKIM version (only v1) */
+ if (sig->version != 1)
+ {
+ sig->verify_status = PDKIM_VERIFY_INVALID;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
+
+ DEBUG(D_acl) debug_printf(
+ " Error in DKIM-Signature header: unsupported DKIM version\n"
+ "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ goto NEXT_VERIFY;
+ }
+
+ DEBUG(D_acl)
+ {
+ debug_printf( "DKIM [%s] b from mail: ", sig->domain);
+ debug_printf("%.*H\n", sig->sighash.len, sig->sighash.data);
+ }
+
+ if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err)))
+ {
+ log_write(0, LOG_MAIN, "DKIM: %s%s %s%s [failed key import]",
+ sig->domain ? "d=" : "", sig->domain ? sig->domain : US"",
+ sig->selector ? "s=" : "", sig->selector ? sig->selector : US"");
+ goto NEXT_VERIFY;
+ }
+
+ /* If the pubkey limits to a list of specific hashes, ignore sigs that
+ do not have the hash part of the sig algorithm matching */
+
+ if (sig->pubkey->hashes)
+ {
+ const uschar * list = sig->pubkey->hashes, * ele;
+ int sep = ':';
+ while ((ele = string_nextinlist(&list, &sep, NULL, 0)))
+ if (Ustrcmp(ele, pdkim_hashes[sig->hashtype].dkim_hashname) == 0) break;
+ if (!ele)
+ {
+ DEBUG(D_acl) debug_printf("pubkey h=%s vs. sig a=%s_%s\n",
+ sig->pubkey->hashes,
+ pdkim_keytypes[sig->keytype],
+ pdkim_hashes[sig->hashtype].dkim_hashname);
+ sig->verify_status = PDKIM_VERIFY_FAIL;
+ sig->verify_ext_status = PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH;
+ goto NEXT_VERIFY;
+ }
+ }
+
+ hm = sig->keytype == KEYTYPE_ED25519
+#if defined(SIGN_OPENSSL)
+ ? HASH_NULL
+#else
+ ? HASH_SHA2_512
+#endif
+ : pdkim_hashes[sig->hashtype].exim_hashmethod;
+
+ /* Check the signature */
+
+ if ((*err = exim_dkim_verify(&vctx, hm, &hhash, &sig->sighash)))
+ {
+ DEBUG(D_acl) debug_printf("headers verify: %s\n", *err);
+ sig->verify_status = PDKIM_VERIFY_FAIL;
+ sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE;
+ goto NEXT_VERIFY;
+ }
+ if (*dkim_verify_min_keysizes)
+ {
+ unsigned minbits;
+ const uschar * ss = expand_getkeyed(US pdkim_keytypes[sig->keytype],
+ dkim_verify_min_keysizes);
+ if (ss && (minbits = atoi(CCS ss)) > sig->keybits)
+ {
+ DEBUG(D_acl) debug_printf("Key too short: Actual: %s %u Minima '%s'\n",
+ pdkim_keytypes[sig->keytype], sig->keybits, dkim_verify_min_keysizes);
+ sig->verify_status = PDKIM_VERIFY_FAIL;
+ sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE;
+ }
+ }
+
+
+ /* We have a winner! (if bodyhash was correct earlier) */
+ if (sig->verify_status == PDKIM_VERIFY_NONE)
+ {
+ sig->verify_status = PDKIM_VERIFY_PASS;
+ verify_pass = TRUE;
+ /*XXX We used to "break" here if dkim_verify_minimal, but that didn't
+ stop the ACL being called. So move that test. Unfortunately, we
+ need to eval all the sigs here only to possibly ignore some later,
+ because we don't know what verify options might say.
+ Could we change to a later eval of the sig?
+ Both bits are called from receive_msg().
+ Moving the test is also suboptimal for the case of no ACL (or no
+ signers to check!) so keep it for that case, but after debug output */
+ }
+
+NEXT_VERIFY:
+ DEBUG(D_acl)
+ {
+ debug_printf("DKIM [%s] %s signature status: %s",
+ sig->domain, dkim_sig_to_a_tag(sig),
+ pdkim_verify_status_str(sig->verify_status));
+ if (sig->verify_ext_status > 0)
+ debug_printf(" (%s)\n",
+ pdkim_verify_ext_status_str(sig->verify_ext_status));
+ else
+ debug_printf("\n");
+ }
+
+ if ( verify_pass && dkim_verify_minimal
+ && !(acl_smtp_dkim && dkim_verify_signers && *dkim_verify_signers))
+ break;
+ }
+ }
+
+/* If requested, set return pointer to signature(s) */
+if (return_signatures)
+ *return_signatures = ctx->sig;
+
+return ctx->flags & PDKIM_MODE_SIGN || verify_pass
+ ? PDKIM_OK : PDKIM_FAIL;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+DLLEXPORT pdkim_ctx *
+pdkim_init_verify(uschar * (*dns_txt_callback)(const uschar *), BOOL dot_stuffing)
+{
+pdkim_ctx * ctx;
+
+ctx = store_get(sizeof(pdkim_ctx), GET_UNTAINTED);
+memset(ctx, 0, sizeof(pdkim_ctx));
+
+if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM;
+/* The line-buffer is for message data, hence tainted */
+ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, GET_TAINTED);
+ctx->dns_txt_callback = dns_txt_callback;
+ctx->cur_header = string_get_tainted(36, GET_TAINTED);
+
+return ctx;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+DLLEXPORT pdkim_signature *
+pdkim_init_sign(pdkim_ctx * ctx,
+ uschar * domain, uschar * selector, uschar * privkey,
+ uschar * hashname, const uschar ** errstr)
+{
+int hashtype;
+pdkim_signature * sig;
+
+if (!domain || !selector || !privkey)
+ return NULL;
+
+/* Allocate & init one signature struct */
+
+sig = store_get(sizeof(pdkim_signature), GET_UNTAINTED);
+memset(sig, 0, sizeof(pdkim_signature));
+
+sig->bodylength = -1;
+
+sig->domain = string_copy(US domain);
+sig->selector = string_copy(US selector);
+sig->privkey = string_copy(US privkey);
+sig->keytype = -1;
+
+for (hashtype = 0; hashtype < nelem(pdkim_hashes); hashtype++)
+ if (Ustrcmp(hashname, pdkim_hashes[hashtype].dkim_hashname) == 0)
+ { sig->hashtype = hashtype; break; }
+if (hashtype >= nelem(pdkim_hashes))
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "DKIM: unrecognised hashname '%s'", hashname);
+ return NULL;
+ }
+
+DEBUG(D_acl)
+ {
+ pdkim_signature s = *sig;
+ ev_ctx vctx;
+
+ debug_printf("DKIM (checking verify key)>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
+ if (!pdkim_key_from_dns(ctx, &s, &vctx, errstr))
+ debug_printf("WARNING: bad dkim key in dns\n");
+ debug_printf("DKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+ }
+return sig;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+DLLEXPORT void
+pdkim_set_optional(pdkim_signature * sig,
+ char * sign_headers,
+ char * identity,
+ int canon_headers,
+ int canon_body,
+ long bodylength,
+ unsigned long created,
+ unsigned long expires)
+{
+if (identity)
+ sig->identity = string_copy(US identity);
+
+sig->sign_headers = string_copy(sign_headers
+ ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
+
+sig->canon_headers = canon_headers;
+sig->canon_body = canon_body;
+sig->bodylength = bodylength;
+sig->created = created;
+sig->expires = expires;
+
+return;
+}
+
+
+
+/* Set up a blob for calculating the bodyhash according to the
+given needs. Use an existing one if possible, or create a new one.
+
+Return: hashblob pointer, or NULL on error
+*/
+pdkim_bodyhash *
+pdkim_set_bodyhash(pdkim_ctx * ctx, int hashtype, int canon_method,
+ long bodylength)
+{
+pdkim_bodyhash * b;
+
+if (hashtype == -1 || canon_method == -1) return NULL;
+
+if (!ctx)
+ {
+ DEBUG(D_receive) debug_printf("pdkim_set_bodyhash: null context\n");
+ return NULL;
+ }
+
+for (b = ctx->bodyhash; b; b = b->next)
+ if ( hashtype == b->hashtype
+ && canon_method == b->canon_method
+ && bodylength == b->bodylength)
+ {
+ DEBUG(D_receive) debug_printf("DKIM: using existing bodyhash %s/%s/%ld\n",
+ pdkim_hashes[hashtype].dkim_hashname, pdkim_canons[canon_method], bodylength);
+ return b;
+ }
+
+DEBUG(D_receive) debug_printf("DKIM: new bodyhash %s/%s/%ld\n",
+ pdkim_hashes[hashtype].dkim_hashname, pdkim_canons[canon_method], bodylength);
+b = store_get(sizeof(pdkim_bodyhash), GET_UNTAINTED);
+b->next = ctx->bodyhash;
+b->hashtype = hashtype;
+b->canon_method = canon_method;
+b->bodylength = bodylength;
+if (!exim_sha_init(&b->body_hash_ctx, /*XXX hash method: extend for sha512 */
+ pdkim_hashes[hashtype].exim_hashmethod))
+ {
+ DEBUG(D_acl)
+ debug_printf("DKIM: hash init error, possibly nonhandled hashtype\n");
+ return NULL;
+ }
+b->signed_body_bytes = 0;
+b->num_buffered_blanklines = 0;
+ctx->bodyhash = b;
+return b;
+}
+
+
+/* Set up a blob for calculating the bodyhash according to the
+needs of this signature. Use an existing one if possible, or
+create a new one.
+
+Return: hashblob pointer, or NULL on error (only used as a boolean).
+*/
+pdkim_bodyhash *
+pdkim_set_sig_bodyhash(pdkim_ctx * ctx, pdkim_signature * sig)
+{
+pdkim_bodyhash * b = pdkim_set_bodyhash(ctx,
+ sig->hashtype, sig->canon_body, sig->bodylength);
+sig->calc_body_hash = b;
+return b;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+
+void
+pdkim_init_context(pdkim_ctx * ctx, BOOL dot_stuffed,
+ uschar * (*dns_txt_callback)(const uschar *))
+{
+memset(ctx, 0, sizeof(pdkim_ctx));
+ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
+/* The line buffer is for message data, hence tainted */
+ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, GET_TAINTED);
+DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback;
+}
+
+
+void
+pdkim_init(void)
+{
+exim_dkim_signers_init();
+}
+
+
+
+#endif /*DISABLE_DKIM*/
git://git.exim.org / exim.git / commitdiff