X-Git-Url: https://vcs.fsf.org/?p=exim.git;a=blobdiff_plain;f=src%2Fsrc%2Fpdkim%2Fpdkim.c;h=c75b0ae78a96bed3f299f09718a5f620ccc85329;hp=695288162740d0598e7f4caab42c7110908ef38d;hb=9631be11ff85fbdfe1bd8a745d9b0de2bef1af4b;hpb=d5b80e59458182b2d557a929a18cb8c70cd56b68

diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index 695288162..c75b0ae78 100644
--- a/src/src/pdkim/pdkim.c
+++ b/src/src/pdkim/pdkim.c
@@ -2,7 +2,7 @@
  *  PDKIM - a RFC4871 (DKIM) implementation
  *
  *  Copyright (C) 2009 - 2016  Tom Kistner <tom@duncanthrax.net>
- *  Copyright (C) 2016 - 2017  Jeremy Harris <jgh@exim.org>
+ *  Copyright (C) 2016 - 2018  Jeremy Harris <jgh@exim.org>
  *
  *  http://duncanthrax.net/pdkim/
  *
@@ -51,14 +51,6 @@
 #define PDKIM_MAX_HEADERS           512
 #define PDKIM_MAX_BODY_LINE_LEN     16384
 #define PDKIM_DNS_TXT_MAX_NAMELEN   1024
-#define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
-                             "Message-ID:To:Cc:MIME-Version:Content-Type:"\
-                             "Content-Transfer-Encoding:Content-ID:"\
-                             "Content-Description:Resent-Date:Resent-From:"\
-                             "Resent-Sender:Resent-To:Resent-Cc:"\
-                             "Resent-Message-ID:In-Reply-To:References:"\
-                             "List-Id:List-Help:List-Unsubscribe:"\
-                             "List-Subscribe:List-Post:List-Owner:List-Archive"
 
 /* -------------------------------------------------------------------------- */
 struct pdkim_stringlist {
@@ -90,13 +82,22 @@ static const pdkim_hashtype pdkim_hashes[] = {
 };
 
 const uschar * pdkim_keytypes[] = {
-  US"rsa"
+  [KEYTYPE_RSA] =	US"rsa",
+#ifdef SIGN_HAVE_ED25519
+  [KEYTYPE_ED25519] =	US"ed25519",		/* Works for 3.6.0 GnuTLS */
+#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;
+  const uschar *	str;
+  int			canon_headers;
+  int			canon_body;
 } pdkim_combined_canon_entry;
 
 pdkim_combined_canon_entry pdkim_combined_canons[] = {
@@ -163,9 +164,9 @@ switch(status)
   {
   case PDKIM_OK:		return US"OK";
   case PDKIM_FAIL:		return US"FAIL";
-  case PDKIM_ERR_RSA_PRIVKEY:	return US"RSA_PRIVKEY";
-  case PDKIM_ERR_RSA_SIGNING:	return US"RSA SIGNING";
-  case PDKIM_ERR_LONG_LINE:	return US"RSA_LONG_LINE";
+  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_SIGN_PRIVKEY_WRAP:	return US"PRIVKEY_WRAP";
   case PDKIM_SIGN_PRIVKEY_B64D:	return US"PRIVKEY_B64D";
@@ -229,18 +230,20 @@ return new_entry;
 /* Trim whitespace fore & aft */
 
 static void
-pdkim_strtrim(uschar * str)
+pdkim_strtrim(gstring * str)
 {
-uschar * p = str;
-uschar * q = str;
-while (*p == '\t' || *p == ' ') p++;		/* skip whitespace */
-while (*p) {*q = *p; q++; p++;}			/* dump the leading whitespace */
-*q = '\0';
-while (q != str && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) )
-  {						/* dump trailing whitespace */
-  *q = '\0';
-  q--;
-  }
+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);
 }
 
 
@@ -256,16 +259,19 @@ 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. Returns OK or fail-code */
-/*XXX might be safer done using a pdkim_stringlist for "tick" */
+   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)
 {
-uschar * hname;
-uschar * lcopy;
-uschar * p;
-uschar * q;
+const uschar * ticklist = tick;
+int sep = ':';
+BOOL multisign;
+uschar * hname, * p, * ele;
 uschar * hcolon = Ustrchr(header, ':');		/* Get header name */
 
 if (!hcolon)
@@ -274,27 +280,22 @@ if (!hcolon)
 /* if we had strncmpic() we wouldn't need this copy */
 hname = string_copyn(header, hcolon-header);
 
-/* Copy tick-off list locally, so we can punch zeroes into it */
-p = lcopy = string_copy(tick);
-
-for (q = Ustrchr(p, ':'); q; q = Ustrchr(p, ':'))
+while (p = US ticklist, ele = string_nextinlist(&ticklist, &sep, NULL, 0))
   {
-  *q = '\0';
-  if (strcmpic(p, hname) == 0)
-    goto found;
-
-  p = q+1;
+  switch (*ele)
+  {
+  case '=': case '+':	multisign = TRUE; ele++; break;
+  default:		multisign = FALSE; break;
   }
 
-if (strcmpic(p, hname) == 0)
-  goto found;
-
+  if (strcmpic(ele, hname) == 0)
+    {
+    if (!multisign)
+      *p = '_';	/* Invalidate this header name instance in tick-off list */
+    return PDKIM_OK;
+    }
+  }
 return PDKIM_FAIL;
-
-found:
-  /* Invalidate header name instance in tick-off list */
-  tick[p-lcopy] = '_';
-  return PDKIM_OK;
 }
 
 
@@ -432,8 +433,8 @@ pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr)
 {
 pdkim_signature * sig;
 uschar *p, *q;
-uschar * cur_tag = NULL; int ts = 0, tl = 0;
-uschar * cur_val = NULL; int vs = 0, vl = 0;
+gstring * cur_tag = NULL;
+gstring * cur_val = NULL;
 BOOL past_hname = FALSE;
 BOOL in_b_val = FALSE;
 int where = PDKIM_HDR_LIMBO;
@@ -477,12 +478,11 @@ for (p = raw_hdr; ; p++)
   if (where == PDKIM_HDR_TAG)
     {
     if (c >= 'a' && c <= 'z')
-      cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
+      cur_tag = string_catn(cur_tag, p, 1);
 
     if (c == '=')
       {
-      cur_tag[tl] = '\0';
-      if (Ustrcmp(cur_tag, "b") == 0)
+      if (Ustrcmp(string_from_gstring(cur_tag), "b") == 0)
         {
 	*q++ = '=';
 	in_b_val = TRUE;
@@ -499,83 +499,104 @@ for (p = raw_hdr; ; p++)
 
     if (c == ';' || c == '\0')
       {
-      if (tl && vl)
+      /* 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')
+	 )
         {
-	cur_val[vl] = '\0';
+	(void) string_from_gstring(cur_val);
 	pdkim_strtrim(cur_val);
 
-	DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
+	DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag->s, cur_val->s);
 
-	switch (*cur_tag)
+	switch (*cur_tag->s)
 	  {
-	  case 'b':
-	    pdkim_decode_base64(cur_val,
-			    cur_tag[1] == 'h' ? &sig->bodyhash : &sig->sighash);
+	  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)
+			   pdkim_decode_base64(cur_val->s, &sig->bodyhash);
+			 break;
+	      default:   break;
+	      }
 	    break;
-	  case 'v':
+	  case 'v':					/* version */
 	      /* We only support version 1, and that is currently the
 		 only version there is. */
 	    sig->version =
-	      Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
+	      Ustrcmp(cur_val->s, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
 	    break;
-	  case 'a':
+	  case 'a':					/* algorithm */
 	    {
-	    uschar * s = Ustrchr(cur_val, '-');
+	    uschar * s = Ustrchr(cur_val->s, '-');
 
 	    for(i = 0; i < nelem(pdkim_keytypes); i++)
-	      if (Ustrncmp(cur_val, pdkim_keytypes[i], s - cur_val) == 0)
+	      if (Ustrncmp(cur_val->s, pdkim_keytypes[i], s - cur_val->s) == 0)
 		{ sig->keytype = i; break; }
+	    if (sig->keytype < 0)
+	      log_write(0, LOG_MAIN,
+		"DKIM: ignoring signature due to nonhandled keytype in a=%s",
+		cur_val->s);
+
 	    for (++s, i = 0; i < nelem(pdkim_hashes); i++)
 	      if (Ustrcmp(s, pdkim_hashes[i].dkim_hashname) == 0)
 		{ sig->hashtype = i; break; }
+	    if (sig->hashtype < 0)
+	      log_write(0, LOG_MAIN,
+		"DKIM: ignoring signature due to nonhandled hashtype in a=%s",
+		cur_val->s);
 	    break;
 	    }
 
-	  case 'c':
+	  case 'c':					/* canonicalization */
 	    for (i = 0; pdkim_combined_canons[i].str; i++)
-	      if (Ustrcmp(cur_val, pdkim_combined_canons[i].str) == 0)
+	      if (Ustrcmp(cur_val->s, pdkim_combined_canons[i].str) == 0)
 	        {
 		sig->canon_headers = pdkim_combined_canons[i].canon_headers;
 		sig->canon_body    = pdkim_combined_canons[i].canon_body;
 		break;
 		}
 	    break;
-	  case 'q':
+	  case 'q':				/* Query method (for pubkey)*/
 	    for (i = 0; pdkim_querymethods[i]; i++)
-	      if (Ustrcmp(cur_val, pdkim_querymethods[i]) == 0)
+	      if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0)
 	        {
-		sig->querymethod = i;
+		sig->querymethod = i;	/* we never actually use this */
 		break;
 		}
 	    break;
-	  case 's':
-	    sig->selector = string_copy(cur_val); break;
-	  case 'd':
-	    sig->domain = string_copy(cur_val); break;
-	  case 'i':
-	    sig->identity = pdkim_decode_qp(cur_val); break;
-	  case 't':
-	    sig->created = strtoul(CS cur_val, NULL, 10); break;
-	  case 'x':
-	    sig->expires = strtoul(CS cur_val, NULL, 10); break;
-	  case 'l':
-	    sig->bodylength = strtol(CS cur_val, NULL, 10); break;
-	  case 'h':
-	    sig->headernames = string_copy(cur_val); break;
-	  case 'z':
-	    sig->copiedheaders = pdkim_decode_qp(cur_val); break;
+	  case 's':					/* Selector */
+	    sig->selector = string_copyn(cur_val->s, cur_val->ptr); break;
+	  case 'd':					/* SDID */
+	    sig->domain = string_copyn(cur_val->s, cur_val->ptr); 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_copyn(cur_val->s, cur_val->ptr); 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:
 	    DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
 	    break;
 	  }
 	}
-      tl = 0;
-      vl = 0;
+      cur_tag = cur_val = NULL;
       in_b_val = FALSE;
       where = PDKIM_HDR_LIMBO;
       }
     else
-      cur_val = string_catn(cur_val, &vs, &vl, p, 1);
+      cur_val = string_catn(cur_val, p, 1);
     }
 
 NEXT_CHAR:
@@ -586,6 +607,9 @@ NEXT_CHAR:
     *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'))
@@ -602,14 +626,9 @@ DEBUG(D_acl)
 	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
   }
 
-/*XXX hash method: extend for sha512 */
-if (!exim_sha_init(&sig->body_hash_ctx,
-	       pdkim_hashes[sig->hashtype].exim_hashmethod))
-  {
-  DEBUG(D_acl)
-    debug_printf("PDKIM: hash init error, possibly nonhandled hashtype\n");
+if (!pdkim_set_bodyhash(ctx, sig))
   return NULL;
-  }
+
 return sig;
 }
 
@@ -639,7 +658,7 @@ while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0)))
       {
       case 'v': pub->version = val;			break;
       case 'h': pub->hashes = val;			break;
-      case 'k': 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;
@@ -653,7 +672,8 @@ while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0)))
   }
 
 /* Set fallback defaults */
-if (!pub->version    ) pub->version     = string_copy(PDKIM_PUB_RECORD_VERSION);
+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");
@@ -661,9 +681,7 @@ else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0)
   }
 
 if (!pub->granularity) pub->granularity = US"*";
-/*
 if (!pub->keytype    ) pub->keytype     = US"rsa";
-*/
 if (!pub->srvtype    ) pub->srvtype     = US"*";
 
 /* p= is required */
@@ -677,29 +695,22 @@ return NULL;
 
 /* -------------------------------------------------------------------------- */
 
-/* Update the bodyhash for one sig, with some additional data.
+/* Update one bodyhash with some additional data.
 If we have to relax the data for this sig, return our copy of it. */
 
-/*XXX Currently we calculate a hash for each sig.  But it is possible
-that multi-signing will be wanted using different signing algos
-(rsa, ec) using the same hash and canonicalization.  Consider in future
-hanging the hash+cacnon from the ctx and only referencing from the sig,
-so that it can be calculated only once - being over the body this
-caould be meagbytes, hence expensive. */
-
 static blob *
-pdkim_update_sig_bodyhash(pdkim_signature * sig, blob * orig_data, blob * relaxed_data)
+pdkim_update_ctx_bodyhash(pdkim_bodyhash * b, blob * orig_data, blob * relaxed_data)
 {
 blob * canon_data = orig_data;
 /* Defaults to simple canon (no further treatment necessary) */
 
-if (sig->canon_body == PDKIM_CANON_RELAXED)
+if (b->canon_method == PDKIM_CANON_RELAXED)
   {
   /* Relax the line if not done already */
   if (!relaxed_data)
     {
     BOOL seen_wsp = FALSE;
-    const uschar * p;
+    const uschar * p, * r;
     int q = 0;
 
     /* We want to be able to free this else we allocate
@@ -710,7 +721,7 @@ if (sig->canon_body == PDKIM_CANON_RELAXED)
     relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1);
     relaxed_data->data = US (relaxed_data+1);
 
-    for (p = orig_data->data; *p; p++)
+    for (p = orig_data->data, r = p + orig_data->len; p < r; p++)
       {
       char c = *p;
       if (c == '\r')
@@ -736,15 +747,15 @@ if (sig->canon_body == PDKIM_CANON_RELAXED)
   }
 
 /* Make sure we don't exceed the to-be-signed body length */
-if (  sig->bodylength >= 0
-   && sig->signed_body_bytes + (unsigned long)canon_data->len > sig->bodylength
+if (  b->bodylength >= 0
+   && b->signed_body_bytes + (unsigned long)canon_data->len > b->bodylength
    )
-  canon_data->len = sig->bodylength - sig->signed_body_bytes;
+  canon_data->len = b->bodylength - b->signed_body_bytes;
 
 if (canon_data->len > 0)
   {
-  exim_sha_update(&sig->body_hash_ctx, CUS canon_data->data, canon_data->len);
-  sig->signed_body_bytes += canon_data->len;
+  exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, canon_data->len);
+  b->signed_body_bytes += canon_data->len;
   DEBUG(D_acl) pdkim_quoteprint(canon_data->data, canon_data->len);
   }
 
@@ -757,32 +768,32 @@ return relaxed_data;
 static void
 pdkim_finish_bodyhash(pdkim_ctx * ctx)
 {
+pdkim_bodyhash * b;
 pdkim_signature * sig;
 
+for (b = ctx->bodyhash; b; b = b->next)		/* Finish hashes */
+  exim_sha_finish(&b->body_hash_ctx, &b->bh);
+
 /* Traverse all signatures */
 for (sig = ctx->sig; sig; sig = sig->next)
-  {					/* Finish hashes */
-  blob bh;
-
-  exim_sha_finish(&sig->body_hash_ctx, &bh);
+  {
+  b = sig->calc_body_hash;
 
   DEBUG(D_acl)
     {
-    debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
+    debug_printf("PDKIM [%s] Body bytes (%s) hashed: %lu\n"
 		 "PDKIM [%s] Body %s computed: ",
-		sig->domain, sig->signed_body_bytes,
-		sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname);
-    pdkim_hexprint(CUS bh.data, bh.len);
+	sig->domain, pdkim_canons[b->canon_method], b->signed_body_bytes,
+	sig->domain, pdkim_hashes[b->hashtype].dkim_hashname);
+    pdkim_hexprint(CUS b->bh.data, b->bh.len);
     }
 
   /* SIGNING -------------------------------------------------------------- */
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
-    sig->bodyhash = bh;
-
     /* If bodylength limit is set, and we have received less bytes
        than the requested amount, effectively remove the limit tag. */
-    if (sig->signed_body_bytes < sig->bodylength)
+    if (b->signed_body_bytes < sig->bodylength)
       sig->bodylength = -1;
     }
 
@@ -790,9 +801,10 @@ for (sig = ctx->sig; sig; sig = sig->next)
   /* VERIFICATION --------------------------------------------------------- */
   /* Be careful that the header sig included a bodyash */
 
-    if (sig->bodyhash.data && memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
+    if (  sig->bodyhash.data
+       && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0)
       {
-      DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
+      DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash compared OK\n", sig->domain);
       }
     else
       {
@@ -813,7 +825,7 @@ for (sig = ctx->sig; sig; sig = sig->next)
 static void
 pdkim_body_complete(pdkim_ctx * ctx)
 {
-pdkim_signature * sig;
+pdkim_bodyhash * b;
 
 /* In simple body mode, if any empty lines were buffered,
 replace with one. rfc 4871 3.4.3 */
@@ -821,12 +833,12 @@ replace with one. rfc 4871 3.4.3 */
 it indicates that all linebreaks should be buffered, including
 the one terminating a text line */
 
-for (sig = ctx->sig; sig; sig = sig->next)
-  if (  sig->canon_body == PDKIM_CANON_SIMPLE
-     && sig->signed_body_bytes == 0
-     && sig->num_buffered_blanklines > 0
+for (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_sig_bodyhash(sig, &lineending, NULL);
+    (void) pdkim_update_ctx_bodyhash(b, &lineending, NULL);
 
 ctx->flags |= PDKIM_SEEN_EOD;
 ctx->linebuf_offset = 0;
@@ -836,12 +848,13 @@ 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};
-pdkim_signature * sig;
+pdkim_bodyhash * b;
 blob * rnl = NULL;
 blob * rline = NULL;
 
@@ -865,14 +878,14 @@ if (ctx->flags & PDKIM_DOT_TERM)
 /* Empty lines need to be buffered until we find a non-empty line */
 if (memcmp(line.data, "\r\n", 2) == 0)
   {
-  for (sig = ctx->sig; sig; sig = sig->next) sig->num_buffered_blanklines++;
+  for (b = ctx->bodyhash; b; b = b->next) b->num_buffered_blanklines++;
   goto all_skip;
   }
 
-/* Process line for each sig separately */
-for (sig = ctx->sig; sig; sig = sig->next)
+/* Process line for each bodyhash separately */
+for (b = ctx->bodyhash; b; b = b->next)
   {
-  if (sig->canon_body == PDKIM_CANON_RELAXED)
+  if (b->canon_method == PDKIM_CANON_RELAXED)
     {
     /* Lines with just spaces need to be buffered too */
     uschar * cp = line.data;
@@ -881,25 +894,25 @@ for (sig = ctx->sig; sig; sig = sig->next)
     while ((c = *cp))
       {
       if (c == '\r' && cp[1] == '\n') break;
-      if (c != ' ' && c != '\t') goto sig_process;
+      if (c != ' ' && c != '\t') goto hash_process;
       cp++;
       }
 
-    sig->num_buffered_blanklines++;
-    goto sig_skip;
+    b->num_buffered_blanklines++;
+    goto hash_skip;
     }
 
-sig_process:
+hash_process:
   /* At this point, we have a non-empty line, so release the buffered ones. */
 
-  while (sig->num_buffered_blanklines)
+  while (b->num_buffered_blanklines)
     {
-    rnl = pdkim_update_sig_bodyhash(sig, &lineending, rnl);
-    sig->num_buffered_blanklines--;
+    rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl);
+    b->num_buffered_blanklines--;
     }
 
-  rline = pdkim_update_sig_bodyhash(sig, &line, rline);
-sig_skip: ;
+  rline = pdkim_update_ctx_bodyhash(b, &line, rline);
+hash_skip: ;
   }
 
 if (rnl) store_free(rnl);
@@ -922,10 +935,10 @@ pdkim_header_complete(pdkim_ctx * ctx)
 pdkim_signature * sig, * last_sig;
 
 /* Special case: The last header can have an extra \r appended */
-if ( (ctx->cur_header_len > 1) &&
-     (ctx->cur_header[(ctx->cur_header_len)-1] == '\r') )
-  --ctx->cur_header_len;
-ctx->cur_header[ctx->cur_header_len] = '\0';
+if ( (ctx->cur_header->ptr > 1) &&
+     (ctx->cur_header->s[ctx->cur_header->ptr-1] == '\r') )
+  --ctx->cur_header->ptr;
+(void) string_from_gstring(ctx->cur_header);
 
 if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
 
@@ -934,8 +947,7 @@ if (ctx->flags & PDKIM_MODE_SIGN)
   for (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);
+    sig->headers = pdkim_prepend_stringlist(sig->headers, ctx->cur_header->s);
 
 /* VERIFICATION ----------------------------------------------------------- */
 /* DKIM-Signature: headers are added to the verification list */
@@ -945,10 +957,10 @@ else
   DEBUG(D_acl)
     {
     debug_printf("PDKIM >> raw hdr: ");
-    pdkim_quoteprint(CUS ctx->cur_header, ctx->cur_header_len);
+    pdkim_quoteprint(CUS ctx->cur_header->s, ctx->cur_header->ptr);
     }
 #endif
-  if (strncasecmp(CCS ctx->cur_header,
+  if (strncasecmp(CCS ctx->cur_header->s,
 		  DKIM_SIGNATURE_HEADERNAME,
 		  Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
     {
@@ -959,7 +971,7 @@ else
     DEBUG(D_acl) debug_printf(
 	"PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
 
-    sig = pdkim_parse_sig_header(ctx, ctx->cur_header);
+    sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s);
 
     if (!(last_sig = ctx->sig))
       ctx->sig = sig;
@@ -971,11 +983,11 @@ else
     }
 
   /* all headers are stored for signature verification */
-  ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
+  ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s);
   }
 
 BAIL:
-ctx->cur_header[ctx->cur_header_len = 0] = '\0';	/* leave buffer for reuse */
+ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0';	/* leave buffer for reuse */
 return PDKIM_OK;
 }
 
@@ -1027,8 +1039,7 @@ else for (p = 0; p<len; p++)
     else if (c == '\n')
       {
       if (!(ctx->flags & PDKIM_SEEN_CR))		/* emulate the CR */
-	ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size,
-				&ctx->cur_header_len, CUS "\r", 1);
+	ctx->cur_header = string_catn(ctx->cur_header, CUS "\r", 1);
 
       if (ctx->flags & PDKIM_SEEN_LF)		/* Seen last header line */
 	{
@@ -1051,9 +1062,8 @@ else for (p = 0; p<len; p++)
       ctx->flags &= ~PDKIM_SEEN_LF;
       }
 
-    if (ctx->cur_header_len < PDKIM_MAX_HEADER_LEN)
-      ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size,
-				  &ctx->cur_header_len, CUS &data[p], 1);
+    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;
@@ -1061,12 +1071,12 @@ return PDKIM_OK;
 
 
 
-/* Extend a grwong header with a continuation-linebreak */
-static uschar *
-pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col)
+/* Extend a growing header with a continuation-linebreak */
+static gstring *
+pdkim_hdr_cont(gstring * str, int * col)
 {
 *col = 1;
-return string_catn(str, size, ptr, US"\r\n\t", 3);
+return string_catn(str, US"\r\n\t", 3);
 }
 
 
@@ -1080,8 +1090,6 @@ return string_catn(str, size, ptr, US"\r\n\t", 3);
  *
  * col: this int holds and receives column number (octets since last '\n')
  * str: partial string to append to
- * size: current buffer size for str
- * ptr: current tail-pointer for str
  * pad: padding, split line or space after before or after eg: ";"
  * intro: - must join to payload eg "h=", usually the tag name
  * payload: eg base64 data - long data can be split arbitrarily.
@@ -1095,8 +1103,8 @@ return string_catn(str, size, ptr, US"\r\n\t", 3);
  * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
  */
 
-static uschar *
-pdkim_headcat(int * col, uschar * str, int * size, int * ptr,
+static gstring *
+pdkim_headcat(int * col, gstring * str,
   const uschar * pad, const uschar * intro, const uschar * payload)
 {
 size_t l;
@@ -1105,8 +1113,8 @@ if (pad)
   {
   l = Ustrlen(pad);
   if (*col + l > 78)
-    str = pdkim_hdr_cont(str, size, ptr, col);
-  str = string_catn(str, size, ptr, pad, l);
+    str = pdkim_hdr_cont(str, col);
+  str = string_catn(str, pad, l);
   *col += l;
   }
 
@@ -1114,7 +1122,7 @@ l = (pad?1:0) + (intro?Ustrlen(intro):0);
 
 if (*col + l > 78)
   { /*can't fit intro - start a new line to make room.*/
-  str = pdkim_hdr_cont(str, size, ptr, col);
+  str = pdkim_hdr_cont(str, col);
   l = intro?Ustrlen(intro):0;
   }
 
@@ -1124,7 +1132,7 @@ while (l>77)
   { /* this fragment will not fit on a single line */
   if (pad)
     {
-    str = string_catn(str, size, ptr, US" ", 1);
+    str = string_catn(str, US" ", 1);
     *col += 1;
     pad = NULL; /* only want this once */
     l--;
@@ -1134,7 +1142,7 @@ while (l>77)
     {
     size_t sl = Ustrlen(intro);
 
-    str = string_catn(str, size, ptr, intro, sl);
+    str = string_catn(str, intro, sl);
     *col += sl;
     l -= sl;
     intro = NULL; /* only want this once */
@@ -1145,25 +1153,25 @@ while (l>77)
     size_t sl = Ustrlen(payload);
     size_t chomp = *col+sl < 77 ? sl : 78-*col;
 
-    str = string_catn(str, size, ptr, payload, chomp);
+    str = string_catn(str, payload, chomp);
     *col += chomp;
     payload += chomp;
     l -= chomp-1;
     }
 
   /* the while precondition tells us it didn't fit. */
-  str = pdkim_hdr_cont(str, size, ptr, col);
+  str = pdkim_hdr_cont(str, col);
   }
 
 if (*col + l > 78)
   {
-  str = pdkim_hdr_cont(str, size, ptr, col);
+  str = pdkim_hdr_cont(str, col);
   pad = NULL;
   }
 
 if (pad)
   {
-  str = string_catn(str, size, ptr, US" ", 1);
+  str = string_catn(str, US" ", 1);
   *col += 1;
   pad = NULL;
   }
@@ -1172,7 +1180,7 @@ if (intro)
   {
   size_t sl = Ustrlen(intro);
 
-  str = string_catn(str, size, ptr, intro, sl);
+  str = string_catn(str, intro, sl);
   *col += sl;
   l -= sl;
   intro = NULL;
@@ -1182,7 +1190,7 @@ if (payload)
   {
   size_t sl = Ustrlen(payload);
 
-  str = string_catn(str, size, ptr, payload, sl);
+  str = string_catn(str, payload, sl);
   *col += sl;
   }
 
@@ -1192,37 +1200,31 @@ 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;
-uschar * hdr;       int hdr_size = 0, hdr_len = 0;
-uschar * canon_all; int can_size = 0, can_len = 0;
+gstring * hdr;
+gstring * canon_all;
 
-canon_all = string_cat (NULL, &can_size, &can_len,
-		      pdkim_canons[sig->canon_headers]);
-canon_all = string_catn(canon_all, &can_size, &can_len, US"/", 1);
-canon_all = string_cat (canon_all, &can_size, &can_len,
-		      pdkim_canons[sig->canon_body]);
-canon_all[can_len] = '\0';
+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, &hdr_size, &hdr_len,
-		      US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
-col = hdr_len;
+hdr = string_cat(NULL, US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
+col = hdr->ptr;
 
 /* Required and static bits */
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=",
-		    dkim_sig_to_a_tag(sig));
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=",
-		    pdkim_querymethods[sig->querymethod]);
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"c=",
-		    canon_all);
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=",
-		    sig->domain);
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
-		    sig->selector);
+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. */
   {
@@ -1237,9 +1239,9 @@ hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
     if (c) *c ='\0';
 
     if (!i)
-      hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":");
+      hdr = pdkim_headcat(&col, hdr, NULL, NULL, US":");
 
-    hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n);
+    hdr = pdkim_headcat(&col, hdr, s, i, n);
 
     if (!c)
       break;
@@ -1250,19 +1252,19 @@ hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
     }
   }
 
-base64_bh = pdkim_encode_base64(&sig->bodyhash);
-hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh);
+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, &hdr_size, &hdr_len, US";", US"i=", sig->identity);
+  hdr = pdkim_headcat(&col, hdr, US";", US"i=", sig->identity);
 
 if (sig->created > 0)
   {
   uschar minibuf[20];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
-  hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf);
+  hdr = pdkim_headcat(&col, hdr, US";", US"t=", minibuf);
 }
 
 if (sig->expires > 0)
@@ -1270,7 +1272,7 @@ if (sig->expires > 0)
   uschar minibuf[20];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
-  hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf);
+  hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf);
   }
 
 if (sig->bodylength >= 0)
@@ -1278,17 +1280,17 @@ if (sig->bodylength >= 0)
   uschar minibuf[20];
 
   snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
-  hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf);
+  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, &hdr_size, &hdr_len, US";", US"b=", base64_b);
+  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, &hdr_size, &hdr_len, NULL, US";", US"");
+  hdr = pdkim_headcat(&col, hdr, NULL, US";", US"");
   }
 else
   {
@@ -1297,11 +1299,10 @@ else
   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, &hdr_size, &hdr_len, US";", US"b=;", US"");
+  hdr = pdkim_headcat(&col, hdr, US";", US"b=;", US"");
   }
 
-hdr[hdr_len] = '\0';
-return hdr;
+return string_from_gstring(hdr);
 }
 
 
@@ -1318,10 +1319,7 @@ pdkim_pubkey * p;
 
 dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain);
 
-dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN);
-memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN);
-
-if (  ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK 
+if (  !(dns_txt_reply = ctx->dns_txt_callback(CS dns_txt_name))
    || dns_txt_reply[0] == '\0'
    )
   {
@@ -1363,7 +1361,10 @@ DEBUG(D_acl) debug_printf(
       "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
 
 /* Import public key */
-if ((*errstr = exim_dkim_verify_init(&p->key, vctx)))
+
+if ((*errstr = exim_dkim_verify_init(&p->key,
+	    sig->keytype == KEYTYPE_ED25519 ? KEYFMT_ED25519_BARE : KEYFMT_DER,
+	    vctx)))
   {
   DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr);
   sig->verify_status =      PDKIM_VERIFY_INVALID;
@@ -1371,6 +1372,7 @@ if ((*errstr = exim_dkim_verify_init(&p->key, vctx)))
   return NULL;
   }
 
+vctx->keytype = sig->keytype;
 return p;
 }
 
@@ -1381,12 +1383,14 @@ DLLEXPORT int
 pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures,
   const uschar ** err)
 {
+pdkim_bodyhash * b;
 pdkim_signature * sig;
+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_len)
+if (ctx->cur_header && ctx->cur_header->ptr > 0)
   {
   blob * rnl = NULL;
   int rc;
@@ -1394,14 +1398,20 @@ if (ctx->cur_header && ctx->cur_header_len)
   if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK)
     return rc;
 
-  for (sig = ctx->sig; sig; sig = sig->next)
-    rnl = pdkim_update_sig_bodyhash(sig, &lineending, rnl);
+  for (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(
       "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
 
+if (!ctx->sig)
+  {
+  DEBUG(D_acl) debug_printf("PDKIM: no signatures\n");
+  return PDKIM_OK;
+  }
+
 /* Build (and/or evaluate) body hash */
 pdkim_finish_bodyhash(ctx);
 
@@ -1410,16 +1420,34 @@ for (sig = ctx->sig; sig; sig = sig->next)
   hctx hhash_ctx;
   uschar * sig_hdr = US"";
   blob hhash;
-  blob hdata;
-  int hdata_alloc = 0;
-
-  hdata.data = NULL;
-  hdata.len = 0;
+  gstring * hdata = NULL;
+  es_ctx sctx;
+
+  /*XXX The hash of the headers is needed for GCrypt (for which we can do RSA
+  suging 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))
     {
-    DEBUG(D_acl)
-      debug_printf("PDKIM: hash setup error, possibly nonhandled hashtype\n");
+    log_write(0, LOG_MAIN|LOG_PANIC,
+      "PDKIM: hash setup error, possibly nonhandled hashtype");
     break;
     }
 
@@ -1430,7 +1458,8 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	sig->sign_headers);
 
   DEBUG(D_acl) debug_printf(
-      "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>\n");
+      "PDKIM >> Header data for hash, canonicalized (%-7s), in sequence >>\n",
+	pdkim_canons[sig->canon_headers]);
 
 
   /* SIGNING ---------------------------------------------------------------- */
@@ -1441,23 +1470,32 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
-    int hs = 0, hl = 0;
+    gstring * g = NULL;
     pdkim_stringlist *p;
     const uschar * l;
     uschar * s;
     int sep = 0;
 
-    sig->headernames = NULL;		/* Collected signed header names */
+    /* Import private key, including the keytype which we need for building
+    the signature header  */
 
-    for (p = sig->headers; p; p = p->next)
+/*XXX extend for non-RSA algos */
+    if ((*err = exim_dkim_signing_init(US sig->privkey, &sctx)))
+      {
+      log_write(0, LOG_MAIN|LOG_PANIC, "signing_init: %s", *err);
+      return PDKIM_ERR_RSA_PRIVKEY;
+      }
+    sig->keytype = sctx.keytype;
+
+    for (sig->headernames = NULL,		/* Collected signed header names */
+	  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) */
-	sig->headernames = string_append_listele_n(sig->headernames, &hs, &hl,
-				':', rh, Ustrchr(rh, ':') - rh);
+	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 */
@@ -1466,18 +1504,25 @@ for (sig = ctx->sig; sig; sig = sig->next)
 	exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
 
 	/* Remember headers block for signing (when the library cannot do incremental)  */
-	(void) exim_dkim_data_append(&hdata, &hdata_alloc, rh);
+	/*XXX we could avoid doing this for all but the GnuTLS/RSA case */
+	hdata = exim_dkim_data_append(hdata, rh);
 
 	DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
 	}
       }
 
-    /* Any headers we wanted to sign but were not present must also be listed */
+    /* 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 != '_')
-	sig->headernames = string_append_listele(sig->headernames, &hs, &hl, ':', s);
-    sig->headernames[hl] = '\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);
@@ -1551,8 +1596,8 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
   DEBUG(D_acl)
     {
-    debug_printf(
-	    "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
+    debug_printf("PDKIM >> Signed DKIM-Signature header, canonicalized (%-7s) >>>>>>>\n",
+	    pdkim_canons[sig->canon_headers]);
     pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
     debug_printf(
 	    "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
@@ -1572,35 +1617,30 @@ for (sig = ctx->sig; sig; sig = sig->next)
   /* Remember headers block for signing (when the signing library cannot do
   incremental)  */
   if (ctx->flags & PDKIM_MODE_SIGN)
-    (void) exim_dkim_data_append(&hdata, &hdata_alloc, US sig_hdr);
+    hdata = exim_dkim_data_append(hdata, US sig_hdr);
 
   /* SIGNING ---------------------------------------------------------------- */
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
-    es_ctx sctx;
+    hashmethod hm = sig->keytype == KEYTYPE_ED25519
+      ? HASH_SHA2_512 : pdkim_hashes[sig->hashtype].exim_hashmethod;
 
-    /* Import private key, including the keytype */
-/*XXX extend for non-RSA algos */
-    if ((*err = exim_dkim_signing_init(US sig->privkey, &sctx)))
-      {
-      DEBUG(D_acl) debug_printf("signing_init: %s\n", *err);
-      return PDKIM_ERR_RSA_PRIVKEY;
-      }
-
-    /* Do signing.  With OpenSSL we are signing the hash of headers just
-    calculated, with GnuTLS we have to sign an entire block of headers
-    (due to available interfaces) and it recalculates the hash internally. */
+#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 defined(SIGN_OPENSSL) || defined(SIGN_GCRYPT)
-    hdata = hhash;
+    if (sig->keytype != KEYTYPE_ED25519)
 #endif
+      {
+      hhash.data = hdata->s;
+      hhash.len = hdata->ptr;
+      }
 
 /*XXX extend for non-RSA algos */
-    if ((*err = exim_dkim_sign(&sctx,
-		  pdkim_hashes[sig->hashtype].exim_hashmethod,
-		  &hdata, &sig->sighash)))
+/*- done for GnuTLS */
+    if ((*err = exim_dkim_sign(&sctx, hm, &hhash, &sig->sighash)))
       {
-      DEBUG(D_acl) debug_printf("signing: %s\n", *err);
+      log_write(0, LOG_MAIN|LOG_PANIC, "signing: %s", *err);
       return PDKIM_ERR_RSA_SIGNING;
       }
 
@@ -1657,7 +1697,12 @@ for (sig = ctx->sig; sig; sig = sig->next)
       }
 
     if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err)))
+      {
+      log_write(0, LOG_MAIN, "PDKIM: %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 */
@@ -1681,10 +1726,11 @@ for (sig = ctx->sig; sig; sig = sig->next)
       }
 
     /* Check the signature */
-/*XXX needs extension for non-RSA */
+/*XXX extend for non-RSA algos */
+/*- done for GnuTLS */
     if ((*err = exim_dkim_verify(&vctx,
-		  pdkim_hashes[sig->hashtype].exim_hashmethod,
-		  &hhash, &sig->sighash)))
+				pdkim_hashes[sig->hashtype].exim_hashmethod,
+				&hhash, &sig->sighash)))
       {
       DEBUG(D_acl) debug_printf("headers verify: %s\n", *err);
       sig->verify_status =      PDKIM_VERIFY_FAIL;
@@ -1695,14 +1741,18 @@ for (sig = ctx->sig; sig; sig = sig->next)
 
     /* 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;
+      }
 
 NEXT_VERIFY:
 
     DEBUG(D_acl)
       {
-      debug_printf("PDKIM [%s] signature status: %s",
-	      sig->domain, pdkim_verify_status_str(sig->verify_status));
+      debug_printf("PDKIM [%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));
@@ -1716,14 +1766,15 @@ NEXT_VERIFY:
 if (return_signatures)
   *return_signatures = ctx->sig;
 
-return PDKIM_OK;
+return ctx->flags & PDKIM_MODE_SIGN  ||  verify_pass
+  ? PDKIM_OK : PDKIM_FAIL;
 }
 
 
 /* -------------------------------------------------------------------------- */
 
 DLLEXPORT pdkim_ctx *
-pdkim_init_verify(int(*dns_txt_callback)(char *, char *), BOOL dot_stuffing)
+pdkim_init_verify(uschar * (*dns_txt_callback)(char *), BOOL dot_stuffing)
 {
 pdkim_ctx * ctx;
 
@@ -1740,8 +1791,6 @@ return ctx;
 
 /* -------------------------------------------------------------------------- */
 
-/*XXX ? needs extension to cover non-RSA algo?  */
-
 DLLEXPORT pdkim_signature *
 pdkim_init_sign(pdkim_ctx * ctx,
   uschar * domain, uschar * selector, uschar * privkey,
@@ -1763,22 +1812,15 @@ sig->bodylength = -1;
 sig->domain = string_copy(US domain);
 sig->selector = string_copy(US selector);
 sig->privkey = string_copy(US privkey);
-/*XXX no keytype yet; comes from 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))
   {
-  DEBUG(D_acl)
-    debug_printf("PDKIM: unrecognised hashname '%s'\n", hashname);
-  return NULL;
-  }
-
-if (!exim_sha_init(&sig->body_hash_ctx, pdkim_hashes[hashtype].exim_hashmethod))
-  {
-  DEBUG(D_acl)
-    debug_printf("PDKIM: hash setup error, possibly nonhandled hashtype\n");
+  log_write(0, LOG_MAIN|LOG_PANIC,
+    "PDKIM: unrecognised hashname '%s'", hashname);
   return NULL;
   }
 
@@ -1825,9 +1867,51 @@ return;
 
 
 
+/* 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_bodyhash(pdkim_ctx * ctx, pdkim_signature * sig)
+{
+pdkim_bodyhash * b;
+
+for (b = ctx->bodyhash; b; b = b->next)
+  if (  sig->hashtype == b->hashtype
+     && sig->canon_body == b->canon_method
+     && sig->bodylength == b->bodylength)
+    goto old;
+
+b = store_get(sizeof(pdkim_bodyhash));
+b->next = ctx->bodyhash;
+b->hashtype = sig->hashtype;
+b->canon_method = sig->canon_body;
+b->bodylength = sig->bodylength;
+if (!exim_sha_init(&b->body_hash_ctx,		/*XXX hash method: extend for sha512 */
+		  pdkim_hashes[sig->hashtype].exim_hashmethod))
+  {
+  DEBUG(D_acl)
+    debug_printf("PDKIM: hash init error, possibly nonhandled hashtype\n");
+  return NULL;
+  }
+b->signed_body_bytes = 0;
+b->num_buffered_blanklines = 0;
+ctx->bodyhash = b;
+
+old:
+sig->calc_body_hash = b;
+return b;
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+
 void
 pdkim_init_context(pdkim_ctx * ctx, BOOL dot_stuffed,
-  int(*dns_txt_callback)(char *, char *))
+  uschar * (*dns_txt_callback)(char *))
 {
 memset(ctx, 0, sizeof(pdkim_ctx));
 ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;