X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/4dc2379ac1ab6c21f265abed06dd9aaa214976af..78a3bbd585b7ee0961dee45163c36904a419388b:/src/src/pdkim/pdkim.c

diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index 7bfcdf4aa..e4384d7f7 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  Jeremy Harris <jgh@exim.org>
+ *  Copyright (C) 2016 - 2017  Jeremy Harris <jgh@exim.org>
  *
  *  http://duncanthrax.net/pdkim/
  *
@@ -142,19 +142,19 @@ switch(ext_status)
   }
 }
 
-const char *
+const uschar *
 pdkim_errstr(int status)
 {
 switch(status)
   {
-  case PDKIM_OK:		return "OK";
-  case PDKIM_FAIL:		return "FAIL";
-  case PDKIM_ERR_RSA_PRIVKEY:	return "RSA_PRIVKEY";
-  case PDKIM_ERR_RSA_SIGNING:	return "RSA SIGNING";
-  case PDKIM_ERR_LONG_LINE:	return "RSA_LONG_LINE";
-  case PDKIM_ERR_BUFFER_TOO_SMALL:	return "BUFFER_TOO_SMALL";
-  case PDKIM_SIGN_PRIVKEY_WRAP:	return "PRIVKEY_WRAP";
-  case PDKIM_SIGN_PRIVKEY_B64D:	return "PRIVKEY_B64D";
+  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_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";
   default: return "(unknown)";
   }
 }
@@ -192,7 +192,8 @@ static void
 pdkim_hexprint(const uschar *data, int len)
 {
 int i;
-for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
+if (data) for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
+else debug_printf("<NULL>");
 debug_printf("\n");
 }
 
@@ -415,7 +416,7 @@ return b64encode(b->data, b->len);
 static pdkim_signature *
 pdkim_parse_sig_header(pdkim_ctx *ctx, uschar * raw_hdr)
 {
-pdkim_signature *sig ;
+pdkim_signature * sig;
 uschar *p, *q;
 uschar * cur_tag = NULL; int ts = 0, tl = 0;
 uschar * cur_val = NULL; int vs = 0, vl = 0;
@@ -493,10 +494,8 @@ for (p = raw_hdr; ; p++)
 	switch (*cur_tag)
 	  {
 	  case 'b':
-	    if (cur_tag[1] == 'h')
-	      pdkim_decode_base64(cur_val, &sig->bodyhash);
-	    else
-	      pdkim_decode_base64(cur_val, &sig->sigdata);
+	    pdkim_decode_base64(cur_val,
+			    cur_tag[1] == 'h' ? &sig->bodyhash : &sig->sighash);
 	    break;
 	  case 'v':
 	      /* We only support version 1, and that is currently the
@@ -578,12 +577,17 @@ DEBUG(D_acl)
 	  "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
   pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val));
   debug_printf(
-	  "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sigdata.len*8);
+	  "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8);
   debug_printf(
 	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
   }
 
-exim_sha_init(&sig->body_hash, sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
+if (!exim_sha_init(&sig->body_hash_ctx,
+	       sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256))
+  {
+  DEBUG(D_acl) debug_printf("PDKIM: hash init internal error\n");
+  return NULL;
+  }
 return sig;
 }
 
@@ -603,90 +607,87 @@ pub = store_get(sizeof(pdkim_pubkey));
 memset(pub, 0, sizeof(pdkim_pubkey));
 
 for (p = raw_record; ; p++)
-  {
-  char c = *p;
-
-  /* Ignore FWS */
-  if (c == '\r' || c == '\n')
-    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 >= 'a' && c <= 'z')
-      cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
+    uschar c = *p;
 
-    if (c == '=')
+    /* Ignore FWS */
+    if (c != '\r' && c != '\n') switch (where)
       {
-      cur_tag[tl] = '\0';
-      where = PDKIM_HDR_VALUE;
-      goto NEXT_CHAR;
-      }
-    }
+      case PDKIM_HDR_LIMBO:		/* In limbo, just wait for a tag-char to appear */
+	if (!(c >= 'a' && c <= 'z'))
+	  break;
+	where = PDKIM_HDR_TAG;
+	/*FALLTHROUGH*/
 
-  if (where == PDKIM_HDR_VALUE)
-    {
-    if (c == ';' || c == '\0')
-      {
-      if (tl && vl)
-        {
-	cur_val[vl] = '\0';
-	pdkim_strtrim(cur_val);
-	DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
+      case PDKIM_HDR_TAG:
+	if (c >= 'a' && c <= 'z')
+	  cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
 
-	switch (cur_tag[0])
+	if (c == '=')
 	  {
-	  case 'v':
-	    /* This tag isn't evaluated because:
-	       - We only support version DKIM1.
-	       - Which is the default for this value (set below)
-	       - Other versions are currently not specified.      */
-	    break;
-	  case 'h':
-	  case 'k':
-	    pub->hashes = string_copy(cur_val); break;
-	  case 'g':
-	    pub->granularity = string_copy(cur_val); break;
-	  case 'n':
-	    pub->notes = pdkim_decode_qp(cur_val); break;
-	  case 'p':
-	    pdkim_decode_base64(US cur_val, &pub->key);
-            break;
-	  case 's':
-	    pub->srvtype = string_copy(cur_val); break;
-	  case 't':
-	    if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1;
-	    if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1;
-	    break;
-	  default:
-	    DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
-	    break;
+	  cur_tag[tl] = '\0';
+	  where = PDKIM_HDR_VALUE;
 	  }
-	}
-      tl = 0;
-      vl = 0;
-      where = PDKIM_HDR_LIMBO;
+	break;
+
+      case PDKIM_HDR_VALUE:
+	if (c == ';' || c == '\0')
+	  {
+	  if (tl && vl)
+	    {
+	    cur_val[vl] = '\0';
+	    pdkim_strtrim(cur_val);
+	    DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
+
+	    switch (cur_tag[0])
+	      {
+	      case 'v':
+		pub->version = string_copy(cur_val); break;
+	      case 'h':
+	      case 'k':
+/* This field appears to never be used. Also, unclear why
+a 'k' (key-type_ would go in this field name.  There is a field
+"keytype", also never used.
+		pub->hashes = string_copy(cur_val);
+*/
+		break;
+	      case 'g':
+		pub->granularity = string_copy(cur_val); break;
+	      case 'n':
+		pub->notes = pdkim_decode_qp(cur_val); break;
+	      case 'p':
+		pdkim_decode_base64(US cur_val, &pub->key); break;
+	      case 's':
+		pub->srvtype = string_copy(cur_val); break;
+	      case 't':
+		if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1;
+		if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1;
+		break;
+	      default:
+		DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
+		break;
+	      }
+	    }
+	  tl = 0;
+	  vl = 0;
+	  where = PDKIM_HDR_LIMBO;
+	  }
+	else
+	  cur_val = string_catn(cur_val, &vs, &vl, p, 1);
+	break;
       }
-    else
-      cur_val = string_catn(cur_val, &vs, &vl, p, 1);
-    }
 
-NEXT_CHAR:
-  if (c == '\0') break;
-  }
+    if (c == '\0') break;
+    }
 
 /* Set fallback defaults */
 if (!pub->version    ) pub->version     = string_copy(PDKIM_PUB_RECORD_VERSION);
+else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0) return NULL;
+
 if (!pub->granularity) pub->granularity = string_copy(US"*");
+/*
 if (!pub->keytype    ) pub->keytype     = string_copy(US"rsa");
+*/
 if (!pub->srvtype    ) pub->srvtype     = string_copy(US"*");
 
 /* p= is required */
@@ -700,15 +701,14 @@ return NULL;
 /* -------------------------------------------------------------------------- */
 
 static int
-pdkim_update_bodyhash(pdkim_ctx *ctx, const char *data, int len)
+pdkim_update_bodyhash(pdkim_ctx * ctx, const char * data, int len)
 {
-pdkim_signature *sig = ctx->sig;
-/* Cache relaxed version of data */
-uschar *relaxed_data = NULL;
-int     relaxed_len  = 0;
+pdkim_signature * sig;
+uschar * relaxed_data = NULL;	/* Cache relaxed version of data */
+int relaxed_len = 0;
 
 /* Traverse all signatures, updating their hashes. */
-while (sig)
+for (sig = ctx->sig; sig; sig = sig->next)
   {
   /* Defaults to simple canon (no further treatment necessary) */
   const uschar *canon_data = CUS data;
@@ -764,12 +764,10 @@ while (sig)
 
   if (canon_len > 0)
     {
-    exim_sha_update(&sig->body_hash, CUS canon_data, canon_len);
+    exim_sha_update(&sig->body_hash_ctx, CUS canon_data, canon_len);
     sig->signed_body_bytes += canon_len;
     DEBUG(D_acl) pdkim_quoteprint(canon_data, canon_len);
     }
-
-  sig = sig->next;
   }
 
 if (relaxed_data) store_free(relaxed_data);
@@ -789,12 +787,12 @@ for (sig = ctx->sig; sig; sig = sig->next)
   {					/* Finish hashes */
   blob bh;
 
-  exim_sha_finish(&sig->body_hash, &bh);
+  exim_sha_finish(&sig->body_hash_ctx, &bh);
 
   DEBUG(D_acl)
     {
     debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
-		 "PDKIM [%s] bh  computed: ",
+		 "PDKIM [%s] Body hash computed: ",
 		sig->domain, sig->signed_body_bytes, sig->domain);
     pdkim_hexprint(CUS bh.data, bh.len);
     }
@@ -810,11 +808,11 @@ for (sig = ctx->sig; sig; sig = sig->next)
       sig->bodylength = -1;
     }
 
-  /* VERIFICATION --------------------------------------------------------- */
   else
-    {
-    /* Compare bodyhash */
-    if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
+  /* VERIFICATION --------------------------------------------------------- */
+  /* Be careful that the header sig included a bodyash */
+
+    if (sig->bodyhash.data && memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
       {
       DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
       }
@@ -822,15 +820,13 @@ for (sig = ctx->sig; sig; sig = sig->next)
       {
       DEBUG(D_acl)
         {
-	debug_printf("PDKIM [%s] bh signature: ", sig->domain);
-	pdkim_hexprint(sig->bodyhash.data,
-			 exim_sha_hashlen(&sig->body_hash));
+	debug_printf("PDKIM [%s] Body hash signature from headers: ", sig->domain);
+	pdkim_hexprint(sig->bodyhash.data, sig->bodyhash.len);
 	debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
 	}
       sig->verify_status     = PDKIM_VERIFY_FAIL;
       sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
       }
-    }
   }
 }
 
@@ -879,7 +875,7 @@ ctx->linebuf[ctx->linebuf_offset] = '\0';
 /* Terminate on EOD marker */
 if (ctx->flags & PDKIM_DOT_TERM)
   {
-  if ( memcmp(p, ".\r\n", 3) == 0)
+  if (memcmp(p, ".\r\n", 3) == 0)
     return pdkim_body_complete(ctx);
 
   /* Unstuff dots */
@@ -935,68 +931,65 @@ return PDKIM_OK;
 #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
 
 static int
-pdkim_header_complete(pdkim_ctx *ctx)
+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';
 
-ctx->num_headers++;
-if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
+if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
 
 /* SIGNING -------------------------------------------------------------- */
 if (ctx->flags & PDKIM_MODE_SIGN)
-  {
-  pdkim_signature *sig;
-
   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);
-  }
 
 /* VERIFICATION ----------------------------------------------------------- */
 /* DKIM-Signature: headers are added to the verification list */
 else
   {
+#ifdef notdef
+  DEBUG(D_acl)
+    {
+    debug_printf("PDKIM >> raw hdr: ");
+    pdkim_quoteprint(CUS ctx->cur_header, ctx->cur_header_len);
+    }
+#endif
   if (strncasecmp(CCS ctx->cur_header,
 		  DKIM_SIGNATURE_HEADERNAME,
 		  Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
     {
-    pdkim_signature *new_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. */
 
-    /* Create and chain new signature block */
     DEBUG(D_acl) debug_printf(
 	"PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
 
-    if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header)))
+    sig = pdkim_parse_sig_header(ctx, ctx->cur_header);
+
+    if (!(last_sig = ctx->sig))
+      ctx->sig = sig;
+    else
       {
-      pdkim_signature *last_sig = ctx->sig;
-      if (!last_sig)
-	ctx->sig = new_sig;
-      else
-        {
-	while (last_sig->next) last_sig = last_sig->next;
-	last_sig->next = new_sig;
-	}
+      while (last_sig->next) last_sig = last_sig->next;
+      last_sig->next = sig;
       }
-    else
-      DEBUG(D_acl) debug_printf(
-	  "Error while parsing signature header\n"
-	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
     }
 
-  /* every other header is stored for signature verification */
-  else
-    ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
+  /* all headers are stored for signature verification */
+  ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
   }
 
 BAIL:
-*ctx->cur_header = '\0';
-ctx->cur_header_len = 0;	/* leave buffer for reuse */
+ctx->cur_header[ctx->cur_header_len = 0] = '\0';	/* leave buffer for reuse */
 return PDKIM_OK;
 }
 
@@ -1008,7 +1001,7 @@ return PDKIM_OK;
 DLLEXPORT int
 pdkim_feed(pdkim_ctx *ctx, char *data, int len)
 {
-int p;
+int p, rc;
 
 /* Alternate EOD signal, used in non-dotstuffing mode */
 if (!data)
@@ -1020,45 +1013,57 @@ else for (p = 0; p<len; p++)
 
   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 == '\n')
+    if (c == '\r')
+      ctx->flags |= PDKIM_SEEN_CR;
+    else if (c == '\n')
       {
-      int rc = pdkim_bodyline_complete(ctx); /* End of line */
-      if (rc != PDKIM_OK) return rc;
+      ctx->flags &= ~PDKIM_SEEN_CR;
+      if ((rc = pdkim_bodyline_complete(ctx)) != PDKIM_OK)
+	return rc;
       }
-    if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1))
+
+    if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1)
       return PDKIM_ERR_LONG_LINE;
     }
   else
     {
     /* Processing header byte */
-    if (c != '\r')
+    if (c == '\r')
+      ctx->flags |= PDKIM_SEEN_CR;
+    else if (c == '\n')
       {
-      if (c == '\n')
-        {
-	if (ctx->flags & PDKIM_SEEN_LF)
-	  {
-	  int rc = pdkim_header_complete(ctx); /* Seen last header line */
-	  if (rc != PDKIM_OK) return rc;
+      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->flags = ctx->flags & ~PDKIM_SEEN_LF | PDKIM_PAST_HDRS;
-	  DEBUG(D_acl) debug_printf(
-	      "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>\n");
-	  continue;
-	  }
-	else
-	  ctx->flags |= PDKIM_SEEN_LF;
-	}
-      else if (ctx->flags & PDKIM_SEEN_LF)
-        {
-	if (!(c == '\t' || c == ' '))
-	  {
-	  int rc = pdkim_header_complete(ctx); /* End of header */
-	  if (rc != PDKIM_OK) return rc;
-	  }
-	ctx->flags &= ~PDKIM_SEEN_LF;
+      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(
+	    "PDKIM >> 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_len < PDKIM_MAX_HEADER_LEN)
@@ -1292,7 +1297,7 @@ if (sig->bodylength >= 0)
   }
 
 /* Preliminary or final version? */
-base64_b = final ? pdkim_encode_base64(&sig->sigdata) : US"";
+base64_b = final ? pdkim_encode_base64(&sig->sighash) : US"";
 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"b=", base64_b);
 
 /* add trailing semicolon: I'm not sure if this is actually needed */
@@ -1303,10 +1308,79 @@ return hdr;
 }
 
 
+/* -------------------------------------------------------------------------- */
+
+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);
+
+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 
+   || 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(
+    "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
+    " Raw record: ");
+  pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
+  }
+
+if (  !(p = pdkim_parse_pubkey_record(ctx, 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(
+      "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+    }
+  return NULL;
+  }
+
+DEBUG(D_acl) debug_printf(
+      "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+
+/* Import public key */
+if ((*errstr = exim_rsa_verify_init(&p->key, vctx)))
+  {
+  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;
+  }
+
+return p;
+}
+
+
 /* -------------------------------------------------------------------------- */
 
 DLLEXPORT int
-pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures)
+pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures,
+  const uschar ** err)
 {
 pdkim_signature *sig = ctx->sig;
 
@@ -1338,10 +1412,14 @@ while (sig)
   hdata.data = NULL;
   hdata.len = 0;
 
-  exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256);
+  if (!exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256))
+    {
+    DEBUG(D_acl) debug_printf("PDKIM: hask setup internal error\n");
+    break;
+    }
 
   DEBUG(D_acl) debug_printf(
-      "PDKIM >> Hashed header data, canonicalized, in sequence >>>>>>>>>>>>>>\n");
+      "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>>>\n");
 
   /* SIGNING ---------------------------------------------------------------- */
   /* When signing, walk through our header list and add them to the hash. As we
@@ -1471,7 +1549,7 @@ while (sig)
 
   DEBUG(D_acl)
     {
-    debug_printf("PDKIM [%s] hh computed: ", sig->domain);
+    debug_printf("PDKIM [%s] Header hash computed: ", sig->domain);
     pdkim_hexprint(hhash.data, hhash.len);
     }
 
@@ -1483,12 +1561,11 @@ while (sig)
   if (ctx->flags & PDKIM_MODE_SIGN)
     {
     es_ctx sctx;
-    const uschar * errstr;
 
     /* Import private key */
-    if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
+    if ((*err = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
       {
-      DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr);
+      DEBUG(D_acl) debug_printf("signing_init: %s\n", *err);
       return PDKIM_ERR_RSA_PRIVKEY;
       }
 
@@ -1500,16 +1577,16 @@ while (sig)
     hdata = hhash;
 #endif
 
-    if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata)))
+    if ((*err = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sighash)))
       {
-      DEBUG(D_acl) debug_printf("signing: %s\n", errstr);
+      DEBUG(D_acl) debug_printf("signing: %s\n", *err);
       return PDKIM_ERR_RSA_SIGNING;
       }
 
     DEBUG(D_acl)
       {
       debug_printf( "PDKIM [%s] b computed: ", sig->domain);
-      pdkim_hexprint(sig->sigdata.data, sig->sigdata.len);
+      pdkim_hexprint(sig->sighash.data, sig->sighash.len);
       }
 
     sig->signature_header = pdkim_create_header(sig, TRUE);
@@ -1519,16 +1596,13 @@ while (sig)
   else
     {
     ev_ctx vctx;
-    const uschar * errstr;
-
-    uschar *dns_txt_name, *dns_txt_reply;
 
     /* 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->sigdata.data
+	 && sig->sighash.data
 	 && sig->algo > -1
 	 && sig->version
        ) )
@@ -1554,64 +1628,20 @@ while (sig)
       goto NEXT_VERIFY;
       }
 
-    /* Fetch public key for signing domain, from DNS */
-
-    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 
-       || dns_txt_reply[0] == '\0')
-      {
-      sig->verify_status =      PDKIM_VERIFY_INVALID;
-      sig->verify_ext_status =  PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
-      goto NEXT_VERIFY;
-      }
-
-    DEBUG(D_acl)
-      {
-      debug_printf(
-          "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
-          " Raw record: ");
-      pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
-      }
-
-    if (!(sig->pubkey = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)))
-      {
-      sig->verify_status =      PDKIM_VERIFY_INVALID;
-      sig->verify_ext_status =  PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
-
-      DEBUG(D_acl) debug_printf(
-	  " Error while parsing public key record\n"
-	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
-      goto NEXT_VERIFY;
-      }
-
-    DEBUG(D_acl) debug_printf(
-	  "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
-
-    /* Import public key */
-    if ((errstr = exim_rsa_verify_init(&sig->pubkey->key, &vctx)))
-      {
-      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;
+    if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err)))
       goto NEXT_VERIFY;
-      }
 
     /* Check the signature */
-    if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata)))
+    if ((*err = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sighash)))
       {
-      DEBUG(D_acl) debug_printf("headers verify: %s\n", errstr);
+      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;
       }
 
 
-    /* We have a winner! (if bodydhash was correct earlier) */
+    /* We have a winner! (if bodyhash was correct earlier) */
     if (sig->verify_status == PDKIM_VERIFY_NONE)
       sig->verify_status = PDKIM_VERIFY_PASS;
 
@@ -1661,22 +1691,25 @@ return ctx;
 /* -------------------------------------------------------------------------- */
 
 DLLEXPORT pdkim_ctx *
-pdkim_init_sign(char *domain, char *selector, char *rsa_privkey, int algo,
-  BOOL dot_stuffed)
+pdkim_init_sign(char * domain, char * selector, char * rsa_privkey, int algo,
+  BOOL dot_stuffed, int(*dns_txt_callback)(char *, char *),
+  const uschar ** errstr)
 {
-pdkim_ctx *ctx;
-pdkim_signature *sig;
+pdkim_ctx * ctx;
+pdkim_signature * sig;
 
 if (!domain || !selector || !rsa_privkey)
   return NULL;
 
-ctx = store_get(sizeof(pdkim_ctx));
+ctx = store_get(sizeof(pdkim_ctx) + PDKIM_MAX_BODY_LINE_LEN + sizeof(pdkim_signature));
 memset(ctx, 0, sizeof(pdkim_ctx));
 
 ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
-ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
+ctx->linebuf = CS (ctx+1);
 
-sig = store_get(sizeof(pdkim_signature));
+DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback;
+
+sig = (pdkim_signature *)(ctx->linebuf + PDKIM_MAX_BODY_LINE_LEN);
 memset(sig, 0, sizeof(pdkim_signature));
 
 sig->bodylength = -1;
@@ -1687,7 +1720,23 @@ sig->selector = string_copy(US selector);
 sig->rsa_privkey = string_copy(US rsa_privkey);
 sig->algo = algo;
 
-exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
+if (!exim_sha_init(&sig->body_hash_ctx,
+	       algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256))
+  {
+  DEBUG(D_acl) debug_printf("PDKIM: hash setup internal error\n");
+  return NULL;
+  }
+
+DEBUG(D_acl)
+  {
+  pdkim_signature s = *sig;
+  ev_ctx vctx;
+
+  debug_printf("PDKIM (checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+  if (!pdkim_key_from_dns(ctx, &s, &vctx, errstr))
+    debug_printf("WARNING: bad dkim key in dns\n");
+  debug_printf("PDKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
+  }
 return ctx;
 }