exim_msgdate: more options, better perl version compatibility

[exim.git] / src / src / arc.c

diff --git a/src/src/arc.c b/src/src/arc.c
index 466c1399079d6e1e15c72459ff3b50367d388a5d..ef44672f8fb740747d3aeb5a31603cc15f1c78d7 100644 (file)
--- a/src/src/arc.c
+++ b/src/src/arc.c
@@ -2,15 +2,15 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 /* Experimental ARC support for Exim
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 /* Experimental ARC support for Exim

-   Copyright (c) Jeremy Harris 2018
+   Copyright (c) Jeremy Harris 2018 - 2020
+   Copyright (c) The Exim Maintainers 2021 - 2022

    License: GPL
    License: GPL

+   SPDX-License-Identifier: GPL-2.0-or-later

 */
 
 #include "exim.h"
 */
 
 #include "exim.h"

-#ifdef EXPERIMENTAL_ARC
-# if !defined SUPPORT_SPF
-#  error SPF must also be enabled for ARC
-# elif defined DISABLE_DKIM
+#if defined EXPERIMENTAL_ARC
+# if defined DISABLE_DKIM

 #  error DKIM must also be enabled for ARC
 # else
 
 #  error DKIM must also be enabled for ARC
 # else
 


@@ -143,7 +143,7 @@ for (pas = &ctx->arcset_chain, prev = NULL, next = ctx->arcset_chain;
   }
 
 DEBUG(D_acl) debug_printf("ARC: new instance %u\n", i);
   }
 
 DEBUG(D_acl) debug_printf("ARC: new instance %u\n", i);

-*pas = as = store_get(sizeof(arc_set));
+*pas = as = store_get(sizeof(arc_set), GET_UNTAINTED);

 memset(as, 0, sizeof(arc_set));
 as->next = next;
 as->prev = prev;
 memset(as, 0, sizeof(arc_set));
 as->next = next;
 as->prev = prev;


@@ -201,7 +201,7 @@ al->complete = h;
 
 if (!instance_only)
   {
 
 if (!instance_only)
   {

-  al->rawsig_no_b_val.data = store_get(h->slen + 1);
+  al->rawsig_no_b_val.data = store_get(h->slen + 1, GET_TAINTED);

   memcpy(al->rawsig_no_b_val.data, h->text, off);      /* copy the header name blind */
   r = al->rawsig_no_b_val.data + off;
   al->rawsig_no_b_val.len = off;
   memcpy(al->rawsig_no_b_val.data, h->text, off);      /* copy the header name blind */
   r = al->rawsig_no_b_val.data + off;
   al->rawsig_no_b_val.len = off;


@@ -260,9 +260,9 @@ while ((c = *s))
          while ((c = *++s) && c != ';')
            if (c != ' ' && c != '\t' && c != '\n' && c != '\r')
              g = string_catn(g, s, 1);
          while ((c = *++s) && c != ';')
            if (c != ' ' && c != '\t' && c != '\n' && c != '\r')
              g = string_catn(g, s, 1);

-         al->b.data = string_from_gstring(g);
-         al->b.len = g->ptr;
-         gstring_reset_unused(g);
+         if (!g) return US"no b= value";
+         al->b.len = len_string_from_gstring(g, &al->b.data);
+         gstring_release_unused(g);

          bend = s;
          break;
        case 'h':                       /* bh= AMS body hash */
          bend = s;
          break;
        case 'h':                       /* bh= AMS body hash */


@@ -276,9 +276,9 @@ while ((c = *s))
          while ((c = *++s) && c != ';')
            if (c != ' ' && c != '\t' && c != '\n' && c != '\r')
              g = string_catn(g, s, 1);
          while ((c = *++s) && c != ';')
            if (c != ' ' && c != '\t' && c != '\n' && c != '\r')
              g = string_catn(g, s, 1);

-         al->bh.data = string_from_gstring(g);
-         al->bh.len = g->ptr;
-         gstring_reset_unused(g);
+         if (!g) return US"no bh= value";
+         al->bh.len = len_string_from_gstring(g, &al->bh.data);
+         gstring_release_unused(g);

          break;
        default:
          return US"b? tag";
          break;
        default:
          return US"b? tag";


@@ -381,11 +381,11 @@ adding instances as needed and checking for duplicate lines.
 
 static uschar *
 arc_insert_hdr(arc_ctx * ctx, header_line * h, unsigned off, unsigned hoff,
 
 static uschar *
 arc_insert_hdr(arc_ctx * ctx, header_line * h, unsigned off, unsigned hoff,

-  BOOL instance_only)
+  BOOL instance_only, arc_line ** alp_ret)

 {
 unsigned i;
 arc_set * as;
 {
 unsigned i;
 arc_set * as;

-arc_line * al = store_get(sizeof(arc_line)), ** alp;
+arc_line * al = store_get(sizeof(arc_line), GET_UNTAINTED), ** alp;

 uschar * e;
 
 memset(al, 0, sizeof(arc_line));
 uschar * e;
 
 memset(al, 0, sizeof(arc_line));


@@ -401,6 +401,7 @@ if (!(as = arc_find_set(ctx, i)))   return US"set find";
 if (*(alp = (arc_line **)(US as + hoff))) return US"dup hdr";
 
 *alp = al;
 if (*(alp = (arc_line **)(US as + hoff))) return US"dup hdr";
 
 *alp = al;

+if (alp_ret) *alp_ret = al;

 return NULL;
 }
 
 return NULL;
 }
 


@@ -424,7 +425,7 @@ if (strncmpic(ARC_HDR_AAR, h->text, ARC_HDRLEN_AAR) == 0)
     debug_printf("ARC: found AAR: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AAR, offsetof(arc_set, hdr_aar),
     debug_printf("ARC: found AAR: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AAR, offsetof(arc_set, hdr_aar),

-                         TRUE)))
+                         TRUE, NULL)))

     {
     DEBUG(D_acl) debug_printf("inserting AAR: %s\n", e);
     return US"inserting AAR";
     {
     DEBUG(D_acl) debug_printf("inserting AAR: %s\n", e);
     return US"inserting AAR";


@@ -443,15 +444,13 @@ else if (strncmpic(ARC_HDR_AMS, h->text, ARC_HDRLEN_AMS) == 0)
     debug_printf("ARC: found AMS: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AMS, offsetof(arc_set, hdr_ams),
     debug_printf("ARC: found AMS: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AMS, offsetof(arc_set, hdr_ams),

-                         instance_only)))
+                         instance_only, &ams)))

     {
     DEBUG(D_acl) debug_printf("inserting AMS: %s\n", e);
     return US"inserting AMS";
     }
 
   /* defaults */
     {
     DEBUG(D_acl) debug_printf("inserting AMS: %s\n", e);
     return US"inserting AMS";
     }
 
   /* defaults */

-  /*XXX dubious selection of ams here */
-  ams = ctx->arcset_chain->hdr_ams;

   if (!ams->c.data)
     {
     ams->c_head.data = US"simple"; ams->c_head.len = 6;
   if (!ams->c.data)
     {
     ams->c_head.data = US"simple"; ams->c_head.len = 6;


@@ -469,7 +468,7 @@ else if (strncmpic(ARC_HDR_AS, h->text, ARC_HDRLEN_AS) == 0)
     debug_printf("ARC: found AS: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AS, offsetof(arc_set, hdr_as),
     debug_printf("ARC: found AS: %.*s\n", len, h->text);
     }
   if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AS, offsetof(arc_set, hdr_as),

-                         instance_only)))
+                         instance_only, NULL)))

     {
     DEBUG(D_acl) debug_printf("inserting AS: %s\n", e);
     return US"inserting AS";
     {
     DEBUG(D_acl) debug_printf("inserting AS: %s\n", e);
     return US"inserting AS";


@@ -497,7 +496,7 @@ const uschar * e;
 DEBUG(D_acl) debug_printf("ARC: collecting arc sets\n");
 for (h = header_list; h; h = h->next)
   {
 DEBUG(D_acl) debug_printf("ARC: collecting arc sets\n");
 for (h = header_list; h; h = h->next)
   {

-  r = store_get(sizeof(hdr_rlist));
+  r = store_get(sizeof(hdr_rlist), GET_UNTAINTED);

   r->prev = rprev;
   r->used = FALSE;
   r->h = h;
   r->prev = rprev;
   r->used = FALSE;
   r->h = h;


@@ -542,7 +541,8 @@ hctx hhash_ctx;
 const uschar * s;
 int len;
 
 const uschar * s;
 int len;
 

-if (!exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod))
+if (  hashtype == -1
+   || !exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod))

   {
   DEBUG(D_acl)
       debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n");
   {
   DEBUG(D_acl)
       debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n");


@@ -568,7 +568,7 @@ while ((hn = string_nextinlist(&headernames, &sep, NULL, 0)))
 
       len = Ustrlen(s);
       DEBUG(D_acl) pdkim_quoteprint(s, len);
 
       len = Ustrlen(s);
       DEBUG(D_acl) pdkim_quoteprint(s, len);

-      exim_sha_update(&hhash_ctx, s, Ustrlen(s));
+      exim_sha_update_string(&hhash_ctx, s);

       r->used = TRUE;
       break;
       }
       r->used = TRUE;
       break;
       }


@@ -597,7 +597,7 @@ uschar * dns_txt;
 pdkim_pubkey * p;
 
 if (!(dns_txt = dkim_exim_query_dns_txt(string_sprintf("%.*s._domainkey.%.*s",
 pdkim_pubkey * p;
 
 if (!(dns_txt = dkim_exim_query_dns_txt(string_sprintf("%.*s._domainkey.%.*s",

-         al->s.len, al->s.data, al->d.len, al->d.data))))
+         (int)al->s.len, al->s.data, (int)al->d.len, al->d.data))))

   {
   DEBUG(D_acl) debug_printf("pubkey dns lookup fail\n");
   return NULL;
   {
   DEBUG(D_acl) debug_printf("pubkey dns lookup fail\n");
   return NULL;


@@ -637,7 +637,7 @@ return p;
 static pdkim_bodyhash *
 arc_ams_setup_vfy_bodyhash(arc_line * ams)
 {
 static pdkim_bodyhash *
 arc_ams_setup_vfy_bodyhash(arc_line * ams)
 {

-int canon_head, canon_body;
+int canon_head = -1, canon_body = -1;

 long bodylen;
 
 if (!ams->c.data) ams->c.data = US"simple";    /* RFC 6376 (DKIM) default */
 long bodylen;
 
 if (!ams->c.data) ams->c.data = US"simple";    /* RFC 6376 (DKIM) default */


@@ -735,7 +735,7 @@ arc_get_verify_hhash(ctx, ams, &hhash);
 
 /* Setup the interface to the signing library */
 
 
 /* Setup the interface to the signing library */
 

-if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx)))
+if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx, NULL)))

   {
   DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr);
   as->ams_verify_done = arc_state_reason = US"internal sigverify init error";
   {
   DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr);
   as->ams_verify_done = arc_state_reason = US"internal sigverify init error";


@@ -743,6 +743,11 @@ if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx)))
   }
 
 hashtype = pdkim_hashname_to_hashtype(ams->a_hash.data, ams->a_hash.len);
   }
 
 hashtype = pdkim_hashname_to_hashtype(ams->a_hash.data, ams->a_hash.len);

+if (hashtype == -1)
+  {
+  DEBUG(D_acl) debug_printf("ARC i=%d AMS verify bad a_hash\n", as->instance);
+  return as->ams_verify_done = arc_state_reason = US"AMS sig nonverify";
+  }

 
 if ((errstr = exim_dkim_verify(&vctx,
          pdkim_hashes[hashtype].exim_hashmethod, &hhash, &sighash)))
 
 if ((errstr = exim_dkim_verify(&vctx,
          pdkim_hashes[hashtype].exim_hashmethod, &hhash, &sighash)))


@@ -869,7 +874,8 @@ if (  as->instance == 1 && !arc_cv_match(hdr_as, US"none")
 
 hashtype = pdkim_hashname_to_hashtype(hdr_as->a_hash.data, hdr_as->a_hash.len);
 
 
 hashtype = pdkim_hashname_to_hashtype(hdr_as->a_hash.data, hdr_as->a_hash.len);
 

-if (!exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod))
+if (  hashtype == -1
+   || !exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod))

   {
   DEBUG(D_acl)
       debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n");
   {
   DEBUG(D_acl)
       debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n");


@@ -958,14 +964,12 @@ if (!(p = arc_line_to_pubkey(hdr_as)))
 /* We know the b-tag blob is of a nul-term string, so safe as a string */
 pdkim_decode_base64(hdr_as->b.data, &sighash);
 
 /* We know the b-tag blob is of a nul-term string, so safe as a string */
 pdkim_decode_base64(hdr_as->b.data, &sighash);
 

-if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx)))
+if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx, NULL)))

   {
   DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr);
   return US"fail";
   }
 
   {
   DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr);
   return US"fail";
   }
 

-hashtype = pdkim_hashname_to_hashtype(hdr_as->a_hash.data, hdr_as->a_hash.len);
-

 if ((errstr = exim_dkim_verify(&vctx,
              pdkim_hashes[hashtype].exim_hashmethod,
              &hhash_computed, &sighash)))
 if ((errstr = exim_dkim_verify(&vctx,
              pdkim_hashes[hashtype].exim_hashmethod,
              &hhash_computed, &sighash)))


@@ -984,16 +988,13 @@ return NULL;
 static const uschar *
 arc_verify_seals(arc_ctx * ctx)
 {
 static const uschar *
 arc_verify_seals(arc_ctx * ctx)
 {

-arc_set * as = ctx->arcset_chain;
+arc_set * as = ctx->arcset_chain_last;

 
 if (!as)
   return US"none";
 
 
 if (!as)
   return US"none";
 

-while (as)
-  {
-  if (arc_seal_verify(ctx, as)) return US"fail";
-  as = as->next;
-  }
+for ( ; as; as = as->prev) if (arc_seal_verify(ctx, as)) return US"fail";
+

 DEBUG(D_acl) debug_printf("ARC: AS vfy overall pass\n");
 return NULL;
 }
 DEBUG(D_acl) debug_printf("ARC: AS vfy overall pass\n");
 return NULL;
 }


@@ -1101,7 +1102,7 @@ out:
 static hdr_rlist *
 arc_rlist_entry(hdr_rlist * list, const uschar * s, int len)
 {
 static hdr_rlist *
 arc_rlist_entry(hdr_rlist * list, const uschar * s, int len)
 {

-hdr_rlist * r = store_get(sizeof(hdr_rlist) + sizeof(header_line));
+hdr_rlist * r = store_get(sizeof(hdr_rlist) + sizeof(header_line), GET_UNTAINTED);

 header_line * h = r->h = (header_line *)(r+1);
 
 r->prev = list;
 header_line * h = r->h = (header_line *)(r+1);
 
 r->prev = list;


@@ -1111,11 +1112,6 @@ h->type = 0;
 h->slen = len;
 h->text = US s;
 
 h->slen = len;
 h->text = US s;
 

-/* This works for either NL or CRLF lines; also nul-termination */
-while (*++s)
-  if (*s == '\n' && s[1] != '\t' && s[1] != ' ') break;
-s++;           /* move past end of line */
-

 return r;
 }
 
 return r;
 }
 


@@ -1191,13 +1187,14 @@ static gstring *
 arc_sign_append_aar(gstring * g, arc_ctx * ctx,
   const uschar * identity, int instance, blob * ar)
 {
 arc_sign_append_aar(gstring * g, arc_ctx * ctx,
   const uschar * identity, int instance, blob * ar)
 {

-int aar_off = g ? g->ptr : 0;
-arc_set * as = store_get(sizeof(arc_set) + sizeof(arc_line) + sizeof(header_line));
+int aar_off = gstring_length(g);
+arc_set * as =
+  store_get(sizeof(arc_set) + sizeof(arc_line) + sizeof(header_line), GET_UNTAINTED);

 arc_line * al = (arc_line *)(as+1);
 header_line * h = (header_line *)(al+1);
 
 g = string_catn(g, ARC_HDR_AAR, ARC_HDRLEN_AAR);
 arc_line * al = (arc_line *)(as+1);
 header_line * h = (header_line *)(al+1);
 
 g = string_catn(g, ARC_HDR_AAR, ARC_HDRLEN_AAR);

-g = string_cat(g, string_sprintf(" i=%d; %s;\r\n\t", instance, identity));
+g = string_fmt_append(g, " i=%d; %s;\r\n\t", instance, identity);

 g = string_catn(g, US ar->data, ar->len);
 
 h->slen = g->ptr - aar_off;
 g = string_catn(g, US ar->data, ar->len);
 
 h->slen = g->ptr - aar_off;


@@ -1283,7 +1280,7 @@ for (;;)
   g = string_catn(g, US"\r\n\t  ", 5);
   }
 g = string_catn(g, US";\r\n", 3);
   g = string_catn(g, US"\r\n\t  ", 5);
   }
 g = string_catn(g, US";\r\n", 3);

-gstring_reset_unused(g);
+gstring_release_unused(g);

 string_from_gstring(g);
 return g;
 }
 string_from_gstring(g);
 return g;
 }


@@ -1302,28 +1299,22 @@ int col;
 int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6);      /*XXX hardwired */
 blob sig;
 int ams_off;
 int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6);      /*XXX hardwired */
 blob sig;
 int ams_off;

-arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line));
+arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line), GET_UNTAINTED);

 header_line * h = (header_line *)(al+1);
 
 /* debug_printf("%s\n", __FUNCTION__); */
 
 /* Construct the to-be-signed AMS pseudo-header: everything but the sig. */
 
 header_line * h = (header_line *)(al+1);
 
 /* debug_printf("%s\n", __FUNCTION__); */
 
 /* Construct the to-be-signed AMS pseudo-header: everything but the sig. */
 

-ams_off = g->ptr;
-g = string_append(g, 7,
-      ARC_HDR_AMS,
-      US" i=", string_sprintf("%d", instance),
-      US"; a=rsa-sha256; c=relaxed; d=", identity,             /*XXX hardwired */
-      US"; s=", selector);
+ams_off = gstring_length(g);
+g = string_fmt_append(g, "%s i=%d; a=rsa-sha256; c=relaxed; d=%s; s=%s",
+      ARC_HDR_AMS, instance, identity, selector);      /*XXX hardwired a= */

 if (options & ARC_SIGN_OPT_TSTAMP)
 if (options & ARC_SIGN_OPT_TSTAMP)

-  g = string_append(g, 2,
-      US"; t=", string_sprintf("%lu", (u_long)now));
+  g = string_fmt_append(g, "; t=%lu", (u_long)now);

 if (options & ARC_SIGN_OPT_EXPIRE)
 if (options & ARC_SIGN_OPT_EXPIRE)

-  g = string_append(g, 2,
-      US"; x=", string_sprintf("%lu", (u_long)expire));
-g = string_append(g, 3,
-      US";\r\n\tbh=", pdkim_encode_base64(bodyhash),
-      US";\r\n\th=");
+  g = string_fmt_append(g, "; x=%lu", (u_long)expire);
+g = string_fmt_append(g, ";\r\n\tbh=%s;\r\n\th=",
+      pdkim_encode_base64(bodyhash));

 
 for(col = 3; rheaders; rheaders = rheaders->prev)
   {
 
 for(col = 3; rheaders; rheaders = rheaders->prev)
   {


@@ -1359,7 +1350,7 @@ for(col = 3; rheaders; rheaders = rheaders->prev)
 
 /* Lose the last colon from the h= list */
 
 
 /* Lose the last colon from the h= list */
 

-if (g->s[g->ptr - 1] == ':') g->ptr--;
+gstring_trim_trailing(g, ':');

 
 g = string_catn(g, US";\r\n\tb=;", 7);
 
 
 g = string_catn(g, US";\r\n\tb=;", 7);
 


@@ -1377,7 +1368,7 @@ if (!arc_sig_from_pseudoheader(hdata, hashtype, privkey, &sig, US"AMS"))
 /* Lose the trailing semicolon from the psuedo-header, and append the signature
 (folded over lines) and termination to complete it. */
 
 /* Lose the trailing semicolon from the psuedo-header, and append the signature
 (folded over lines) and termination to complete it. */
 

-g->ptr--;
+gstring_trim(g, 1);

 g = arc_sign_append_sig(g, &sig);
 
 h->slen = g->ptr - ams_off;
 g = arc_sign_append_sig(g, &sig);
 
 h->slen = g->ptr - ams_off;


@@ -1422,10 +1413,10 @@ arc_sign_prepend_as(gstring * arcset_interim, arc_ctx * ctx,
   const uschar * privkey, unsigned options)
 {
 gstring * arcset;
   const uschar * privkey, unsigned options)
 {
 gstring * arcset;

-arc_set * as;

 uschar * status = arc_ar_cv_status(ar);
 uschar * status = arc_ar_cv_status(ar);

-arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line));
+arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line), GET_UNTAINTED);

 header_line * h = (header_line *)(al+1);
 header_line * h = (header_line *)(al+1);

+uschar * badline_str;

 
 gstring * hdata = NULL;
 int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6);      /*XXX hardwired */
 
 gstring * hdata = NULL;
 int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6);      /*XXX hardwired */


@@ -1443,6 +1434,7 @@ blob sig;
       - all ARC set headers, set-number order, aar then ams then as,
         including self (but with an empty b= in self)
 */
       - all ARC set headers, set-number order, aar then ams then as,
         including self (but with an empty b= in self)
 */

+DEBUG(D_transport) debug_printf("ARC: building AS for status '%s'\n", status);

 
 /* Construct the AS except for the signature */
 
 
 /* Construct the AS except for the signature */
 


@@ -1466,18 +1458,25 @@ ctx->arcset_chain_last->hdr_as = al;
 /* For any but "fail" chain-verify status, walk the entire chain in order by
 instance.  For fail, only the new arc-set.  Accumulate the elements walked. */
 
 /* For any but "fail" chain-verify status, walk the entire chain in order by
 instance.  For fail, only the new arc-set.  Accumulate the elements walked. */
 

-for (as = Ustrcmp(status, US"fail") == 0
+for (arc_set * as = Ustrcmp(status, US"fail") == 0

        ? ctx->arcset_chain_last : ctx->arcset_chain;
      as; as = as->next)
   {
        ? ctx->arcset_chain_last : ctx->arcset_chain;
      as; as = as->next)
   {

+  arc_line * l;

   /* Accumulate AAR then AMS then AS.  Relaxed canonicalisation
   is required per standard. */
 
   /* Accumulate AAR then AMS then AS.  Relaxed canonicalisation
   is required per standard. */
 

-  h = as->hdr_aar->complete;
+  badline_str = US"aar";
+  if (!(l = as->hdr_aar)) goto badline;
+  h = l->complete;

   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE));
   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE));

-  h = as->hdr_ams->complete;
+  badline_str = US"ams";
+  if (!(l = as->hdr_ams)) goto badline;
+  h = l->complete;

   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE));
   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE));

-  h = as->hdr_as->complete;
+  badline_str = US"as";
+  if (!(l = as->hdr_as)) goto badline;
+  h = l->complete;

   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, !!as->next));
   }
 
   hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, !!as->next));
   }
 


@@ -1494,6 +1493,11 @@ DEBUG(D_transport) debug_printf("ARC: AS  '%.*s'\n", arcset->ptr - 2, arcset->s)
 /* Finally, append the AMS and AAR to the new AS */
 
 return string_catn(arcset, arcset_interim->s, arcset_interim->ptr);
 /* Finally, append the AMS and AAR to the new AS */
 
 return string_catn(arcset, arcset_interim->s, arcset_interim->ptr);

+
+badline:
+  DEBUG(D_transport)
+    debug_printf("ARC: while building AS, missing %s in chain\n", badline_str);
+  return NULL;

 }
 
 
 }
 
 


@@ -1522,6 +1526,7 @@ void
 arc_sign_init(void)
 {
 memset(&arc_sign_ctx, 0, sizeof(arc_sign_ctx));
 arc_sign_init(void)
 {
 memset(&arc_sign_ctx, 0, sizeof(arc_sign_ctx));

+headers_rlist = NULL;

 }
 
 
 }
 
 


@@ -1541,13 +1546,30 @@ into the copies.
 static const uschar *
 arc_header_sign_feed(gstring * g)
 {
 static const uschar *
 arc_header_sign_feed(gstring * g)
 {

-uschar * s = string_copyn(g->s, g->ptr);
+uschar * s = string_copy_from_gstring(g);

 headers_rlist = arc_rlist_entry(headers_rlist, s, g->ptr);
 return arc_try_header(&arc_sign_ctx, headers_rlist->h, TRUE);
 }
 
 
 
 headers_rlist = arc_rlist_entry(headers_rlist, s, g->ptr);
 return arc_try_header(&arc_sign_ctx, headers_rlist->h, TRUE);
 }
 
 
 

+/* Per RFCs 6376, 7489 the only allowed chars in either an ADMD id
+or a selector are ALPHA/DIGGIT/'-'/'.'
+
+Check, to help catch misconfigurations such as a missing selector
+element in the arc_sign list.
+*/
+
+static BOOL
+arc_valid_id(const uschar * s)
+{
+for (uschar c; c = *s++; )
+  if (!isalnum(c) && c != '-' && c != '.') return FALSE;
+return TRUE;
+}
+
+
+

 /* ARC signing.  Called from the smtp transport, if the arc_sign option is set.
 The dkim_exim_sign() function has already been called, so will have hashed the
 message body for us so long as we requested a hash previously.
 /* ARC signing.  Called from the smtp transport, if the arc_sign option is set.
 The dkim_exim_sign() function has already been called, so will have hashed the
 message body for us so long as we requested a hash previously.


@@ -1581,17 +1603,18 @@ expire = now = 0;
 
 /* Parse the signing specification */
 
 
 /* Parse the signing specification */
 

-identity = string_nextinlist(&signspec, &sep, NULL, 0);
-selector = string_nextinlist(&signspec, &sep, NULL, 0);
-if (  !*identity || !*selector
-   || !(privkey = string_nextinlist(&signspec, &sep, NULL, 0)) || !*privkey)
-  {
-  log_write(0, LOG_MAIN, "ARC: bad signing-specification (%s)",
-    !*identity ? "identity" : !*selector ? "selector" : "private-key");
-  return sigheaders ? sigheaders : string_get(0);
-  }
+if (!(identity = string_nextinlist(&signspec, &sep, NULL, 0)) || !*identity)
+  { s = US"identity"; goto bad_arg_ret; }
+if (!(selector = string_nextinlist(&signspec, &sep, NULL, 0)) || !*selector)
+  { s = US"selector"; goto bad_arg_ret; }
+if (!(privkey = string_nextinlist(&signspec, &sep, NULL, 0))  || !*privkey)
+  { s = US"privkey"; goto bad_arg_ret; }
+if (!arc_valid_id(identity))
+  { s = US"identity"; goto bad_arg_ret; }
+if (!arc_valid_id(selector))
+  { s = US"selector"; goto bad_arg_ret; }

 if (*privkey == '/' && !(privkey = expand_file_big_buffer(privkey)))
 if (*privkey == '/' && !(privkey = expand_file_big_buffer(privkey)))

-  return sigheaders ? sigheaders : string_get(0);
+  goto ret_sigheaders;

 
 if ((opts = string_nextinlist(&signspec, &sep, NULL, 0)))
   {
 
 if ((opts = string_nextinlist(&signspec, &sep, NULL, 0)))
   {


@@ -1608,13 +1631,13 @@ if ((opts = string_nextinlist(&signspec, &sep, NULL, 0)))
       if (*(s += 6) == '=')
        if (*++s == '+')
          {
       if (*(s += 6) == '=')
        if (*++s == '+')
          {

-         if (!(expire = (time_t)atoi(++s)))
+         if (!(expire = (time_t)atoi(CS ++s)))

            expire = ARC_SIGN_DEFAULT_EXPIRE_DELTA;
          if (!now) now = time(NULL);
          expire += now;
          }
        else
            expire = ARC_SIGN_DEFAULT_EXPIRE_DELTA;
          if (!now) now = time(NULL);
          expire += now;
          }
        else

-         expire = (time_t)atol(s);
+         expire = (time_t)atol(CS s);

       else
        {
        if (!now) now = time(NULL);
       else
        {
        if (!now) now = time(NULL);


@@ -1650,7 +1673,7 @@ if ((rheaders = arc_sign_scan_headers(&arc_sign_ctx, sigheaders)))
 if (!(arc_sign_find_ar(headers, identity, &ar)))
   {
   log_write(0, LOG_MAIN, "ARC: no Authentication-Results header for signing");
 if (!(arc_sign_find_ar(headers, identity, &ar)))
   {
   log_write(0, LOG_MAIN, "ARC: no Authentication-Results header for signing");

-  return sigheaders ? sigheaders : string_get(0);
+  goto ret_sigheaders;

   }
 
 /* We previously built the data-struct for the existing ARC chain, if any, using a headers
   }
 
 /* We previously built the data-struct for the existing ARC chain, if any, using a headers


@@ -1706,9 +1729,19 @@ if (g)
 /* Finally, append the dkim headers and return the lot. */
 
 if (sigheaders) g = string_catn(g, sigheaders->s, sigheaders->ptr);
 /* Finally, append the dkim headers and return the lot. */
 
 if (sigheaders) g = string_catn(g, sigheaders->s, sigheaders->ptr);

-(void) string_from_gstring(g);
-gstring_reset_unused(g);
-return g;
+
+out:
+  if (!g) return string_get(1);
+  (void) string_from_gstring(g);
+  gstring_release_unused(g);
+  return g;
+
+
+bad_arg_ret:
+  log_write(0, LOG_MAIN, "ARC: bad signing-specification (%s)", s);
+ret_sigheaders:
+  g = sigheaders;
+  goto out;

 }
 
 
 }
 
 


@@ -1737,14 +1770,19 @@ if (strncmpic(ARC_HDR_AMS, g->s, ARC_HDRLEN_AMS) != 0) return US"not AMS";
 DEBUG(D_receive) debug_printf("ARC: spotted AMS header\n");
 /* Parse the AMS header */
 
 DEBUG(D_receive) debug_printf("ARC: spotted AMS header\n");
 /* Parse the AMS header */
 

-h.next = NULL;
-h.slen = g->size;
-h.text = g->s;

 memset(&al, 0, sizeof(arc_line));
 memset(&al, 0, sizeof(arc_line));

+h.next = NULL;
+h.slen = len_string_from_gstring(g, &h.text);

 if ((errstr = arc_parse_line(&al, &h, ARC_HDRLEN_AMS, FALSE)))
   {
   DEBUG(D_acl) if (errstr) debug_printf("ARC: %s\n", errstr);
 if ((errstr = arc_parse_line(&al, &h, ARC_HDRLEN_AMS, FALSE)))
   {
   DEBUG(D_acl) if (errstr) debug_printf("ARC: %s\n", errstr);

-  return US"line parsing error";
+  goto badline;
+  }
+
+if (!al.a_hash.data)
+  {
+  DEBUG(D_acl) debug_printf("ARC: no a_hash from '%.*s'\n", h.slen, h.text);
+  goto badline;

   }
 
 /* defaults */
   }
 
 /* defaults */


@@ -1763,6 +1801,9 @@ if (!(b = arc_ams_setup_vfy_bodyhash(&al)))
 should have been created here. */
 
 return NULL;
 should have been created here. */
 
 return NULL;

+
+badline:
+  return US"line parsing error";

 }
 
 
 }
 
 


@@ -1813,7 +1854,8 @@ for (as = arc_verify_ctx.arcset_chain, inst = 1; as; as = as->next, inst++)
   else
     g = string_catn(g, US":", 1);
   }
   else
     g = string_catn(g, US":", 1);
   }

-return g ? g->s : US"";
+if (!g) return US"";
+return string_from_gstring(g);

 }
 
 
 }
 
 


@@ -1826,29 +1868,27 @@ if (arc_state)
   {
   arc_line * highest_ams;
   int start = 0;               /* Compiler quietening */
   {
   arc_line * highest_ams;
   int start = 0;               /* Compiler quietening */

-  DEBUG(D_acl) start = g->ptr;
+  DEBUG(D_acl) start = gstring_length(g);

 
   g = string_append(g, 2, US";\n\tarc=", arc_state);
   if (arc_received_instance > 0)
     {
 
   g = string_append(g, 2, US";\n\tarc=", arc_state);
   if (arc_received_instance > 0)
     {

-    g = string_append(g, 3, US" (i=",
-      string_sprintf("%d", arc_received_instance), US")");
+    g = string_fmt_append(g, " (i=%d)", arc_received_instance);

     if (arc_state_reason)
       g = string_append(g, 3, US"(", arc_state_reason, US")");
     g = string_catn(g, US" header.s=", 10);
     highest_ams = arc_received->hdr_ams;
     g = string_catn(g, highest_ams->s.data, highest_ams->s.len);
 
     if (arc_state_reason)
       g = string_append(g, 3, US"(", arc_state_reason, US")");
     g = string_catn(g, US" header.s=", 10);
     highest_ams = arc_received->hdr_ams;
     g = string_catn(g, highest_ams->s.data, highest_ams->s.len);
 

-    g = string_append(g, 2,
-      US" arc.oldest-pass=", string_sprintf("%d", arc_oldest_pass));
+    g = string_fmt_append(g, " arc.oldest-pass=%d", arc_oldest_pass);

 
     if (sender_host_address)
 
     if (sender_host_address)

-      g = string_append(g, 2, US" smtp.client-ip=", sender_host_address);
+      g = string_append(g, 2, US" smtp.remote-ip=", sender_host_address);

     }
   else if (arc_state_reason)
     g = string_append(g, 3, US" (", arc_state_reason, US")");
   DEBUG(D_acl) debug_printf("ARC:  authres '%.*s'\n",
     }
   else if (arc_state_reason)
     g = string_append(g, 3, US" (", arc_state_reason, US")");
   DEBUG(D_acl) debug_printf("ARC:  authres '%.*s'\n",

-                 g->ptr - start - 3, g->s + start + 3);
+                 gstring_length(g) - start - 3, g->s + start + 3);

   }
 else
   DEBUG(D_acl) debug_printf("ARC:  no authres\n");
   }
 else
   DEBUG(D_acl) debug_printf("ARC:  no authres\n");


@@ -1856,7 +1896,7 @@ return g;
 }
 
 
 }
 
 

-# endif /* SUPPORT_SPF */
+# endif /* DISABLE_DKIM */

 #endif /* EXPERIMENTAL_ARC */
 /* vi: aw ai sw=2
  */
 #endif /* EXPERIMENTAL_ARC */
 /* vi: aw ai sw=2
  */