X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/1058096b8c5317376c1df7473f6ca7c543d20715..d8b76fa95c55331db4f475ee34caa7e8725ec421:/src/src/expand.c

diff --git a/src/src/expand.c b/src/src/expand.c
index 810fc1cde..6478920f8 100644
--- a/src/src/expand.c
+++ b/src/src/expand.c
@@ -4398,6 +4398,36 @@ return yield;
 
 
 
+/************************************************/
+static void
+debug_expansion_interim(const uschar * what, const uschar * value, int nchar,
+  BOOL skipping)
+{
+DEBUG(D_noutf8)
+  debug_printf_indent("|");
+else
+  debug_printf_indent(UTF8_VERT_RIGHT);
+
+for (int fill = 11 - Ustrlen(what); fill > 0; fill--)
+  DEBUG(D_noutf8)
+    debug_printf("-");
+  else
+    debug_printf(UTF8_HORIZ);
+
+debug_printf("%s: %.*s\n", what, nchar, value);
+if (is_tainted(value))
+  {
+  DEBUG(D_noutf8)
+    debug_printf_indent("%s     \\__", skipping ? "|     " : "      ");
+  else
+    debug_printf_indent("%s",
+      skipping
+      ? UTF8_VERT "             " : "           " UTF8_UP_RIGHT UTF8_HORIZ UTF8_HORIZ);
+  debug_printf("(tainted)\n");
+  }
+}
+
+
 /*************************************************
 *                 Expand string                  *
 *************************************************/
@@ -4522,16 +4552,12 @@ while (*s)
       {
       const uschar * t = s + 2;
       for (s = t; *s ; s++) if (*s == '\\' && s[1] == 'N') break;
+
       DEBUG(D_expand)
-	DEBUG(D_noutf8)
-	  debug_printf_indent("|--protected: %.*s\n", (int)(s - t), t);
-	else
-	  debug_printf_indent(UTF8_VERT_RIGHT UTF8_HORIZ UTF8_HORIZ
-	    "protected: %.*s\n", (int)(s - t), t);
+	debug_expansion_interim(US"protected", t, (int)(s - t), skipping);
       yield = string_catn(yield, t, s - t);
-      if (*s != 0) s += 2;
+      if (*s) s += 2;
       }
-
     else
       {
       uschar ch[1];
@@ -4544,30 +4570,22 @@ while (*s)
       s++;
       yield = string_catn(yield, ch, 1);
       }
-
     continue;
     }
 
-  /*{*/
+									/*{{*/
   /* Anything other than $ is just copied verbatim, unless we are
   looking for a terminating } character. */
 
-  /*{*/
   if (ket_ends && *s == '}') break;
 
   if (*s != '$' || !honour_dollar)
     {
     int i = 1;								/*{*/
-    for(const uschar * t = s+1; *t && *t != '$' && *t != '}' && *t != '\\'; t++)
-      i++;
+    for (const uschar * t = s+1;
+	*t && *t != '$' && *t != '}' && *t != '\\'; t++) i++;
 
-    DEBUG(D_expand)
-      DEBUG(D_noutf8)
-	debug_printf_indent("|-------text: %.*s\n", i, s);
-      else
-	debug_printf_indent(UTF8_VERT_RIGHT
-	  UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ
-	  "text: %.*s\n", i, s);
+    DEBUG(D_expand) debug_expansion_interim(US"text", s, i, skipping);
 
     yield = string_catn(yield, s, i);
     s += i;
@@ -4582,11 +4600,10 @@ while (*s)
   "$header_". A non-existent header yields a NULL value; nothing is
   inserted. */	/*}*/
 
-  if (isalpha((*(++s))))
+  if (isalpha(*++s))
     {
     const uschar * value;
-    int len;
-    int newsize = 0;
+    int newsize = 0, len;
     gstring * g = NULL;
     uschar * t;
 
@@ -4627,7 +4644,7 @@ while (*s)
       But there is no error here - nothing gets inserted. */
 
       if (!value)
-        {		/*{*/
+        {								/*{*/
         if (Ustrchr(name, '}')) malformed_header = TRUE;
         continue;
         }
@@ -4685,12 +4702,12 @@ while (*s)
   /* After { there can be various things, but they all start with
   an initial word, except for a number for a string match variable. */	/*}*/
 
-  if (isdigit((*(++s))))
+  if (isdigit(*++s))
     {
     int n;
-    s = read_cnumber(&n, s);		/*{*/
+    s = read_cnumber(&n, s);						/*{{*/
     if (*s++ != '}')
-      {					/*{*/
+      {
       expand_string_message = US"} expected after number";
       goto EXPAND_FAILED;
       }
@@ -4712,6 +4729,11 @@ while (*s)
   s = read_name(name, sizeof(name), s, US"_-");
   item_type = chop_match(name, item_table, nelem(item_table));
 
+  /* Switch on item type.  All nondefault choices should "continue* when
+  skipping, but "break" otherwise so we get debug output for the item
+  expansion. */
+  {
+  int start = gstring_length(yield);
   switch(item_type)
     {
     /* Call an ACL from an expansion.  We feed data in via $acl_arg1 - $acl_arg9.
@@ -4726,8 +4748,8 @@ while (*s)
     case EITEM_ACL:
       /* ${acl {name} {arg1}{arg2}...} */
       {
-      uschar *sub[10];	/* name + arg1-arg9 (which must match number of acl_arg[]) */
-      uschar *user_msg;
+      uschar * sub[10];	/* name + arg1-arg9 (which must match number of acl_arg[]) */
+      uschar * user_msg;
       int rc;
 
       switch(read_subs(sub, nelem(sub), 1, &s, skipping, TRUE, name,
@@ -4748,7 +4770,7 @@ while (*s)
 	    debug_printf_indent("acl expansion yield: %s\n", user_msg);
 	  if (user_msg)
             yield = string_cat(yield, user_msg);
-	  continue;
+	  break;
 
 	case DEFER:
           f.expand_string_forcedfail = TRUE;
@@ -4758,12 +4780,13 @@ while (*s)
 	    rc_names[rc], sub[0]);
 	  goto EXPAND_FAILED;
 	}
+      break;
       }
 
     case EITEM_AUTHRESULTS:
       /* ${authresults {mysystemname}} */
       {
-      uschar *sub_arg[1];
+      uschar * sub_arg[1];
 
       switch(read_subs(sub_arg, nelem(sub_arg), 1, &s, skipping, TRUE, name,
 		      &resetok))
@@ -4792,7 +4815,7 @@ while (*s)
 #ifdef EXPERIMENTAL_ARC
       yield = authres_arc(yield);
 #endif
-      continue;
+      break;
       }
 
     /* Handle conditionals - preserve the values of the numerical expansion
@@ -4812,21 +4835,11 @@ while (*s)
 	goto EXPAND_FAILED;  /* message already set */
 
       DEBUG(D_expand)
-	DEBUG(D_noutf8)
-	  {
-	  debug_printf_indent("|--condition: %.*s\n", (int)(next_s - s), s);
-	  debug_printf_indent("|-----result: %s\n", cond ? "true" : "false");
-	  }
-	else
-	  {
-	  debug_printf_indent(UTF8_VERT_RIGHT UTF8_HORIZ UTF8_HORIZ
-	    "condition: %.*s\n",
-	    (int)(next_s - s), s);
-	  debug_printf_indent(UTF8_VERT_RIGHT UTF8_HORIZ UTF8_HORIZ
-	    UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ
-	    "result: %s\n",
-	    cond ? "true" : "false");
-	  }
+	{
+	debug_expansion_interim(US"condition", s, (int)(next_s - s), skipping);
+	debug_expansion_interim(US"result",
+	  cond ? US"true" : US"false", cond ? 4 : 5, skipping);
+	}
 
       s = next_s;
 
@@ -4851,7 +4864,7 @@ while (*s)
 
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
-      continue;
+      break;
       }
 
 #ifdef SUPPORT_I18N
@@ -4882,14 +4895,13 @@ while (*s)
 	goto EXPAND_FAILED;
 	}
 
-      if (!skipping)
-	{
-	if (!(encoded = imap_utf7_encode(sub_arg[0], headers_charset,
-			    sub_arg[1][0], sub_arg[2], &expand_string_message)))
-	  goto EXPAND_FAILED;
-	yield = string_cat(yield, encoded);
-	}
-      continue;
+      if (skipping) continue;
+
+      if (!(encoded = imap_utf7_encode(sub_arg[0], headers_charset,
+			  sub_arg[1][0], sub_arg[2], &expand_string_message)))
+	goto EXPAND_FAILED;
+      yield = string_cat(yield, encoded);
+      break;
       }
 #endif
 
@@ -4905,9 +4917,9 @@ while (*s)
       int stype, partial, affixlen, starflags;
       int expand_setup = 0;
       int nameptr = 0;
-      uschar *key, *filename;
+      uschar * key, * filename;
       const uschar * affix, * opts;
-      uschar *save_lookup_value = lookup_value;
+      uschar * save_lookup_value = lookup_value;
       int save_expand_nmax =
         save_expand_strings(save_expand_nstring, save_expand_nlength);
 
@@ -4975,15 +4987,12 @@ while (*s)
           goto EXPAND_FAILED;
           }
         }
-      else
-        {
-        if (key)
-          {
-          expand_string_message = string_sprintf("a single key was given for "
-            "lookup type \"%s\", which is not a single-key lookup type", name);
-          goto EXPAND_FAILED;
-          }
-        }
+      else if (key)
+	{
+	expand_string_message = string_sprintf("a single key was given for "
+	  "lookup type \"%s\", which is not a single-key lookup type", name);
+	goto EXPAND_FAILED;
+	}
 
       /* Get the next string in brackets and expand it. It is the file name for
       single-key+file lookups, and the whole query otherwise. In the case of
@@ -5069,7 +5078,9 @@ while (*s)
 
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
-      continue;
+
+      if (skipping) continue;
+      break;
       }
 
     /* If Perl support is configured, handle calling embedded perl subroutines,
@@ -5077,20 +5088,20 @@ while (*s)
     or ${perl{sub}{arg1}{arg2}} or up to a maximum of EXIM_PERL_MAX_ARGS
     arguments (defined below). */
 
-  #define EXIM_PERL_MAX_ARGS 8
+#define EXIM_PERL_MAX_ARGS 8
 
     case EITEM_PERL:
-  #ifndef EXIM_PERL
-    expand_string_message = US"\"${perl\" encountered, but this facility "	/*}*/
-      "is not included in this binary";
-    goto EXPAND_FAILED;
+#ifndef EXIM_PERL
+      expand_string_message = US"\"${perl\" encountered, but this facility "	/*}*/
+	"is not included in this binary";
+      goto EXPAND_FAILED;
 
-  #else   /* EXIM_PERL */
+#else   /* EXIM_PERL */
       {
-      uschar *sub_arg[EXIM_PERL_MAX_ARGS + 2];
-      gstring *new_yield;
+      uschar * sub_arg[EXIM_PERL_MAX_ARGS + 2];
+      gstring * new_yield;
 
-      if ((expand_forbid & RDO_PERL) != 0)
+      if (expand_forbid & RDO_PERL)
         {
         expand_string_message = US"Perl calls are not permitted";
         goto EXPAND_FAILED;
@@ -5112,7 +5123,7 @@ while (*s)
 
       if (!opt_perl_started)
         {
-        uschar *initerror;
+        uschar * initerror;
         if (!opt_perl_startup)
           {
           expand_string_message = US"A setting of perl_startup is needed when "
@@ -5156,17 +5167,16 @@ while (*s)
 
       f.expand_string_forcedfail = FALSE;
       yield = new_yield;
-      continue;
+      break;
       }
-  #endif /* EXIM_PERL */
+#endif /* EXIM_PERL */
 
     /* Transform email address to "prvs" scheme to use
        as BATV-signed return path */
 
     case EITEM_PRVS:
       {
-      uschar *sub_arg[3];
-      uschar *p,*domain;
+      uschar * sub_arg[3], * p, * domain;
 
       switch(read_subs(sub_arg, 3, 2, &s, skipping, TRUE, name, &resetok))
         {
@@ -5215,17 +5225,16 @@ while (*s)
       yield = string_catn(yield, US"@", 1);
       yield = string_cat (yield, domain);
 
-      continue;
+      break;
       }
 
     /* Check a prvs-encoded address for validity */
 
     case EITEM_PRVSCHECK:
       {
-      uschar *sub_arg[3];
+      uschar * sub_arg[3], * p;
       gstring * g;
-      const pcre2_code *re;
-      uschar *p;
+      const pcre2_code * re;
 
       /* TF: Ugliness: We want to expand parameter 1 first, then set
          up expansion variables that are used in the expansion of
@@ -5254,11 +5263,11 @@ while (*s)
 
       if (regex_match_and_setup(re,sub_arg[0],0,-1))
         {
-        uschar *local_part = string_copyn(expand_nstring[4],expand_nlength[4]);
-        uschar *key_num = string_copyn(expand_nstring[1],expand_nlength[1]);
-        uschar *daystamp = string_copyn(expand_nstring[2],expand_nlength[2]);
-        uschar *hash = string_copyn(expand_nstring[3],expand_nlength[3]);
-        uschar *domain = string_copyn(expand_nstring[5],expand_nlength[5]);
+        uschar * local_part = string_copyn(expand_nstring[4],expand_nlength[4]);
+        uschar * key_num = string_copyn(expand_nstring[1],expand_nlength[1]);
+        uschar * daystamp = string_copyn(expand_nstring[2],expand_nlength[2]);
+        uschar * hash = string_copyn(expand_nstring[3],expand_nlength[3]);
+        uschar * domain = string_copyn(expand_nstring[5],expand_nlength[5]);
 
         DEBUG(D_expand) debug_printf_indent("prvscheck localpart: %s\n", local_part);
         DEBUG(D_expand) debug_printf_indent("prvscheck key number: %s\n", key_num);
@@ -5356,15 +5365,16 @@ while (*s)
           case 3: goto EXPAND_FAILED;
           }
 
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* Handle "readfile" to insert an entire file */
 
     case EITEM_READFILE:
       {
-      FILE *f;
-      uschar *sub_arg[2];
+      FILE * f;
+      uschar * sub_arg[2];
 
       if ((expand_forbid & RDO_READFILE) != 0)
         {
@@ -5393,7 +5403,7 @@ while (*s)
 
       yield = cat_file(f, yield, sub_arg[1]);
       (void)fclose(f);
-      continue;
+      break;
       }
 
     /* Handle "readsocket" to insert data from a socket, either
@@ -5517,7 +5527,8 @@ while (*s)
 	expand_string_message = US"missing '}' closing readsocket";
 	goto EXPAND_FAILED_CURLY;
 	}
-      continue;
+      if (skipping) continue;
+      break;
 
       /* Come here on failure to create socket, connect socket, write to the
       socket, or timeout on reading. If another substring follows, expand and
@@ -5542,9 +5553,9 @@ while (*s)
 
     case EITEM_RUN:
       {
-      FILE *f;
-      uschar *arg;
-      const uschar **argv;
+      FILE * f;
+      uschar * arg;
+      const uschar ** argv;
       pid_t pid;
       int fd_in, fd_out;
 
@@ -5651,7 +5662,8 @@ while (*s)
         case 2: goto EXPAND_FAILED_CURLY;    /* returned value is 0 */
         }
 
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* Handle character translation for "tr" */
@@ -5660,7 +5672,7 @@ while (*s)
       {
       int oldptr = gstring_length(yield);
       int o2m;
-      uschar *sub[3];
+      uschar * sub[3];
 
       switch(read_subs(sub, 3, 3, &s, skipping, TRUE, name, &resetok))
         {
@@ -5682,7 +5694,8 @@ while (*s)
           }
         }
 
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* Handle "hash", "length", "nhash", and "substr" when they are given with
@@ -5696,7 +5709,7 @@ while (*s)
       int len;
       uschar *ret;
       int val[2] = { 0, -1 };
-      uschar *sub[3];
+      uschar * sub[3];
 
       /* "length" takes only 2 arguments whereas the others take 2 or 3.
       Ensure that sub[2] is set in the ${length } case. */
@@ -5745,7 +5758,8 @@ while (*s)
       if (!ret)
 	goto EXPAND_FAILED;
       yield = string_catn(yield, ret, len);
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* Handle HMAC computation: ${hmac{<algorithm>}{<secret>}{<text>}}
@@ -5760,14 +5774,14 @@ while (*s)
 
     case EITEM_HMAC:
       {
-      uschar *sub[3];
+      uschar * sub[3];
       md5 md5_base;
       hctx sha1_ctx;
-      void *use_base;
+      void * use_base;
       int type;
       int hashlen;      /* Number of octets for the hash algorithm's output */
       int hashblocklen; /* Number of octets the hash algorithm processes */
-      uschar *keyptr, *p;
+      uschar * keyptr, * p;
       unsigned int keylen;
 
       uschar keyhash[MAX_HASHLEN];
@@ -5784,79 +5798,78 @@ while (*s)
         case 3: goto EXPAND_FAILED;
         }
 
-      if (!skipping)
+      if (skipping) continue;
+
+      if (Ustrcmp(sub[0], "md5") == 0)
 	{
-	if (Ustrcmp(sub[0], "md5") == 0)
-	  {
-	  type = HMAC_MD5;
-	  use_base = &md5_base;
-	  hashlen = 16;
-	  hashblocklen = 64;
-	  }
-	else if (Ustrcmp(sub[0], "sha1") == 0)
-	  {
-	  type = HMAC_SHA1;
-	  use_base = &sha1_ctx;
-	  hashlen = 20;
-	  hashblocklen = 64;
-	  }
-	else
-	  {
-	  expand_string_message =
-	    string_sprintf("hmac algorithm \"%s\" is not recognised", sub[0]);
-	  goto EXPAND_FAILED;
-	  }
+	type = HMAC_MD5;
+	use_base = &md5_base;
+	hashlen = 16;
+	hashblocklen = 64;
+	}
+      else if (Ustrcmp(sub[0], "sha1") == 0)
+	{
+	type = HMAC_SHA1;
+	use_base = &sha1_ctx;
+	hashlen = 20;
+	hashblocklen = 64;
+	}
+      else
+	{
+	expand_string_message =
+	  string_sprintf("hmac algorithm \"%s\" is not recognised", sub[0]);
+	goto EXPAND_FAILED;
+	}
 
-	keyptr = sub[1];
-	keylen = Ustrlen(keyptr);
+      keyptr = sub[1];
+      keylen = Ustrlen(keyptr);
 
-	/* If the key is longer than the hash block length, then hash the key
-	first */
+      /* If the key is longer than the hash block length, then hash the key
+      first */
 
-	if (keylen > hashblocklen)
-	  {
-	  chash_start(type, use_base);
-	  chash_end(type, use_base, keyptr, keylen, keyhash);
-	  keyptr = keyhash;
-	  keylen = hashlen;
-	  }
+      if (keylen > hashblocklen)
+	{
+	chash_start(type, use_base);
+	chash_end(type, use_base, keyptr, keylen, keyhash);
+	keyptr = keyhash;
+	keylen = hashlen;
+	}
 
-	/* Now make the inner and outer key values */
+      /* Now make the inner and outer key values */
 
-	memset(innerkey, 0x36, hashblocklen);
-	memset(outerkey, 0x5c, hashblocklen);
+      memset(innerkey, 0x36, hashblocklen);
+      memset(outerkey, 0x5c, hashblocklen);
 
-	for (int i = 0; i < keylen; i++)
-	  {
-	  innerkey[i] ^= keyptr[i];
-	  outerkey[i] ^= keyptr[i];
-	  }
+      for (int i = 0; i < keylen; i++)
+	{
+	innerkey[i] ^= keyptr[i];
+	outerkey[i] ^= keyptr[i];
+	}
 
-	/* Now do the hashes */
+      /* Now do the hashes */
 
-	chash_start(type, use_base);
-	chash_mid(type, use_base, innerkey);
-	chash_end(type, use_base, sub[2], Ustrlen(sub[2]), innerhash);
+      chash_start(type, use_base);
+      chash_mid(type, use_base, innerkey);
+      chash_end(type, use_base, sub[2], Ustrlen(sub[2]), innerhash);
 
-	chash_start(type, use_base);
-	chash_mid(type, use_base, outerkey);
-	chash_end(type, use_base, innerhash, hashlen, finalhash);
+      chash_start(type, use_base);
+      chash_mid(type, use_base, outerkey);
+      chash_end(type, use_base, innerhash, hashlen, finalhash);
 
-	/* Encode the final hash as a hex string */
+      /* Encode the final hash as a hex string */
 
-	p = finalhash_hex;
-	for (int i = 0; i < hashlen; i++)
-	  {
-	  *p++ = hex_digits[(finalhash[i] & 0xf0) >> 4];
-	  *p++ = hex_digits[finalhash[i] & 0x0f];
-	  }
+      p = finalhash_hex;
+      for (int i = 0; i < hashlen; i++)
+	{
+	*p++ = hex_digits[(finalhash[i] & 0xf0) >> 4];
+	*p++ = hex_digits[finalhash[i] & 0x0f];
+	}
 
-	DEBUG(D_any) debug_printf("HMAC[%s](%.*s,%s)=%.*s\n",
-	  sub[0], (int)keylen, keyptr, sub[2], hashlen*2, finalhash_hex);
+      DEBUG(D_any) debug_printf("HMAC[%s](%.*s,%s)=%.*s\n",
+	sub[0], (int)keylen, keyptr, sub[2], hashlen*2, finalhash_hex);
 
-	yield = string_catn(yield, finalhash_hex, hashlen*2);
-	}
-      continue;
+      yield = string_catn(yield, finalhash_hex, hashlen*2);
+      break;
       }
 
     /* Handle global substitution for "sg" - like Perl's s/xxx/yyy/g operator.
@@ -5869,8 +5882,7 @@ while (*s)
       PCRE2_SIZE roffset;
       pcre2_match_data * md;
       int err, emptyopt;
-      uschar *subject;
-      uschar *sub[3];
+      uschar * subject, * sub[3];
       int save_expand_nmax =
         save_expand_strings(save_expand_nstring, save_expand_nlength);
 
@@ -5881,6 +5893,7 @@ while (*s)
         case 3: goto EXPAND_FAILED;
         }
 
+      /*XXX no handling of skipping? */
       /* Compile the regular expression */
 
       if (!(re = pcre2_compile((PCRE2_SPTR)sub[1], PCRE2_ZERO_TERMINATED,
@@ -5908,7 +5921,7 @@ while (*s)
 	PCRE2_SIZE * ovec = pcre2_get_ovector_pointer(md);
 	int n = pcre2_match(re, (PCRE2_SPTR)subject, slen, moffset + moffsetextra,
 	  PCRE_EOPT | emptyopt, md, pcre_mtc_ctx);
-        uschar *insert;
+        uschar * insert;
 
         /* No match - if we previously set PCRE_NOTEMPTY after a null match, this
         is not necessarily the end. We want to repeat the match from one
@@ -5943,7 +5956,8 @@ while (*s)
 
         /* Copy the characters before the match, plus the expanded insertion. */
 
-        yield = string_catn(yield, subject + moffset, ovec[0] - moffset);
+	yield = string_catn(yield, subject + moffset, ovec[0] - moffset);
+
         if (!(insert = expand_string(sub[2])))
 	  goto EXPAND_FAILED;
         yield = string_cat(yield, insert);
@@ -5970,7 +5984,8 @@ while (*s)
 
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* Handle keyed and numbered substring extraction. If the first argument
@@ -5980,8 +5995,7 @@ while (*s)
       {
       int field_number = 1;
       BOOL field_number_set = FALSE;
-      uschar *save_lookup_value = lookup_value;
-      uschar *sub[3];
+      uschar * save_lookup_value = lookup_value, * sub[3];
       int save_expand_nmax =
         save_expand_strings(save_expand_nstring, save_expand_nlength);
 
@@ -6007,7 +6021,7 @@ while (*s)
 
       if (skipping)
 	{
-        for (int j = 5; j > 0 && *s == '{'; j--)		/*'}'*/
+        for (int j = 5; j > 0 && *s == '{'; j--)			/*'}'*/
 	  {
           if (!expand_string_internal(s+1, TRUE, &s, skipping, TRUE, &resetok))
 	    goto EXPAND_FAILED;					/*'{'*/
@@ -6018,13 +6032,13 @@ while (*s)
 	    }
 	  Uskip_whitespace(&s);
 	  }
-	if (  Ustrncmp(s, "fail", 4) == 0			/*'{'*/
+	if (  Ustrncmp(s, "fail", 4) == 0				/*'{'*/
 	   && (s[4] == '}' || s[4] == ' ' || s[4] == '\t' || !s[4])
 	   )
 	  {
 	  s += 4;
 	  Uskip_whitespace(&s);
-	  }							/*'{'*/
+	  }								/*'{'*/
 	if (*s != '}')
 	  {
 	  expand_string_message = US"missing '}' closing extract";
@@ -6034,10 +6048,10 @@ while (*s)
 
       else for (int i = 0, j = 2; i < j; i++) /* Read the proper number of arguments */
         {
-	if (Uskip_whitespace(&s) == '{') 						/*'}'*/
+	if (Uskip_whitespace(&s) == '{') 				/*'}'*/
           {
           if (!(sub[i] = expand_string_internal(s+1, TRUE, &s, skipping, TRUE, &resetok)))
-	    goto EXPAND_FAILED;					/*'{'*/
+	    goto EXPAND_FAILED;						/*'{'*/
           if (*s++ != '}')
 	    {
 	    expand_string_message = string_sprintf(
@@ -6054,7 +6068,7 @@ while (*s)
             {
             int len;
             int x = 0;
-            uschar *p = sub[0];
+            uschar * p = sub[0];
 
             Uskip_whitespace(&p);
             sub[0] = p;
@@ -6063,7 +6077,7 @@ while (*s)
             while (len > 0 && isspace(p[len-1])) len--;
             p[len] = 0;
 
-	    if (*p == 0)
+	    if (!*p)
 	      {
 	      expand_string_message = US"first argument of \"extract\" must "
 		"not be empty";
@@ -6075,8 +6089,8 @@ while (*s)
 	      field_number = -1;
 	      p++;
 	      }
-	    while (*p != 0 && isdigit(*p)) x = x * 10 + *p++ - '0';
-	    if (*p == 0)
+	    while (*p && isdigit(*p)) x = x * 10 + *p++ - '0';
+	    if (!*p)
 	      {
 	      field_number *= x;
 	      if (fmt == extract_basic) j = 3;               /* Need 3 args */
@@ -6206,7 +6220,8 @@ while (*s)
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
 
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     /* return the Nth item from a list */
@@ -6214,8 +6229,7 @@ while (*s)
     case EITEM_LISTEXTRACT:
       {
       int field_number = 1;
-      uschar *save_lookup_value = lookup_value;
-      uschar *sub[2];
+      uschar * save_lookup_value = lookup_value, * sub[2];
       int save_expand_nmax =
         save_expand_strings(save_expand_nstring, save_expand_nlength);
 
@@ -6223,15 +6237,15 @@ while (*s)
 
       for (int i = 0; i < 2; i++)
         {
-        if (Uskip_whitespace(&s) != '{')					/*'}'*/
+        if (Uskip_whitespace(&s) != '{')				/*}*/
 	  {
 	  expand_string_message = string_sprintf(
-	    "missing '{' for arg %d of listextract", i+1);
+	    "missing '{' for arg %d of listextract", i+1);		/*}*/
 	  goto EXPAND_FAILED_CURLY;
 	  }
 
 	sub[i] = expand_string_internal(s+1, TRUE, &s, skipping, TRUE, &resetok);
-	if (!sub[i])     goto EXPAND_FAILED;		/*{*/
+	if (!sub[i])     goto EXPAND_FAILED;				/*{{*/
 	if (*s++ != '}')
 	  {
 	  expand_string_message = string_sprintf(
@@ -6304,7 +6318,8 @@ while (*s)
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
 
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     case EITEM_LISTQUOTE:
@@ -6322,14 +6337,14 @@ while (*s)
 	yield = string_catn(yield, sub[1], 1);
 	}
       else yield = string_catn(yield, US" ", 1);
-      continue;
+      if (skipping) continue;
+      break;
       }
 
 #ifndef DISABLE_TLS
     case EITEM_CERTEXTRACT:
       {
-      uschar *save_lookup_value = lookup_value;
-      uschar *sub[2];
+      uschar * save_lookup_value = lookup_value, * sub[2];
       int save_expand_nmax =
         save_expand_strings(save_expand_nstring, save_expand_nlength);
 
@@ -6337,10 +6352,10 @@ while (*s)
       if (Uskip_whitespace(&s) != '{')					/*}*/
 	{
 	expand_string_message = US"missing '{' for field arg of certextract";
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
       sub[0] = expand_string_internal(s+1, TRUE, &s, skipping, TRUE, &resetok);
-      if (!sub[0])     goto EXPAND_FAILED;		/*{*/
+      if (!sub[0])     goto EXPAND_FAILED;				/*{{*/
       if (*s++ != '}')
         {
 	expand_string_message = US"missing '}' closing field arg of certextract";
@@ -6363,7 +6378,7 @@ while (*s)
       if (Uskip_whitespace(&s) != '{')					/*}*/
 	{
 	expand_string_message = US"missing '{' for cert variable arg of certextract";
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
       if (*++s != '$')
         {
@@ -6372,7 +6387,7 @@ while (*s)
 	goto EXPAND_FAILED;
 	}
       sub[1] = expand_string_internal(s+1, TRUE, &s, skipping, FALSE, &resetok);
-      if (!sub[1])     goto EXPAND_FAILED;		/*{*/
+      if (!sub[1])     goto EXPAND_FAILED;				/*{{*/
       if (*s++ != '}')
         {
 	expand_string_message = US"missing '}' closing cert variable arg of certextract";
@@ -6401,7 +6416,8 @@ while (*s)
 
       restore_expand_strings(save_expand_nmax, save_expand_nstring,
         save_expand_nlength);
-      continue;
+      if (skipping) continue;
+      break;
       }
 #endif	/*DISABLE_TLS*/
 
@@ -6411,27 +6427,24 @@ while (*s)
     case EITEM_MAP:
     case EITEM_REDUCE:
       {
-      int sep = 0;
-      int save_ptr = gstring_length(yield);
+      int sep = 0, save_ptr = gstring_length(yield);
       uschar outsep[2] = { '\0', '\0' };
       const uschar *list, *expr, *temp;
-      uschar *save_iterate_item = iterate_item;
-      uschar *save_lookup_value = lookup_value;
+      uschar * save_iterate_item = iterate_item;
+      uschar * save_lookup_value = lookup_value;
 
       Uskip_whitespace(&s);
-      if (*s++ != '{')	/*}*/
+      if (*s++ != '{')							/*}*/
         {
 	expand_string_message =
 	  string_sprintf("missing '{' for first arg of %s", name);
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
 
       if (!(list = expand_string_internal(s, TRUE, &s, skipping, TRUE, &resetok)))
-	goto EXPAND_FAILED;
-      /*{*/
+	goto EXPAND_FAILED;						/*{{*/
       if (*s++ != '}')
         {
-	/*{*/
 	expand_string_message =
 	  string_sprintf("missing '}' closing first arg of %s", name);
 	goto EXPAND_FAILED_CURLY;
@@ -6441,14 +6454,14 @@ while (*s)
         {
 	uschar * t;
         Uskip_whitespace(&s);
-        if (*s++ != '{')
+        if (*s++ != '{')						/*}*/
 	  {
 	  expand_string_message = US"missing '{' for second arg of reduce";
-	  goto EXPAND_FAILED_CURLY;
+	  goto EXPAND_FAILED_CURLY;					/*}*/
 	  }
         t = expand_string_internal(s, TRUE, &s, skipping, TRUE, &resetok);
         if (!t) goto EXPAND_FAILED;
-        lookup_value = t;
+        lookup_value = t;						/*{{*/
         if (*s++ != '}')
 	  {
 	  expand_string_message = US"missing '}' closing second arg of reduce";
@@ -6457,7 +6470,7 @@ while (*s)
         }
 
       Uskip_whitespace(&s);
-      if (*s++ != '{')	/*}*/
+      if (*s++ != '{')							/*}*/
         {
 	expand_string_message =
 	  string_sprintf("missing '{' for last arg of %s", name);	/*}*/
@@ -6484,18 +6497,18 @@ while (*s)
         goto EXPAND_FAILED;
         }
 
-      Uskip_whitespace(&s);				/*{*/
+      Uskip_whitespace(&s);						/*{{{*/
       if (*s++ != '}')
-        {						/*{*/
+        {
         expand_string_message = string_sprintf("missing } at end of condition "
           "or expression inside \"%s\"; could be an unquoted } in the content",
 	  name);
         goto EXPAND_FAILED;
         }
 
-      Uskip_whitespace(&s);				/*{*/
+      Uskip_whitespace(&s);						/*{{*/
       if (*s++ != '}')
-        {						/*{*/
+        {
         expand_string_message = string_sprintf("missing } at end of \"%s\"",
           name);
         goto EXPAND_FAILED;
@@ -6575,7 +6588,7 @@ while (*s)
           too many; backup and end the loop. Otherwise arrange to double the
           separator. */
 
-          if (temp[seglen] == '\0') { yield->ptr--; break; }
+          if (!temp[seglen]) { yield->ptr--; break; }
           yield = string_catn(yield, outsep, 1);
           temp += seglen + 1;
           }
@@ -6604,28 +6617,27 @@ while (*s)
       /* Restore preserved $item */
 
       iterate_item = save_iterate_item;
-      continue;
+      if (skipping) continue;
+      break;
       }
 
     case EITEM_SORT:
       {
-      int cond_type;
-      int sep = 0;
-      const uschar *srclist, *cmp, *xtract;
+      int sep = 0, cond_type;
+      const uschar * srclist, * cmp, * xtract;
       uschar * opname, * srcitem;
-      const uschar *dstlist = NULL, *dstkeylist = NULL;
-      uschar * tmp;
-      uschar *save_iterate_item = iterate_item;
+      const uschar * dstlist = NULL, * dstkeylist = NULL;
+      uschar * tmp, * save_iterate_item = iterate_item;
 
       Uskip_whitespace(&s);
-      if (*s++ != '{')
+      if (*s++ != '{')							/*}*/
         {
         expand_string_message = US"missing '{' for list arg of sort";
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
 
       srclist = expand_string_internal(s, TRUE, &s, skipping, TRUE, &resetok);
-      if (!srclist) goto EXPAND_FAILED;
+      if (!srclist) goto EXPAND_FAILED;					/*{{*/
       if (*s++ != '}')
         {
         expand_string_message = US"missing '}' closing list arg of sort";
@@ -6633,14 +6645,14 @@ while (*s)
 	}
 
       Uskip_whitespace(&s);
-      if (*s++ != '{')
+      if (*s++ != '{')							/*}*/
         {
         expand_string_message = US"missing '{' for comparator arg of sort";
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
 
       cmp = expand_string_internal(s, TRUE, &s, skipping, FALSE, &resetok);
-      if (!cmp) goto EXPAND_FAILED;
+      if (!cmp) goto EXPAND_FAILED;					/*{{*/
       if (*s++ != '}')
         {
         expand_string_message = US"missing '}' closing comparator arg of sort";
@@ -6667,25 +6679,25 @@ while (*s)
 	}
 
       Uskip_whitespace(&s);
-      if (*s++ != '{')
+      if (*s++ != '{')							/*}*/
         {
         expand_string_message = US"missing '{' for extractor arg of sort";
-	goto EXPAND_FAILED_CURLY;
+	goto EXPAND_FAILED_CURLY;					/*}*/
 	}
 
       xtract = s;
       if (!(tmp = expand_string_internal(s, TRUE, &s, TRUE, TRUE, &resetok)))
 	goto EXPAND_FAILED;
       xtract = string_copyn(xtract, s - xtract);
-
+									/*{{*/
       if (*s++ != '}')
         {
         expand_string_message = US"missing '}' closing extractor arg of sort";
 	goto EXPAND_FAILED_CURLY;
 	}
-							/*{*/
+									/*{{*/
       if (*s++ != '}')
-        {						/*{*/
+        {
         expand_string_message = US"missing } at end of \"sort\"";
         goto EXPAND_FAILED;
         }
@@ -6695,8 +6707,7 @@ while (*s)
       while ((srcitem = string_nextinlist(&srclist, &sep, NULL, 0)))
 	{
 	uschar * srcfield, * dstitem;
-	gstring * newlist = NULL;
-	gstring * newkeylist = NULL;
+	gstring * newlist = NULL, * newkeylist = NULL;
 
         DEBUG(D_expand) debug_printf_indent("%s: $item = \"%s\"\n", name, srcitem);
 
@@ -6720,7 +6731,7 @@ while (*s)
 
 	  /* field for comparison */
 	  if (!(dstfield = string_nextinlist(&dstkeylist, &sep, NULL, 0)))
-	    goto sort_mismatch;
+	    goto SORT_MISMATCH;
 
 	  /* String-comparator names start with a letter; numeric names do not */
 
@@ -6741,7 +6752,7 @@ while (*s)
 	    while ((dstitem = string_nextinlist(&dstlist, &sep, NULL, 0)))
 	      {
 	      if (!(dstfield = string_nextinlist(&dstkeylist, &sep, NULL, 0)))
-		goto sort_mismatch;
+		goto SORT_MISMATCH;
 	      newlist = string_append_listele(newlist, sep, dstitem);
 	      newkeylist = string_append_listele(newkeylist, sep, dstfield);
 	      }
@@ -6772,9 +6783,9 @@ while (*s)
 
       /* Restore preserved $item */
       iterate_item = save_iterate_item;
-      continue;
+      break;
 
-      sort_mismatch:
+      SORT_MISMATCH:
 	expand_string_message = US"Internal error in sort (list mismatch)";
 	goto EXPAND_FAILED;
       }
@@ -6795,13 +6806,13 @@ while (*s)
 
 #else   /* EXPAND_DLFUNC */
       {
-      tree_node *t;
-      exim_dlfunc_t *func;
-      uschar *result;
+      tree_node * t;
+      exim_dlfunc_t * func;
+      uschar * result;
       int status, argc;
-      uschar *argv[EXPAND_DLFUNC_MAX_ARGS + 3];
+      uschar * argv[EXPAND_DLFUNC_MAX_ARGS + 3];
 
-      if ((expand_forbid & RDO_DLFUNC) != 0)
+      if (expand_forbid & RDO_DLFUNC)
         {
         expand_string_message =
           US"dynamically-loaded functions are not permitted";
@@ -6825,7 +6836,7 @@ while (*s)
 
       if (!(t = tree_search(dlobj_anchor, argv[0])))
         {
-        void *handle = dlopen(CS argv[0], RTLD_LAZY);
+        void * handle = dlopen(CS argv[0], RTLD_LAZY);
         if (!handle)
           {
           expand_string_message = string_sprintf("dlopen \"%s\" failed: %s",
@@ -6859,15 +6870,9 @@ while (*s)
 
       resetok = FALSE;
       result = NULL;
-      for (argc = 0; argv[argc]; argc++);
-      status = func(&result, argc - 2, &argv[2]);
-      if(status == OK)
-        {
-        if (!result) result = US"";
-        yield = string_cat(yield, result);
-        continue;
-        }
-      else
+      for (argc = 0; argv[argc]; argc++) ;
+
+      if ((status = func(&result, argc - 2, &argv[2])) != OK)
         {
         expand_string_message = result ? result : US"(no message)";
         if (status == FAIL_FORCED)
@@ -6877,6 +6882,9 @@ while (*s)
               argv[0], argv[1], status, expand_string_message);
         goto EXPAND_FAILED;
         }
+
+      if (result) yield = string_cat(yield, result);
+      break;
       }
 #endif /* EXPAND_DLFUNC */
 
@@ -6889,10 +6897,10 @@ while (*s)
 	goto EXPAND_FAILED;
 
       key = expand_string_internal(s+1, TRUE, &s, skipping, TRUE, &resetok);
-      if (!key) goto EXPAND_FAILED;			/*{*/
+      if (!key) goto EXPAND_FAILED;					/*{{*/
       if (*s++ != '}')
         {
-        expand_string_message = US"missing '{' for name arg of env";	/*}*/
+        expand_string_message = US"missing '}' for name arg of env";
 	goto EXPAND_FAILED_CURLY;
 	}
 
@@ -6910,7 +6918,8 @@ while (*s)
         case 1: goto EXPAND_FAILED;          /* when all is well, the */
         case 2: goto EXPAND_FAILED_CURLY;    /* returned value is 0 */
         }
-      continue;
+      if (skipping) continue;
+      break;
       }
 
 #ifdef SUPPORT_SRS
@@ -6991,10 +7000,25 @@ while (*s)
       /* @$original_domain */
       yield = string_catn(yield, US"@", 1);
       yield = string_cat(yield, sub[2]);
-      continue;
+
+      if (skipping) continue;
+      break;
       }
 #endif /*SUPPORT_SRS*/
+
+    default:
+      goto NOT_ITEM;
     }	/* EITEM_* switch */
+    /*NOTREACHED*/
+
+  DEBUG(D_expand)
+    if (yield && (start > 0 || *s))	/* only if not the sole expansion of the line */
+      debug_expansion_interim(US"item-res",
+			      yield->s + start, yield->ptr - start, skipping);
+  continue;
+
+NOT_ITEM: ;
+  }
 
   /* Control reaches here if the name is not recognized as one of the more
   complicated expansion items. Check for the "operator" syntax (name terminated
@@ -7004,10 +7028,9 @@ while (*s)
   if (*s == ':')
     {
     int c;
-    uschar *arg = NULL;
-    uschar *sub;
+    uschar * arg = NULL, * sub;
 #ifndef DISABLE_TLS
-    var_entry *vp = NULL;
+    var_entry * vp = NULL;
 #endif
 
     /* Owing to an historical mis-design, an underscore may be part of the
@@ -8137,34 +8160,9 @@ while (*s)
 	}	/* EOP_* switch */
 
        DEBUG(D_expand)
-	{
-	const uschar * s = yield->s + start;
-	int i = yield->ptr - start;
-	BOOL tainted = is_tainted(s);
-
-	DEBUG(D_noutf8)
-	  {
-	  debug_printf_indent("|-----op-res: %.*s\n", i, s);
-	  if (tainted)
-	    {
-	    debug_printf_indent("%s     \\__", skipping ? "|     " : "      ");
-	    debug_printf("(tainted)\n");
-	    }
-	  }
-	else
-	  {
-	  debug_printf_indent(UTF8_VERT_RIGHT
-	    UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ UTF8_HORIZ
-	    "op-res: %.*s\n", i, s);
-	  if (tainted)
-	    {
-	    debug_printf_indent("%s",
-	      skipping
-	      ? UTF8_VERT "             " : "           " UTF8_UP_RIGHT UTF8_HORIZ UTF8_HORIZ);
-	    debug_printf("(tainted)\n");
-	    }
-	  }
-	}
+	if (start > 0 || *s)		/* only if not the sole expansion of the line */
+	  debug_expansion_interim(US"op-res",
+				  yield->s + start, yield->ptr - start, skipping);
        continue;
        }
     }