string.c: do not interpret '\\' before '\0' (CVE-2019-15846)

[exim.git] / src / src / utf8.c

diff --git a/src/src/utf8.c b/src/src/utf8.c
index 8a7cf38a346da35e4c60a07cbc57e3de71a0fe06..16a53037de383165904c11bb33aee7d532e76253 100644 (file)
--- a/src/src/utf8.c
+++ b/src/src/utf8.c
@@ -2,37 +2,78 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 

-/* Copyright (c) Jeremy Harris 2015 */
+/* Copyright (c) Jeremy Harris 2015 - 2018 */

 /* See the file NOTICE for conditions of use and distribution. */
 
 
 #include "exim.h"
 
 /* See the file NOTICE for conditions of use and distribution. */
 
 
 #include "exim.h"
 

-#ifdef EXPERIMENTAL_INTERNATIONAL
+#ifdef SUPPORT_I18N
+
+#ifdef SUPPORT_I18N_2008
+# include <idn2.h>
+#else
+# include <idna.h>
+#endif

 
 

-#include <idna.h>

 #include <punycode.h>
 #include <stringprep.h>
 
 #include <punycode.h>
 #include <stringprep.h>
 

+static uschar *
+string_localpart_alabel_to_utf8_(const uschar * alabel, uschar ** err);
+
+/**************************************************/
+

 BOOL
 string_is_utf8(const uschar * s)
 {
 uschar c;
 BOOL
 string_is_utf8(const uschar * s)
 {
 uschar c;

-while ((c = *s++)) if (c & 0x80) return TRUE;
+if (s) while ((c = *s++)) if (c & 0x80) return TRUE;

 return FALSE;
 }
 
 return FALSE;
 }
 

+static BOOL
+string_is_alabel(const uschar * s)
+{
+return s[0] == 'x' && s[1] == 'n' && s[2] == '-' && s[3] == '-';
+}
+

 /**************************************************/
 /**************************************************/

-/* Domain conversions */
-/* the *err string pointer should be null before the call */
+/* Domain conversions.
+The *err string pointer should be null before the call
+
+Return NULL for error, with optional errstr pointer filled in
+*/

 
 uschar *
 string_domain_utf8_to_alabel(const uschar * utf8, uschar ** err)
 {
 
 uschar *
 string_domain_utf8_to_alabel(const uschar * utf8, uschar ** err)
 {

-uschar * s1;
-uschar * s;
+uschar * s1, * s;

 int rc;
 
 int rc;
 

+#ifdef SUPPORT_I18N_2008
+/* Avoid lowercasing plain-ascii domains */
+if (!string_is_utf8(utf8))
+  return string_copy(utf8);
+
+/* Only lowercase is accepted by the library call.  A pity since we lose
+any mixed-case annotation.  This does not really matter for a domain. */
+  {
+  uschar c;
+  for (s1 = s = US utf8; (c = *s1); s1++) if (!(c & 0x80) && isupper(c))
+    {
+    s = string_copy(utf8);
+    for (s1 = s + (s1 - utf8); (c = *s1); s1++) if (!(c & 0x80) && isupper(c))
+      *s1 = tolower(c);
+    break;
+    }
+  }
+if ((rc = idn2_lookup_u8((const uint8_t *) s, &s1, IDN2_NFC_INPUT)) != IDN2_OK)
+  {
+  if (err) *err = US idn2_strerror(rc);
+  return NULL;
+  }
+#else

 s = US stringprep_utf8_nfkc_normalize(CCS utf8, -1);
 if (  (rc = idna_to_ascii_8z(CCS s, CSS &s1, IDNA_ALLOW_UNASSIGNED))
    != IDNA_SUCCESS)
 s = US stringprep_utf8_nfkc_normalize(CCS utf8, -1);
 if (  (rc = idna_to_ascii_8z(CCS s, CSS &s1, IDNA_ALLOW_UNASSIGNED))
    != IDNA_SUCCESS)


@@ -42,6 +83,7 @@ if (  (rc = idna_to_ascii_8z(CCS s, CSS &s1, IDNA_ALLOW_UNASSIGNED))
   return NULL;
   }
 free(s);
   return NULL;
   }
 free(s);

+#endif

 s = string_copy(s1);
 free(s1);
 return s;
 s = string_copy(s1);
 free(s1);
 return s;


@@ -52,8 +94,23 @@ return s;
 uschar *
 string_domain_alabel_to_utf8(const uschar * alabel, uschar ** err)
 {
 uschar *
 string_domain_alabel_to_utf8(const uschar * alabel, uschar ** err)
 {

-uschar * s1;
-uschar * s;
+#ifdef SUPPORT_I18N_2008
+const uschar * label;
+int sep = '.';
+gstring * g = NULL;
+
+while (label = string_nextinlist(&alabel, &sep, NULL, 0))
+  if (  string_is_alabel(label)
+     && !(label = string_localpart_alabel_to_utf8_(label, err))
+     )
+    return NULL;
+  else
+    g = string_append_listele(g, '.', label);
+return string_from_gstring(g);
+
+#else
+
+uschar * s1, * s;

 int rc;
 
 if (  (rc = idna_to_unicode_8z8z(CCS alabel, CSS &s1, IDNA_USE_STD3_ASCII_RULES))
 int rc;
 
 if (  (rc = idna_to_unicode_8z8z(CCS alabel, CSS &s1, IDNA_USE_STD3_ASCII_RULES))


@@ -65,6 +122,7 @@ if (  (rc = idna_to_unicode_8z8z(CCS alabel, CSS &s1, IDNA_USE_STD3_ASCII_RULES)
 s = string_copy(s1);
 free(s1);
 return s;
 s = string_copy(s1);
 free(s1);
 return s;

+#endif

 }
 
 /**************************************************/
 }
 
 /**************************************************/


@@ -103,25 +161,20 @@ return res;
 }
 
 
 }
 
 

-uschar *
-string_localpart_alabel_to_utf8(const uschar * alabel, uschar ** err)
+static uschar *
+string_localpart_alabel_to_utf8_(const uschar * alabel, uschar ** err)

 {
 {

-size_t p_len = Ustrlen(alabel);
+size_t p_len;

 punycode_uint * p;
 punycode_uint * p;

-uschar * s;
-uschar * res;

 int rc;
 int rc;

+uschar * s, * res;

 
 

-if (alabel[0] != 'x' || alabel[1] != 'n' || alabel[2] != '-' || alabel[3] != '-')
-  {
-  if (err) *err = US"bad alabel prefix";
-  return NULL;
-  }
-
-p_len -= 4;
+DEBUG(D_expand) debug_printf("l_a2u: '%s'\n", alabel);
+alabel += 4;
+p_len = Ustrlen(alabel);

 p = (punycode_uint *) store_get((p_len+1) * sizeof(*p));
 
 p = (punycode_uint *) store_get((p_len+1) * sizeof(*p));
 

-if ((rc = punycode_decode(p_len, CCS alabel+4, &p_len, p, NULL)) != PUNYCODE_SUCCESS)
+if ((rc = punycode_decode(p_len, CCS alabel, &p_len, p, NULL)) != PUNYCODE_SUCCESS)

   {
   if (err) *err = US punycode_strerror(rc);
   return NULL;
   {
   if (err) *err = US punycode_strerror(rc);
   return NULL;


@@ -134,9 +187,23 @@ return res;
 }
 
 
 }
 
 

+uschar *
+string_localpart_alabel_to_utf8(const uschar * alabel, uschar ** err)
+{
+if (string_is_alabel(alabel))
+  return string_localpart_alabel_to_utf8_(alabel, err);
+
+if (err) *err = US"bad alabel prefix";
+return NULL;
+}
+
+

 /**************************************************/
 /**************************************************/

-/* whole address conversion */
-/* the *err string pointer should be null before the call */
+/* Whole address conversion.
+The *err string pointer should be null before the call.
+
+Return NULL on error, with (optional) errstring pointer filled in
+*/

 
 uschar *
 string_address_utf8_to_alabel(const uschar * utf8, uschar ** err)
 
 uschar *
 string_address_utf8_to_alabel(const uschar * utf8, uschar ** err)


@@ -153,8 +220,8 @@ for (s = utf8; *s; s++)
   if (*s == '@')
     {
     l = string_copyn(utf8, s - utf8);
   if (*s == '@')
     {
     l = string_copyn(utf8, s - utf8);

-    if (  (l = string_localpart_utf8_to_alabel(l, err), err && *err)
-       || (d = string_domain_utf8_to_alabel(++s, err),  err && *err)
+    if (  !(l = string_localpart_utf8_to_alabel(l, err))
+       || !(d = string_domain_utf8_to_alabel(++s, err))

        )
       return NULL;
     l = string_sprintf("%s@%s", l, d);
        )
       return NULL;
     l = string_sprintf("%s@%s", l, d);


@@ -182,10 +249,21 @@ Returns:     nothing
 void
 utf8_version_report(FILE *f)
 {
 void
 utf8_version_report(FILE *f)
 {

+#ifdef SUPPORT_I18N_2008
+fprintf(f, "Library version: IDN2: Compile: %s\n"
+           "                       Runtime: %s\n",
+       IDN2_VERSION,
+       idn2_check_version(NULL));
+fprintf(f, "Library version: Stringprep: Compile: %s\n"
+           "                             Runtime: %s\n",
+       STRINGPREP_VERSION,
+       stringprep_check_version(NULL));
+#else

 fprintf(f, "Library version: IDN: Compile: %s\n"
            "                      Runtime: %s\n",
        STRINGPREP_VERSION,
        stringprep_check_version(NULL));
 fprintf(f, "Library version: IDN: Compile: %s\n"
            "                      Runtime: %s\n",
        STRINGPREP_VERSION,
        stringprep_check_version(NULL));

+#endif

 }
 
 #endif /* whole file */
 }
 
 #endif /* whole file */