inet/idna.c

   1 /* IDNA functions, forwarding to implementations in libidn2.
   2    Copyright (C) 2018-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <allocate_once.h>
  20 #include <dlfcn.h>
  21 #include <inet/net-internal.h>
  22 #include <netdb.h>
  23 #include <stdbool.h>
  24
  25 /* Use the soname and version to locate libidn2, to ensure a
  26    compatible ABI.  */
  27 #define LIBIDN2_SONAME "libidn2.so.0"
  28 #define LIBIDN2_VERSION "IDN2_0.0.0"
  29
  30 /* Return codes from libidn2.  */
  31 enum
  32   {
  33     IDN2_OK = 0,
  34     IDN2_MALLOC = -100,
  35   };
  36
  37 /* Functions from libidn2.  */
  38 struct functions
  39 {
  40   void *handle;
  41   int (*lookup_ul) (const char *src, char **result, int flags);
  42   int (*to_unicode_lzlz) (const char *name, char **result, int flags);
  43 };
  44
  45 static void *
  46 functions_allocate (void *closure)
  47 {
  48   struct functions *result = malloc (sizeof (*result));
  49   if (result == NULL)
  50     return NULL;
  51
  52   void *handle = __libc_dlopen (LIBIDN2_SONAME);
  53   if (handle == NULL)
  54     /* Do not cache open failures.  The library may appear
  55        later.  */
  56     {
  57       free (result);
  58       return NULL;
  59     }
  60
  61   void *ptr_lookup_ul
  62     = __libc_dlvsym (handle, "idn2_lookup_ul", LIBIDN2_VERSION);
  63   void *ptr_to_unicode_lzlz
  64     = __libc_dlvsym (handle, "idn2_to_unicode_lzlz", LIBIDN2_VERSION);
  65   if (ptr_lookup_ul == NULL || ptr_to_unicode_lzlz == NULL)
  66     {
  67       __libc_dlclose (handle);
  68       free (result);
  69       return NULL;
  70     }
  71
  72   result->handle = handle;
  73   result->lookup_ul = ptr_lookup_ul;
  74   result->to_unicode_lzlz = ptr_to_unicode_lzlz;
  75 #ifdef PTR_MANGLE
  76   PTR_MANGLE (result->lookup_ul);
  77   PTR_MANGLE (result->to_unicode_lzlz);
  78 #endif
  79
  80   return result;
  81 }
  82
  83 static void
  84 functions_deallocate (void *closure, void *ptr)
  85 {
  86   struct functions *functions = ptr;
  87   __libc_dlclose (functions->handle);
  88   free (functions);
  89 }
  90
  91 /* Ensure that *functions is initialized and return the value of the
  92    pointer.  If the library cannot be loaded, return NULL.  */
  93 static inline struct functions *
  94 get_functions (void)
  95 {
  96   static void *functions;
  97   return allocate_once (&functions, functions_allocate, functions_deallocate,
  98                         NULL);
  99 }
 100
 101 /* strdup with an EAI_* error code.  */
 102 static int
 103 gai_strdup (const char *name, char **result)
 104 {
 105   char *ptr = __strdup (name);
 106   if (ptr == NULL)
 107     return EAI_MEMORY;
 108   *result = ptr;
 109   return 0;
 110 }
 111
 112 int
 113 __idna_to_dns_encoding (const char *name, char **result)
 114 {
 115   switch (__idna_name_classify (name))
 116     {
 117     case idna_name_ascii:
 118       /* Nothing to convert.  */
 119       return gai_strdup (name, result);
 120     case idna_name_nonascii:
 121       /* Encoding needed.  Handled below.  */
 122       break;
 123     case idna_name_nonascii_backslash:
 124     case idna_name_encoding_error:
 125       return EAI_IDN_ENCODE;
 126     case idna_name_memory_error:
 127       return EAI_MEMORY;
 128     case idna_name_error:
 129       return EAI_SYSTEM;
 130     }
 131
 132   struct functions *functions = get_functions ();
 133   if (functions == NULL)
 134     /* We report this as an encoding error (assuming that libidn2 is
 135        not installed), although the root cause may be a temporary
 136        error condition due to resource shortage.  */
 137     return EAI_IDN_ENCODE;
 138   char *ptr = NULL;
 139   __typeof__ (functions->lookup_ul) fptr = functions->lookup_ul;
 140 #ifdef PTR_DEMANGLE
 141   PTR_DEMANGLE (fptr);
 142 #endif
 143   int ret = fptr (name, &ptr, 0);
 144   if (ret == 0)
 145     {
 146       /* Assume that idn2_free is equivalent to free.  */
 147       *result = ptr;
 148       return 0;
 149     }
 150   else if (ret == IDN2_MALLOC)
 151     return EAI_MEMORY;
 152   else
 153     return EAI_IDN_ENCODE;
 154 }
 155 libc_hidden_def (__idna_to_dns_encoding)
 156
 157 int
 158 __idna_from_dns_encoding (const char *name, char **result)
 159 {
 160   struct functions *functions = get_functions ();
 161   if (functions == NULL)
 162     /* Simply use the encoded name, assuming that it is not punycode
 163        (but even a punycode name would be syntactically valid).  */
 164     return gai_strdup (name, result);
 165   char *ptr = NULL;
 166   __typeof__ (functions->to_unicode_lzlz) fptr = functions->to_unicode_lzlz;
 167 #ifdef PTR_DEMANGLE
 168   PTR_DEMANGLE (fptr);
 169 #endif
 170   int ret = fptr (name, &ptr, 0);
 171   if (ret == 0)
 172     {
 173       /* Assume that idn2_free is equivalent to free.  */
 174       *result = ptr;
 175       return 0;
 176     }
 177   else if (ret == IDN2_MALLOC)
 178     return EAI_MEMORY;
 179   else
 180     return EAI_IDN_ENCODE;
 181 }
 182 libc_hidden_def (__idna_from_dns_encoding)