src/src/imap_utf7.c

   1 #include "exim.h"
   2
   3 #ifdef SUPPORT_I18N
   4
   5 uschar *
   6 imap_utf7_encode(uschar *string, const uschar *charset, uschar sep,
   7   uschar *specials, uschar **error)
   8 {
   9 static uschar encode_base64[64] =
  10   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
  11 size_t slen;
  12 uschar *sptr;
  13 gstring * yield = NULL;
  14 int i = 0, j;   /* compiler quietening */
  15 uschar c = 0;   /* compiler quietening */
  16 BOOL base64mode = FALSE;
  17 BOOL lastsep = FALSE;
  18 uschar utf16buf[256];
  19 uschar *utf16ptr;
  20 uschar *s;
  21 uschar outbuf[256];
  22 uschar *outptr = outbuf;
  23 #if HAVE_ICONV
  24 iconv_t icd;
  25 #endif
  26
  27 if (!specials) specials = US"";
  28
  29 /* Pass over the string. If it consists entirely of "normal" characters
  30    (possibly with leading seps), return it as is. */
  31 for (s = string; *s; s++)
  32   {
  33   if (s == string && *s == sep)
  34     string++;
  35   if (  *s >= 0x7f
  36      || *s < 0x20
  37      || strchr("./&", *s)
  38      || *s == sep
  39      || Ustrchr(specials, *s)
  40      )
  41     break;
  42   }
  43
  44 if (!*s)
  45   return string;
  46
  47 sptr = string;
  48 slen = Ustrlen(string);
  49
  50 #if HAVE_ICONV
  51 if ((icd = iconv_open("UTF-16BE", CCS charset)) == (iconv_t)-1)
  52   {
  53   *error = string_sprintf(
  54         "imapfolder: iconv_open(\"UTF-16BE\", \"%s\") failed: %s%s",
  55     charset, strerror(errno),
  56     errno == EINVAL ? " (maybe unsupported conversion)" : "");
  57   return NULL;
  58   }
  59 #endif
  60
  61 while (slen > 0)
  62   {
  63 #if HAVE_ICONV
  64   size_t left = sizeof(utf16buf);
  65   utf16ptr = utf16buf;
  66
  67   if (  iconv(icd, (ICONV_ARG2_TYPE)&sptr, &slen, CSS &utf16ptr, &left)
  68                 == (size_t)-1
  69      && errno != E2BIG
  70          )
  71     {
  72     *error = string_sprintf("imapfolder: iconv() failed to convert from %s: %s",
  73                               charset, strerror(errno));
  74     iconv_close(icd);
  75     return NULL;
  76     }
  77 #else
  78   for (utf16ptr = utf16buf;
  79        slen > 0 && (utf16ptr - utf16buf) < sizeof(utf16buf);
  80        utf16ptr += 2, slen--, sptr++)
  81     {
  82     *utf16ptr = *sptr;
  83     *(utf16ptr+1) = '\0';
  84     }
  85 #endif
  86
  87   s = utf16buf;
  88   while (s < utf16ptr)
  89     {
  90     /* Now encode utf16buf as modified UTF-7 */
  91     if (  s[0] != 0
  92        || s[1] >= 0x7f
  93        || s[1] < 0x20
  94        || (Ustrchr(specials, s[1]) && s[1] != sep)
  95        )
  96       {
  97       lastsep = FALSE;
  98       /* Encode as modified BASE64 */
  99       if (!base64mode)
 100         {
 101         *outptr++ = '&';
 102         base64mode = TRUE;
 103         i = 0;
 104         }
 105
 106       for (j = 0; j < 2; j++, s++) switch (i++)
 107         {
 108         case 0:
 109           /* Top 6 bits of the first octet */
 110           *outptr++ = encode_base64[(*s >> 2) & 0x3F];
 111           c = (*s & 0x03); break;
 112         case 1:
 113           /* Bottom 2 bits of the first octet, and top 4 bits of the second */
 114           *outptr++ = encode_base64[(c << 4) | ((*s >> 4) & 0x0F)];
 115           c = (*s & 0x0F); break;
 116         case 2:
 117           /* Bottom 4 bits of the second octet and top 2 bits of the third */
 118           *outptr++ = encode_base64[(c << 2) | ((*s >> 6) & 0x03)];
 119           /* Bottom 6 bits of the third octet */
 120           *outptr++ = encode_base64[*s & 0x3F];
 121           i = 0;
 122         }
 123       }
 124
 125     else if (  (s[1] != '.' && s[1] != '/')
 126             || s[1] == sep
 127             )
 128       {
 129       /* Encode as self (almost) */
 130       if (base64mode)
 131         {
 132         switch (i)
 133           {
 134           case 1:
 135                 /* Remaining bottom 2 bits of the last octet */
 136                 *outptr++ = encode_base64[c << 4];
 137                 break;
 138           case 2:
 139                 /* Remaining bottom 4 bits of the last octet */
 140                 *outptr++ = encode_base64[c << 2];
 141           }
 142         *outptr++ = '-';
 143         base64mode = FALSE;
 144         }
 145
 146       if (*++s == sep)
 147         {
 148         if (!lastsep)
 149           {
 150           *outptr++ = '.';
 151           lastsep = TRUE;
 152           }
 153         }
 154       else
 155         {
 156         *outptr++ = *s;
 157         if (*s == '&')
 158           *outptr++ = '-';
 159         lastsep = FALSE;
 160         }
 161
 162       s++;
 163       }
 164     else
 165       {
 166       *error = string_sprintf("imapfolder: illegal character '%c'", s[1]);
 167       return NULL;
 168       }
 169
 170     if (outptr > outbuf + sizeof(outbuf) - 3)
 171       {
 172       yield = string_catn(yield, outbuf, outptr - outbuf);
 173       outptr = outbuf;
 174       }
 175
 176     }
 177   } /* End of input string */
 178
 179 if (base64mode)
 180   {
 181   switch (i)
 182     {
 183     case 1:
 184       /* Remaining bottom 2 bits of the last octet */
 185       *outptr++ = encode_base64[c << 4];
 186       break;
 187     case 2:
 188       /* Remaining bottom 4 bits of the last octet */
 189       *outptr++ = encode_base64[c << 2];
 190     }
 191   *outptr++ = '-';
 192   }
 193
 194 #if HAVE_ICONV
 195 iconv_close(icd);
 196 #endif
 197
 198 yield = string_catn(yield, outbuf, outptr - outbuf);
 199
 200 if (yield->s[yield->ptr-1] == '.')
 201   yield->ptr--;
 202
 203 return string_from_gstring(yield);
 204 }
 205
 206 #endif  /* whole file */
 207 /* vi: aw ai sw=2
 208 */