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#include <stdlib.h>
#include <errno.h>
#include <iconv.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#define iswsp(c) (((c) == ' ' || (c) == '\t'))
// ASCII lowercase without alpha check (wrong for "@[\]^_")
#define lc(c) ((c) | 0x20)
// XXX error detection on decode
// XXX keep trying bytewise on invalid iconv
int
decode_qp(char *start, char *stop, char **deco, size_t *decleno)
{
static signed char hex[] = {
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1, -1,-1,-1,-1,
-1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1
};
char *buf = malloc(4 * (stop - start));
if (!buf)
return 0;
*deco = buf;
char *s = start;
size_t declen;
while (s < stop) {
if (*s == '=' && s[1] == '\n') {
s += 2;
} else if (*s == '=' && s+2 < stop) {
*buf++ = (hex[s[1]] << 4) | hex[s[2]];
s += 3;
} else if (*s == '_') {
*buf++ = ' ';
s++;
} else {
*buf++ = *s++;
}
}
*buf = 0;
*decleno = buf - *deco;
return 1;
}
int
decode_b64(char *s, char *e, char **deco, size_t *decleno)
{
static signed char b64[128] = {
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-1,-1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};
char *buf = malloc(e - s); // XXX better bound
if (!buf)
return 0;
*deco = buf;
while (s + 4 <= e) {
while (s < e && isspace((unsigned char) *s))
s++;
if (s < e) {
uint32_t v = 0;
v |= b64[s[0]]; v <<= 6;
v |= b64[s[1]]; v <<= 6;
v |= b64[s[2]]; v <<= 6;
v |= b64[s[3]];
char d2 = v & 0xff; v >>= 8;
char d1 = v & 0xff; v >>= 8;
char d0 = v & 0xff;
if (s[1] != '=') *buf++ = d0;
if (s[2] != '=') *buf++ = d1;
if (s[3] != '=') *buf++ = d2;
s += 4;
}
}
*decleno = buf - *deco;
return 1;
}
int
blaze822_decode_rfc2047(char *dst, char *src, size_t dlen, char *tgtenc)
{
iconv_t ic;
char *b = src;
// use memmem
char *s = strstr(src, "=?");
if (!s)
goto nocodeok;
do {
char *t;
t = b;
while (t < s) // strip space-only inbetween encoded words
if (!isspace((unsigned char) *t++)) {
while (b < s && dlen) {
*dst++ = *b++;
dlen--;
}
break;
}
if (!dlen)
break;
s += 2;
char *e = strchr(s, '?');
if (!e)
goto nocode;
*e = 0;
ic = iconv_open(tgtenc, s);
*e = '?';
e++;
if (ic < 0) {
perror("iconv_open");
goto nocode;
}
char enc = lc(*e++);
if (*e++ != '?')
goto nocode;
char *start = e++;
char *stop = strstr(e, "?=");
if (!stop)
goto nocode;
char *dec;
size_t declen;
if (enc == 'q')
decode_qp(start, stop, &dec, &declen);
else if (enc == 'b')
decode_b64(start, stop, &dec, &declen);
else
goto nocode;
int r = iconv(ic, &dec, &declen, &dst, &dlen);
if (r < 0) {
if (errno == E2BIG)
break;
perror("iconv");
iconv_close(ic);
goto nocode;
}
iconv_close(ic);
while (declen-- && dlen) {
*dst++ = *dec++;
dlen--;
}
b = stop + 2;
} while (dlen && (s = strstr(b, "=?")));
while (*b && dlen-- > 0)
*dst++ = *b++;
*dst = 0;
return 1;
nocode:
fprintf(stderr, "error decoding rfc2047\n");
nocodeok:
while (*src && dlen) {
*dst++ = *src++;
dlen--;
}
*dst = 0;
return 1;
}
#ifdef TEST
int
main() {
char *r;
size_t l;
char test[] = "Keld_J=F8rn_Simonsen";
decode_qp(test, test + sizeof test, &r, &l);
printf("%s %d\n", r, l);
char *r2;
size_t l2;
char test2[] = "SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=dSB1bmRlcnN0YW5kIHRoZSBleGFtcGxlLg==";
decode_b64(test2, test2+sizeof test2, &r2, &l2);
printf("%s %d\n", r2, l2);
char test3[] = "=?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= <keld@dkuug.dk>";
char test3dec[255];
blaze822_decode_rfc2047(test3dec, test3, sizeof test3dec, "UTF-8");
printf("%s\n", test3dec);
char test4[] = "=?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=?= "
"=?ISO-8859-2?B?dSB1bmRlcnN0YW5kIHRoZSBleGFtcGxlLg==?= z "
"=?ISO-8859-1?Q?a?= =?ISO-8859-2?Q?_b?=";
char test4dec[255];
blaze822_decode_rfc2047(test4dec, test4, sizeof test4dec, "UTF-8");
printf("%s\n", test4dec);
}
#endif
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