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/*
rfc2047e.c - encode a string as per RFC-2047
Copyright (C) 2004 Matthias Andree
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define _GNU_SOURCE
#include "fetchmail.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
static const char noenc[] = "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
static const char encchars[] = "!\"#$%&'*+,-./0123456789:;<>@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^`abcdefghijklmnopqrstuvwxyz{|}~";
static const char ws[] = " \t\r\n";
#ifdef TEST
void report (FILE *fp, const char *format, ...) { (void)fp; (void)format;}
#endif
static int needs_enc(const char *string) {
if (strspn(string, noenc) < strlen(string))
return 1;
if (strncmp(string, "=?", 2) == 0
&& strcmp(string + strlen(string) - 2, "?=") == 0)
return 1;
return 0;
}
static char *encode_words(char *const *words, int nwords, const char *charset)
{
char *out, *t, *v;
size_t l = 0;
int i;
for (i = 0; i < nwords; i++)
l += strlen(words[i]) * 3; /* worst case, encode everything */
l += (strlen(charset) + 8) * (l/60 + 1);
out = v = (char *)xmalloc(l);
t = stpcpy(out, "=?");
t = stpcpy(t, charset);
t = stpcpy(t, "?Q?");
for (i = 0; i < nwords; i++) {
const char *u;
for (u = words[i]; *u; u++) {
if (t - v >= 69) {
t = stpcpy(t, "?=\r\n=?");
v = t - 2;
t = stpcpy(t, charset);
t = stpcpy(t, "?Q?");
}
if (*u == ' ') { *t++ = '_'; continue; }
if (strchr(encchars, *u)) { *t++ = *u; continue; }
sprintf(t, "=%02X", (unsigned int)((unsigned char)*u));
t += 3;
}
}
strcpy(t, "?=");
return out;
}
/** RFC-2047 encode string with given charset. Only the Q encoding
* (quoted-printable) supported at this time.
* WARNING: this code returns a static buffer!
*/
char *rfc2047e(const char *string, const char *charset) {
static char *out;
char *t;
const char *r;
int count, minlen, idx, i;
char **words = NULL;
size_t l;
assert(strlen(charset) < 40);
if (out) {
free(out);
out = NULL;
}
/* phase 1: split original into words */
/* 1a: count, 1b: copy */
count = 0;
r = string;
while (*r) {
count++;
r += strcspn(r, ws);
if (!*r) break;
count++;
r += strspn(r, ws);
}
words = (char **)xmalloc(sizeof(char *) * (count + 1));
idx = 0;
r = string;
while (*r) {
l = strcspn(r, ws);
words[idx] = (char *)xmalloc(l+1);
memcpy(words[idx], r, l);
words[idx][l] = '\0';
idx++;
r += l;
if (!*r) break;
l = strspn(r, ws);
words[idx] = (char *)xmalloc(l+1);
memcpy(words[idx], r, l);
words[idx][l] = '\0';
idx++;
r += l;
}
/* phase 2: encode words */
/* a: find ranges of adjacent words to need encoding */
/* b: encode ranges */
idx = 0;
while (idx < count) {
int end; char *tmp;
if (!needs_enc(words[idx])) {
idx += 2;
continue;
}
for (end = idx + 2; end < count; end += 2) {
if (!needs_enc(words[end]))
break;
}
end -= 2;
tmp = encode_words(&words[idx], end - idx + 1, charset);
free(words[idx]);
words[idx] = tmp;
for (i = idx + 1; i <= end; i++)
words[i][0] = '\0';
idx = end + 2;
}
l = 0;
for (idx = 0; idx < count; idx++) {
l += strlen(words[idx]);
}
/* phase 3: limit lengths */
minlen = strlen(charset) + 7;
/* allocate ample memory */
out = (char *)xmalloc(l + (l / (72 - minlen) + 1) * (minlen + 2) + 1);
if (count)
t = stpcpy(out, words[0]);
else
t = out, *out = 0;
l = strlen(out);
for (i = 1; i < count; i+=2) {
size_t m;
char *tmp;
m = strlen(words[i]);
if (i + 1 < count)
m += strcspn(words[i+1], "\r\n");
if (l + m > 74)
t = stpcpy(t, "\r\n");
t = stpcpy(t, words[i]);
if (i + 1 < count) {
t = stpcpy(t, words[i+1]);
}
tmp = strrchr(out, '\n');
if (tmp == NULL)
tmp = out;
else
tmp++;
l = strlen(tmp);
}
/* free memory */
for (i = 0; i < count; i++) free(words[i]);
free(words);
return out;
}
#ifdef TEST
int main(int argc, char **argv) {
char *t;
if (argc > 1) {
t = rfc2047e(argv[1], argc > 2 ? argv[2] : "utf-8");
printf( " input: \"%s\"\n"
"output: \"%s\"\n", argv[1], t);
free(t);
}
return EXIT_SUCCESS;
}
#endif
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