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mls_mime.c
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mls_mime.c
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/****************************************************************************
MailListStat - print useful statistics on email messages
MIME & charset conversion functions
Copyright (C) 2001-2003 Marek Podmaka
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
****************************************************************************/
#include "mls.h"
#include "mls_mime.h"
#include "mls_stat.h"
regex_t r_qp, r_base64, r_hex;
void replaceStr(char *input, int so, int eo, char *repl) {
// replace part of input from index so to eo with repl
// repl should be smaller than eo-so+1!
// max. length of remainder of input is 256!
char tmp[256];
int l;
myCopy(tmp,input+eo+1,256); // put remainder of input to tmp
l=strlen(repl);
strncpy(input+so,repl,l); // put repl to right place (no \0 after)
strcpy(input+so+l,tmp); // it should fit
}
void Decode_QuotedPrint(char *encoded, char *charset) {
// decode quoted-printable encoded-word
// copy result to input -- its length will be smaller or equal, so it's safe
regmatch_t pm[10]; // buffer for matching substrings
char hex[4];
char *tmp;
int ihex;
// change underscore to space [RFC-1522 4.2.(2)]
for (tmp=encoded; *tmp!='\0'; tmp++) if (*tmp=='_') *tmp=' ';
while (!regexec(&r_hex, encoded, 10, pm, 0)) {
myCopy(hex,encoded+pm[1].rm_so+1,3);
ihex=strtol(hex,NULL,16);
hex[0]=ihex;
hex[1]='\0';
replaceStr(encoded,pm[1].rm_so,pm[1].rm_eo-1,hex);
}
}
int base64_table(char *lookup) {
// The base64 alphabet according to RFC-1521 sec. 5.2, Table 1
if (*lookup>='A' && *lookup<='Z') return *lookup-65;
if (*lookup>='a' && *lookup<='z') return *lookup-71;
if (*lookup>='0' && *lookup<='9') return *lookup+04;
if (*lookup=='+') return 62;
if (*lookup=='/') return 63;
return 0;
}
void Decode_base64(char *encoded, char *charset) {
// decode base64 encoded-word
// copy result to input -- its length will be smaller or equal, so it's safe
char decoded[76]="";
char ch;
char *tmp,*tmp2;
unsigned long bits24,mask24;
int i;
tmp2=decoded;
for (tmp=encoded; *tmp!='\0'; tmp+=4) {
bits24=0;
for (i=0; i<4; i++) {
if (*(tmp+i)!='=') bits24+=base64_table(tmp+i); // ignore padding char (=)
bits24 = bits24 << 6; // shift 6bits left
}
bits24 = bits24 >> 6; // shift 6bits right
// now we have 24bits of encoded data
// split into 3 8bit chars
mask24=255 << 16;
for (i=2; i>=0; i--) {
ch=(short)((bits24 & mask24) >> (i*8));
if (ch!='\0') *(tmp2++)=ch; // ignore chars made of padding
mask24 = mask24 >> 8;
}
}
*tmp2='\0';
strcpy(encoded,decoded); // decoded should be smaller!
}
void compile_mime_regex() {
char sB[]="(=\\?([0-9a-z-]*)\\?B\\?([0-9a-z+/=]*)\\?=)";
char sQ[]="(=\\?([0-9a-z-]*)\\?Q\\?(([!-<]|[>-~]|=[0-9a-f]{2}|\\0x9| |_)*)\\?=)";
char sH[]="(=[0-9a-z]{2})";
if (regcomp(&r_base64, sB, REG_EXTENDED | REG_ICASE) > 0) myWarn("Error compiling regex!","(mime_base64)",5);
if (regcomp(&r_qp , sQ, REG_EXTENDED | REG_ICASE) > 0) myWarn("Error compiling regex!","(mime_qp)",5);
if (regcomp(&r_hex , sH, REG_EXTENDED | REG_ICASE) > 0) myWarn("Error compiling regex!","(mime_hex)",5);
}
void Decode_mime_string(char *txt, unsigned int max_size) {
// decode string containing 0 or more MIME-encoded parts; no newlines
// overwrite input, but it should be at most max_size
// decoded string will be smaller (at most equal)
// charset conversion can make it bigger
int i;
char charset[40]; // charset name
char enc[76]; // encoded text
regmatch_t pm[10]; // buffer for matching substrings
// try to decode Qouted-Printable parts
while (!regexec(&r_qp, txt, 10, pm, 0)) {
i=pm[2].rm_eo - pm[2].rm_so + 1;
myCopy(charset, txt+pm[2].rm_so, (i>40)?40:i);
i=pm[3].rm_eo - pm[3].rm_so + 1;
myCopy(enc, txt+pm[3].rm_so, (i>76)?76:i);
Decode_QuotedPrint(enc,charset);
replaceStr(txt,pm[1].rm_so,pm[1].rm_eo-1,enc);
}
// try to decode Base64 parts
while (!regexec(&r_base64, txt, 10, pm, 0)) {
i=pm[2].rm_eo - pm[2].rm_so + 1;
myCopy(charset, txt+pm[2].rm_so, (i>40)?40:i);
i=pm[3].rm_eo - pm[3].rm_so + 1;
myCopy(enc, txt+pm[3].rm_so, (i>76)?76:i);
Decode_base64(enc,charset);
replaceStr(txt,pm[1].rm_so,pm[1].rm_eo-1,enc);
}
}