/* 使用方法大致如下: innbbsd 中
在 SUBJECT 從 news 讀進來後, 呼叫 str_decode_M3(SUBJECT) 就行了 */
/* bsd 底下使用要編譯時要加 -I/usr/local/include -L/usr/local/lib -liconv
並安裝 libiconv,
若真的沒有iconv就把底下的 #define USE_ICONV 1 刪了 */
/*-------------------------------------------------------*/
/* lib/str_decode.c ( NTHU CS MapleBBS Ver 3.00 ) */
/*-------------------------------------------------------*/
/* target : included C for QP/BASE64 decoding */
/* create : 95/03/29 */
/* update : 97/03/29 */
/*-------------------------------------------------------*/
/* ----------------------------------------------------- */
/* QP code : "0123456789ABCDEF" */
/* ----------------------------------------------------- */
#include <stdio.h>
#include <errno.h>
#include <string.h>
#define USE_ICONV 1
/* bsd 底下使用要編譯時要加 -I/usr/local/include -L/usr/local/lib -liconv
若真的沒有iconv就把上面這行 #define 刪了 */
#ifdef USE_ICONV
#include <iconv.h>
#endif
static int qp_code(int x)
{
if (x >= '0' && x <= '9')
return x - '0';
if (x >= 'a' && x <= 'f')
return x - 'a' + 10;
if (x >= 'A' && x <= 'F')
return x - 'A' + 10;
return -1;
}
/* ------------------------------------------------------------------ */
/* BASE64 : */
/* "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" */
/* ------------------------------------------------------------------ */
static int base64_code(int x)
{
if (x >= 'A' && x <= 'Z')
return x - 'A';
if (x >= 'a' && x <= 'z')
return x - 'a' + 26;
if (x >= '0' && x <= '9')
return x - '0' + 52;
if (x == '+')
return 62;
if (x == '/')
return 63;
return -1;
}
/* ----------------------------------------------------- */
/* judge & decode QP / BASE64 */
/* ----------------------------------------------------- */
static inline int isreturn(unsigned char c)
{
return c == '\r' || c == '\n';
}
static inline int isspace(unsigned char c)
{
return c == ' ' || c == '\t' || isreturn(c);
}
/* static inline */
int mmdecode(unsigned char *src, unsigned char encode, unsigned char *dst)
{
/* Thor.980901: src和dst可相同, 但src 一定有?或\0結束 */
/* Thor.980901: 注意, decode出的結果不會自己加上 \0 */
unsigned char *t = dst;
int pattern = 0, bits = 0;
encode |= 0x20; /* Thor: to lower */
switch(encode)
{
case 'q': /* Thor: quoted-printable */
while(*src && *src != '?') /* Thor: delimiter */
{ /* Thor.980901: 0 算是 delimiter */
if(*src == '=')
{
int x = *++src, y = x ? *++src : 0;
if(isreturn(x)) continue;
if( (x = qp_code(x)) < 0 || ( y = qp_code(y)) < 0) return -1;
*t++ = (x << 4) + y , src++;
}
else if(*src == '_')
*t++ = ' ', src++;
#if 0
else if(!*src) /* Thor: no delimiter is not successful */
return -1;
#endif
else /* Thor: *src != '=' '_' */
*t++ = *src++;
}
return t - dst;
case 'b': /* Thor: base 64 */
while(*src && *src != '?') /* Thor: delimiter */ /* Thor.980901: 0也算 */
{ /* Thor: pattern & bits are cleared outside */
int x;
#if 0
if (!*src) return -1; /* Thor: no delimiter is not successful */
#endif
x = base64_code(*src++);
if(x < 0) continue; /* Thor: ignore everything not in the base64,=,.. */
pattern = (pattern << 6) | x;
bits += 6; /* Thor: 1 code gains 6 bits */
if(bits >= 8) /* Thor: enough to form a byte */
{
bits -= 8;
*t++ = (pattern >> bits) & 0xff;
}
}
return t - dst;
}
return -1;
}
#ifdef USE_ICONV
int str_iconv(
const char *fromcode, /* charset of source string*/
const char *tocode, /* charset of destination string */
char *src, /* source string */
int srclen, /* source string length */
char *dst, /* destination string */
int dstlen) /* destination string length */
/* 這個函式會將一個字串 (src) 從 charset=fromcode 轉成 charset=tocode,
srclen 是 src 的長度, dst 是輸出的buffer, dstlen 則指定了
dst 的大小, 最後會補 '\0', 所以要留一個byte給'\0'.
如果遇到 src 中有非字集的字, 或是 src 中有未完整的 byte,
都會砍掉.
*/
{
iconv_t iconv_descriptor;
int iconv_ret,dstlen_old;
dstlen--; /* keep space for '\0' */
dstlen_old = dstlen;
/* Open a descriptor for iconv */
iconv_descriptor = iconv_open(tocode, fromcode);
if (iconv_descriptor == ((iconv_t)(-1)) ) /* if open fail */
{
strncpy(dst,src,dstlen);
return dstlen;
}
/* Start translation */
while (srclen > 0 && dstlen > 0)
{
iconv_ret = iconv(iconv_descriptor, (const char* *)&src, &srclen,
&dst, &dstlen);
if (iconv_ret != 0)
{
switch(errno)
{
/* invalid multibyte happened */
case EILSEQ:
/* forward that byte */
*dst = *src;
src++; srclen--;
dst++; dstlen--;
break;
/* incomplete multibyte happened */
case EINVAL:
/* forward that byte (maybe wrong)*/
*dst = *src;
src++; srclen--;
dst++; dstlen--;
break;
/* dst no rooms */
case E2BIG:
/* break out the while loop */
srclen = 0;
break;
}
}
}
*dst = '\0';
/* close descriptor of iconv*/
iconv_close(iconv_descriptor);
return (dstlen_old - dstlen);
}
#endif
void str_decode_M3(unsigned char *str)
{
int adj;
int i;
unsigned char *src, *dst;
unsigned char buf[512];
unsigned char charset[512],dst1[512];
src = str;
dst = buf;
adj = 0;
while (*src && (dst - buf) < sizeof(buf) - 1)
{
if (*src != '=')
{ /* Thor: not coded */
unsigned char *tmp = src;
while(adj && *tmp && isspace(*tmp)) tmp++;
if(adj && *tmp=='=')
{ /* Thor: jump over space */
adj = 0;
src = tmp;
}
else
*dst++ = *src++;
/* continue;*/ /* Thor: take out */
}
else /* Thor: *src == '=' */
{
unsigned char *tmp = src + 1;
if(*tmp == '?') /* Thor: =? coded */
{
/* "=?%s?Q?" for QP, "=?%s?B?" for BASE64 */
tmp ++;
i=0;
while(*tmp && *tmp != '?')
{
if (i+1<sizeof(charset))
{
charset[i] = *tmp;
charset[i+1]='\0';
i++;
}
tmp++;
}
if(*tmp && tmp[1] && tmp[2]=='?') /* Thor: *tmp == '?' */
{
#ifdef USE_ICONV
int i = mmdecode(tmp + 3, tmp[1], dst1);
i = str_iconv(charset,"big5",dst1,i,dst,
sizeof(buf)-((int)(dst-buf)) );
#else
int i = mmdecode(tmp + 3, tmp[1], dst);
#endif
if (i >= 0)
{
tmp += 3; /* Thor: decode's src */
#if 0
while(*tmp++ != '?'); /* Thor: no ? end, mmdecode -1 */
#endif
while(*tmp && *tmp++ != '?'); /* Thor: no ? end, mmdecode -1 */
/* Thor.980901: 0 也算 decode 結束 */
if(*tmp == '=') tmp++;
src = tmp; /* Thor: decode over */
dst += i;
adj = 1; /* Thor: adjcent */
}
}
}
while(src != tmp) /* Thor: not coded */
*dst++ = *src++;
}
}
*dst = 0;
strcpy(str, buf);
}
