encoding.c

Vovida 社区开源的 SIP 协议源码

/*
 * encoding.c : implements the encoding conversion functions needed for XML
 *
 * Related specs: 
 * rfc2044        (UTF-8 and UTF-16) F. Yergeau Alis Technologies
 * [ISO-10646]    UTF-8 and UTF-16 in Annexes
 * [ISO-8859-1]   ISO Latin-1 characters codes.
 * [UNICODE]      The Unicode Consortium, "The Unicode Standard --
 *                Worldwide Character Encoding -- Version 1.0", Addison-
 *                Wesley, Volume 1, 1991, Volume 2, 1992.  UTF-8 is
 *                described in Unicode Technical Report #4.
 * [US-ASCII]     Coded Character Set--7-bit American Standard Code for
 *                Information Interchange, ANSI X3.4-1986.
 *
 * Original code for IsoLatin1 and UTF-16 by "Martin J. Duerst" <[e-mail]>
 *
 * See Copyright for the status of this software.
 *
 * [e-mail]
 */

#ifdef WIN32
#include "win32config.h"
#else
#include "config.h"
#endif

#include <stdio.h>
#include <string.h>

#ifdef HAVE_CTYPE_H
#include <ctype.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <libxml/encoding.h>
#include <libxml/xmlmemory.h>

xmlCharEncodingHandlerPtr xmlUTF16LEHandler = NULL;
xmlCharEncodingHandlerPtr xmlUTF16BEHandler = NULL;

/*
 * From rfc2044: encoding of the Unicode values on UTF-8:
 *
 * UCS-4 range (hex.)           UTF-8 octet sequence (binary)
 * 0000 0000-0000 007F   0xxxxxxx
 * 0000 0080-0000 07FF   110xxxxx 10xxxxxx
 * 0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx 
 *
 * I hope we won't use values > 0xFFFF anytime soon !
 */

/**
 * xmlCheckUTF8: Check utf-8 string for legality.
 * @utf: Pointer to putative utf-8 encoded string.
 *
 * Checks @utf for being valid utf-8. @utf is assumed to be
 * null-terminated. This function is not super-strict, as it will
 * allow longer utf-8 sequences than necessary. Note that Java is
 * capable of producing these sequences if provoked. Also note, this
 * routine checks for the 4-byte maxiumum size, but does not check for
 * 0x10ffff maximum value.
 *
 * Return value: true if @utf is valid.
 **/
int
xmlCheckUTF8(const unsigned char *utf)
{
    int ix;
    unsigned char c;

    for (ix = 0; (c = utf[ix]);) {
        if (c & 0x80) {
	    if ((utf[ix + 1] & 0xc0) != 0x80)
	        return(0);
	    if ((c & 0xe0) == 0xe0) {
	        if ((utf[ix + 2] & 0xc0) != 0x80)
		    return(0);
	        if ((c & 0xf0) == 0xf0) {
		    if ((c & 0xf8) != 0xf0 || (utf[ix + 3] & 0xc0) != 0x80)
		        return(0);
		    ix += 4;
		    /* 4-byte code */
	        } else
		  /* 3-byte code */
		    ix += 3;
	    } else
	      /* 2-byte code */
	        ix += 2;
	} else
	    /* 1-byte code */
	    ix++;
      }
      return(1);
}

/**
 * isolat1ToUTF8:
 * @out:  a pointer to an array of bytes to store the result
 * @outlen:  the length of @out
 * @in:  a pointer to an array of ISO Latin 1 chars
 * @inlen:  the length of @in
 *
 * Take a block of ISO Latin 1 chars in and try to convert it to an UTF-8
 * block of chars out.
 * Returns the number of byte written, or -1 by lack of space.
 */
int
isolat1ToUTF8(unsigned char* out, int outlen,
              const unsigned char* in, int *inlen) {
    unsigned char* outstart= out;
    unsigned char* outend= out+outlen;
    const unsigned char* inend= in+*inlen;
    unsigned char c;

    while (in < inend) {
        c= *in++;
        if (c < 0x80) {
            if (out >= outend)  return(-1);
            *out++ = c;
        }
        else {
            if (out >= outend)  return(-1);
            *out++ = 0xC0 | (c >> 6);
            if (out >= outend)  return(-1);
            *out++ = 0x80 | (0x3F & c);
        }
    }
    return(out-outstart);
}

/**
 * UTF8Toisolat1:
 * @out:  a pointer to an array of bytes to store the result
 * @outlen:  the length of @out
 * @in:  a pointer to an array of UTF-8 chars
 * @inlen:  the length of @in
 *
 * Take a block of UTF-8 chars in and try to convert it to an ISO Latin 1
 * block of chars out.
 * TODO: UTF8Toisolat1 need a fallback mechanism ...
 *
 * Returns the number of byte written, or -1 by lack of space, or -2
 *     if the transcoding fails (for *in is not valid utf8 string or
 *     the result of transformation can't fit into the encoding we want)
 * The value of @inlen after return is the number of octets consumed
 *     as the return value is positive, else unpredictiable.
 */
int
UTF8Toisolat1(unsigned char* out, int outlen,
              const unsigned char* in, int *inlen) {
    unsigned char* outstart= out;
    unsigned char* outend= out+outlen;
    const unsigned char* inend= in+*inlen;
    unsigned char c;

    while (in < inend) {
        c= *in++;
        if (c < 0x80) {
            if (out >= outend)  return(-1);
            *out++= c;
        }
	else if (in == inend) {
            *inlen -= 1;
            break;
	}
	else if (((c & 0xFC) == 0xC0) && ((*in & 0xC0) == 0x80)) {
	    /* a two byte utf-8 and can be encoding as isolate1 */
            *out++= ((c & 0x03) << 6) | (*in++ & 0x3F);
	}
	else
	    return(-2);
	/* TODO : some should be represent as "&#x____;" */
    }
    return(out-outstart);
}

/**
 * UTF16LEToUTF8:
 * @out:  a pointer to an array of bytes to store the result
 * @outlen:  the length of @out
 * @inb:  a pointer to an array of UTF-16LE passwd as a byte array
 * @inlenb:  the length of @in in UTF-16LE chars
 *
 * Take a block of UTF-16LE ushorts in and try to convert it to an UTF-8
 * block of chars out. This function assume the endian properity
 * is the same between the native type of this machine and the
 * inputed one.
 *
 * Returns the number of byte written, or -1 by lack of space, or -2
 *     if the transcoding fails (for *in is not valid utf16 string)
 *     The value of *inlen after return is the number of octets consumed
 *     as the return value is positive, else unpredictiable.
 */
int
UTF16LEToUTF8(unsigned char* out, int outlen,
            const unsigned char* inb, int *inlenb)
{
    unsigned char* outstart= out;
    unsigned char* outend= out+outlen;
    unsigned short* in = (unsigned short*) inb;
    unsigned short* inend;
    unsigned int c, d, inlen;
    unsigned char *tmp;
    int bits;

    if ((*inlenb % 2) == 1)
        (*inlenb)--;
    inlen = *inlenb / 2;
    inend= in + inlen;
    while (in < inend) {
#ifdef BIG_ENDIAN
	tmp = (unsigned char *) in;
	c = *tmp++;
	c = c | (((unsigned int)*tmp) << 8);
	in++;
#else /* BIG_ENDIAN */
        c= *in++;
#endif /* BIG_ENDIAN */
        if ((c & 0xFC00) == 0xD800) {    /* surrogates */
            if (in >= inend) {           /* (in > inend) shouldn't happens */
                (*inlenb) -= 2;
                break;
            }
#ifdef BIG_ENDIAN
            tmp = (unsigned char *) in;
            d = *tmp++;
	    d = d | (((unsigned int)*tmp) << 8);
	    in++;
#else /* BIG_ENDIAN */
            d = *in++;
#endif /* BIG_ENDIAN */
            if ((d & 0xFC00) == 0xDC00) {
                c &= 0x03FF;
                c <<= 10;
                c |= d & 0x03FF;
                c += 0x10000;
            }
            else
	        return(-2);
        }

	/* assertion: c is a single UTF-4 value */
        if (out >= outend)
	    return(-1);
        if      (c <    0x80) {  *out++=  c;                bits= -6; }
        else if (c <   0x800) {  *out++= ((c >>  6) & 0x1F) | 0xC0;  bits=  0; }
        else if (c < 0x10000) {  *out++= ((c >> 12) & 0x0F) | 0xE0;  bits=  6; }
        else                  {  *out++= ((c >> 18) & 0x07) | 0xF0;  bits= 12; }
 
        for ( ; bits >= 0; bits-= 6) {
            if (out >= outend)
	        return(-1);
            *out++= ((c >> bits) & 0x3F) | 0x80;
        }
    }
    return(out-outstart);
}

/**
 * UTF8ToUTF16LE:
 * @outb:  a pointer to an array of bytes to store the result
 * @outlen:  the length of @outb
 * @in:  a pointer to an array of UTF-8 chars
 * @inlen:  the length of @in
 *
 * Take a block of UTF-8 chars in and try to convert it to an UTF-16LE
 * block of chars out.
 * TODO: UTF8ToUTF16LE need a fallback mechanism ...
 *
 * Returns the number of byte written, or -1 by lack of space, or -2
 *     if the transcoding failed. 
 */
int
UTF8ToUTF16LE(unsigned char* outb, int outlen,
            const unsigned char* in, int *inlen)
{
    unsigned short* out = (unsigned short*) outb;
    unsigned short* outstart= out;
    unsigned short* outend;
    const unsigned char* inend= in+*inlen;
    unsigned int c, d, trailing;
#ifdef BIG_ENDIAN
    unsigned char *tmp;
    unsigned short tmp1, tmp2;
#endif /* BIG_ENDIAN */

    outlen /= 2; /* convert in short length */
    outend = out + outlen;
    while (in < inend) {
      d= *in++;
      if      (d < 0x80)  { c= d; trailing= 0; }
      else if (d < 0xC0)
          return(-2);    /* trailing byte in leading position */
      else if (d < 0xE0)  { c= d & 0x1F; trailing= 1; }
      else if (d < 0xF0)  { c= d & 0x0F; trailing= 2; }
      else if (d < 0xF8)  { c= d & 0x07; trailing= 3; }
      else
          return(-2);    /* no chance for this in UTF-16 */

      if (inend - in < trailing) {
          *inlen -= (inend - in);
          break;
      } 

      for ( ; trailing; trailing--) {
          if ((in >= inend) || (((d= *in++) & 0xC0) != 0x80))
	      return(-1);
          c <<= 6;
          c |= d & 0x3F;
      }

      /* assertion: c is a single UTF-4 value */
        if (c < 0x10000) {
            if (out >= outend)
	        return(-1);
#ifdef BIG_ENDIAN
            tmp = (unsigned char *) out;
            *tmp = c ;
            *(tmp + 1) = c >> 8 ;
            out++;
#else /* BIG_ENDIAN */
            *out++ = c;
#endif /* BIG_ENDIAN */
        }
        else if (c < 0x110000) {
            if (out+1 >= outend)
	        return(-1);
            c -= 0x10000;
#ifdef BIG_ENDIAN
            tmp1 = 0xD800 | (c >> 10);
            tmp = (unsigned char *) out;
            *tmp = tmp1;
            *(tmp + 1) = tmp1 >> 8;
            out++;

            tmp2 = 0xDC00 | (c & 0x03FF);
            tmp = (unsigned char *) out;
            *tmp  = tmp2;
            *(tmp + 1) = tmp2 >> 8;
            out++;
#else /* BIG_ENDIAN */
            *out++ = 0xD800 | (c >> 10);
            *out++ = 0xDC00 | (c & 0x03FF);
#endif /* BIG_ENDIAN */
        }
        else
	    return(-1);
    }
    return(out-outstart);
}

/**
 * UTF16BEToUTF8:
 * @out:  a pointer to an array of bytes to store the result
 * @outlen:  the length of @out
 * @inb:  a pointer to an array of UTF-16 passwd as a byte array
 * @inlenb:  the length of @in in UTF-16 chars
 *
 * Take a block of UTF-16 ushorts in and try to convert it to an UTF-8
 * block of chars out. This function assume the endian properity
 * is the same between the native type of this machine and the
 * inputed one.
 *
 * Returns the number of byte written, or -1 by lack of space, or -2
 *     if the transcoding fails (for *in is not valid utf16 string)
 * The value of *inlen after return is the number of octets consumed
 *     as the return value is positive, else unpredictiable.
 */
int
UTF16BEToUTF8(unsigned char* out, int outlen,
            const unsigned char* inb, int *inlenb)
{
    unsigned char* outstart= out;
    unsigned char* outend= out+outlen;
    unsigned short* in = (unsigned short*) inb;
    unsigned short* inend;
    unsigned int c, d, inlen;
#ifdef BIG_ENDIAN
#else /* BIG_ENDIAN */
    unsigned char *tmp;
#endif /* BIG_ENDIAN */    
    int bits;

    if ((*inlenb % 2) == 1)
        (*inlenb)--;
    inlen = *inlenb / 2;
    inend= in + inlen;
    while (in < inend) {
#ifdef BIG_ENDIAN    
        c= *in++;
#else
        tmp = (unsigned char *) in;
	c = *tmp++;
	c = c << 8;
	c = c | (unsigned int) *tmp;
	in++;
#endif	
        if ((c & 0xFC00) == 0xD800) {    /* surrogates */
	    if (in >= inend) {           /* (in > inend) shouldn't happens */
	        (*inlenb) -= 2;
		break;
	    }

#ifdef BIG_ENDIAN
            d= *in++;
#else
            tmp = (unsigned char *) in;
	    d = *tmp++;
	    d = d << 8;
	    d = d | (unsigned int) *tmp;
	    in++;
#endif	    
            if ((d & 0xFC00) == 0xDC00) {
                c &= 0x03FF;
                c <<= 10;
                c |= d & 0x03FF;
                c += 0x10000;
            }
            else 
	        return(-2);
        }

	/* assertion: c is a single UTF-4 value */
        if (out >= outend) 
	    return(-1);
        if      (c <    0x80) {  *out++=  c;                bits= -6; }
        else if (c <   0x800) {  *out++= ((c >>  6) & 0x1F) | 0xC0;  bits=  0; }
        else if (c < 0x10000) {  *out++= ((c >> 12) & 0x0F) | 0xE0;  bits=  6; }
        else                  {  *out++= ((c >> 18) & 0x07) | 0xF0;  bits= 12; }
 
        for ( ; bits >= 0; bits-= 6) {
            if (out >= outend) 
	        return(-1);
            *out++= ((c >> bits) & 0x3F) | 0x80;
        }
    }
    return(out-outstart);
}