th_mask.c

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#include <string.h>

#include "../../dprint.h"
#include "../../md5.h"
#include "../../crc.h"
#include "../../mem/mem.h"
#include "th_mask.h"

#define TH_EB64I \
                "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-"

char _th_EB64[65];
int _th_DB64[256];
char *_th_PD64 = "*";

extern str _th_key;

void th_shuffle(char *in, int size)
{
        char tmp;
        int last;
        unsigned int r;
        unsigned char md5[16];
        unsigned int *md5i;
        unsigned int crc;
        MD5_CTX ctx;

        MD5Init(&ctx);
        MD5Update(&ctx, _th_key.s, _th_key.len);
        MD5Update(&ctx, _th_key.s, _th_key.len);
        U_MD5Final(md5, &ctx);

        md5i = (unsigned int*)md5;

        crc = (unsigned int)crcitt_string(_th_key.s, _th_key.len);
        for (last = size; last > 1; last--)
        {
                r = (md5i[(crc+last+_th_key.len)%4]
                                + _th_key.s[(crc+last+_th_key.len)%_th_key.len]) % last;
                tmp = in[r];
                in[r] = in[last - 1];
                in[last - 1] = tmp;
        }
}

void th_mask_init(void)
{
        int i;

        _th_key.len = strlen(_th_key.s);
        memcpy(_th_EB64, TH_EB64I, sizeof(TH_EB64I));
        th_shuffle(_th_EB64, 64);
        LM_ERR("+++ %s\n", TH_EB64I);
        LM_ERR("+++ %s\n", _th_EB64);
        for(i=0; i<256; i++)
                _th_DB64[i] = -1;
        for(i=0; i<64; i++)
                _th_DB64[(int)_th_EB64[i]] = i;

        return;
}

char* th_mask_encode(char *in, int ilen, str *prefix, int *olen)
{
        char *out;
        int  left;
        int  idx;
        int  i;
        int  r;
        char *p;
        int  block;

        *olen = (((ilen+2)/3)<<2) + ((prefix!=NULL&&prefix->len>0)?prefix->len:0);
        out = (char*)pkg_malloc((*olen+1)*sizeof(char));
        if(out==NULL)
        {
                LM_ERR("no more pkg\n");
                *olen = 0;
                return NULL;
        }
        memset(out, 0, (*olen+1)*sizeof(char));
        if(prefix!=NULL&&prefix->len>0)
                memcpy(out, prefix->s, prefix->len);

        p = out + (int)((prefix!=NULL&&prefix->len>0)?prefix->len:0);
        for(idx=0; idx<ilen; idx+=3)
        {
                left = ilen - idx - 1 ;
                left = (left>1)?2:left;

                block = 0;
                for(i=0, r=16; i<=left; i++, r-=8)
                        block += ((unsigned char)in[idx+i]) << r;

                *(p++) = _th_EB64[(block >> 18) & 0x3f];
                *(p++) = _th_EB64[(block >> 12) & 0x3f];
                *(p++) = (left>0)?_th_EB64[(block >> 6) & 0x3f]:_th_PD64[0];
                *(p++) = (left>1)?_th_EB64[block & 0x3f]:_th_PD64[0];
        }

        return out;
}

char* th_mask_decode(char *in, int ilen, str *prefix, int extra, int *olen)
{
        char *out;
        int n;
        int block;
        int idx;
        int i;
        int j;
        int end;
        char c;

        for(n=0,i=ilen-1; in[i]==_th_PD64[0]; i--)
                n++;

        *olen = (((ilen-((prefix!=NULL&&prefix->len>0)?prefix->len:0)) * 6) >> 3)
                                - n;
        out = (char*)pkg_malloc((*olen+1+extra)*sizeof(char));

        if(out==NULL)
        {
                LM_ERR("no more pkg\n");
                *olen = 0;
                return NULL;
        }
        memset(out, 0, (*olen+1+extra)*sizeof(char));

        end = ilen - n;
        i = (prefix!=NULL&&prefix->len>0)?prefix->len:0;
        for(idx=0; i<end; idx+=3)
        {
                block = 0;
                for(j=0; j<4 && i<end ; j++)
                {
                        c = _th_DB64[(int)in[i++]];
                        if(c<0)
                        {
                                LM_ERR("invalid input string\"%.*s\"\n", ilen, in);
                                pkg_free(out);
                                *olen = 0;
                                return NULL;
                        }
                        block += c << (18 - 6*j);
                }

                for(j=0, n=16; j<3 && idx+j< *olen; j++, n-=8)
                        out[idx+j] = (char)((block >> n) & 0xff);
        }

        return out;
}