Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <bio.h>
#include "authcmdlib.h"

/*
 * compute the key verification checksum
 */
void
checksum(char key[], char csum[]) {
        uchar buf[8];

        memset(buf, 0, 8);
        encrypt(key, buf, 8);
        sprint(csum, "C %.2ux%.2ux%.2ux%.2ux", buf[0], buf[1], buf[2], buf[3]);
}

/*
 * compute the proper response.  We encrypt the ascii of
 * challenge number, with trailing binary zero fill.
 * This process was derived empirically.
 * this was copied from inet's guard.
 */
char *
netresp(char *key, long chal, char *answer)
{
        uchar buf[8];

        memset(buf, 0, 8);
        snprint((char *)buf, sizeof buf, "%lud", chal);
        if(encrypt(key, buf, 8) < 0)
                error("can't encrypt response");
        chal = (buf[0]<<24)+(buf[1]<<16)+(buf[2]<<8)+buf[3];
        sprint(answer, "%.8lux", chal);

        return answer;
}

char *
netdecimal(char *answer)
{
        int i;

        for(i = 0; answer[i]; i++)
                switch(answer[i]){
                case 'a': case 'b': case 'c':
                        answer[i] = '2';
                        break;
                case 'd': case 'e': case 'f':
                        answer[i] = '3';
                        break;
                }
        return answer;
}

int
netcheck(void *key, long chal, char *response)
{
        char answer[32], *p;
        int i;

        if(smartcheck(key, chal, response))
                return 1;

        if(p = strchr(response, '\n'))
                *p = '\0';
        netresp(key, chal, answer);

        /*
         * check for hex response -- securenet mode 1 or 5
         */
        for(i = 0; response[i]; i++)
                if(response[i] >= 'A' && response[i] <= 'Z')
                        response[i] -= 'A' - 'a';
        if(strcmp(answer, response) == 0)
                return 1;

        /*
         * check for decimal response -- securenet mode 0 or 4
         */
        return strcmp(netdecimal(answer), response) == 0;
}

int
smartcheck(void *key, long chal, char *response)
{
        uchar buf[2*8];
        int i, c, cslo, cshi;

        snprint((char*)buf, sizeof buf, "%lud        ", chal);
        cslo = 0x52;
        cshi = cslo;
        for(i = 0; i < 8; i++){
                c = buf[i];
                if(c >= '0' && c <= '9')
                        c -= '0';
                cslo += c;
                if(cslo > 0xff)
                        cslo -= 0xff;
                cshi += cslo;
                if(cshi > 0xff)
                        cshi -= 0xff;
                buf[i] = c | (cshi & 0xf0);
        }

        encrypt(key, buf, 8);
        for(i = 0; i < 8; i++)
                if(response[i] != buf[i] % 10 + '0')
                        return 0;
        return 1;
}