Buffer Overflow - The Byzantine Attack

#include
#include
#include

/* Like gets, except that characters */
/* are typed as pairs of hex digits. */
/* Nondigit characters are ignored. */
/* Stops when encounters newline */

char *getxs(char *dest)
{
int c;
int even = 1; /* Have read even number of digits */
int otherd = 0; /* Other hex digit of pair */
char *sp = dest;
while ((c = getchar()) != EOF && c != '\n') {
if (isxdigit(c)) {
int val;
if ('0' <= c && c <= '9')
val = c - '0';
else if ('A' <= c && c <= 'F')
val = c - 'A' 10;
else
val = c - 'a' 10;
if (even) {
otherd = val;
even = 0;
} else {
*sp = otherd * 16 val;
even = 1;
}
}
}
*sp = '\0';
return dest;
}

/* $begin getbuf-c */
int getbuf()
{
char buf[12];
getxs(buf);
return 1;
}

void test()
{
int val;
printf('Type Hex string:');
val = getbuf();
printf('getbuf returned 0x%x\n', val);
}
/* $end getbuf-c */

int main()
{

int buf[16];
/* This little hack is an attempt */
/* to get the stack to be in a */
/* stable position */

int offset = (((int) buf) & 0xFFF);
int *space = (int *) alloca(offset);

*space = 0; /* So th"