defcon 2014 byhd hook

// gcc -shared -ldl hook.c -o hook.so -fPIC -ldl

#define _GNU_SOURCE
#include <stdio.h>
#include<sys/types.h>
#include <dlfcn.h>

void * memcpy ( void * destination, const void * source, size_t num ) {
        static void (*memcpy_real)(void*, const void*, size_t) = NULL;
        int i=0;

        if (__builtin_return_address(0) == 0x401c9e)
        {
                //FILE *fp = fopen("scode", "w");
                fprintf(stdout, "Memcpy: ");

                int length = num*2;

                send(4, &length, 4, 0);

                for (i=0; i<num; i++)
                {
                        fprintf(stdout, "%02x ", *(char *)(source + i) & 0xFF);
                        char buf[2];
                        sprintf(buf, "%02x", *(char *)(source + i) & 0xFF);
                        send(4, &buf, 2, 0);
                }
                //for (i=0; i<num; i++)
                //      fprintf(fp, "%c", *(char *)(source + i) & 0xFF);

                //fclose(fp);

                fprintf(stdout, "\n\n");
                //system("ndisasm scode");
                fprintf(stdout, "-------------------------------\n\n");
        }

        if (!memcpy_real)
                memcpy_real = dlsym(RTLD_NEXT, "memcpy");

        memcpy_real(destination, source, num);
}