====== Net 1 ======

<code C>
#include "../common/common.c"

#define NAME "net1"
#define UID 998
#define GID 998
#define PORT 2998

void run()
{
    char buf[12];
    char fub[12];
    char *q;

    unsigned int wanted;

    wanted = random();

    sprintf(fub, "%d", wanted);

    if(write(0, &wanted, sizeof(wanted)) != sizeof(wanted)) { 
        errx(1, ":(\n");
    }

    if(fgets(buf, sizeof(buf)-1, stdin) == NULL) {
        errx(1, ":(\n");
    }

    q = strchr(buf, '\r'); if(q) *q = 0;
    q = strchr(buf, '\n'); if(q) *q = 0;

    if(strcmp(fub, buf) == 0) {
        printf("you correctly sent the data\n");
    } else {
        printf("you didn't send the data properly\n");
    }
}

int main(int argc, char **argv, char **envp)
{
    int fd;
    char *username;

    /* Run the process as a daemon */
    background_process(NAME, UID, GID);  

    /* Wait for socket activity and return */
    fd = serve_forever(PORT);

    /* Set the client socket to STDIN, STDOUT, and STDERR */
    set_io(fd);

    /* Don't do this :> */
    srandom(time(NULL));

    run();
}
</code>

Le programme choisis une chaine au hasard et attends la représentation décimale de cette chaine. Dans le challenge [[exploit_exercises_protostar:net0|net0]] nous avons utilisé la fonction ''pack'', cette fois ci nous utiliserons la fonction ''unpack''

<code Python>
#!/usr/bin/env python
# encoding: utf-8

import telnetlib
from struct import unpack

HOST = "192.168.1.29"
PORT = 2998

t = telnetlib.Telnet(HOST, PORT)

chaine =  t.read_some()
print "Chaine : %s" % repr(chaine)
print "Retour : %d" % unpack('<I', chaine)[0]
t.write("%d\n" % unpack('<I', chaine)[0])
print t.read_some()

t.close()
</code>