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/* fatvpn daemon by eeeee
* Public Domain */
#include "config.h"
#include "common.h"
#define LOGFILE "/tmp/fatvpnd.log"
#define MAX_PEERS 16
#define TIMEOUT_D 180 /* timeout (no packets) in seconds for disconnect */
struct {
struct sockaddr_in6 a;
u32 lptime; /* time of last packet */
u8 mac[6]; /* internal mac */
} peer[MAX_PEERS];
u32 ccnt;
int main(int argc, char *argv[]){
u8 *pkt;
s32 res, tap, fdmax, skt, i, psz;
struct sockaddr_in6 c;
struct timespec t;
struct termios attr;
struct ifreq ifr;
fd_set rset;
/* arguments */
if (argc != 3 && argc != 4){
fprintf(stderr, "Using:\n\t"
"%s <tap name> [address] <port>\n\n"
"Example:\n\t"
"%s tap0 2222\n\t%s tap0 127.0.0.1 2222\n\n",
argv[0], argv[0], argv[0]);
exit(1);
}
memset(&c, 0, sizeof(c));
c.sin6_family = AF_INET6;
c.sin6_port = htons((u16)atoi(argv[argc-1]));
if (argc == 4){
res = inet_pton(AF_INET6, argv[2], c.sin6_addr.s6_addr);
if (res != 1){
res = inet_pton(AF_INET, argv[2], &psz);
if (res != 1){
fprintf(stderr, "wrong addr: %s\n",argv[2]);
exit(1);
}
c.sin6_addr.s6_addr[10] = 0xFF;
c.sin6_addr.s6_addr[11] = 0xFF;
memcpy(&c.sin6_addr.s6_addr[12], &psz, 4);
}
}
if (strlen(argv[1]) + 1 > IFNAMSIZ)
fputs("tap name is too long\n", stderr), exit(1);
if (password[0] == 0){
/* TODO: test std streams redirected to file */
/* get term attrs */
res = tcgetattr(STDOUT_FILENO, &attr);
ERRDIE(res, "tcgetattr");
/* echo off */
attr.c_lflag &= ~ECHO;
res = tcsetattr(STDOUT_FILENO, TCSANOW, &attr);
ERRDIE(res, "tcsetattr");
/* get password */
fputs("Password: ", stdout), fflush(stdout);
pkt = fgets(password, PASSWORD_BUF_SZ, stdin);
fputs("\n", stdout);
if (pkt == NULL)
fputs("can't read password\n", stderr), exit(1);
/* echo on */
attr.c_lflag |= ECHO;
res = tcsetattr(STDOUT_FILENO, TCSANOW, &attr);
ERRDIE(res, "tcsetattr");
}
/* password without '\r\n' */
res = 0;
while (password[res] != '\0'
&& password[res] != '\r'
&& password[res] != '\n') res++;
/* hash password */
sponge256_hash32(key, password, res);
memset(password, 0, PASSWORD_BUF_SZ);
/* feed prng with key and current time */
duplex257_prng_feed(prng_state, ((u32*)key)[0]);
duplex257_prng_feed(prng_state, ((u32*)key)[1]);
duplex257_prng_feed(prng_state, ((u32*)key)[2]);
duplex257_prng_feed(prng_state, ((u32*)key)[3]);
duplex257_prng_feed(prng_state, ((u32*)key)[4]);
duplex257_prng_feed(prng_state, ((u32*)key)[5]);
duplex257_prng_feed(prng_state, ((u32*)key)[6]);
duplex257_prng_feed(prng_state, ((u32*)key)[7]);
clock_gettime(CLOCK_MONOTONIC, &t);
duplex257_prng_feed(prng_state, (u32)t.tv_sec);
duplex257_prng_feed(prng_state, (u32)t.tv_nsec);
/* daemonize: redirect std streams */
res = open("/dev/null", O_RDONLY); ERRDIE(res, "open(/dev/null)");
close(STDIN_FILENO), dup(res), close(res);
res = open(LOGFILE, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR | S_IWUSR);
ERRDIE(res, "open(logfile)");
close(STDOUT_FILENO);
close(STDERR_FILENO);
dup(res), dup(res), close(res);
/* daemonize: fork 1 */
res = fork(); ERRDIE(res, "fork 1");
if (res != 0) exit(0);
/* daemonize: become session leader */
setsid();
/* daemonize: fork 2 */
res = fork(); ERRDIE(res, "fork 2");
if (res != 0) exit(0); /* kill session leader */
/* daemonized! */
/* cur pkt buf */
pkt = malloc(MAX_PKT_SZ);
if (pkt == NULL) fputs("pkt = malloc() failed\n",stderr), exit(1);
/* socket, setsockopt */
skt = socket(PF_INET6, SOCK_DGRAM, 0); ERRDIE(skt, "socket");
res = 1;
res = setsockopt(skt, SOL_SOCKET, SO_REUSEADDR, &res, sizeof(res));
ERRDIE(res, "SO_REUSEADDR");
/* bind */
res = bind(skt, (struct sockaddr*) &c, sizeof(c));
ERRDIE(res, "bind");
/* tap */
tap = open("/dev/net/tun", O_RDWR);
ERRDIE(tap, "open(/dev/net/tun)");
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
strncpy(ifr.ifr_name, argv[1], IFNAMSIZ);
res = ioctl(tap, TUNSETIFF, &ifr);
ERRDIE(res, "TUNSETIFF");
fdmax = (tap > skt) ? tap+1 : skt+1;
inf_loop:
/* "disconnect" peers with timeout */
clock_gettime(CLOCK_MONOTONIC, &t);
for (i=0; i < ccnt; i++){
if (t.tv_sec - peer[i].lptime < TIMEOUT_D) continue;
if (i != ccnt-1)
memcpy(&peer[i], &peer[ccnt-1], sizeof(peer[0]));
ccnt--, i--;
memset(&peer[ccnt], 0, sizeof(peer[0]));
}
/* select */
FD_ZERO(&rset);
FD_SET(skt, &rset);
FD_SET(tap, &rset);
select(fdmax, &rset, NULL, NULL, NULL);
/* read packet from tap */
if (FD_ISSET(tap, &rset)){
psz = read(tap, pkt, MAX_PKT_SZ);
ERRDIE(psz, "read(tap)");
for (i=0; i < ccnt; i++){
if (0 == memcmp(peer[i].mac, pkt, 6)){
send_pkt(skt, pkt, psz,
(struct sockaddr_storage*) &peer[i].a);
break;
}
}
}
/* recv packet from client */
if (0 == FD_ISSET(skt, &rset)) goto inf_loop;
psz = recv_pkt(skt, pkt, MAX_PKT_SZ, (struct sockaddr_storage*) &c);
for (i=0; i < ccnt; i++)
if (c.sin6_port == peer[i].a.sin6_port &&
0 == memcmp(c.sin6_addr.s6_addr,
peer[i].a.sin6_addr.s6_addr, 16)) break;
if (i == ccnt){
/* client not connected */
if (psz <= 14) /* ethernet header len == 14 */
goto inf_loop;
if (ccnt == MAX_PEERS) goto inf_loop;
/* add peer to array */
memcpy(&peer[i].a, &c, sizeof(c));
memcpy(&peer[i].mac, &pkt[6], 6);
ccnt++;
}
/* client connected */
clock_gettime(CLOCK_MONOTONIC, &t);
duplex257_prng_feed(prng_state, t.tv_nsec);
peer[i].lptime = t.tv_sec;
/* if connected peer send small packet, it's a ping packet for NAT
* keepalive, all i need to do is update lptime */
if (psz <= 14) goto inf_loop;
i = write(tap, pkt, psz);
if (i == -1) perror("write(tap)");
if (i < psz)
fprintf(stderr, "i < psz, i=%d, psz=%d\n", i, psz), exit(1);
goto inf_loop;
return 0;
}
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