#11 basic support for multiple users. some work left

src/common.h

@@ -43,9 +43,16 @@ struct query {
 };
 
 struct user {
-	int id;
+	char id;
+	int active;
+	time_t last_pkt;
+	int seed;
+	in_addr_t tun_ip;
 	struct sockaddr host;
 	int addrlen;
+	struct query q;
+	struct packet inpacket;
+	struct packet outpacket;
 };
 
 int open_dns(int, in_addr_t);

src/iodine.c

@@ -54,6 +54,7 @@ uint16_t rand_seed;
 
 /* Current IP packet */
 static char activepacket[4096];
+static char userid;
 static int lastlen;
 static int packetpos;
 static int packetlen;
@@ -223,10 +224,12 @@ tunnel(int tun_fd, int dns_fd)
 static void
 send_chunk(int fd)
 {
+	char hex[] = "0123456789ABCDEF";
 	char packet[4096];
 	struct query q;
 	char buf[4096];
 	int avail;
+	int code;
 	char *p;
 	int len;
 
@@ -238,11 +241,14 @@ send_chunk(int fd)
 	avail = packetlen - packetpos;
 
 	lastlen = dns_build_hostname(buf + 1, sizeof(buf) - 1, p, avail, topdomain);
-	if (lastlen == avail)
-		buf[0] = '1';
-	else
-		buf[0] = '0';
 
+	if (lastlen == avail)
+		code = 1;
+	else
+		code = 0;
+		
+	code |= (userid << 1);
+	buf[0] = hex[code];
 	len = dns_encode(packet, sizeof(packet), &q, QR_QUERY, buf, strlen(buf));
 
 	sendto(fd, packet, len, 0, (struct sockaddr*)&peer, sizeof(peer));
@@ -251,13 +257,14 @@ send_chunk(int fd)
 void
 send_login(int fd, char *login, int len)
 {
-	char data[18];
+	char data[19];
 
 	memset(data, 0, sizeof(data));
-	memcpy(data, login, MIN(len, 16));
+	data[0] = userid;
+	memcpy(&data[1], login, MIN(len, 16));
 
-	data[16] = (rand_seed >> 8) & 0xff;
+	data[17] = (rand_seed >> 8) & 0xff;
-	data[17] = (rand_seed >> 0) & 0xff;
+	data[18] = (rand_seed >> 0) & 0xff;
 	
 	rand_seed++;
 
@@ -267,7 +274,7 @@ send_login(int fd, char *login, int len)
 static void
 send_ping(int fd)
 {
-	char data[2];
+	char data[3];
 	
 	if (is_sending()) {
 		lastlen = 0;
@@ -275,8 +282,9 @@ send_ping(int fd)
 		packetlen = 0;
 	}
 
-	data[0] = (rand_seed >> 8) & 0xff;
+	data[0] = userid;
-	data[1] = (rand_seed >> 0) & 0xff;
+	data[1] = (rand_seed >> 8) & 0xff;
+	data[2] = (rand_seed >> 0) & 0xff;
 	
 	rand_seed++;
 
@@ -336,7 +344,7 @@ handshake(int dns_fd)
 				continue;
 			}
 
-			if (read >= 8) {
+			if (read >= 9) {
 				payload =  (((in[4] & 0xff) << 24) |
 							((in[5] & 0xff) << 16) |
 							((in[6] & 0xff) << 8) |
@@ -344,13 +352,17 @@ handshake(int dns_fd)
 
 				if (strncmp("VACK", in, 4) == 0) {
 					seed = payload;
+					userid = in[8];
 
-					printf("Version ok, both running 0x%08x\n", VERSION);
+					printf("Version ok, both running 0x%08x. You are user #%d\n", VERSION, userid);
 					goto perform_login;
-				} else {
+				} else if (strncmp("VACK", in, 4) == 0) {
 					errx(1, "you run 0x%08x, server runs 0x%08x. giving up\n", 
 							VERSION, payload);
 					/* NOTREACHED */
+				} else if (strncmp("VFUL", in, 4) == 0) {
+					errx(1, "server full, all %d slots are taken. try again later\n", payload);
+					/* NOTREACHED */
 				}
 			} else 
 				warnx("did not receive proper login challenge\n");

src/iodined.c

@@ -30,6 +30,7 @@
 #include <pwd.h>
 #include <arpa/inet.h>
 #include <netinet/in.h>
+#include <netinet/ip.h>
 #include <zlib.h>
 
 #include "common.h"
@@ -41,15 +42,10 @@
 
 int running = 1;
 
-struct packet packetbuf;
-struct packet outpacket;
-int outid;
-
 char *topdomain;
 
-struct query q;
+#define USERS 8
-
+struct user users[USERS];
-struct user u;
 char password[33];
 
 int my_mtu;
@@ -64,34 +60,96 @@ sigint(int sig)
 	running = 0;
 }
 
+static void
+init_users()
+{
+	int i;
+	char newip[16];
+	
+	memset(users, 0, USERS * sizeof(struct user));
+	for (i = 0; i < USERS; i++) {
+		users[i].id = i;
+		snprintf(newip, sizeof(newip), "0.0.0.%d", i + 1);
+		users[i].tun_ip = my_ip + inet_addr(newip);;
+		users[i].inpacket.len = 0;
+		users[i].inpacket.offset = 0;
+		users[i].outpacket.len = 0;
+		users[i].q.id = 0;
+	}
+}
+
+static int
+find_user_by_ip(uint32_t ip)
+{
+	int ret = -1;
+	int i;
+
+	for (i = 0; i < USERS; i++) {
+		/* Not used at all or not used in one minute */
+		if (users[i].active && users[i].last_pkt + 60 > time(NULL) &&
+			ip == users[i].tun_ip) {
+			ret = i;
+			break;
+		}
+	}
+	return ret;
+}
+
+static int
+find_available_user()
+{
+	int ret = -1;
+	int i;
+
+	for (i = 0; i < USERS; i++) {
+		/* Not used at all or not used in one minute */
+		if (!users[i].active || users[i].last_pkt + 60 < time(NULL)) {
+			users[i].active = 1;
+			users[i].last_pkt = time(NULL);
+			ret = i;
+			break;
+		}
+	}
+	return ret;
+}
+
 static int
 tunnel_tun(int tun_fd, int dns_fd)
 {
 	unsigned long outlen;
+	struct iphdr *header;
 	char out[64*1024];
 	char in[64*1024];
+	int userid;
 	int read;
 
 	if ((read = read_tun(tun_fd, in, sizeof(in))) <= 0)
 		return 0;
 	
+	/* find target ip in packet, in is padded with 4 bytes TUN header */
+	header = (struct iphdr*) (in + 4);
+	userid = find_user_by_ip(header->daddr);
+	if (userid < 0)
+		return 0;
+
 	outlen = sizeof(out);
 	compress2((uint8_t*)out, &outlen, (uint8_t*)in, read, 9);
-	memcpy(outpacket.data, out, outlen);
+	memcpy(users[userid].outpacket.data, out, outlen);
-	outpacket.len = outlen;
+	users[userid].outpacket.len = outlen;
 
 	return outlen;
 }
 
 typedef enum {
 	VERSION_ACK,
-	VERSION_NACK
+	VERSION_NACK,
+	VERSION_FULL
 } version_ack_t;
 
 static void
-send_version_response(int fd, version_ack_t ack, uint32_t payload)
+send_version_response(int fd, version_ack_t ack, uint32_t payload, struct user *u)
 {
-	char out[8];
+	char out[9];
 	
 	switch (ack) {
 	case VERSION_ACK:
@@ -100,31 +158,37 @@ send_version_response(int fd, version_ack_t ack, uint32_t payload)
 	case VERSION_NACK:
 		strncpy(out, "VNAK", sizeof(out));
 		break;
+	case VERSION_FULL:
+		strncpy(out, "VFUL", sizeof(out));
+		break;
 	}
 	
 	out[4] = ((payload >> 24) & 0xff);
 	out[5] = ((payload >> 16) & 0xff);
 	out[6] = ((payload >> 8) & 0xff);
 	out[7] = ((payload) & 0xff);
+	out[8] = u->id;
 
-	write_dns(fd, &q, out, 8);
+
+	write_dns(fd, &u->q, out, sizeof(out));
 }
 
 static int
 tunnel_dns(int tun_fd, int dns_fd)
 {
-	struct in_addr clientip;
+	struct in_addr tempip;
+	struct query q;
 	unsigned long outlen;
-	struct in_addr myip;
 	char logindata[16];
 	char out[64*1024];
 	char in[64*1024];
-	static int seed;
 	char *tmp[2];
+	int userid;
 	int version;
 	int read;
 	int code;
 
+	userid = -1;
 	if ((read = read_dns(dns_fd, &q, in, sizeof(in))) <= 0)
 		return 0;
 				
@@ -139,34 +203,48 @@ tunnel_dns(int tun_fd, int dns_fd)
 					   ((in[4] & 0xff)));
 
 			if (version == VERSION) {
-				seed = rand();
+				userid = find_available_user();
-		
+				if (userid >= 0) {
-				send_version_response(dns_fd, VERSION_ACK, seed);
+					users[userid].seed = rand();
+					memcpy(&(users[userid].host), &(q.from), q.fromlen);
+					memcpy(&(users[userid].q), &q, sizeof(struct query));
+					users[userid].addrlen = q.fromlen;
+					send_version_response(dns_fd, VERSION_ACK, users[userid].seed, &users[userid]);
 				} else {
-				send_version_response(dns_fd, VERSION_NACK, VERSION);
+					/* No space for another user */
+					send_version_response(dns_fd, VERSION_FULL, USERS, NULL);
 				}
 			} else {
-			send_version_response(dns_fd, VERSION_NACK, VERSION);
+				send_version_response(dns_fd, VERSION_NACK, VERSION, NULL);
+			}
+		} else {
+			send_version_response(dns_fd, VERSION_NACK, VERSION, NULL);
 		}
 	} else if(in[0] == 'L' || in[0] == 'l') {
 		/* Login phase, handle auth */
-		login_calculate(logindata, 16, password, seed);
+		userid = in[1];
+		if (userid < 0 || userid >= USERS) {
+			write_dns(dns_fd, &q, "BADIP", 5);
+			return 0; /* illegal id */
+		}
+		users[userid].last_pkt = time(NULL);
+		login_calculate(logindata, 16, password, users[userid].seed);
 
-		if (read >= 17 && (memcmp(logindata, in+1, 16) == 0)) {
+		if (q.fromlen != users[userid].addrlen ||
+				memcmp(&(users[userid].host), &(q.from), q.fromlen) != 0) {
+			write_dns(dns_fd, &q, "BADIP", 5);
+		} else {
+			if (read >= 18 && (memcmp(logindata, in+2, 16) == 0)) {
 				/* Login ok, send ip/mtu info */
-			myip.s_addr = my_ip;
-			clientip.s_addr = my_ip + inet_addr("0.0.0.1");
 
-			tmp[0] = strdup(inet_ntoa(myip));
+				tempip.s_addr = my_ip;
-			tmp[1] = strdup(inet_ntoa(clientip));
+				tmp[0] = strdup(inet_ntoa(tempip));
+				tempip.s_addr = users[userid].tun_ip;
+				tmp[1] = strdup(inet_ntoa(tempip));
 
 				read = snprintf(out, sizeof(out), "%s-%s-%d", 
 						tmp[0], tmp[1], my_mtu);
 
-			/* Store user ip */
-			memcpy(&(u.host), &(q.from), q.fromlen);
-			u.addrlen = q.fromlen;
-
 				write_dns(dns_fd, &q, out, read);
 				q.id = 0;
 
@@ -175,6 +253,14 @@ tunnel_dns(int tun_fd, int dns_fd)
 			} else {
 				write_dns(dns_fd, &q, "LNAK", 4);
 			}
+		}
+	} else if(in[0] == 'P' || in[0] == 'p') {
+		/* Ping packet, store userid */
+		userid = in[1];
+		if (userid < 0 || userid >= USERS) {
+			write_dns(dns_fd, &q, "BADIP", 5);
+			return 0; /* illegal id */
+		}
 	} else if((in[0] >= '0' && in[0] <= '9')
 			|| (in[0] >= 'a' && in[0] <= 'f')
 			|| (in[0] >= 'A' && in[0] <= 'F')) {
@@ -185,32 +271,40 @@ tunnel_dns(int tun_fd, int dns_fd)
 		if ((in[0] >= 'A' && in[0] <= 'F'))
 			code = in[0] - 'A' + 10;
 
+		userid = code >> 1;
+		if (userid < 0 || userid >= USERS) {
+			write_dns(dns_fd, &q, "BADIP", 5);
+			return 0; /* illegal id */
+		}
+		users[userid].last_pkt = time(NULL);
+
 		/* Check sending ip number */
-		if (q.fromlen != u.addrlen ||
+		if (q.fromlen != users[userid].addrlen ||
-				memcmp(&(u.host), &(q.from), q.fromlen) != 0) {
+				memcmp(&(users[userid].host), &(q.from), q.fromlen) != 0) {
 			write_dns(dns_fd, &q, "BADIP", 5);
 		} else {
-			memcpy(packetbuf.data + packetbuf.offset, in + 1, read - 1);
+			memcpy(users[userid].inpacket.data + users[userid].inpacket.offset, in + 1, read - 1);
-			packetbuf.len += read - 1;
+			users[userid].inpacket.len += read - 1;
-			packetbuf.offset += read - 1;
+			users[userid].inpacket.offset += read - 1;
 
 			if (code & 1) {
 				outlen = sizeof(out);
 				uncompress((uint8_t*)out, &outlen, 
-						   (uint8_t*)packetbuf.data, packetbuf.len);
+						   (uint8_t*)users[userid].inpacket.data, users[userid].inpacket.len);
 
 				write_tun(tun_fd, out, outlen);
 
-				packetbuf.len = packetbuf.offset = 0;
+				users[userid].inpacket.len = users[userid].inpacket.offset = 0;
 			}
 		}
 	}
-	if (q.fromlen == u.addrlen &&
+	/* userid must be set for a reply to be sent */
-			memcmp(&(u.host), &(q.from), q.fromlen) == 0 &&
+	if (userid >= 0 && userid < USERS && q.fromlen == users[userid].addrlen &&
-			outpacket.len > 0) {
+			memcmp(&(users[userid].host), &(q.from), q.fromlen) == 0 &&
+			users[userid].outpacket.len > 0) {
 
-		write_dns(dns_fd, &q, outpacket.data, outpacket.len);
+		write_dns(dns_fd, &q, users[userid].outpacket.data, users[userid].outpacket.len);
-		outpacket.len = 0;
+		users[userid].outpacket.len = 0;
 		q.id = 0;
 	}
 
@@ -223,18 +317,19 @@ tunnel(int tun_fd, int dns_fd)
 	struct timeval tv;
 	fd_set fds;
 	int i;
+	int j;
 
 	while (running) {
-		if (q.id != 0) {
+		//if (q.id != 0) {
 			tv.tv_sec = 0;
 			tv.tv_usec = 5000;
-		} else {
+		/*} else {
 			tv.tv_sec = 1;
 			tv.tv_usec = 0;
-		}
+		}*/
 
 		FD_ZERO(&fds);
-		if(outpacket.len == 0)
+		//if(outpacket.len == 0) TODO fix this
 			FD_SET(tun_fd, &fds);
 		FD_SET(dns_fd, &fds);
 
@@ -247,10 +342,12 @@ tunnel(int tun_fd, int dns_fd)
 		}
 	
 		if (i==0) {	
-			if (q.id != 0) {
+			for (j = 0; j < USERS; j++) {
-				write_dns(dns_fd, &q, outpacket.data, outpacket.len);
+				if (users[j].q.id != 0) {
-				outpacket.len = 0;
+					write_dns(dns_fd, &(users[j].q), users[j].outpacket.data, users[j].outpacket.len);
-				q.id = 0;
+					users[j].outpacket.len = 0;
+					users[j].q.id = 0;
+				}
 			}
 		} else {
 			if(FD_ISSET(tun_fd, &fds)) {
@@ -370,10 +467,6 @@ main(int argc, char **argv)
 	listen_ip = INADDR_ANY;
 	port = 53;
 
-	packetbuf.len = 0;
-	packetbuf.offset = 0;
-	outpacket.len = 0;
-	q.id = 0;
 	memset(password, 0, 33);
 	srand(time(NULL));
 	
@@ -466,6 +559,7 @@ main(int argc, char **argv)
 
 	my_ip = inet_addr(argv[0]);
 	my_mtu = mtu;
+	init_users();
 
 	printf("Listening to dns for domain %s\n", argv[1]);
 

src/version.h

@@ -19,7 +19,7 @@
 
 // This is the version of the network protocol
 // It is usually equal to the latest iodine version number
-#define VERSION 0x00000305
+#define VERSION 0x00000400
 
 #endif /* _VERSION_H_ */