Support raw mode for both IPv4 and IPv6

Read destination address of IP request packet and return it.
Check length in client and use it as IPv4 or v6 depending on length.

CHANGELOG

@@ -14,7 +14,8 @@ master:
 	- Linux: use pkg-config for systemd support flags.
 		Patch by Jason A. Donenfeld.
 	- Change external IP webservice to ipify.org
-	- Add support for IPv6 in the server. (Raw mode missing)
+	- Add support for IPv6 in the server.
+	   Raw mode will be with same protocol as used for login.
 	   Traffic inside tunnel is still IPv4.
 
 2014-06-16: 0.7.0 "Kryoptonite"

README.md

@@ -124,8 +124,7 @@ end of the tunnel. In this case, `ping 192.168.99.1` from the iodine client, and
 The data inside the tunnel is IPv4 only.
 
 The server listens to both IPv4 and IPv6 for incoming requests. Raw mode
-currently only works for IPv4, or can use IPv4 from IPv6 login if -n option is
+will be attempted on the same protocol as used for the login.
-used.
 
 The client can use IPv4 or IPv6 nameservers to connect to iodined. The relay
 nameservers will translate between protocols automatically if needed. Use

doc/proto_00000502.txt

@@ -50,14 +50,16 @@ Server replies:
 	LNAK means not accepted
 	x.x.x.x-y.y.y.y-mtu-netmask means accepted (server ip, client ip, mtu, netmask bits)
 
-IP Request:
+IP Request: (for where to try raw login)
 Client sends:
 	First byte i or I
 	5 bits coded as Base32 char, meaning userid
 	CMC as 3 Base32 chars
 Server replies
-	BADIP if bad userid, or
+	BADIP if bad userid
-	I and then 4 bytes network order external IP address of iodined server
+	First byte I
+	Then comes external IP address of iodined server
+	as 4 bytes (IPv4) or 16 bytes (IPv6)
 
 Upstream codec check / bounce:
 Client sends:

src/client.c

@@ -64,7 +64,8 @@ static const char *password;
 
 static struct sockaddr_storage nameserv;
 static int nameserv_len;
-static struct sockaddr_in raw_serv;
+static struct sockaddr_storage raw_serv;
+static int raw_serv_len;
 static const char *topdomain;
 
 static uint16_t rand_seed;
@@ -242,7 +243,7 @@ client_set_hostname_maxlen(int i)
 const char *
 client_get_raw_addr()
 {
-	return inet_ntoa(raw_serv.sin_addr);
+	return format_addr(&raw_serv, raw_serv_len);
 }
 
 static void
@@ -1488,8 +1489,10 @@ handshake_raw_udp(int dns_fd, int seed)
 	int i;
 	int r;
 	int len;
-	unsigned remoteaddr = 0;
+	int got_addr;
-	struct in_addr server;
+
+	memset(&raw_serv, 0, sizeof(raw_serv));
+	got_addr = 0;
 
 	fprintf(stderr, "Testing raw UDP data to the server (skip with -r)");
 	for (i=0; running && i<3 ;i++) {
@@ -1499,15 +1502,23 @@ handshake_raw_udp(int dns_fd, int seed)
 		len = handshake_waitdns(dns_fd, in, sizeof(in), 'i', 'I', i+1);
 
 		if (len == 5 && in[0] == 'I') {
-			/* Received IP address */
+			/* Received IPv4 address */
-			remoteaddr = (in[1] & 0xff);
+			struct sockaddr_in *raw4_serv = (struct sockaddr_in *) &raw_serv;
-			remoteaddr <<= 8;
+			raw4_serv->sin_family = AF_INET;
-			remoteaddr |= (in[2] & 0xff);
+			memcpy(&raw4_serv->sin_addr, &in[1], sizeof(struct in_addr));
-			remoteaddr <<= 8;
+			raw4_serv->sin_port = htons(53);
-			remoteaddr |= (in[3] & 0xff);
+			raw_serv_len = sizeof(struct sockaddr_in);
-			remoteaddr <<= 8;
+			got_addr = 1;
-			remoteaddr |= (in[4] & 0xff);
+			break;
-			server.s_addr = ntohl(remoteaddr);
+		}
+		if (len == 17 && in[0] == 'I') {
+			/* Received IPv6 address */
+			struct sockaddr_in6 *raw6_serv = (struct sockaddr_in6 *) &raw_serv;
+			raw6_serv->sin6_family = AF_INET6;
+			memcpy(&raw6_serv->sin6_addr, &in[1], sizeof(struct in6_addr));
+			raw6_serv->sin6_port = htons(53);
+			raw_serv_len = sizeof(struct sockaddr_in6);
+			got_addr = 1;
 			break;
 		}
 
@@ -1518,19 +1529,13 @@ handshake_raw_udp(int dns_fd, int seed)
 	if (!running)
 		return 0;
 
-	if (!remoteaddr) {
+	if (!got_addr) {
 		fprintf(stderr, "Failed to get raw server IP, will use DNS mode.\n");
 		return 0;
 	}
-	fprintf(stderr, "Server is at %s, trying raw login: ", inet_ntoa(server));
+	fprintf(stderr, "Server is at %s, trying raw login: ", format_addr(&raw_serv, raw_serv_len));
 	fflush(stderr);
 
-	/* Store address to iodined server */
-	memset(&raw_serv, 0, sizeof(raw_serv));
-	raw_serv.sin_family = AF_INET;
-	raw_serv.sin_port = htons(53);
-	raw_serv.sin_addr = server;
-
 	/* do login against port 53 on remote server
 	 * based on the old seed. If reply received,
 	 * switch to raw udp mode */

src/common.c

@@ -173,7 +173,7 @@ get_addr(char *host, int port, int addr_family, int flags, struct sockaddr_stora
 int
 open_dns(struct sockaddr_storage *sockaddr, size_t sockaddr_len)
 {
-	int flag = 1;
+	int flag;
 	int fd;
 
 	if ((fd = socket(sockaddr->ss_family, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
@@ -187,9 +187,6 @@ open_dns(struct sockaddr_storage *sockaddr, size_t sockaddr_len)
 	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (const void*) &flag, sizeof(flag));
 
 #ifndef WINDOWS32
-	/* To get destination address from each UDP datagram, see iodined.c:read_dns() */
-	setsockopt(fd, IPPROTO_IP, DSTADDR_SOCKOPT, (const void*) &flag, sizeof(flag));
-
 	fd_set_close_on_exec(fd);
 #endif
 

src/common.h

@@ -53,14 +53,6 @@ extern const unsigned char raw_header[RAW_HDR_LEN];
 
 #define QUERY_NAME_SIZE 256
 
-#if defined IP_RECVDSTADDR
-# define DSTADDR_SOCKOPT IP_RECVDSTADDR
-# define dstaddr(x) ((struct in_addr *) CMSG_DATA(x))
-#elif defined IP_PKTINFO
-# define DSTADDR_SOCKOPT IP_PKTINFO
-# define dstaddr(x) (&(((struct in_pktinfo *)(CMSG_DATA(x)))->ipi_addr))
-#endif
-
 #if defined IP_MTU_DISCOVER
   /* Linux */
 # define IP_OPT_DONT_FRAG IP_MTU_DISCOVER
@@ -95,12 +87,13 @@ struct query {
 	unsigned short type;
 	unsigned short rcode;
 	unsigned short id;
-	struct in_addr destination;
+	struct sockaddr_storage destination;
+	socklen_t dest_len;
 	struct sockaddr_storage from;
 	socklen_t fromlen;
 	unsigned short id2;
-	struct sockaddr from2;
+	struct sockaddr_storage from2;
-	int fromlen2;
+	socklen_t fromlen2;
 };
 
 enum connection {

src/iodined.c

@@ -72,6 +72,18 @@ WSADATA wsa_data;
 
 #define PASSWORD_ENV_VAR "IODINED_PASS"
 
+#if defined IP_RECVDSTADDR
+# define DSTADDR_SOCKOPT IP_RECVDSTADDR
+# define dstaddr(x) ((struct in_addr *) CMSG_DATA(x))
+#elif defined IP_PKTINFO
+# define DSTADDR_SOCKOPT IP_PKTINFO
+# define dstaddr(x) (&(((struct in_pktinfo *)(CMSG_DATA(x)))->ipi_addr))
+#endif
+
+#ifndef IPV6_RECVPKTINFO
+#define IPV6_RECVPKTINFO IPV6_PKTINFO
+#endif
+
 static int running = 1;
 static char *topdomain;
 static char password[33];
@@ -917,9 +929,8 @@ handle_null_request(int tun_fd, int dns_fd, struct dnsfd *dns_fds, struct query
 		return;
 	} else if(in[0] == 'I' || in[0] == 'i') {
 		/* Request for IP number */
-		in_addr_t replyaddr;
+		char reply[17];
-		unsigned addr;
+		int length;
-		char reply[5];
 
 		userid = b32_8to5(in[1]);
 		if (check_authenticated_user_and_ip(userid, q) != 0) {
@@ -927,21 +938,24 @@ handle_null_request(int tun_fd, int dns_fd, struct dnsfd *dns_fds, struct query
 			return; /* illegal id */
 		}
 
-		if (ns_ip != INADDR_ANY) {
+		reply[0] = 'I';
-			/* If set, use assigned external ip (-n option) */
+		if (q->from.ss_family == AF_INET) {
-			replyaddr = ns_ip;
+			if (ns_ip != INADDR_ANY) {
+				/* If set, use assigned external ip (-n option) */
+				memcpy(&reply[1], &ns_ip, sizeof(ns_ip));
+			} else {
+				/* otherwise return destination ip from packet */
+				struct sockaddr_in *addr = (struct sockaddr_in *) &q->destination;
+				memcpy(&reply[1], &addr->sin_addr, sizeof(struct in_addr));
+			}
+			length = 1 + sizeof(struct in_addr);
 		} else {
-			/* otherwise return destination ip from packet */
+			struct sockaddr_in6 *addr = (struct sockaddr_in6 *) &q->destination;
-			memcpy(&replyaddr, &q->destination.s_addr, sizeof(in_addr_t));
+			memcpy(&reply[1], &addr->sin6_addr, sizeof(struct in6_addr));
+			length = 1 + sizeof(struct in6_addr);
 		}
 
-		addr = htonl(replyaddr);
+		write_dns(dns_fd, q, reply, length, 'T');
-		reply[0] = 'I';
-		reply[1] = (addr >> 24) & 0xFF;
-		reply[2] = (addr >> 16) & 0xFF;
-		reply[3] = (addr >>  8) & 0xFF;
-		reply[4] = (addr >>  0) & 0xFF;
-		write_dns(dns_fd, q, reply, sizeof(reply), 'T');
 	} else if(in[0] == 'Z' || in[0] == 'z') {
 		/* Check for case conservation and chars not allowed according to RFC */
 
@@ -1539,7 +1553,8 @@ handle_ns_request(int dns_fd, struct query *q)
 	if (ns_ip != INADDR_ANY) {
 		/* If ns_ip set, overwrite destination addr with it.
 		 * Destination addr will be sent as additional record (A, IN) */
-		memcpy(&q->destination.s_addr, &ns_ip, sizeof(in_addr_t));
+		struct sockaddr_in *addr = (struct sockaddr_in *) &q->destination;
+		memcpy(&addr->sin_addr, &ns_ip, sizeof(ns_ip));
 	}
 
 	len = dns_encode_ns_response(buf, sizeof(buf), q, topdomain);
@@ -1566,12 +1581,14 @@ handle_a_request(int dns_fd, struct query *q, int fakeip)
 
 	if (fakeip) {
 		in_addr_t ip = inet_addr("127.0.0.1");
-		memcpy(&q->destination.s_addr, &ip, sizeof(in_addr_t));
+		struct sockaddr_in *addr = (struct sockaddr_in *) &q->destination;
+		memcpy(&addr->sin_addr, &ip, sizeof(ip));
 
 	} else if (ns_ip != INADDR_ANY) {
 		/* If ns_ip set, overwrite destination addr with it.
 		 * Destination addr will be sent as additional record (A, IN) */
-		memcpy(&q->destination.s_addr, &ns_ip, sizeof(in_addr_t));
+		struct sockaddr_in *addr = (struct sockaddr_in *) &q->destination;
+		memcpy(&addr->sin_addr, &ns_ip, sizeof(ns_ip));
 	}
 
 	len = dns_encode_a_response(buf, sizeof(buf), q);
@@ -2038,7 +2055,7 @@ read_dns(int fd, struct dnsfd *dns_fds, int tun_fd, struct query *q)
 	char packet[64*1024];
 	int r;
 #ifndef WINDOWS32
-	char address[96];
+	char control[CMSG_SPACE(sizeof (struct in6_pktinfo))];
 	struct msghdr msg;
 	struct iovec iov;
 	struct cmsghdr *cmsg;
@@ -2051,8 +2068,8 @@ read_dns(int fd, struct dnsfd *dns_fds, int tun_fd, struct query *q)
 	msg.msg_namelen = (unsigned) addrlen;
 	msg.msg_iov = &iov;
 	msg.msg_iovlen = 1;
-	msg.msg_control = address;
+	msg.msg_control = control;
-	msg.msg_controllen = sizeof(address);
+	msg.msg_controllen = sizeof(control);
 	msg.msg_flags = 0;
 
 	r = recvmsg(fd, &msg, 0);
@@ -2074,13 +2091,29 @@ read_dns(int fd, struct dnsfd *dns_fds, int tun_fd, struct query *q)
 		}
 
 #ifndef WINDOWS32
+		memset(&q->destination, 0, sizeof(struct sockaddr_storage));
+		/* Read destination IP address */
 		for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
 			cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 
 			if (cmsg->cmsg_level == IPPROTO_IP &&
 				cmsg->cmsg_type == DSTADDR_SOCKOPT) {
 
-				q->destination = *dstaddr(cmsg);
+				struct sockaddr_in *addr = (struct sockaddr_in *) &q->destination;
+				addr->sin_family = AF_INET;
+				addr->sin_addr = *dstaddr(cmsg);
+				q->dest_len = sizeof(*addr);
+				break;
+			}
+			if (cmsg->cmsg_level == IPPROTO_IPV6 &&
+				cmsg->cmsg_type == IPV6_PKTINFO) {
+
+				struct in6_pktinfo *pktinfo;
+				struct sockaddr_in6 *addr = (struct sockaddr_in6 *) &q->destination;
+				pktinfo = (struct in6_pktinfo *) CMSG_DATA(cmsg);
+				addr->sin6_family = AF_INET6;
+				memcpy(&addr->sin6_addr, &pktinfo->ipi6_addr, sizeof(struct in6_addr));
+				q->dest_len = sizeof(*addr);
 				break;
 			}
 		}
@@ -2311,6 +2344,24 @@ version() {
 	exit(0);
 }
 
+static void
+prepare_dns_fd(int fd)
+{
+#ifndef WINDOWS32
+	int flag = 1;
+
+	/* To get destination address from each UDP datagram, see read_dns() */
+	setsockopt(fd, IPPROTO_IP, DSTADDR_SOCKOPT, (const void*) &flag, sizeof(flag));
+#ifdef IPV6_RECVPKTINFO
+	setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, (const void*) &flag, sizeof(flag));
+#endif
+#ifdef IPV6_PKTINFO
+	setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, (const void*) &flag, sizeof(flag));
+#endif
+
+#endif
+}
+
 int
 main(int argc, char **argv)
 {
@@ -2629,6 +2680,13 @@ main(int argc, char **argv)
 #ifdef HAVE_SYSTEMD
 	}
 #endif
+
+	/* Setup dns file descriptors to get destination IP address */
+	if (dns_fds.v4fd >= 0)
+		prepare_dns_fd(dns_fds.v4fd);
+	if (dns_fds.v6fd >= 0)
+		prepare_dns_fd(dns_fds.v6fd);
+
 	if (bind_enable) {
 		if ((bind_fd = open_dns_from_host(NULL, 0, AF_INET, 0)) < 0) {
 			retval = 1;