From 03509b9e78c0063c49ff61120377d25ccc869e54 Mon Sep 17 00:00:00 2001
From: Bjorn Andersson <flex@kryo.se>
Date: Sun, 11 Jun 2006 16:13:40 +0000
Subject: [PATCH] handshake

---
 dns.c    | 20 +++++++++++++++-----
 dns.h    |  2 +-
 iodine.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 6 deletions(-)

diff --git a/dns.c b/dns.c
index 2fe1d7c..1861d06 100644
--- a/dns.c
+++ b/dns.c
@@ -32,6 +32,7 @@
 #include "read.h"
 
 static int host2dns(const char *, char *, int);
+static int dns_write(int, int, char *, int, char);
 
 struct sockaddr_in peer;
 char topdomain[256];
@@ -202,7 +203,16 @@ dns_ping(int dns_fd)
 	}
 	data[0] = (pingid & 0xFF00) >> 8;
 	data[1] = (pingid & 0xFF);
-	dns_write(dns_fd, ++pingid, data, 2, 1);
+	dns_write(dns_fd, ++pingid, data, 2, 'P');
+}
+
+void 
+dns_handshake(int dns_fd)
+{
+	char data[2];
+	data[0] = (pingid & 0xFF00) >> 8;
+	data[1] = (pingid & 0xFF);
+	dns_write(dns_fd, ++pingid, data, 2, 'H');
 }
 
 void 
@@ -262,8 +272,8 @@ put_hex(char *p, char h)
 	p[1] = to_hex[t];
 }
 
-int
-dns_write(int fd, int id, char *buf, int len, int ping)
+static int
+dns_write(int fd, int id, char *buf, int len, char flag)
 {
 	int avail;
 	int i;
@@ -285,8 +295,8 @@ dns_write(int fd, int id, char *buf, int len, int ping)
 	bzero(data, sizeof(data));
 	d = data;
 
-	if (ping) {
-		*d = 'P';
+	if (flag != 0) {
+		*d = flag;
 	} else {
 		// First byte is 0 for middle packet and 1 for last packet
 		*d = '0' + final;
diff --git a/dns.h b/dns.h
index d332cfb..781d585 100644
--- a/dns.h
+++ b/dns.h
@@ -23,8 +23,8 @@ void close_dns(int);
 int dns_sending();
 void dns_handle_tun(int, char *, int);
 void dns_ping(int);
+void dns_handshake(int);
 void dns_query(int, int, char *, int);
-int dns_write(int, int, char *, int, int);
 int dns_read(int, char *, int);
 
 extern struct sockaddr_in peer;
diff --git a/iodine.c b/iodine.c
index 5d9cc4a..d536c84 100644
--- a/iodine.c
+++ b/iodine.c
@@ -101,6 +101,52 @@ tunnel(int tun_fd, int dns_fd)
 	return 0;
 }
 
+static int
+handshake(int dns_fd)
+{
+	int i;
+	int r;
+	char *p;
+	int read;
+	fd_set fds;
+	int timeout;
+	char in[4096];
+	struct timeval tv;
+
+	timeout = 1;
+	
+	for (i=0;i<5;i++) {
+		tv.tv_sec = timeout++;
+		tv.tv_usec = 0;
+
+		dns_handshake(dns_fd);
+		
+		FD_ZERO(&fds);
+		FD_SET(dns_fd, &fds);
+
+		r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
+
+		if(r > 0) {
+			read = dns_read(dns_fd, in, sizeof(in));
+			
+			if(read <= 0) {
+				perror("read");
+				continue;
+			}
+
+			p = strchr(in, '-');
+			*p++ = '\0';
+
+			if (tun_setip(in) == 0 && tun_setmtu(atoi(p)) == 0)
+				return 0;
+		}
+
+		printf("Retrying...\n");
+	}
+
+	return 1;
+}
+
 extern char *__progname;
 
 static void
@@ -192,6 +238,9 @@ main(int argc, char **argv)
 
 	signal(SIGINT, sigint);
 
+	if(handshake(dns_fd))
+		goto cleanup2;
+
 	if (newroot) {
 		if (chroot(newroot) != 0 || chdir("/") != 0)
 			err(1, "%s", newroot);