From 8441a5c3976e209805c862081d0987a74a7bb929 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Philipp=20T=C3=B6lke?= <toelke@in.tum.de>
Date: Tue, 26 Oct 2010 13:55:55 +0000
Subject: [PATCH] Restart the hijack, if the tun was down

---
 src/include/gnunet_protocols.h |  4 ++++
 src/vpn/gnunet-daemon-vpn.c    | 27 ++++++++++++++++++++++++---
 src/vpn/gnunet-service-dns.c   |  9 +++++++++
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/include/gnunet_protocols.h b/src/include/gnunet_protocols.h
index bf696c743..0bcd59838 100644
--- a/src/include/gnunet_protocols.h
+++ b/src/include/gnunet_protocols.h
@@ -693,6 +693,10 @@ extern "C"
  * Type of messages the local service-dns responds with
  */
 #define GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS 206
+/**
+ * Type of messages to instruct the local service-dns to rehijack the dns
+ */
+#define GNUNET_MESSAGE_TYPE_REHIJACK 207
 
 
 /**
diff --git a/src/vpn/gnunet-daemon-vpn.c b/src/vpn/gnunet-daemon-vpn.c
index 5be4f9378..227bcd9ae 100644
--- a/src/vpn/gnunet-daemon-vpn.c
+++ b/src/vpn/gnunet-daemon-vpn.c
@@ -53,6 +53,7 @@ struct vpn_cls {
 	struct GNUNET_SCHEDULER_Handle *sched;
 
 	struct GNUNET_CLIENT_Connection *dns_connection;
+	unsigned char restart_hijack;
 
 	pid_t helper_pid;
 
@@ -67,6 +68,8 @@ struct vpn_cls {
 
 static struct vpn_cls mycls;
 
+size_t send_query(void* cls, size_t size, void* buf);
+
 static void cleanup(void* cls, const struct GNUNET_SCHEDULER_TaskContext* tskctx) {
   GNUNET_assert (0 != (tskctx->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN));
   PLIBC_KILL(mycls.helper_pid, SIGTERM);
@@ -108,7 +111,11 @@ static void restart_helper(void* cls, const struct GNUNET_SCHEDULER_TaskContext*
 	PLIBC_KILL(mycls.helper_pid, SIGKILL);
 	GNUNET_OS_process_wait(mycls.helper_pid);
 
-	// FIXME: send msg to service-dns -- the hijacker has to be started again, too, the routing table is flushed if it depends on one interface
+	/* Tell the dns-service to rehijack the dns-port
+	 * The routing-table gets flushed if an interface disappears.
+	 */
+	mycls.restart_hijack = 1;
+	GNUNET_CLIENT_notify_transmit_ready(mycls.dns_connection, sizeof(struct GNUNET_MessageHeader), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 
 	GNUNET_DISK_pipe_close(mycls.helper_in);
 	GNUNET_DISK_pipe_close(mycls.helper_out);
@@ -202,8 +209,20 @@ static void helper_write(void* cls, const struct GNUNET_SCHEDULER_TaskContext* t
 
 size_t send_query(void* cls, size_t size, void* buf)
 {
+  size_t len;
+  if (mycls.restart_hijack == 1)
+    {
+      mycls.restart_hijack = 0;
+      GNUNET_assert(sizeof(struct GNUNET_MessageHeader) >= size);
+      struct GNUNET_MessageHeader* hdr = buf;
+      len = sizeof(struct GNUNET_MessageHeader);
+      hdr->size = htons(len);
+      hdr->type = htons(GNUNET_MESSAGE_TYPE_REHIJACK);
+    }
+  else
+    {
 	struct query_packet_list* query = mycls.head;
-	size_t len = ntohs(query->pkt.hdr.size);
+	len = ntohs(query->pkt.hdr.size);
 
 	GNUNET_assert(len <= size);
 
@@ -212,8 +231,9 @@ size_t send_query(void* cls, size_t size, void* buf)
 	GNUNET_CONTAINER_DLL_remove (mycls.head, mycls.tail, query);
 
 	GNUNET_free(query);
+    }
 
-	if (mycls.head != NULL) {
+	if (mycls.head != NULL || mycls.restart_hijack == 1) {
 		GNUNET_CLIENT_notify_transmit_ready(mycls.dns_connection, ntohs(mycls.head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_YES, &send_query, NULL);
 	}
 
@@ -360,6 +380,7 @@ run (void *cls,
   mycls.sched = sched;
   mycls.mst = GNUNET_SERVER_mst_create(&message_token, NULL);
   mycls.cfg = cfg;
+  mycls.restart_hijack = 0;
   GNUNET_SCHEDULER_add_now (sched, &reconnect_to_service_dns, NULL);
   GNUNET_SCHEDULER_add_delayed(sched, GNUNET_TIME_UNIT_FOREVER_REL, &cleanup, cls); 
   GNUNET_SCHEDULER_add_now (sched, start_helper_and_schedule, NULL);
diff --git a/src/vpn/gnunet-service-dns.c b/src/vpn/gnunet-service-dns.c
index 0c688db34..4849749c0 100644
--- a/src/vpn/gnunet-service-dns.c
+++ b/src/vpn/gnunet-service-dns.c
@@ -134,6 +134,14 @@ void receive_dht(void *cls,
   GNUNET_DHT_get_stop(handle);
 }
 
+/**
+ * This receives a GNUNET_MESSAGE_TYPE_REHIJACK and rehijacks the DNS
+ */
+void rehijack(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) {
+    unhijack(mycls.dnsoutport);
+    hijack(mycls.dnsoutport);
+}
+
 /**
  * This receives the dns-payload from the daemon-vpn and sends it on over the udp-socket
  */
@@ -337,6 +345,7 @@ run (void *cls,
   static const struct GNUNET_SERVER_MessageHandler handlers[] = {
 	  /* callback, cls, type, size */
     {&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
+    {&rehijack, NULL, GNUNET_MESSAGE_TYPE_REHIJACK, sizeof(struct GNUNET_MessageHeader)},
     {NULL, NULL, 0, 0}
   };
 
-- 
2.25.1