From fef76af3a5e264db9028ecec668e02ed93e91f19 Mon Sep 17 00:00:00 2001
From: wangyu- <wangyucn@gmail.com>
Date: Wed, 18 Jul 2018 02:02:30 -0500
Subject: [PATCH] add option --dev to bind to a specific interface

---
 main.cpp    | 23 ++++++++++++-----------
 misc.cpp    |  6 ++++++
 network.cpp | 24 ++++++++++++++++++++++--
 network.h   |  3 ++-
 4 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/main.cpp b/main.cpp
index f295b6f..42d2dea 100755
--- a/main.cpp
+++ b/main.cpp
@@ -69,14 +69,6 @@ int client_on_timer(conn_info_t &conn_info) //for client. called when a timer is
 
 			mylog(log_info,"source_addr is now %s\n",new_addr.get_ip());
 
-			if(new_addr.get_type()==AF_INET)
-			{
-				send_info.src_ip=new_addr.inner.ipv4.sin_addr.s_addr;
-			}
-			else
-			{
-				assert(0==1);
-			}
 			/*
 			if(new_ip!=source_ip_uint32)
 			{
@@ -92,6 +84,15 @@ int client_on_timer(conn_info_t &conn_info) //for client. called when a timer is
 			new_addr=source_addr;
 		}
 
+		if(new_addr.get_type()==AF_INET)
+		{
+			send_info.src_ip=new_addr.inner.ipv4.sin_addr.s_addr;
+		}
+		else
+		{
+			assert(0==1);
+		}
+
 		if (force_source_port == 0)
 		{
 			send_info.src_port = client_bind_to_a_new_port2(bind_fd,new_addr);
@@ -1090,7 +1091,7 @@ int client_event_loop()
 		if(lower_level_manual)
 		{
 			int index;
-			init_ifindex(if_name,index);
+			init_ifindex(if_name,raw_send_fd,index);
 			//init_ifindex(if_name);
 			memset(&send_info.addr_ll, 0, sizeof(send_info.addr_ll));
 			send_info.addr_ll.sll_family = AF_PACKET;
@@ -1148,7 +1149,7 @@ int client_event_loop()
 
 			//mylog(log_fatal,"--lower-level auto for client hasnt been implemented\n");
 			int index;
-			init_ifindex(if_name_string.c_str(),index);
+			init_ifindex(if_name_string.c_str(),raw_send_fd,index);
 
 			memset(&send_info.addr_ll, 0, sizeof(send_info.addr_ll));
 			send_info.addr_ll.sll_family = AF_PACKET;
@@ -1462,7 +1463,7 @@ int server_event_loop()
 	{
 		if(lower_level_manual)
 		{
-			init_ifindex(if_name,ifindex);
+			init_ifindex(if_name,raw_send_fd,ifindex);
 			mylog(log_info,"we are running at lower-level (manual) mode\n");
 		}
 		else
diff --git a/misc.cpp b/misc.cpp
index caf82a3..189cc28 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -264,6 +264,7 @@ void process_arg(int argc, char *argv[])  //process all options
 		{"gen-rule", no_argument,    0, 'g'},
 		{"gen-add", no_argument,    0, 1},
 		{"debug", no_argument,    0, 1},
+		{"dev", required_argument,    0, 1},
 		{"retry-on-error", no_argument,    0, 1},
 		{"clear", no_argument,    0, 1},
 		{"simple-rule", no_argument,    0, 1},
@@ -567,6 +568,11 @@ void process_arg(int argc, char *argv[])  //process all options
 				debug_flag=1;
 				//enable_log_color=0;
 			}
+			else if(strcmp(long_options[option_index].name,"dev")==0)
+			{
+				sscanf(optarg,"%s",dev);
+				//enable_log_color=0;
+			}
 			else if(strcmp(long_options[option_index].name,"debug-resend")==0)
 			{
 				//debug_resend=1;
diff --git a/network.cpp b/network.cpp
index 1e8344e..93033f2 100644
--- a/network.cpp
+++ b/network.cpp
@@ -28,6 +28,8 @@ int lower_level_manual=0;
 int ifindex=-1;
 char if_name[100]="";
 
+char dev[100]="";
+
 unsigned short g_ip_id_counter=0;
 
 unsigned char dest_hw_addr[sizeof(sockaddr_ll::sll_addr)]=
@@ -235,6 +237,24 @@ int init_raw_socket()
         //perror("");
         myexit(1);
     }
+    if(strlen(dev)!=0)
+    {
+        struct sockaddr_ll bind_address;
+        memset(&bind_address, 0, sizeof(bind_address));
+
+        int index=-1;
+        assert(init_ifindex(dev,raw_recv_fd,index)==0);
+
+        bind_address.sll_family = AF_PACKET;
+        bind_address.sll_protocol = htons(ETH_P_ALL);
+        bind_address.sll_ifindex = index;
+
+        if(bind(raw_recv_fd, (struct sockaddr *)&bind_address, sizeof(bind_address))==-1)
+        {
+        	mylog(log_fatal,"bind to dev [%s] failed\n",dev);
+        	myexit(1);
+        }
+    }
 
 	if(force_socket_buf)
 	{
@@ -319,7 +339,7 @@ void remove_filter()
 		//exit(-1);
 	}
 }
-int init_ifindex(const char * if_name,int &index)
+int init_ifindex(const char * if_name,int fd,int &index)
 {
 	struct ifreq ifr;
 	size_t if_name_len=strlen(if_name);
@@ -330,7 +350,7 @@ int init_ifindex(const char * if_name,int &index)
 		mylog(log_fatal,"interface name is too long\n");
 		myexit(-1);
 	}
-	if (ioctl(raw_send_fd,SIOCGIFINDEX,&ifr)==-1) {
+	if (ioctl(fd,SIOCGIFINDEX,&ifr)==-1) {
 
 		mylog(log_fatal,"SIOCGIFINDEX fail ,%s\n",strerror(errno));
 		myexit(-1);
diff --git a/network.h b/network.h
index 0531f16..7b11129 100644
--- a/network.h
+++ b/network.h
@@ -19,6 +19,7 @@ extern int disable_bpf_filter;
 extern int lower_level;
 extern int lower_level_manual;
 extern char if_name[100];
+extern char dev[100];
 extern unsigned char dest_hw_addr[];
 
 extern int random_drop;
@@ -94,7 +95,7 @@ void init_filter(int port);
 
 void remove_filter();
 
-int init_ifindex(const char * if_name,int &index);
+int init_ifindex(const char * if_name,int fd,int &index);
 
 int find_lower_level_info(u32_t ip,u32_t &dest_ip,string &if_name,string &hw);