From 003f31bfef8175c1535dd0a8ae2b17b24f9f017f Mon Sep 17 00:00:00 2001
From: wangyu- <wangyucn@gmail.com>
Date: Tue, 13 Nov 2018 02:08:32 -0600
Subject: [PATCH] new option --no-pcap-mutex

---
 misc.cpp    |  6 ++++++
 network.cpp | 30 +++++++++++++++++++-----------
 network.h   |  2 ++
 3 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/misc.cpp b/misc.cpp
index eec3d56..f551770 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -297,6 +297,7 @@ void process_arg(int argc, char *argv[])  //process all options
 		{"dns-resolve", no_argument,    0, 1},
 		{"pcap-send", no_argument,    0, 1},
 		{"easy-tcp", no_argument,    0, 1},
+		{"no-pcap-mutex", no_argument,    0, 1},
 		{NULL, 0, 0, 0}
 	  };
 
@@ -756,6 +757,11 @@ void process_arg(int argc, char *argv[])  //process all options
 				send_with_pcap=1;
 				mylog(log_info,"--pcap-send enabled, now pcap will be used for sending packet instead of libnet\n");
 			}
+			else if(strcmp(long_options[option_index].name,"no-pcap-mutex")==0)
+			{
+				use_pcap_mutex=9;
+				mylog(log_warn,"--no-pcap-mutex enabled, we will assume the underlying pcap calls are threadsafe\n");
+			}
 			else if(strcmp(long_options[option_index].name,"easy-tcp")==0)
 			{
 				use_tcp_dummy_socket=1;
diff --git a/network.cpp b/network.cpp
index 9ab9b4c..a0cd749 100644
--- a/network.cpp
+++ b/network.cpp
@@ -73,6 +73,7 @@ queue_t my_queue;
 
 pthread_mutex_t queue_mutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_t pcap_mutex = PTHREAD_MUTEX_INITIALIZER;
+int use_pcap_mutex=1;
 
 ev_async async_watcher;
 
@@ -326,9 +327,9 @@ void *pcap_recv_thread_entry(void *none)
 
 	while(1)
 	{
-		pthread_mutex_lock(&pcap_mutex);
+		if(use_pcap_mutex) pthread_mutex_lock(&pcap_mutex);
 		int ret=pcap_loop(pcap_handle, -1, my_packet_handler, NULL); //use -1 instead of 0 as cnt, since 0 is undefined in old versions
-		pthread_mutex_unlock(&pcap_mutex);
+		if(use_pcap_mutex) pthread_mutex_unlock(&pcap_mutex);
 		if(ret==-1)
 			mylog(log_warn,"pcap_loop exited with value %d\n",ret);
 		else
@@ -845,19 +846,26 @@ void init_filter(int port)
 	//pthread_mutex_lock(&pcap_mutex);//not sure if mutex is needed here
 
 	long long tmp_cnt=0;
-	while(pthread_mutex_trylock(&pcap_mutex)!=0)
+	if(use_pcap_mutex)
 	{
-		tmp_cnt++;
-		pcap_breakloop(pcap_handle);
-		if(tmp_cnt%500==0)
+		while(pthread_mutex_trylock(&pcap_mutex)!=0)
 		{
-			mylog(log_warn,"%lld attempts of pcap_breakloop()\n", tmp_cnt);
-			if(tmp_cnt>5000)
+			tmp_cnt++;
+			pcap_breakloop(pcap_handle);
+			if(tmp_cnt==100)
 			{
-				 mylog(log_fatal,"we might have already run into a deadlock\n");
+				mylog(log_warn,"%lld attempts of pcap_breakloop()\n", tmp_cnt);
 			}
+			if(tmp_cnt%1000==0)
+			{
+				mylog(log_warn,"%lld attempts of pcap_breakloop()\n", tmp_cnt);
+				if(tmp_cnt>5000)
+				{
+					 mylog(log_fatal,"we might have already run into a deadlock\n");
+				}
+			}
+			ev_sleep(0.001);
 		}
-		ev_sleep(0.001);
 	}
 
 	mylog(log_info,"breakloop() succeed after %lld attempt(s)\n", tmp_cnt);
@@ -884,7 +892,7 @@ void init_filter(int port)
 	 }
 
 
-	pthread_mutex_unlock(&pcap_mutex);
+	if(use_pcap_mutex) pthread_mutex_unlock(&pcap_mutex);
 	/*
 	if(disable_bpf_filter) return;
 	//if(raw_mode==mode_icmp) return ;
diff --git a/network.h b/network.h
index 9bdf4d7..e3ce380 100644
--- a/network.h
+++ b/network.h
@@ -37,6 +37,8 @@ extern ev_async async_watcher;
 extern ev_loop* g_default_loop;
 
 extern pthread_mutex_t queue_mutex;
+extern int use_pcap_mutex;
+
 extern int pcap_cnt;
 
 extern int pcap_link_header_len;