From bc04a6898d72d22bea102321bcb8e8163cff4a89 Mon Sep 17 00:00:00 2001
From: wangyu <wangyu.cn@gmail.com>
Date: Fri, 4 Aug 2017 12:46:46 +0800
Subject: [PATCH] ack increase monotonically

---
 common.cpp  | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 common.h    |  3 ++-
 main.cpp    |  1 +
 network.cpp |  6 ++++--
 4 files changed, 68 insertions(+), 4 deletions(-)

diff --git a/common.cpp b/common.cpp
index 7c637ae..c638a27 100644
--- a/common.cpp
+++ b/common.cpp
@@ -14,6 +14,7 @@ unordered_map<int, const char*> raw_mode_tostring = {{mode_faketcp, "faketcp"},
 int socket_buf_size=1024*1024;
 static int random_number_fd=-1;
 char iptables_rule[200];
+program_mode_t program_mode=unset_mode;//0 unset; 1client 2server
 
 uint64_t get_current_time()
 {
@@ -218,5 +219,64 @@ int char_to_numbers(const char * data,int len,id_t &id1,id_t &id2,id_t &id3)
 	return 0;
 }
 
+bool larger_than_u32(uint32_t a,uint32_t b)
+{
 
-program_mode_t program_mode=unset_mode;//0 unset; 1client 2server
+	uint32_t smaller,bigger;
+	smaller=min(a,b);//smaller in normal sense
+	bigger=max(a,b);
+	uint32_t distance=min(bigger-smaller,smaller+(0xffffffff-bigger+1));
+	if(distance==bigger-smaller)
+	{
+		if(bigger==a)
+		{
+			return 1;
+		}
+		else
+		{
+			return 0;
+		}
+	}
+	else
+	{
+		if(smaller==b)
+		{
+			return 0;
+		}
+		else
+		{
+			return 1;
+		}
+	}
+}
+
+bool larger_than_u16(uint16_t a,uint16_t b)
+{
+
+	uint16_t smaller,bigger;
+	smaller=min(a,b);//smaller in normal sense
+	bigger=max(a,b);
+	uint16_t distance=min(bigger-smaller,smaller+(0xffff-bigger+1));
+	if(distance==bigger-smaller)
+	{
+		if(bigger==a)
+		{
+			return 1;
+		}
+		else
+		{
+			return 0;
+		}
+	}
+	else
+	{
+		if(smaller==b)
+		{
+			return 0;
+		}
+		else
+		{
+			return 1;
+		}
+	}
+}
diff --git a/common.h b/common.h
index 3ec9d83..398bb35 100644
--- a/common.h
+++ b/common.h
@@ -117,7 +117,8 @@ uint32_t get_true_random_number();
 uint32_t get_true_random_number_nz();
 uint64_t ntoh64(uint64_t a);
 uint64_t hton64(uint64_t a);
-
+bool larger_than_u16(uint16_t a,uint16_t b);
+bool larger_than_u32(uint32_t a,uint32_t b);
 void setnonblocking(int sock);
 int set_buf_size(int fd);
 
diff --git a/main.cpp b/main.cpp
index 8af5e7c..9becd66 100755
--- a/main.cpp
+++ b/main.cpp
@@ -2763,6 +2763,7 @@ void iptables_warn()
 }
 int main(int argc, char *argv[])
 {
+	//printf("%d %d %d %d",larger_than_u32(1,2),larger_than_u32(2,1),larger_than_u32(0xeeaaeebb,2),larger_than_u32(2,0xeeaaeebb));
 	//assert(0==1);
 	dup2(1, 2);//redirect stderr to stdout
 	signal(SIGINT, INThandler);
diff --git a/network.cpp b/network.cpp
index d6bd409..de4ef05 100644
--- a/network.cpp
+++ b/network.cpp
@@ -1318,14 +1318,16 @@ int after_recv_raw0(raw_info_t &raw_info)
 			send_info.ts_ack=recv_info.ts;
 		if (recv_info.syn == 0 && recv_info.ack == 1 && raw_info.last_recv_len != 0) //only modify   send_info when the packet is not part of handshake
 		{
-			send_info.ack_seq = recv_info.seq+raw_info.last_recv_len;//TODO only update if its larger
+			if(larger_than_u32(recv_info.seq+raw_info.last_recv_len,send_info.ack_seq))
+				send_info.ack_seq = recv_info.seq+raw_info.last_recv_len;//TODO only update if its larger
 		}
 	}
 	if(raw_mode==mode_icmp)
 	{
 		if(program_mode==server_mode)
 		{
-			send_info.icmp_seq = recv_info.icmp_seq;  //TODO only update if its larger
+			if(larger_than_u16(recv_info.icmp_seq,send_info.icmp_seq))
+				send_info.icmp_seq = recv_info.icmp_seq;  //TODO only update if its larger
 		}
 	}
 	return 0;