问题描述
我正在开发跨平台的服务器和客户端。客户端是 Unity3d 应用程序，客户端是用 C++ 编写的。它在 Linux 和 Mac 中运行良好，但在 Windows 中不起作用。所以我认为我在使用 Winsock2 时做错了。
这很奇怪。我第一次编译它，它工作正常。当我关闭可执行文件并再次运行它时，服务器端在一段时间后无法接收（发送/接收大约 5~10 条消息后）。它只是挂在 recv 函数上。用wireshark检查了它。客户端发送了消息。但是服务器无法接收。一旦发生这种情况，即使再次建立连接，它也会停止工作。
我强制关闭应用程序。这可能不会正确关闭套接字。但是当用户只是关闭可执行文件时，我没有看到很好地关闭它的方法。
#include <chrono>
#undef UNICODE
#include <winsock2.h>
#include <windows.h>
#include <ws2tcpip.h>
#include <atomic>
#include <fstream>
#include <iterator>
#include <string>
#include <thread>
#include <iostream>
#include <vector>
std::vector<char> receive_buffer;
int client_;
int server_fd;
int port_ = 8080;
bool terminateRequested_ = false;
bool connected_=false;
char tempBuffer[1024];
inline bool processRequests() {
std::cout<<"recv \n";
int recv_size = recv(client_,&receive_buffer[0],1024,0);
std::cout<<"recv "<<recv_size<<" \n";
if (recv_size <= 0) {
std::cout<<"recv Failed \n\n";
return false;
}
tempBuffer[1023] = 'e';
send(client_,&tempBuffer[0],0);
}
inline bool waitForReadEvent(int timeout) {
fd_set sdset;
struct timeval tv;
tv.tv_sec = timeout;
tv.tv_usec = 0;
FD_ZERO(&sdset);
FD_SET(server_fd,&sdset);
return select(server_fd + 1,&sdset,NULL,&tv) > 0;
}
inline void loop() {
WSADATA wsaData;
int iResult;
struct addrinfo *result = NULL;
struct addrinfo hints;
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2,2),&wsaData);
// holds address info for socket to connect to
struct addrinfo *ptr = NULL;
int opt = 1000000000;
ZeroMemory(&hints,sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;
std::string portInString = std::to_string(port_);
// Resolve the server address and port
iResult = getaddrinfo(NULL,portInString.c_str(),&hints,&result);
if (iResult != 0) {
printf("getaddrinfo Failed with error: %d\n",iResult);
WSACleanup();
return;
}
// Create a SOCKET for connecting to server
server_fd =
socket(result->ai_family,result->ai_socktype,result->ai_protocol);
if (server_fd == INVALID_SOCKET) {
printf("socket Failed with error: %ld\n",WSAGetLastError());
freeaddrinfo(result);
WSACleanup();
return;
}
setsockopt(server_fd,SOL_SOCKET,SO_SNDBUF,(char *)&opt,sizeof(opt));
setsockopt(server_fd,SO_RCVBUF,sizeof(opt));
// Setup the TCP listening socket
iResult = bind(server_fd,result->ai_addr,(int)result->ai_addrlen);
if (iResult == SOCKET_ERROR) {
printf("bind Failed with error: %d\n",WSAGetLastError());
closesocket(server_fd);
WSACleanup();
return;
}
iResult = listen(server_fd,SOMAXCONN);
if (iResult == SOCKET_ERROR) {
printf("listen Failed with error: %d\n",WSAGetLastError());
closesocket(server_fd);
WSACleanup();
return;
}
while (!terminateRequested_) {
if (waitForReadEvent(2.0)) {
client_ = accept(server_fd,NULL);
connected_ = true;
}
std::chrono::steady_clock::time_point lastChecked,current;
lastChecked = std::chrono::steady_clock::Now();
while (connected_) {
if (processRequests()) {
lastChecked = std::chrono::steady_clock::Now();
} else {
current = std::chrono::steady_clock::Now();
if (std::chrono::duration_cast<std::chrono::seconds>(current - lastChecked).count() > 3.0) {
std::cout<<"The client has been disconnected for "<<std::chrono::duration_cast<std::chrono::seconds>(current - lastChecked).count()<<" seconds. Waiting for a new connection..."<<std::endl;
connected_ = false;
}
}
}
}
closesocket(server_fd);
WSACleanup();
}
int main() {
receive_buffer.resize(1024);
std::fill(receive_buffer.begin(),receive_buffer.end(),0);
loop();
return 0;
}
这是wireshark的输出
No. Time Source Destination Protocol Length Info
110 4.532631 127.0.0.1 127.0.0.1 TCP 56 9910 → 8080 [PSH,ACK] Seq=133 Ack=455184963 Win=2609408 Len=12
Frame 110: 56 bytes on wire (448 bits),56 bytes captured (448 bits) on interface \Device\NPF_Loopback,id 0
Null/Loopback
Internet Protocol Version 4,Src: 127.0.0.1,Dst: 127.0.0.1
Transmission Control Protocol,Src Port: 9910,Dst Port: 8080,Seq: 133,Ack: 455184963,Len: 12
No. Time Source Destination Protocol Length Info
111 4.532650 127.0.0.1 127.0.0.1 TCP 44 8080 → 9910 [ACK] Seq=455184963 Ack=145 Win=999997440 Len=0
Frame 111: 44 bytes on wire (352 bits),44 bytes captured (352 bits) on interface \Device\NPF_Loopback,Src Port: 8080,Dst Port: 9910,Seq: 455184963,Ack: 145,Len: 0
No. Time Source Destination Protocol Length Info
112 4.532856 127.0.0.1 127.0.0.1 TCP 1068 8080 → 9910 [PSH,ACK] Seq=455184963 Ack=145 Win=999997440 Len=1024
Frame 112: 1068 bytes on wire (8544 bits),1068 bytes captured (8544 bits) on interface \Device\NPF_Loopback,Len: 1024
No. Time Source Destination Protocol Length Info
113 4.532873 127.0.0.1 127.0.0.1 TCP 44 9910 → 8080 [ACK] Seq=145 Ack=455185987 Win=2608384 Len=0
Frame 113: 44 bytes on wire (352 bits),Seq: 145,Ack: 455185987,Len: 0
No. Time Source Destination Protocol Length Info
114 4.540624 127.0.0.1 127.0.0.1 TCP 56 [TCP Retransmission] 9912 → 8080 [SYN] Seq=0 Win=65535 Len=0 MSS=65495 WS=256 SACK_PERM=1
Frame 114: 56 bytes on wire (448 bits),Src Port: 9912,Seq: 0,Len: 0
No. Time Source Destination Protocol Length Info
115 4.540673 127.0.0.1 127.0.0.1 TCP 56 [TCP Port numbers reused] 8080 → 9912 [SYN,ACK] Seq=810974615 Ack=1 Win=65535 Len=0 MSS=65495 WS=16384 SACK_PERM=1
Frame 115: 56 bytes on wire (448 bits),Dst Port: 9912,Seq: 810974615,Ack: 1,Len: 0
No. Time Source Destination Protocol Length Info
116 4.540693 127.0.0.1 127.0.0.1 TCP 44 9912 → 8080 [ACK] Seq=1 Ack=810974616 Win=327424 Len=0
Frame 116: 44 bytes on wire (352 bits),Seq: 1,Ack: 810974616,Len: 0
No. Time Source Destination Protocol Length Info
117 4.546600 127.0.0.1 127.0.0.1 TCP 56 9912 → 8080 [PSH,ACK] Seq=1 Ack=810974616 Win=327424 Len=12
Frame 117: 56 bytes on wire (448 bits),Len: 12
No. Time Source Destination Protocol Length Info
118 4.546614 127.0.0.1 127.0.0.1 TCP 44 8080 → 9912 [ACK] Seq=810974616 Ack=13 Win=999997440 Len=0
Frame 118: 44 bytes on wire (352 bits),Seq: 810974616,Ack: 13,Len: 0
No. Time Source Destination Protocol Length Info
119 4.665321 127.0.0.1 127.0.0.1 TCP 56 [TCP Retransmission] 9909 → 8080 [SYN] Seq=0 Win=65535 Len=0 MSS=65495 WS=256 SACK_PERM=1
Frame 119: 56 bytes on wire (448 bits),Src Port: 9909,Len: 0
No. Time Source Destination Protocol Length Info
120 4.665382 127.0.0.1 127.0.0.1 TCP 56 [TCP Port numbers reused] 8080 → 9909 [SYN,ACK] Seq=2078265275 Ack=1 Win=65535 Len=0 MSS=65495 WS=16384 SACK_PERM=1
Frame 120: 56 bytes on wire (448 bits),Dst Port: 9909,Seq: 2078265275,Len: 0
No. Time Source Destination Protocol Length Info
121 4.665401 127.0.0.1 127.0.0.1 TCP 44 9909 → 8080 [ACK] Seq=1 Ack=2078265276 Win=327424 Len=0
Frame 121: 44 bytes on wire (352 bits),Ack: 2078265276,Len: 0
No. Time Source Destination Protocol Length Info
122 6.055260 127.0.0.1 127.0.0.1 TCP 44 9909 → 8080 [FIN,ACK] Seq=1 Ack=2078265276 Win=327424 Len=0
Frame 122: 44 bytes on wire (352 bits),Len: 0
No. Time Source Destination Protocol Length Info
123 6.055277 127.0.0.1 127.0.0.1 TCP 44 8080 → 9909 [ACK] Seq=2078265276 Ack=2 Win=999997440 Len=0
Frame 123: 44 bytes on wire (352 bits),Seq: 2078265276,Ack: 2,Len: 0
No. Time Source Destination Protocol Length Info
124 6.420665 127.0.0.1 127.0.0.1 TCP 56 9915 → 8080 [SYN] Seq=0 Win=65535 Len=0 MSS=65495 WS=256 SACK_PERM=1
Frame 124: 56 bytes on wire (448 bits),Src Port: 9915,Len: 0
No. Time Source Destination Protocol Length Info
125 6.420705 127.0.0.1 127.0.0.1 TCP 56 8080 → 9915 [SYN,ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=65495 WS=16384 SACK_PERM=1
Frame 125: 56 bytes on wire (448 bits),Dst Port: 9915,Len: 0
No. Time Source Destination Protocol Length Info
126 6.420724 127.0.0.1 127.0.0.1 TCP 44 9915 → 8080 [ACK] Seq=1 Ack=1 Win=2619648 Len=0
Frame 126: 44 bytes on wire (352 bits),Len: 0
No. Time Source Destination Protocol Length Info
127 6.445091 127.0.0.1 127.0.0.1 TCP 56 9915 → 8080 [PSH,ACK] Seq=1 Ack=1 Win=2619648 Len=12
Frame 127: 56 bytes on wire (448 bits),Len: 12
No. Time Source Destination Protocol Length Info
128 6.445109 127.0.0.1 127.0.0.1 TCP 44 8080 → 9915 [ACK] Seq=1 Ack=13 Win=999997440 Len=0
Frame 128: 44 bytes on wire (352 bits),Len: 0
No. Time Source Destination Protocol Length Info
129 7.948501 127.0.0.1 127.0.0.1 TCP 44 9915 → 8080 [FIN,ACK] Seq=13 Ack=1 Win=2619648 Len=0
Frame 129: 44 bytes on wire (352 bits),Seq: 13,Len: 0
解决方法
客户端正在创建一个新线程并在那里建立连接。 Atfer 将其移动到主线程，问题就消失了。我不确定这如何影响 tcp，但它现在可以在我所有的五台 Windows 机器上运行