嗨，我是Socket编程的新手，并尝试创建一个客户端服务器应用程序，其中我的服务器是Camera，而我的C ++应用程序中的客户端。
当我看到计算机与相机之间的数据包传输时，表明相机在停止后发送了150000个以上的数据包。但是，当我接收到400 - 450 packets函数进入等待状态之后，便可以一次接收到recvfrom了。如果我再次运行该exe文件而不停止前一个文件，它将再次收到400-450 packets。
接收数据包的代码
SOCKET out1 = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if (out1 == INVALID_SOCKET)
{
cout << out1 << endl;
}
server.sin_family = AF_INET;
server.sin_port = htons(3956);
inet_pton(AF_INET, "192.168.1.140", &server.sin_addr);
int serverLength = sizeof(server);
connect(out1, (sockaddr*)&server, serverLength);
while (1)
{
memset(buf, 0, sizeof(buf));
int bytesIn = recvfrom(out1, buf, 1444, 0, (sockaddr*)&server, &serverLength);
if (bytesIn > 0)
{
cout << "Image Received :" << bytesIn <<packet_counter << endl;
packet_counter++;
}
else
{
cout << "Not Received : " << endl;
}
}
我正在以管理员权限运行.exe。
所以任何人都可以告诉我为什么recvfrom函数进入等待状态。
谢谢。
编辑：-
很抱歉，我提供了完整的代码。
#include <stdio.h>
#include <Windows.h>
#include <thread>
#include <WinSock2.h>
// Library
#pragma comment(lib, "ws2_32.lib")
using namespace std;
//***** Function Decleration *****//
void _packetConfig(SOCKET);
void _sendPacket(SOCKET, const char*, int, int);
// Global Variable
sockaddr_in server;
//***** Main Function *****//
void main(char argc, char* argv[])
{
WSADATA data;
WORD version = MAKEWORD(2, 2);
if(WSAStartup(version, &data) == SOCKET_ERROR)
{
cout << "Can't Start Socket" << WSAGetLastError<<endl;
return;
}
char buf[2000];
SOCKET out1 = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if (out1 == INVALID_SOCKET)
{
cout << out1 << endl;
}
server.sin_family = AF_INET;
server.sin_port = htons(3956);
inet_pton(AF_INET, "192.168.1.140", &server.sin_addr);
int serverLength = sizeof(server);
connect(out1, (sockaddr*)&server, serverLength);
int packet_counter = 0;
SOCKET out = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
_packetConfig(out);
cout << "Inside Main" << endl;
while (1)
{
//connect(out1, (sockaddr*)&server, serverLength);
memset(buf, 0, sizeof(buf));
int bytesIn = recvfrom(out1, buf, 1444, 0, (sockaddr*)&server, &serverLength);
if (bytesIn > 0)
{
cout << "Image Received :" << bytesIn <<packet_counter << endl;
packet_counter++;
}
else
{
cout << "Not Received : " << endl;
}
}
WSACleanup();
}
//***** Function to Send Bytes to the Camera *****//
void _sendPacket(SOCKET sock, const char* s, int len, int i)
{
int sendOk = sendto(sock, (const char*)s, len, 0, (sockaddr*)&server, sizeof(server));
if (sendOk == SOCKET_ERROR)
{
cout << "Didn't Work" << WSAGetLastError() << endl;
}
else
{
cout << "\nSend Succesfully" << " " << i << endl;
}
char buf[2000];
int serverLength = sizeof(server);
int bytesIn = recvfrom(sock, buf, 2000, 0, (sockaddr*)&server, &serverLength);
if (bytesIn > 0)
{
cout << "Message Received :" << bytesIn << endl;
}
}
//***** Function to call the _sendPacket function and send commands to the Camera *****//
void _packetConfig(SOCKET sock)
{
// 59 Commands and every command call _snedPacket function to send commands to camera it will working properly
}
在上面的代码中，我必须首先发送用59 commands函数编写的_packetConfig，然后只有摄像机会发送Image packets，我将收到所有命令的答复。
当我也使用该代码运行wireshark时，我可以看到在这59条命令之后
相机正在提供3580*51个数据包，即51帧，每帧包含3580数据包
答案 0 :(得分：2)
感谢您发布代码。实际上存在一些问题，因此首先我将发布一些代码作为参考，然后提及我随后在您的代码中注意到的主要问题。
好的，这是一些对我有用的代码：
#include <WinSock2.h> // ** before** windows.h
#include <WS2tcpip.h>
#include <iostream>
#include <stdio.h>
#include <Windows.h>
#include <assert.h>
#pragma comment (lib, "ws2_32.lib")
const int port = 3956;
// main
int main (char argc, char* argv[])
{
WSADATA wsadata;
WORD version = MAKEWORD(2, 2);
int err = WSAStartup (MAKEWORD (2, 2), &wsadata);
if (err)
{
std::cout << "WSAStartup failed, error: " << err << std::endl;
return 255;
}
char buf [1444];
bool send = argc > 1 && _stricmp (argv [1], "send") == 0;
if (send)
{
// Send
SOCKET skt_out = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
assert (skt_out != INVALID_SOCKET);
sockaddr_in destination_address = { };
destination_address.sin_family = AF_INET;
destination_address.sin_port = htons (port);
inet_pton (AF_INET, "192.168.1.2", &destination_address.sin_addr);
memset (buf, 'Q', sizeof (buf));
printf ("Sending: ");
for ( ; ; )
{
sendto (skt_out, buf, sizeof (buf), 0, (const sockaddr *) &destination_address, sizeof (destination_address));
printf (".");
Sleep (50);
}
closesocket (skt_out);
WSACleanup ();
return 0;
}
// Receive
SOCKET skt_in = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
assert (skt_in != INVALID_SOCKET);
int receive_buffer_size = 65536;
if ((setsockopt (skt_in, SOL_SOCKET, SO_RCVBUF, (const char *) &receive_buffer_size, sizeof (int)) ) < 0)
std::cout << "Could not set SO_RCVBUF, error: " << WSAGetLastError () << std::endl;
sockaddr_in receive_address = { };
receive_address.sin_family = AF_INET;
receive_address.sin_port = htons (port);
receive_address.sin_addr.s_addr = htonl (INADDR_ANY);
if (bind (skt_in, (const sockaddr *) &receive_address, sizeof (receive_address)) == -1)
{
std::cout << "bind failed , error: " << WSAGetLastError () << std::endl;
return 255;
}
int packetCounter = 0;
printf ("Receiving: ");
for ( ; ; )
{
int bytesIn = recvfrom (skt_in, buf, sizeof (buf), 0, NULL, 0);
if (bytesIn > 0)
std::cout << "Packet received:" << bytesIn << " bytes (" << ++packetCounter << ")" << std::endl;
else
std::cout << "Receive error: " << WSAGetLastError () << std::endl;
}
closesocket (skt_in);
WSACleanup ();
return 0;
}
要以“发送”模式运行此命令，请在命令行上将 send 指定为第一个参数。否则，它将充当接收器（也称为服务器）。
那么您的代码有什么问题？好吧，没有特定的顺序：
SOCK_RAW bind，以便它知道要监听的端口。 sockaddr *from的{{1}}参数并不意味着您认为的含义（请检查docs）。您会看到我将其传递为NULL。recvfrom的返回值。再次，请检查文档。但是说了这么多，从本质上讲，您对WSAStartup的呼吁是失踪的。我重写了代码，因为您的代码很乱。
同样重要的是，UDP不能保证传送的正确性-有很多原因导致发送的数据包没有被接收甚至是接收顺序不正确（相机会以某种方式对数据包进行排序） ？）
您需要在应用程序的逻辑中做到这一点（这是一个问题，最好使用TCP，它可以保证数据包的传送和排序）。