C 客户端服务器未按预期工作

Question

我在下面用 C 编写了这个简单的客户端-服务器。客户端向服务器发送 2 个数字，服务器将这 2 个数字的总和返回给客户端。我的问题是将总和从服务器发送回客户端，我不明白为什么它不起作用。它不会给出任何错误，只是 receivedData 变量没有填充所需的 int。客户端成功将带有2个号码的数据包发送给服务器，服务器成功接收。

请注意，这只是一个教学示例，我没有使用线程来处理客户端。它只是一个客户端和一个服务器。

这是服务器:

// SERVER
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <signal.h>
#include <netinet/in.h>
#include <string.h>
#include <stdlib.h>

#define PORT 2012

struct Packet
{
    int a;
    int b;
};


int main()
{
    struct sockaddr_in clientAddress;
    int sd;

    if((sd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf("Error creating socketsss\n");
    }

    memset(&clientAddress, 0, sizeof(clientAddress));

    clientAddress.sin_family = AF_INET;
    clientAddress.sin_port = htons(PORT);
    clientAddress.sin_addr.s_addr = htonl(INADDR_ANY);

    if(bind(sd, (struct sockaddr*)&clientAddress, sizeof(clientAddress)) < 0)
    {
        printf("Bind error\n");
    }

    if(listen(sd, 5) < 0)
    {
        printf("Listen error\n");
    }

    unsigned int len = 0;

    int fd = accept(sd, (struct sockaddr*)&clientAddress, &len);

    struct Packet received;

    if(recv(fd, &received, sizeof(struct Packet), 0) < 0)
    {
        printf("Receive error");
    }

    int sum = received.a + received.b;

    printf("Numarul ce trebui trimis este %d\n", sum);

    if(send(sd, &sum, sizeof(sum), 0) < 0)
    {
        printf("Error sending data\n");
    }

    return 0;
}

这是客户端:

// CLIENT
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define SERVER_IP "127.0.0.1"
#define PORT 2012

struct Packet
{
    int a;
    int b;
};

int main()
{
    struct sockaddr_in serverAddress;
    int sd;

    if((sd = socket(AF_INET,SOCK_STREAM,0)) < 0)
    {
        printf("Error creating socket\n");
    }

    memset((char *)&serverAddress, 0, sizeof(serverAddress));

    serverAddress.sin_family = AF_INET;
    serverAddress.sin_addr.s_addr = inet_addr(SERVER_IP);
    serverAddress.sin_port = htons(PORT);

    if ((connect(sd,(struct sockaddr *)&serverAddress, sizeof(serverAddress))) < 0)
    {
        printf("Error connectiong to server!\n");
    }

    struct Packet packToSend;
    packToSend.a = 14;
    packToSend.b = 21;

    if(send(sd, &packToSend, sizeof(packToSend), 0) < 0)
    {
        printf("Error sending data\n");
    }

    int receivedData = 0;

    if(recv(sd, &receivedData, sizeof(int), 0) < 0)
    {
        printf("Receive error\n");
    }

    printf("I received %d \n", receivedData);

    return 0;
}

谢谢!

Answer 1

您在监听套接字上发送，而不是您接受的套接字。