Question

我试图以非常简单/基本的方式在C中实现UDP套接字。我的程序用于在终端之间发送/接收文件，每个程序上运行一个程序。我的客户端代码中的sendto()函数出现问题。这是我的代码：

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include <errno.h>

#define BUFFER_SIZE 512

int main(int argc, char *argv[])
{
    struct sockaddr_in client;
    int sockfd, bytes, errno, slen = sizeof(client);
    char buffer[BUFFER_SIZE];

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);

    if(sockfd == -1)
    {
        perror("Socket creation failed.");
        return 0;
    }

    client.sin_addr.s_addr = INADDR_ANY;
    client.sin_family = AF_INET;
    client.sin_port = htons( 0 );

    if( bind(sockfd, (struct sockaddr *)&client, sizeof(client)) == -1)
    {
        perror("Bind call failed.");
        return 0;
    }

    while(1)
    {
        printf("Enter message : ");
        fgets(buffer, BUFFER_SIZE, stdin);

        printf("Message: %s\n", buffer);
        bytes = sendto(sockfd, buffer, strlen(buffer), 0, (struct sockaddr *)&client, sizeof(client));

        printf("Bytes: %d\n", bytes);

        if(bytes == -1)
        {
            printf("Error number: %d", errno);
            perror("Send failed.");
            return 0;
        }

        memset(buffer,'\0', BUFFER_SIZE);

        if( recvfrom(sockfd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&client, &slen) == -1)
        {
            perror("Recieve failed.");
            return 0;
        }

        puts(buffer);
    }

    close(sockfd);

    return 0;   
}

无论我进入缓冲区，我总是从sendto（）获取无效参数的错误号22。我尝试过每一个解决方案或调整，但似乎没有任何效果。

Answer 1

只需在bind（）

之后添加这段代码即可

getsockname(sockfd, (struct sockaddr *)&client, &slen);

手册页

 DESCRIPTION
     The getsockname() function returns the current address for the specified
     socket.

     The address_len parameter should be initialized to indicate the amount of
     space pointed to by address.  On return it contains the actual size of
     the address returned (in bytes).

     The address is truncated if the buffer provided is too small.

RETURN VALUES
     The getsockname() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.

C中的UDP套接字 - Sendto（）发送失败：参数无效

1 个答案: