C套接字：连接错误 - 无效参数。

Question

我写了一个简单的基于进程的并行套接字程序。

我的客户端代码到达连接部分时会抛出“无效参数”错误，而我的服务器没有输出任何东西，只有光标...

我将终端分成两个部分来运行代码。

我使用以下命令运行代码:

gcc -o p-server p-server.c -Wall
./p-server

gcc -o p-client p-client.c -Wall

输出结果是：

[C] 连接中...
[C] 无法连接服务器：参数无效

p-server.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
//#include <sys/wait.h>

#define BUFFSIZE 4096
#define SERVERPORT 7799

int main(void){
    int i, j, s_sock, c_sock;
    struct sockaddr_in server_addr, client_addr;
    socklen_t c_addr_size;
    char buf[BUFFSIZE] = {0};
    char hello[] = "Hello~ I am Server!\n";
    
    //int option = 1;
    //setsockopt(s_sock, SOL_SOCKET, SO_REUSEADDR, &option, sizeof(option));
    
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVERPORT);
    server_addr.sin_addr.s_addr = inet_addr("10.0.0.131");

    s_sock = socket(AF_INET, SOCK_STREAM, 0);

  
    if (bind(s_sock, (struct sockaddr *) &server_addr, sizeof(server_addr)) == -1) {
        perror("[S] Can't bind a socket");
        exit(1);
    }

    if(listen(s_sock, 5)) {
        perror("[S] Can't listen");
        exit(1);
    }
    
    c_addr_size = sizeof(client_addr);

    
    for ( i=0; i<3; i++) {
        if ((c_sock = accept(s_sock, (struct sockaddr *) &client_addr, sizeof(client_addr))) == -1 ){
            perror("[S] Can't accept a connection");
            exit(1);
        }

        printf("[S] Connected: client IP addr=%s port=%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

        
        //fork
        switch(fork()){
            case 0:
                close(s_sock);
                //1. say hello to client
                if(send(c_sock, hello, sizeof(hello)+1, 0) == -1) {
                    perror("[S] Can't send message");
                    exit(1);
                }

                printf("[S] I said Hello to Client!\n");

                //2. recv msg from client
                if(recv(c_sock, buf, BUFFSIZE, 0) == -1) {
                    perror("[S] Can't receive message");
                    exit(1);
                }

                printf("[S] Client says: %s\n", buf);
                exit(0);
        } 
        
        close(c_sock);
    }

    
    /*
    for(j=0; j<3; j++){
        wait(&status);
        printf("Patren waits %d\n"), wstatus;
    }*/
}

p-client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUFFSIZE 4096
#define SERVERPORT 7799

int main(void){
    int c_sock;
    struct sockaddr_in server_addr;
    socklen_t c_addr_size;
    char buf[BUFFSIZE] = {0};
    char hello[] = "Hi~I am Client!\n";

    if((c_sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }
    
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVERPORT);
    server_addr.sin_addr.s_addr = inet_addr("10.0.0.131");

    printf("[C] Connecting...\n");

    if (connect(c_sock, (struct sockaddr *) &server_addr, sizeof(server_addr) == -1)) {
        perror("[C] Can't connect to a Server");
        exit(1);
    }

    printf("[C] connected!\n");

    //1. recv msg from server (maybe it's "hello")
    if (recv(c_sock, buf, BUFFSIZE, 0) == -1) {
        perror("[C] Can't receive message");
        exit(1);
    }

    printf("[C] Server says: %s\n", buf);

    //2. say hi to server
    if(send(c_sock, hello, sizeof(hello)+1, 0) == -1) {
        perror("[C] Can't send message");
        exit(1);
    }

    printf("[C] I said Hi to Server!!\n");

    printf("[C] I am going to sleep...\n");
    sleep(10);

    close(c_sock);

    return 0;
}

- Aine

---

嗯...在客户端中SERVERPORT是在哪里定义的呢？ - Serge Ballesta

你对accept的第三个参数是错误的。它应该是一个socklen_t*而不是size_t，你的编译器在这个错误上应该会发出警告或直接报错。 - WhozCraig

不完全是，SERVERPORT并不是一个变量，而只是一个宏。 - Gerhardh

@Gerhardh 谢谢。但那只是第二步，我的代码还没有到那一步... 还在连接之前 - Aine

@Aine 这不是唯一的错误。你的地址设置也不正确。老实说，你应该使用getaddrinfo和AI_PASSIVE来设置两个地址，并根据需要限制hints。它确实可以帮助你填补空白。 - WhozCraig

Answer 1

你在连接调用的括号中有一个错误。

 if (connect(c_sock, (struct sockaddr *) &server_addr, sizeof(server_addr) == -1)) {
    perror("[C] Can't connect to a Server");
    exit(1);
}

应该是

if (connect(c_sock, (struct sockaddr *) &server_addr, sizeof(server_addr)) == -1) {
    perror("[C] Can't connect to a Server");
    exit(1);
}

- Guillermo Gutiérrez