c - 服务器从多个客户端接收数据并在Linux中使用C通过线程同时存储在单独的文件中

Question

我有一个服务器和两个客户端。我想同时将来自客户端的数据存储在不同的文件中。目前，我将来自两个客户端的数据存储在同一个文件中。在一个客户端发送数据后，第二个客户端开始发送。

我希望两个客户端同时发送数据。任何人都可以帮助我...

服务器.c

void *function1(void *ptr);

typedef struct{
    int port_id;
    int thread_id;
}conn_id;

int main(int argc, char *argv[])
{
    conn_id conn_id1[2];

    conn_id1[0].port_id=7350;
    conn_id1[0].thread_id=1;
    conn_id1[1].port_id=7351;
    conn_id1[1].thread_id=2;

    conn_id* conn_ptr;


    pthread_t thread[2];
    int index=0;

    for(index=0;index<2;index++){
    conn_ptr=&conn_id1[index];

    pthread_create(&thread[index],NULL,&function1,(void*)conn_ptr);}

    pthread_join(thread[0],NULL);
    pthread_join(thread[1],NULL);

    return 0;
    }
void *function1( void *ptr)
{
    //Declaring process variables.
    int server_sockfd, client_sockfd;
    int server_len ; 
    int rc ; 

    conn_id* conn_ptr;
    conn_ptr = (conn_id*)ptr;
    unsigned client_len;
    char revbuf[LENGTH];

    struct sockaddr_in server_address;
    struct sockaddr_in client_address;


    //Remove any old socket and create an unnamed socket for the server.
    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = htons(INADDR_ANY);
    server_address.sin_port = htons(conn_ptr->port_id);
    server_len = sizeof(server_address);

    bzero(&(server_address.sin_zero), 8);
    rc = bind(server_sockfd, (struct sockaddr *) &server_address, server_len);

    printf("RC from bind = %d\n", rc ) ; 

    //Create a connection queue and wait for clients
    rc = listen(server_sockfd, 5);

    printf("RC from listen = %d\n", rc ) ; 

    client_len = sizeof(client_address);
    client_sockfd = accept(server_sockfd, (struct sockaddr *) &client_address,                &client_len);

    printf("after accept()... client = %s\n", inet_ntoa(client_address.sin_addr)) ; 

    while(1)
    {
    /*Receive File from Client */
    char* fr_name = "/home/server/Desktop/fr_client.dat";
    FILE *fr = fopen(fr_name, "a"); 

    if(fr == NULL)
        printf("File %s Cannot be opened file on server.\n", fr_name);
    else
    {
        bzero(revbuf, LENGTH); 
        int fr_block_sz = 0;
        while((fr_block_sz = recv(client_sockfd, revbuf, LENGTH, 0)) > 0) 
        {
            int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);
            if(write_sz < fr_block_sz)
            {
                error("File write failed on server.\n");
            }
            bzero(revbuf, LENGTH);
            if (fr_block_sz == 0 || fr_block_sz != 512) 
            {
                break;
            }
        }
        if(fr_block_sz < 0)
        {
            if (errno == EAGAIN)
            {
                printf("recv() timed out.\n");
            }
            else
            {
                fprintf(stderr, "recv() failed due to errno = %d\n", errno);
                exit(1);
            }
        }
        printf("Ok received from client!\n");
        fclose(fr); 
    }

    /* Call the Script */
    system("cd ; chmod +x script.sh ; ./script.sh");

    /* Send File to Client */

        char* fs_name = "/home/server/Desktop/output.txt";
        char sdbuf[LENGTH]; // Send buffer
        printf("[Server] Sending %s to the Client...", fs_name);
        FILE *fs = fopen(fs_name, "r");
        if(fs == NULL)
        {
            fprintf(stderr, "ERROR: File %s not found on server. (errno =   %d)\n", fs_name, errno);
            exit(1);
        }

        bzero(sdbuf, LENGTH); 
        int fs_block_sz; 
        while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs))>0)
        {
            if(send(client_sockfd, sdbuf, fs_block_sz, 0) < 0)
            {
                fprintf(stderr, "ERROR: Failed to send file %s. (errno =  %d)\n", fs_name, errno);
                exit(1);
            }
            bzero(sdbuf, LENGTH);
        }
        printf("Ok sent to client!\n");

        close(client_sockfd);
        printf("[Server] Connection with Client closed. Server will wait  now...\n");
        while(waitpid(-1, NULL, WNOHANG) > 0);break;

}

}

Answer 1

如果您想同时从多个客户端接收数据，基本上，您有两种选择:

1. 仍然使用同步套接字 I/O，但在多个线程中，每个线程与一个客户端通信，并将数据写入共享文件句柄，该句柄受互斥锁保护。

2. 使用异步套接字I/O，单线程。在循环中，您应该首先在多个套接字上调用 select()，然后在套接字上有事件时执行 I/O。在这种情况下，文件句柄上不需要互斥锁。