c - 网络编程，从客户端发送文件到服务器

Question

我对网络非常陌生，我正在使用回显服务器和回显客户端。在我的实验室中，我有两台计算机连接在网络上，因此我可以在通过“ifconfig eth0 10.1.1.n(n 是端口号)网络掩码 255.255.255.0”配置它们后对它们执行 ping 操作。

echo_server.c

 /* A simple echo server using TCP */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/signal.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>

#define SERVER_TCP_PORT 3000    /* well-known port */
// #define BUFLEN       256 /* buffer length */

int echod(int);
void reaper(int);

int main(int argc, char **argv)
{
    int     sd, new_sd, client_len, port, confd = 0,b,tot;
    struct  sockaddr_in server, client;
    char buff[1025];

    switch(argc){
    case 1:
        port = SERVER_TCP_PORT;
        break;
    case 2:
        port = atoi(argv[1]);
        break;
    default:
        fprintf(stderr, "Usage: %d [port]\n", argv[0]);
        exit(1);
    }

    /* Create a stream socket   */  
    if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        fprintf(stderr, "Can't creat a socket\n");
        exit(1);
    }

    /* Bind an address to the socket    */
    bzero((char *)&server, sizeof(struct sockaddr_in));
    server.sin_family = AF_INET;
    server.sin_port = htons(port);
    server.sin_addr.s_addr = htonl(INADDR_ANY);
    if (bind(sd, (struct sockaddr *)&server, sizeof(server)) == -1){
        fprintf(stderr, "Can't bind name to socket\n");
        exit(1);
    }



    while(1) {
      confd = accept(sd, (struct sockaddr*)NULL, NULL);
        if (confd==-1) {
            perror("Accept");
            continue;
        }
        //Should create a text file.
        FILE* fp = fopen( "test.txt", "wb");
        tot=0;
        if(fp != NULL){
            while( (b = recv(confd, buff, 1024,0))> 0 ) {
                tot+=b;
                fwrite(buff, 1, b, fp);
            }

            printf("Received byte: %d\n",tot);
            if (b<0)
               perror("Error recieving the file");

            fclose(fp);
        } else {
            perror("File doesnt exist");
        }
        close(confd);
    }
}

echo_client.c

/* A simple echo client using TCP */
#include <stdio.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <strings.h>


#define SERVER_TCP_PORT 3000    /* well-known port */
#define BUFLEN      256 /* buffer length */

int main(int argc, char **argv)
{
    int     n, i, bytes_to_read, b;
    int     sd, port;
    struct  hostent     *hp;
    struct  sockaddr_in server;
    char    *host, *bp, rbuf[BUFLEN], sbuf[BUFLEN], sendbuffer[100];

    switch(argc){
    case 2:
        host = argv[1];
        port = SERVER_TCP_PORT;
        break;
    case 3:
        host = argv[1];
        port = atoi(argv[2]);
        break;
    default:
        fprintf(stderr, "Usage: %s host [port]\n", argv[0]);
        exit(1);
    }

    /* Create a stream socket   */  
    if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        fprintf(stderr, "Can't creat a socket\n");
        exit(1);
    }

    bzero((char *)&server, sizeof(struct sockaddr_in));
    server.sin_family = AF_INET;
    server.sin_port = htons(port);
    if (hp = gethostbyname(host)) 
      bcopy(hp->h_addr, (char *)&server.sin_addr, hp->h_length);
    else if ( inet_aton(host, (struct in_addr *) &server.sin_addr) ){
      fprintf(stderr, "Can't get server's address\n");
      exit(1);
    }

    /* Connecting to the server */
    if (connect(sd, (struct sockaddr *)&server, sizeof(server)) == -1){
      fprintf(stderr, "Can't connect \n");
      exit(1);
    }

    FILE *fp = fopen("test.txt", "rb");

    if(fp == NULL){
        perror("File doesnt exist");
        return 2;
    }

    while( (b = fread(sendbuffer, 1, sizeof(sendbuffer), fp))>0 ){
        send(sd, sendbuffer, b, 0);
    }

    fclose(fp);

    close(sd);
    return(0);
}

我试图在脚本运行时将文本文件从客户端发送到服务器。为了运行该脚本，我指定了一个端口号。

当我执行服务器脚本时，我得到接受:无效参数。它似乎在循环中，所以我得到了一百多个这样的输出。那时我必须退出终端。

有关执行脚本时如何将文件从客户端发送到服务器的任何要点或提示？

Answer 1

在调用 accept(2) 之前您需要调用listen(2)将套接字标记为服务器套接字，用于接受传入的连接请求。