Question

我有以下两个文件。 server.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <strings.h>
#include <netinet/in.h>
#include "lib/colors.h"

void dostuff(int);
void error(char *msg){
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[]){
    int sockfd, newsockfd, portno, clilen, pid;
    struct sockaddr_in serv_addr, cli_addr;

    if (argc < 2) {
        fprintf(stderr,"ERROR, no port provided\n");
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) 
        error("ERROR opening socket");

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
        error("ERROR on binding");
    }

    listen(sockfd,5);
    clilen = sizeof(cli_addr);

    while(1){
        newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);

        if (newsockfd < 0){
            error("ERROR on accept");
        }
        pid = fork();

        if (pid < 0){
            error("ERROR on fork");
        }

        if (pid == 0)  {
            close(sockfd);
            append_new(newsockfd);
            exit(0);
        }

        else close(newsockfd);
    }
    return 0;
}

void append_new(int sock){
    int n;
    char buffer[256];

    bzero(buffer,256);
    n = read(sock,buffer,255);
    if (n < 0){
        error("ERROR reading from socket");
    }
    printf("Here is the message: %s\n",buffer);
    n = write(sock,"I got your message",18);
    if (n < 0){
        error("ERROR writing to socket");
    }
}

和client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <strings.h>
#include <netinet/in.h>
#include "lib/colors.h"


void error(char *msg){
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[]){
    int sockfd, portno, n;

    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    if (argc < 3) {
        fprintf(stderr,"usage %s hostname port\n", argv[0]);
        exit(0);
    }

    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0){
        error("ERROR opening socket");
    }
    server = gethostbyname(argv[1]);

    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, 
        (char *)&serv_addr.sin_addr.s_addr,
        server->h_length);
    serv_addr.sin_port = htons(portno);

    if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0){
        error("ERROR connecting");
    }

    while(1){
        printf("Please enter the message: ");
        bzero(buffer,256);
        fgets(buffer,255,stdin);
        n = write(sockfd,buffer,strlen(buffer));
        if (n < 0){
            error("ERROR writing to socket");
        }
        bzero(buffer,256);
        n = read(sockfd,buffer,255);
        if (n < 0){ 
            error("ERROR reading from socket");
        }
        printf("%s\n",buffer);
    } 
    return 0;
}

服务器代码工作正常，客户端代码第一次正常工作。我的问题是我需要能够从客户端向服务器发送连续的消息，看起来服务器似乎没有回复客户端发送的第二条消息。我想用服务器作为接口从一个客户端向另一个客户端发送消息，这怎么可能呢？

TCP / IP套接字无限循环

0 个答案: