다중 프로세스 TCP 서버의 간단한 구현

서버 쪽: 서버.c:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define _BACKLOG_ 10

int CreateSock(char *ip, int port)
{
    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if(sock < 0)
    {
        printf("socket error
");
        exit(1);
    }

    struct sockaddr_in server_addr;
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    inet_pton(AF_INET, ip, &server_addr.sin_addr);

    if(bind(sock, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
    {
        printf("bind error
");
        close(sock);
        exit(2);
    }

    if(listen(sock, _BACKLOG_) < 0)
    {
        printf("listen error
");
        close(sock);
        exit(3);
    }

    return sock;
}

void Service(int client_sock)
{
    for(;;)
    {
        char buf[1024];
        buf[0] = 0;
        int s = read(client_sock, buf, sizeof(buf));
        if(s > 0)
        {
            buf[s-1] = 0;
            if(strncasecmp(buf, "quit", 4) == 0)
            {
                printf("client quit!
");
                exit(0);
            }
            printf("client:%s
", buf);
            write(client_sock, buf, strlen(buf));

        }
    }

}

int main(int argc, char *argv[])
{
    if(argc < 3)
    {
        printf("%s [addr]:[port]
", argv[0]);
        exit(1);
    }

    int sock = CreateSock(argv[1], atoi(argv[2]));
    struct sockaddr_in client_addr;
    bzero(&client_addr, sizeof(client_addr));
    while(1)
    {
        printf("wait connect!
");
        socklen_t len = 0;
        int client_sock = accept(sock, (struct sockaddr*)&client_addr, &len);
        if(client_sock < 0)
        {
            printf("accept arror
");
            continue;
        }

        char buf_ip[INET_ADDRSTRLEN];
        buf_ip[0] = 0;
        inet_ntop(AF_INET, &client_addr, buf_ip, sizeof(buf_ip));   
        printf("get connect, ip is:%s, port is: %d
", buf_ip, ntohs(client_addr.sin_port));

        pid_t pid = fork();
        if(pid < 0)
        {
            printf("fork error");
            continue;
        }
        else if(pid == 0)
        {
            pid_t pid = fork();
            if(pid < 0)
            {
                printf("fork error");
                continue;
            }
            else if(pid > 0)
                exit(4);
        }
        else
        {
            wait(NULL);
            continue;
        }

        Service(client_sock);
    }
    close(sock);
    return 0;
}

클라이언트:client.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, char *argv[])
{
    if(argc < 3)
    {
        printf("%s [addr]:[port]
", argv[0]);
        return 1;
    }
    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if(sock < 0)
    {
        printf("socket error
");
        return 2;
    }

    struct sockaddr_in server_addr;
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(atoi(argv[2]));
    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);

    if(connect(sock, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
    {
        printf("connect error
");
        close(sock);
        return 3;
    }

    printf("connect success!
");
    while(1)
    {
        char buf[1024];
        memset(buf, 0x00, sizeof(buf));
        printf("please input:>");
        fflush(stdout);
        read(0, buf, sizeof(buf));
        write(sock, buf, strlen(buf));
        if(strncasecmp(buf, "quit", 4) == 0)
        {
            printf("client quit!
");
            break;
        }
        int s = read(sock, buf, sizeof(buf));
        if(s > 0)
        {
            buf[s] = 0;
            printf("server:%s
", buf);
        }   
    }


    close(sock);
    return 0;
}

동일한 LAN에서 여러 고객이 동일한 서버에 동시에 액세스할 수 있음