Linux传统fork多进程并发网络编程代码示例

Linux传统Fork多进程并发网络编程代码 ,只是简单实现了一个多进程并发的模型，如果需要真实应用，则需要修改process_client方法即可。这种方式并发编程负载能力不怎么样，但是有一个好处就是， 当子进程处理异常时，哪怕是指针异常导致的段错误，崩溃不会影响主进程。

服务端代码：

//Linux传统Fork多进程并发网络编程代码
 /* sokcet_fork.c*/

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#define PORT 9999
#define MAXSOCKFD 10
int process_client( int connfd );
void handle_sigcld(int signo);
int main( int argc, char *argv[] )
{
    int sockfd, connfd;
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    fd_set readfds;
    char buffer[256];
    char msg[] = "Welcome to server!";
    if ( (sockfd=socket(AF_INET,SOCK_STREAM,0))<0 )
    {
        perror("socket");
        return 1;
    }
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);
    servaddr.sin_addr.s_addr = htonl( INADDR_ANY );
    int reuse = 1;
    if(setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
                &reuse, sizeof(int)) < 0){
        perror("setsockopt error");
        return 1;
    }
    if ( bind(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr) ) != 0 )
    {
        perror("connetc");
        return 1;
    }
    if ( listen(sockfd,5) != 0 )
    {
        perror("listen");
        return 1;
    }
    //允许中断退出
#if 0
    signal(SIGCLD, SIG_IGN); /* now I don't have to wait()! */
#else
    signal(SIGCLD, handle_sigcld); /* 处理中断信息*/
#endif
    while (1)
    {
        cliaddr_len = sizeof( struct sockaddr);
        connfd = accept(sockfd, (struct sockaddr*)&cliaddr,&cliaddr_len );
        if (connfd < 0 ){
            perror("accept");
            continue;
        }
        printf("connetc from %s,sockeid:%d\r\n", inet_ntoa(cliaddr.sin_addr), connfd );
        //if ( connfd == 0)continue;
        int fid = fork();
        if ( fid < 0 )
            break;
        else if ( fid == 0 ){
            printf("child process \r\n");
            //处理客户端请求数据
            process_client(connfd);
            //退出子进程
            return 0;
            //exit(0);
        }
        else {
            // 父进程继续处理连接请求
            continue;
        }
    }
    return 0;
}
int process_client( int connfd )
{
    char buffer[1024];
    bzero(buffer,sizeof(buffer));
    if ( read(connfd,buffer,4)<=0 ){
       return -1;
    }
    int len = atoi(buffer);
    printf("packet length:%04d\n", len );
    bzero(buffer,sizeof(buffer));
    if ( read(connfd,buffer,len)<=0 )
    {
        printf("connetc closed.\r\n");
    }
    else
    {
        printf("recv from client:[%s]\r\n",buffer);
    }
    /*将小写转换成大写*/
    int i = 0;
    while ( i<len ){
        char c = *(buffer+i);
        if ( c>='a' && c<='z' )
            *(buffer+i) -= ('a'-'A');
        i++;
    }
    //模拟5秒等待时间
    sleep(5);
    write(connfd, buffer, strlen(buffer) );
    printf("return client:[%s]\r\n",buffer);
    return 0;
}
void handle_sigcld(int signo)
{
    int pid,status;
    pid = waitpid( -1, &status, 0);//-1表示等待任何子进程
    //printf("child process %d exit with %d\n",pid,status);
}

客户端代码 a.c ：

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

#define PORT 9999
#define SERVER_IP "127.0.0.1"
//#define SERVER_IP "192.168.1.3"

int main()
{
        int s;

        struct sockaddr_in addr;

        char buffer[256];
        if ( (s=socket(AF_INET,SOCK_STREAM,0)) < 0 )
        {
                perror("socket");
                exit(1);
        }


        char server_info[1024] = {0x00};
        sprintf( server_info, "port=%d,ip=%s", PORT, SERVER_IP);
        printf( "%s\n", server_info );

        bzero( &addr, sizeof(addr) );
        addr.sin_family = AF_INET;
        addr.sin_port = htons(PORT);
        addr.sin_addr.s_addr = inet_addr(SERVER_IP);

        int nret = connect(s, (const struct sockaddr *)&addr,sizeof(addr));
        if ( nret < 0)
        {
                //printf("test string here\n");
                perror("connect &*******");
                exit(1);
        }
    printf("nret:%d\n", nret);

    memset(buffer, 0x00, sizeof(buffer) );
    char *psend = "test string";
    snprintf(buffer, sizeof(buffer), "%04d%s", strlen(psend), psend );
    if ( send(s,buffer,strlen(buffer),0) < 0 )
    {
        perror("send");
        return 1;
    }

    memset(buffer,0x00, sizeof(buffer) );
        recv( s, buffer,sizeof(buffer),0);
        printf("recv:%s\r\n",buffer);


        return 0;
}