unix网络编程笔记---5.TCP的C/S实例1功能实现

1. 说明
    第5章的第一个程序
   client从终端读入一行,写到socket中
   server从socket中读入一行，并将读到的data写到socket中
   client从socket中读取一行，并显示到终端
2. 源码
2.1 server.c

cong@msi:/work/test/tcpip/5tcp$ cat serv1/tcpserv.c
#include "utils.h"

#define LISTENQ 10
void str_echo(int sockfd)
{
    ssize_t n;
    char buf[MAXLINE];
again:
    while( (n=read(sockfd, buf, MAXLINE)) > 0)
        write(sockfd, buf, n);

    if( (n<0) && (errno==EINTR) )
        goto again;
    else if(n < 0)
        dbmsg("read_error");
}

int main ( int argc, char *argv[] )
{
    int listenfd, connfd;
    struct sockaddr_in servaddr, cliaddr;
    pid_t childpid;
    char buf[1024];
    int len;
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if(listenfd< 0)
        return -1;
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13999);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    //inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);

    bind(listenfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    listen(listenfd, LISTENQ);
    while(1)
    {
        len = sizeof(cliaddr);
        //connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
        connfd = accept(listenfd, (struct sockaddr*)&cliaddr,(socklen_t*)&len);  -->打印连接的客户端
        dbmsg("accept:%s,port=%d", inet_ntop(AF_INET,&cliaddr.sin_addr,buf, sizeof(buf)), ntohs(cliaddr.sin_port));
        if( (childpid=fork()) == 0)
        {
            close(listenfd);
            str_echo(connfd);
            exit(0);
        }
        dbmsg("close connfd");
        close(connfd);
    }

    return EXIT_SUCCESS;
}

2.2 client.c

#include "utils.h"

//#define TIME_SERV_ADDR "192.168.4.98"
#define TIME_SERV_ADDR "127.0.0.1"

ssize_t readline(int fd, void* vptr, size_t maxlen)
{
    ssize_t n, rc;
    char c,*ptr;
    ptr = vptr;
    for(n=0; n<maxlen; n++)
    {
again:
        if((rc=read(fd,&c,1)) == 1)
        {
            *ptr++ = c;
            if(c == '\n')
                break;
        } else if(rc == 0) {
            *ptr = 0;
            return n;
        }else {
            if( errno == EINTR)
                goto again;
            return -1;
        }
    }
    *ptr = '\0';   //末尾补0
    return n;
}

void str_cli(FILE* fp, int sockfd)
{
    char sendline[MAXLINE], recvline[MAXLINE];
    while(fgets(sendline, MAXLINE, fp) != NULL)
    {
        write(sockfd, sendline, strlen(sendline));
        if(readline(sockfd, recvline, MAXLINE) == 0)
            dbmsg("server terminated");
        fputs(recvline, stdout);
    }
}

int main ( int argc, char *argv[] )
{
    int sockfd, n;
    struct sockaddr_in servaddr;
    char recvline[1024];
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0)
        return -1;
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13999);
    inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);
    dbmsg("next connect");
    connect(sockfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    dbmsg("connect success");

    str_cli(stdin, sockfd);
    return EXIT_SUCCESS;
}

2.3 utils.h
client与server共用一个

cong@msi:/work/test/tcpip/3tcp$ cat utils.h
#ifndef UTILS_H__
#define UTILS_H__
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <errno.h>

#define MAXLINE 1024

#define dbmsg(fmt, args ...) printf("%s:%s[%d]: "fmt"\n", __FILE__,__FUNCTION__, __LINE__,##args)

#endif

3. 状态说明
3.1 当client与server都启动时,client执行connect连接上了server，
     server的accept从阻塞中返回,三次握手结束，此时状态如下

cong@msi:/work/test/tcpip/5tcp/client1$ netstat -a | grep "13999"
tcp        0      0     *:13999                *:*                                    LISTEN      -->serv端

tcp        0      0     localhost:41283                localhost:13999    ESTABLISHED  -->serv端的fork子进制

  tcp 0 0     localhost:13999        localhost:41283    ESTABLISHED   --> client端

3.2当client退出时,执行ps命令查看

cong@msi:/work/test/tcpip/5tcp/client1$ ps -u
USER         PID         STAT  START   TIME  COMMAND
cong   12079     S+      15:31   0:00  ./tcpserv
cong   12081     Z+      15:31   0:00  [tcpserv] <defunct>

发现server的child进制处于Z,僵死状态。下一篇解决
3.2.1
ps命令

ps参数:
-A: 等同于-f列出所有的进制
-a: 显示其他用户启动的进程
-x: 查看系统中属于自己的进程
-u: 按用户名和启动时间的顺序显示进程
-j: 用任务格式来显示进程
-f: 用树形格式来显示进制

状态码:
　　D --> 不可中断 --> uninterruptible sleep (usually IO)
　　R --> 运行 --> running or runnable (on run queue)
　　S --> 中断 --> interruptible sleep (waiting for an event to complete)
　　T --> 停止 --> stopped, either by a job control signal or because it is being traced
　　Z --> 僵死 --> defunct ("zombie") process, terminated but not reaped by its parent

(下载后改名为client.tar.gz)
client.rar

(下载后改名为serv.tar.gz)
serv.rar