#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>

#define IP "192.168.102.175"
#define PORT 7000

void print_err(char *str, int line, int err_no) {
  printf("%d, %s :%s\n",line,str,strerror(err_no));
  _exit(-1);
}

/*子线程中先接收从客户端发来的消息，再发送一个消息给客户端*/
void *receive(void *pth_arg) {
  int ret = 0;
  long cfd = (long)pth_arg;
  char buf[100] = {0};
  while(1) {
    bzero(&buf, sizeof(buf));
    ret = recv(cfd, &buf, sizeof(buf),0); 
    if (-1 == ret) {
      print_err("recv failed",__LINE__,errno);
    }
    else if (ret > 0)
      printf("recv from client %s \n",buf);
    ret = send(cfd,"recv ok\n", sizeof("recv ok\n"), 0);
    if (-1 == ret) print_err("send failed", __LINE__, errno);
  }
}

int main()
{
  int skfd = -1, ret = -1;
  skfd = socket(AF_INET, SOCK_STREAM, 0);
  if ( -1 == skfd) {
    print_err("socket failed",__LINE__,errno);
  }

  struct sockaddr_in addr;
  addr.sin_family = AF_INET; //设置tcp协议族
  addr.sin_port = htons(PORT); //设置端口号
  addr.sin_addr.s_addr = inet_addr(IP); //设置ip地址

  ret = bind(skfd, (struct sockaddr*)&addr, sizeof(addr));
  if ( -1 == ret) {
    print_err("bind failed",__LINE__,errno);
  }
 
  ret = listen(skfd, 3);
  if ( -1 == ret ) {
    print_err("listen failed", __LINE__, errno);
  }
  
  //使用accept阻塞形式得监听客户端的发来的连接，并返回通信描述符
  long cfd = -1;
  pthread_t id;
  while (1) {
    struct sockaddr_in caddr = {0};
    int csize = sizeof(caddr);
    cfd = accept(skfd, (struct sockaddr*)&caddr, &csize);
    if (-1 == cfd) {
      print_err("accept failed", __LINE__, errno);
    }
    //建立连接后打印一下客户端的ip和端口号
    printf("cport = %d, caddr = %s\n", ntohs(caddr.sin_port),inet_ntoa(caddr.sin_addr));
  
    //使用accept返回到描述符，创建子线程进行数据传输
    int ret = pthread_create(&id,NULL,receive,(void*)cfd);
    if(-1 == ret) print_err("accept failed", __LINE__, errno); 
  }
  return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>

#define IP "192.168.102.175"
#define PORT 7000

void print_err(char *str, int line, int err_no) {
  printf("%d, %s :%s\n",line,str,strerror(err_no));
  _exit(-1);
}

int main()
{
  int skfd = -1, ret = -1;
  skfd = socket(AF_INET, SOCK_STREAM, 0);
  if ( -1 == skfd) {
    print_err("socket failed",__LINE__,errno);
  }

  struct sockaddr_in addr;
  addr.sin_family = AF_INET; //设置tcp协议族
  addr.sin_port = htons(PORT); //设置端口号
  addr.sin_addr.s_addr = inet_addr(IP); //设置ip地址
  
  //主动发送连接请求
  ret = connect(skfd,(struct sockaddr*)&addr, sizeof(addr));
  if(-1 == ret) print_err("connect failed", __LINE__, errno);

  char buf[100] = {0};
  char rec[100] = {0};
  //客户端发送消息，并接受从服务端返回的消息
  while (1) {
    bzero(&buf, sizeof(buf));
    scanf("%s",buf);

    ret = send(skfd,&buf,sizeof(buf), 0);
    if (-1 == ret) {
      print_err("send failed", __LINE__, errno);
    }
    bzero(&rec, sizeof(recv));
    ret = recv(skfd, &rec, sizeof(rec), 0);
    if(-1 == ret) print_err("recv failed", __LINE__, errno);
    else if(ret > 0) printf("recv from server %s\n",rec);
  }
  
  return 0;
}

zhang@ubuntu:~/Desktop/cpp_practice$ ps -Tp 24567
   PID   SPID TTY          TIME CMD
 24567  24567 pts/2    00:00:00 server
 24567  24569 pts/2    00:00:00 server
 24567  24604 pts/2    00:00:00 server