#include<stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define PORTNUMBER 3333

int main(int argc,char*argv[])
{
    int sockfd,new_fd;
    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;
    int sin_size;
    int nbytes;
    char buffer[1024];

    //socket

    if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
    {
        fprintf(stderr,"Socket error:%s\n",strerror(errno));
        exit(1);
    }
    //address

    bzero(&server_addr,sizeof(structsockaddr_in));
    server_addr.sin_family=AF_INET;
    server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    server_addr.sin_port=htons(PORTNUMBER);

    //bind

    if(bind(sockfd,(structsockaddr *)(&server_addr),sizeof(structsockaddr_in))==-1)
    {
        fprintf(stderr,"Bind error:%s\n",strerror(errno));
        exit(1);
    }

    //listen

    if(listen(sockfd,5)==-1)
    {
        fprintf(stderr,"Listen error:%s\n",strerror(errno));
        exit(1);
    }

    while(1)
    {
        sin_size=sizeof(structsockaddr_in);
 if((new_fd=accept(sockfd,(structsockaddr *)(&client_addr),&sin_size))==-1)
        {
            fprintf(stderr,"Accept error:%s\n",strerror(errno));
            exit(1);
        }
        fprintf(stderr,"Server get connection from %s\n",inet_ntoa(client_addr.sin_addr));

        if((nbytes=read(new_fd,buffer,1024))==-1)
        {
            fprintf(stderr,"Read Error:%s\n",strerror(errno));
            exit(1);
        }
        buffer[nbytes]='\0';
        printf("Server received %s\n",buffer);
        close(new_fd);
    }
}


#include<stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#define PORTNUMBER 3333

int main(int argc,char*argv[])
{
    int sockfd;
    char buffer[1024];
    struct sockaddr_in server_addr;
    struct hostent*host;

    //使用hostent查询host name

    if(argc!=2)
    {
        fprintf(stderr,"Uage:%s hostname\a\n",argv[0]);
        exit(1);
    }

    if((host=gethostbyname(argv[1]))==NULL)
    fprintf(stderr,"Gethostname error\n");
        exit(1);
    }

    //socket

    if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
    {
        fprintf(stderr,"Socket Error:%s\a\n",strerror(errno));
        exit(1);
    }

    //ip port

    bzero(&server_addr,sizeof(server_addr));
    server_addr.sin_family=AF_INET;
    server_addr.sin_port=htons(PORTNUMBER);
    server_addr.sin_addr=*((structin_addr *)host->h_addr);

    //connect

    if(connect(sockfd,(structsockaddr *)(&server_addr),sizeof(structsockaddr_in))==-1)
    {
        fprintf(stderr,"Connect error:%s\a\n",strerror(errno));
        exit(1);
    }

    printf("Please input char:\n");
    fgets(buffer,1024,stdin);
    write(sockfd,buffer,strlen(buffer));

    close(sockfd);
    exit(0);
}



  1 #include <stdlib.h>
  2 #include<stdio.h>
  3 #include<errno.h>
  4 #include<string.h>
  5 #include<unistd.h>
  6 #include<netdb.h>
  7 #include<sys/socket.h>
  8 #include<netinet/in.h>
  9 #include<arpa/inet.h>
 10 #include<sys/types.h>
 11
 12 #define SERVER_PORT 8888
 13 #define MAX_MSG_SIZE 1024
 14
 15 void udps_respon(int sockfd)
 16 {
 17    struct sockaddr_in addr;
 18    int addrlen,n;
 19    char msg[MAX_MSG_SIZE];
 20
 21    while(1)
 22    {
 23      bzero(msg,sizeof(msg));
 24      addrlen=sizeof(structsockaddr);
 25      n=recvfrom(sockfd,msg,MAX_MSG_SIZE,0,(structsockaddr *)&addr,&addrlen);
 26      msg[n]='\0';
 27      fprintf(stdout,"Server have received %s",msg);
 28    }
 29 }
 30
 31
 32 int main(void)
 33 {
 34    int sockfd;
 35    struct sockaddr_in addr;
 36
 37 //socket

 38    sockfd=socket(AF_INET,SOCK_DGRAM,0);
 39    if(sockfd<0)
 40    {
 41       fprintf(stderr,"Socket Error:%s\n",strerror(errno));
 42       exit(1);
 43    }
 44
 45 //ip port
 46    bzero(&addr,sizeof(structsockaddr_in));
 47    addr.sin_family=AF_INET;
 48    addr.sin_addr.s_addr=htonl(INADDR_ANY);
 49    addr.sin_port=htons(SERVER_PORT);
 50
 51 //bind

 52    if(bind(sockfd,(structsockaddr *)&addr,sizeof(structsockaddr_in))<0)
 53    {
 54       fprintf(stderr,"Bind Error:%s\n",strerror(errno));
 55       exit(1);
 56    }
 57    udps_respon(sockfd);
 58    close(sockfd);
 59 }


  1 #include <stdlib.h>
  2 #include<stdio.h>
  3 #include<errno.h>
  4 #include<string.h>
  5 #include<netdb.h>
  6 #include<sys/types.h>
  7 #include<arpa/inet.h>
  8 #include<sys/socket.h>
  9
 10 #define SERVER_PORT 8888
 11 #define MAX_BUF_SIZE 1024
 12
 13 void udpc_requ(int sockfd,conststruct sockaddr_in*addr,int len)
 14 {
 15    char buffer[MAX_BUF_SIZE];
 16    int n;
 17    while(1)
 18    {
 19       printf("please input char:\n");
 20       fgets(buffer,MAX_BUF_SIZE+1,stdin);
 21       sendto(sockfd,buffer,strlen(buffer),0,(structsockaddr *)addr,len);
 22       bzero(buffer,MAX_BUF_SIZE);
 23    }
 24 }
 25
 26
 27 int main(int argc,char**argv)
 28 {
 29    int sockfd;
 30    struct sockaddr_in addr;
 31    struct hostent*host;
 32
 33    if(argc!=2)
 34    {
 35       fprintf(stderr,"Usage:%s server_ip\n",argv[0]);
 36       exit(1);
 37    }
 38
 39    if((host=gethostbyname(argv[1]))==NULL)
 40    {
 41       fprintf(stderr,"Gethostname error\n");
 42       exit(1);
 43    }
 44
 45 //socket

 46    sockfd=socket(AF_INET,SOCK_DGRAM,0);
 47    if(sockfd<0)
 48    { 
 49       fprintf(stderr,"Socket Error:%s\n",strerror(errno));
 50       exit(1);
 51    }
 52
 53 //ip port

 54    bzero(&addr,sizeof(structsockaddr_in));
 55    addr.sin_family=AF_INET;
 56    addr.sin_port=htons(SERVER_PORT);
 57    /* if(inet_aton(argv[1],&addr.sin_addr)<0)
 58    {
 59    fprintf(stderr,"IP error:%s\n",strerror(errno));
 60    exit(1);
 61    } */
 62    addr.sin_addr=*((structin_addr *)host->h_addr);
 63 
 64
 65    udpc_requ(sockfd,&addr,sizeof(structsockaddr_in));
 66    close(sockfd);
 67 }