Linux TCP/IP-simple sending and receiving (1)

Now, in the network society, I don't know how to use TCP/IP for Linux. I feel empty. So you must study this stuff carefully.

Tutorial objective: to implement client sending and server receiving

============= Server ==============================

# Include <stdio. h> # include <stdlib. h> # include <errno. h> # include <string. h> # include <netdb. h> # include <sys/types. h> # include <netinet/in. h> # include <sys/socket. h> # Define Port 3333int main (INT argc, char * argv []) {int sockfd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int sin_size; char Buf [100]; sockfd = socket (af_inet, sock_stream, 0); // create a socket If (sockfd =-1) {fprintf (stderr, "socket Error: % S \ n ", strerror (errno); exit (1);} bzero (& server_addr, sizeof (struct sockaddr_in )); // set the first n Bytes of the byte string s to zero and include '\ 0' server _ ADDR. sin_family = af_inet; bytes = htonl (inaddr_any); // any IP address can be connected. I am an open drop server_addr.sin_port = htons (port); int on = 1; setsockopt (sockfd, sol_socket, so_reuseaddr, & on, sizeof (on); // you can remove this function and try if (BIND (sockfd, (struct sockaddr *) (& server_addr ), sizeof (struct sockaddr_in) =-1 )/ /Bind {fprintf (stderr, "BIND error: % s \ n", strerror (errno); exit (1) ;}if (Listen (sockfd, 20) =-1) // listen for 20 more {fprintf (stderr, "Listen error: % s \ n", strerror (errno); exit (1 );} int new_fd; pid_t child; int r_size; int w_size; while (1) {printf ("Wait !!!!! \ N "); memset (BUF, 0,100); sin_size = sizeof (struct sockaddr_in); If (new_fd = accept (sockfd, (struct sockaddr *) (& client_addr ), & sin_size) =-1) // receives the message to check whether someone is connected to {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 (r_size = read (new_fd, Buf, 100) =-1) // read data {fprintf (stderr, "read error: % s \ n", strerror (errno); exit (1 );} printf ("received information % d: % s \ n", r_size, Buf);} Close (sockfd); exit (0 );}

============= Client =============================

# Include <stdlib. h> # include <stdio. h> # include <errno. h> # include <string. h> # include <netdb. h> # include <sys/types. h> # include <netinet/in. h> # include <sys/socket. h> # define PORT 3333int main (int argc, char * argv []) {int sockfd; char buf [100]; struct sockaddr_in server_addr; struct hostent * host; sockfd = socket (AF_INET, SOCK_STREAM, 0); // create a Socket if (sockfd =-1) {fprintf (stderr, "socket error: % s \ n ", strerror (errno); exit (1);} bzero (& server_addr, sizeof (server_addr )); // set the first n Bytes of the byte string s to zero and include '\ 0' server _ addr. sin_family = AF_INET; server_addr.sin_port = htons (PORT); region = inet_addr ("192.168.1.155"); // ip address is the server ipint con_flag to be connected; con_flag = connect (sockfd, (struct sockaddr *) (& server_addr), sizeof (struct sockaddr); // Connect if (con_flag =-1) {fprintf (stderr, "Connect Error: % s \ a \ n ", strerror (errno); exit (1);} printf (" Please input some words: "); fgets (buf, 100, stdin ); if (write (sockfd, buf, sizeof (buf) <0) // write data to the socket interface {fprintf (stderr, "write Error: % s \ a \ n ", strerror (errno); exit (1) ;}close (sockfd); // disable exit (0 );}

The experiment results are as follows:

Root @ WYZ-vlinux :~ /Test/SC #./tcp_server
Server GET connection from 192.168.1.155
Server received Hello mama

Server GET connection from 192.168.1.155
Server deployed ed I love Linux

Root @ WYZ-vlinux :~ /Test #./tcp_client
Please input some words: Hello mama
Root @ WYZ-vlinux :~ /Test #./tcp_client
Please input some words: I love Linux
Root @ WYZ-vlinux :~ /Test #