[000] socket communication-a simple example of server and client implementation

I learned scanf and printf in C language. In fact, understanding socket is similar to the two input and output, but it is just information transmission.

1. Default function call sequence of the TCP Server:

According to the above call order, we can write the simplest "Hello World" server program.

1 # include <stdio. h> 2 # include <stdlib. h> 3 # include <string. h> 4 # include <unistd. h> 5 # include <ARPA/inet. h> 6 # include <sys/socket. h> 7 8 void error_handling (char * message); 9 10 void error_handling (char * message) {11 fputs (message, stderr); 12 fputc ('\ n ', stderr); 13 exit (1); 14} 15 16 int main (INT argc, char ** argv) 17 {18 int serv_sock; 19 int clnt_sock; 20 21 // set a server address serv_addr and a client address clnt_addr22 Struct sockaddr_in serv_addr; 23 struct sockaddr_in records; 24 socklen_t records = sizeof (bytes); 25 26 memset (& serv_addr, 0, sizeof (serv_addr); 27 memset (& serv_addr, 0, sizeof (serv_addr); 28 char message [] = "Hello World"; 29 30 if (argc! = 2) {31 printf ("Usage: % S <port> \ n", argv [0]); 32 exit (1 ); 33} 34 35 // create a stream protocol for the Internet (TCP) socket36 serv_sock = socket (pf_inet, sock_stream, 0); 37 If (serv_sock =-1) {38 error_handling ("socket () error"); 39} 40 41 serv_addr.sin_family = af_inet; 42 serv_addr.sin_addr.s_addr = htonl (inaddr_any ); 43 serv_addr.sin_port = htons (atoi (argv [1]); 44 45 // associate the socket with the socket address structure 46 If (BIND (serv_sock, (struct sockaddr *) & serv_addr, sizeof (serv_addr) =-1) {47 error_handling ("BIND () error "); 48} 49 50 // server_socket is used to listen to 51 if (Listen (serv_sock, 5) =-1) {52 error_handling ("lisen () error "); 53} 54 55 // accept connection request 56 clnt_sock = accept (serv_sock, (struct sockaddr *) & clnt_addr, & clnt_addr_size); 57 if (clnt_sock =-1) {58 error_handling ("accept () error"); 59} 60 61 write (clnt_sock, message, sizeof (Message); 62 close (clnt_sock); 63 close (serv_sock ); 64 65 return 0; 66}

2. The client corresponds to the server. The call sequence is as follows:

The corresponding "Hello World" client program is:

1 hello_client.c 2 ------ 3 # include <stdio. h> 4 # include <stdlib. h> 5 # include <string. h> 6 # include <unistd. h> 7 # include <ARPA/inet. h> 8 # include <sys/socket. h> 9 10 void error_handling (char * message); 11 12 Void error_handling (char * message) {13 fputs (message, stderr); 14 fputc ('\ n ', stderr); 15 exit (1); 16} 17 18 int main (INT argc, char ** argv) {19 int sock; 20 struct sockaddr_in serv_addr; 21 char mescript E [30]; 22 int str_len; 23 memset (& serv_addr, 0, sizeof (serv_addr); 24 25 if (argc! = 3) 26 {27 printf ("Usage:/% S <ip> <port> \ n", argv [0]); 28 exit (1 ); 29} 30 31 // create a stream protocol for the Internet (TCP) socket32 sock = socket (pf_inet, sock_stream, 0); 33 If (sock =-1) {34 error_handling ("socket () error"); 35} 36 37 // set a socket address structure client_addr, representing the client Internet address, port 38 serv_addr.sin_family = af_inet; 39 serv_addr.sin_addr.s_addr = inet_addr (argv [1]); 40 serv_addr.sin_port = htons (atoi (argv [2]); 41 42 // link the socket and socket address structures 43 If (connect (sock, (struct sockaddr *) & serv_addr, sizeof (serv_addr) =-1) {44 error_handling ("Connect () error"); 45} 46 47 str_len = read (sock, message, sizeof (Message)-1 ); 48 if (str_len =-1) {49 error_handling ("Read () error"); 50} 51 52 printf ("Message from server: % s \ n ", message); 53 close (sock); 54 return 0; 55}

Start running the server:

# GCC hello_server.c-O hserver #./hserver 9010 ...... start to suspend

Start running the client:

#gcc hello_client.c -o hclient #./hclient 127.0.0.1 9010Message from server: Hello world

 

[000] socket communication-a simple example of server and client implementation