Linux Network programming UDP Socket Program Example _c language

In the network transport Protocol, the TCP protocol provides a reliable, complex, connection-oriented data stream (SOCK_STREAM) transport service that establishes the connection through a three-segment handshake process. TCP has a "retransmission acknowledgement" mechanism, that is, the receiving end of the data to send a positive confirmation of the signal, the sender if the receiver received a positive confirmation of the signal, it will continue to send other data, if not, it will resend.

In contrast, theUDP protocol is a connectionless, unreliable datagram (SOCK_DGRAM) transport service. Instead of establishing a connection using a UDP socket interface, the server can communicate (recvfrom function and SendTo function) after invoking the socket () to generate a socket and invoke bind () binding port (the client is using a socket ()) After you generate a socket, you can send and receive data to the server address.

Special note here:TCP uses a stream socket (SOCK_STREAM) and UDP uses a datagram socket (SOCK_DGRAM)

Examples of UDP socket programming:

The server-side code is as follows:

/************************************************************************* > File name:server.c > Author:song Lee ************************************************************************/#include <sys/types.h> include<sys/socket.h> #include <unistd.h> #include <netinet/in.h> #include <arpa/inet.h> # include<stdio.h> #include <stdlib.h> #include <errno.h> #include <netdb.h> #include < stdarg.h> #include <string.h> #define SERVER_PORT 8000 #define BUFFER_SIZE 1024 #define FILE_NAME_MAX_SIZE 5 
 the int main () {*/* creates the UDP socket interface * * * struct sockaddr_in server_addr; 
 Bzero (&server_addr, sizeof (SERVER_ADDR)); 
 server_addr.sin_family = af_inet; 
 SERVER_ADDR.SIN_ADDR.S_ADDR = htonl (Inaddr_any); 
 
 Server_addr.sin_port = htons (Server_port); 
 /* Create socket */int SERVER_SOCKET_FD = socket (af_inet, SOCK_DGRAM, 0); 
  if (server_socket_fd = = 1) {perror ("Create socket Failed:"); 
 Exit (1); } 
 
 /* Binding Sleeve Interface/if ( -1 = (Bind (server_socket_fd, (struct sockaddr*) &server_addr,sizeof (SERVER_ADDR))) {perror ("Serve 
  R Bind Failed: "); 
 Exit (1); 
  /* Data transfer/while (1) {/* Defines an address for capturing the client address/struct sockaddr_in client_addr; 
 
  socklen_t client_addr_length = sizeof (CLIENT_ADDR); 
  /* Receive data */char buffer[buffer_size]; 
  Bzero (buffer, buffer_size); if (Recvfrom (server_socket_fd, buffer, buffer_size,0, (struct sockaddr*) &client_addr, &client_addr_length) = = 
   -1) {perror ("Receive Data Failed:"); 
  Exit (1); 
  /* * Copy out file_name/char file_name[file_name_max_size+1 from buffer; 
  Bzero (file_name,file_name_max_size+1); strncpy (file_name, buffer, strlen (buffer) >file_name_max_size? 
  File_name_max_size:strlen (buffer)); 
 printf ("%s\n", file_name); 
 Close (SERVER_SOCKET_FD); 
return 0; 

 }

The

client-side code is as follows:

/************************************************************************* > File name:client.c > Author:song Lee ************************************************************************/#include <sys/types.h> include<sys/socket.h> #include <unistd.h> #include <netinet/in.h> #include <arpa/inet.h> # include<stdio.h> #include <stdlib.h> #include <errno.h> #include <netdb.h> #include < stdarg.h> #include <string.h> #define SERVER_PORT 8000 #define BUFFER_SIZE 1024 #define FILE_NAME_MAX_SIZE 5 
 int main () {/* Service End Address * * struct sockaddr_in server_addr; 
 Bzero (&server_addr, sizeof (SERVER_ADDR)); 
 server_addr.sin_family = af_inet; 
 SERVER_ADDR.SIN_ADDR.S_ADDR = inet_addr ("127.0.0.1"); 
 
 Server_addr.sin_port = htons (Server_port); 
 /* Create socket */int CLIENT_SOCKET_FD = socket (af_inet, SOCK_DGRAM, 0); 
  if (CLIENT_SOCKET_FD < 0) {perror ("Create socket Failed:"); 
 Exit (1); 
 
} /* input filename to buffer/char file_name[file_name_max_size+1]; 
 Bzero (file_name, file_name_max_size+1); 
 printf ("Please Input File Name on server:\t"); 
 
 scanf ("%s", file_name); 
 Char Buffer[buffer_size]; 
 Bzero (buffer, buffer_size); strncpy (buffer, file_name, strlen (file_name) >buffer_size? 
 
 Buffer_size:strlen (file_name)); /* Send file name */if (sendto (client_socket_fd, buffer, buffer_size,0, (struct sockaddr*) &server_addr,sizeof (SERVER_ADDR) 
  < 0) {perror ("Send File Name Failed:"); 
 Exit (1); 
 Close (CLIENT_SOCKET_FD); 
return 0; 

 }

Readers can refer to the previous: Linux network programming Socket File Transfer example, pay attention to the UDP and TCP workflow comparison. To deepen understanding of the principle of the program.