Linux C Programming-udp

For more information about Linux C Programming, see

For socket programming, refer:

Socket programming:

Http://www.cnblogs.com/skynet/archive/2010/12/12/1903949.html

Http://www.kuqin.com/networkprog/20080512/8361.html

Network byte sequence and conversion functions

Http://blog.sina.com.cn/s/blog_4ad7c25401019qqb.html

1. Set socket

2. Read socket status

3. UDP client implementation

4. UDP server implementation

1. Set socket

2. Read socket status

#include<sys/types.h>#include<sys/socket.h>#include<stdio.h>int  main(){  int s;  int val=1,len,i ;  len= sizeof(int);  if((s = socket(AF_INET,SOCK_STREAM,0))<0)    //creat  {    perror("connect");    exit(1);  }  else  {    printf("a socket was created.\n");    printf("socket number:%d\n",s);   }   i=setsockopt(s,SOL_SOCKET,SO_TYPE,&val,len);   //set   if("i==0")   {     printf("set socket ok.\n.");    }    else   {     printf("set socket error.\n.");    }    getsockopt(100,SOL_SOCKET,SO_TYPE,&val,&len);  //get   perror("socket");}

3. UDP client implementation

Some compilers report errors when using ADDR (struct sockaddr *) & ADDR

# Include <stdio. h> # include <netinet/in. h> # include <ARPA/inet. h> # include <unistd. h> # include <fcntl. h> # include <sys/STAT. h> # include <sys/types. h> # include <sys/socket. h> # define remoteport 4567 # define remoteip "127.0.0.1" int main (INT argc, char * argv []) {int S, Len; struct sockaddr_in ADDR; int addr_len; char MSG [256]; int I = 0; If (S = socket (af_inet, sock_dgram, 0) <0) // create a socket {perror ("error "); Exit (1);} else {printf ("socket created. \ n "); printf (" socked ID: % d \ n ", S); printf (" remote IP: % s \ n ", remoteip ); printf ("remote port: % d \ n", remoteport);} Len = sizeof (struct sockaddr_in); // length bzero (& ADDR, sizeof (ADDR); ADDR. sin_family = af_inet; // Add the port and address ADDR. sin_port = htons (remoteport); ADDR. sin_addr.s_addr = inet_addr (remoteip); While (1) {bzero (MSG, sizeof (MSG); Len = read (stdin_fileno, MSG, Si Zeof (MSG); sendto (S, MSG, Len, 0, & ADDR, addr_len); // send the message printf ("\ ninput message: % s \ n ", MSG); Len = recvfrom (S, MSG, sizeof (MSG), 0, & ADDR, & addr_len);/* This is the received information. */Printf ("% d:", I); I ++; printf ("received message: % s \ n", MSG);/* this is the information returned by the server. */}}

4. UDP server implementation

Some compilers report errors when using ADDR (struct sockaddr *) & ADDR

# Include <stdio. h> # include <netinet/in. h> # include <ARPA/inet. h> # include <unistd. h> # include <sys/types. h> # include <sys/socket. h> # define localport 4567int main (INT argc, char * argv []) {int mysock, Len; struct sockaddr_in ADDR; int I = 0; char MSG [256]; int addr_len; If (mysock = socket (af_inet, sock_dgram, 0) <0) {perror ("error"); exit (1 );} else {printf ("socket created. \ n "); printf (" socked ID: % d \ n ", mysock);} addr_len = sizeof (struct sockaddr_in); bzero (& ADDR, sizeof (ADDR )); ADDR. sin_family = af_inet; ADDR. sin_port = htons (localport); ADDR. sin_addr.s_addr = htonl (inaddr_any); If (BIND (mysock, & ADDR, sizeof (ADDR) <0) {perror ("Connect"); exit (1 );} else {printf ("bind OK. \ n "); printf (" local port: % d \ n ", localport);} while (1) {bzero (MSG, sizeof (MSG )); len = recvfrom (mysock, MSG, sizeof (MSG), 0, & ADDR, & addr_len);/* received information */printf ("% d:", I ); I ++; printf ("Message from: % s \ n", inet_ntoa (ADDR. sin_addr); printf ("message length: % d \ n", Len); printf ("message: % s \ n", MSG); sendto (mysock, MSG, Len, 0, & ADDR, addr_len);/* The above strings are returned to the client */}}