UDP Communication Programming---6

First, the function of

1.1 Functions used by the server

Create socket----->socket

Bind address-------->bind

Accept Data-------->recvfrom

Send Data-------->sendto

End Connection-------->close

1.2 Client Use functions

Create socket------>socket

Send Data-------->sento

Accept Data-------->recvfrom

End Connection-------->close

Second, function learning

2.1 Sending Data SendTo

2.1.1 Contains header files

#include <sys/types.h>
#include <sys/socket.h>

2.1.2 Function prototypes

ssize_t sendto (int sockfd, const void *buf, size_t len, int flags,
const struct SOCKADDR *dest_addr, socklen_t Addrlen);

2.1.3 Function parameters

SOCKFD: Socket created

*BUF: The data address to send

Len: Data length

Flags: Identifiers

DEST_ADDR: Destination Machine Address

Addrlen: Address length

2.1.4 return value

The amount of data actually sent

2.2 Receiving Data Recvfrom

2.2.1 Contains header files

#include <sys/types.h>
#include <sys/socket.h>

2.2.2 Function prototypes

ssize_t recvfrom (int sockfd, void *buf, size_t len, int flags,
struct sockaddr *src_addr, socklen_t *addrlen);

2.2.3 Function parameters

SOCKFD: Socket created

*BUF: Address of data storage

Len: Data length

Flags: Identifiers

DEST_ADDR: The address of the data source party

Addrlen: pointer to address length

2.2.4 return value

The length of the message in bytes, or 0 if no message is available or the other party has been ordered, or 1 if an error occurs.

Third, write the server code

Touch udp_server.c

chmod 777 UDP_SERVER.C

1 #include <stdio.h>2 #include <String.h>3 #include <sys/socket.h>4 #include <netinet/In.h>567#define PORTNUM 88888#define MSG_SIZE 1289IntMain ()10{11IntSOCKFD;12CharBuffer[msg_size];13structSockaddr_in server_addr;14structSockaddr_in client_addr;15IntAddrlen;16IntN17//1. Creating socketsSOCKFD = socket (Af_inet,sock_dgram,0);1920//2. Binding AddressBzero (&AMP;SERVER_ADDR,sizeofstructsockaddr_in));server_addr.sin_family =Af_inet;Server_addr.sin_port =Htons (Portnum);SERVER_ADDR.SIN_ADDR.S_ADDR =Htonl (Inaddr_any);Bind (SOCKFD, (struct sockaddr *) (&AMP;SERVER_ADDR),sizeofstructSOCKADDR));2627//3. Acceptance of data28While1)29{Addrlen =sizeofstruct sockaddr);//Get Data length AddressBzero (Buffer,sizeof(buffer));n = recvfrom (sockfd,buffer,msg_size,0, (struct sockaddr *) (&CLIENT_ADDR), &addrlen); 0;34 printf ( "server Received:%s\n ",buffer); 35 }36 //4. End connection 37  close ( SOCKFD); 38 return 0; 39}             

Compile run:

Iv. Writing client code

Touch Udp_client,c

chmod 777 Udp_client.c

#include <stdio.h>#include <String.h>#include <sys/socket.h>#include <netinet/In.h>#define BUFFER_SIZE 128#define PORTNUM 8888int main (int argc,char * *Argv[]) {IntSOCKFD;CharBuffer[buffer_size];structSockaddr_in server_addr;if (argc! =2) {printf ("Usage:%s server_ip\n", argv[0]); Exit1); }//1. Create Socket SOCKFD = socket (Af_inet,sock_dgram,0);//Initialize server address bzero (&AMP;SERVER_ADDR,sizeofstructsockaddr_in)); server_addr.sin_family =Af_inet; Server_addr.sin_port =Htons (Portnum); Inet_aton (argv[1],&SERVER_ADDR.SIN_ADDR);//while (1) {printf (please Input char: \n "); Fgets (Buffer,buffer_size,stdin); SendTo (Sockfd,buffer,strlen (buffer), 0, (struct SOCKADDR *) (&SERVER_ADDR), sizeof (struct sockaddr)); Bzero (buffer,buffer_size); } //3. Close connection  close ( SOCKFD); return 0   

Compile run:

4.1 You can see the server running results

UDP Communication Programming---6