底下分別列出UDP Server及Client的範例程式.
UDP Server(udp-server.c) 利用 socket 介面設計網路應用程式程式啟動後等待 client 端連線，連線後印出對方之 IP 位址並顯示對方所傳遞之訊息，並回送給 Client 端。
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/errno.h>
#include <string.h>
#include <arpa/inet.h>
#define SERV_PORT 5134
#define MAXNAME 1024
extern int errno;
main(){
int socket_fd; /* file description into transport */
int recfd; /* file descriptor to accept */
int length; /* length of address structure */
int nbytes; /* the number of read **/
char buf[BUFSIZ];
struct sockaddr_in myaddr; /* address of this service */
struct sockaddr_in client_addr; /* address of client */
/*
* Get a socket into UDP/IP
*/
if ((socket_fd = socket(AF_INET, SOCK_DGRAM, 0)) <0) {
perror ("socket failed");
exit(EXIT_FAILURE);
}
/*
* Set up our address
*/
bzero ((char *)&myaddr, sizeof(myaddr));
myaddr.sin_family = AF_INET;
myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
myaddr.sin_port = htons(SERV_PORT);
/*
* Bind to the address to which the service will be offered
*/
if (bind(socket_fd, (struct sockaddr *)&myaddr, sizeof(myaddr)) <0) {
perror ("bind failed\n");
exit(1);
}
/*
* Loop continuously, waiting for datagrams
* and response a message
*/
length = sizeof(client_addr);
printf("Server is ready to receive !!\n");
printf("Can strike Cntrl-c to stop Server >>\n");
while (1) {
if ((nbytes = recvfrom(socket_fd, &buf, MAXNAME, 0, (struct sockaddr*)&client_addr, (socklen_t *)&length)) <0) {
perror ("could not read datagram!!");
continue;
}
printf("Received data form %s : %d\n", inet_ntoa(client_addr.sin_addr), htons(client_addr.sin_port));
printf("%s\n", buf);
/* return to client */
if (sendto(socket_fd, &buf, nbytes, 0, (struct sockaddr*)&client_addr, length) < 0) {
perror("Could not send datagram!!\n");
continue;
}
printf("Can Strike Crtl-c to stop Server >>\n");
}
}
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <string.h>
#define SERV_PORT 5134
#define MAXDATA 1024
#define MAXNAME 1024
int main(int argc, char **argv){
int fd; /* fd into transport provider */
int i; /* loops through user name */
int length; /* length of message */
int size; /* the length of servaddr */
int fdesc; /* file description */
int ndata; /* the number of file data */
char data[MAXDATA]; /* read data form file */
char data1[MAXDATA]; /*server response a string */
char buf[BUFSIZ]; /* holds message from server */
struct hostent *hp; /* holds IP address of server */
struct sockaddr_in myaddr; /* address that client uses */
struct sockaddr_in servaddr; /* the server's full addr */
/*
* Check for proper usage.
*/
if (argc < 3) {
fprintf (stderr, "Usage: %s host_name(IP address) file_name\n", argv[0]);
exit(2);
}
/*
* Get a socket into UDP
*/
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror ("socket failed!");
exit(1);
}
/*
* Bind to an arbitrary return address.
*/
bzero((char *)&myaddr, sizeof(myaddr));
myaddr.sin_family = AF_INET;
myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
myaddr.sin_port = htons(0);
if (bind(fd, (struct sockaddr *)&myaddr,
sizeof(myaddr)) <0) {
perror("bind failed!");
exit(1);
}
/*
* Fill in the server's UDP/IP address
*/
bzero((char *)&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERV_PORT);
hp = gethostbyname(argv[1]);
if (hp == 0) {
fprintf(stderr, "could not obtain address of %s\n", argv[2]);
return (-1);
}
bcopy(hp->h_addr_list[0], (caddr_t)&servaddr.sin_addr,
hp->h_length);
/**開起檔案讀取文字 **/
fdesc = open(argv[2], O_RDONLY);
if (fdesc == -1) {
perror("open file error!");
exit (1);
}
ndata = read (fdesc, data, MAXDATA);
if (ndata < 0) {
perror("read file error !");
exit (1);
}
data[ndata + 1] = '\0';
/* 發送資料給 Server */
size = sizeof(servaddr);
if (sendto(fd, data, ndata, 0, (struct sockaddr*)&servaddr, size) == -1) {
perror("write to server error !");
exit(1);
}
/** 由伺服器接收回應 **/
if (recvfrom(fd, data1, MAXDATA, 0, (struct sockaddr*)&servaddr, &size) < 0) {
perror ("read from server error !");
exit (1);
}
/* 印出 server 回應 **/
printf("%s\n", data1);
}
Warning 1:
warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default]
加入#include <stdlib.h>
Warning 2:
warning: incompatible implicit declaration of built-in function ‘bzero’ [enabled by default]
加入#include <string.h>
執行結果如下: udp server side:
udp client side:
http://140.127.138.46/tsnien/Teach_Manu/F7858/Aid/udpserver.c
http://140.127.138.46/tsnien/Teach_Manu/F7858/Aid/udpclient.c
6 則留言:
請問一下UDP的傳輸，為甚麼還要回傳
如果你只是問這個範例程式為什麼要回傳, 就只是很單純的它只是個範例程式.
而實務上就必需要思考一件事情, UDP並不保證資料是一定會到的喔!
史丹利先生，不好意思請問一下，有UDP傳輸但不要回傳的範例麻，就是一直傳......
鄭皓謙:
你要的東西, 只要小改一下就會動了.
(1)把udp-server.c 底下的五行拿掉
/* return to client */
if (sendto(socket_fd, &buf, nbytes, 0, (struct sockaddr*)&client_addr, length) < 0) {
perror("Could not send datagram!!\n");
continue;
}
(2)把udp-client.c底下的7行拿掉
/** 由伺服器接收回應 **/
if (recvfrom(fd, data1, MAXDATA, 0, (struct sockaddr*)&servaddr, &size) < 0) {
perror ("read from server error !");
exit (1);
}
/* 印出 server 回應 **/
printf("%s\n", data1);
你有兩個方法可以處理，1:改用noonblock,2:用thread去處理。
你這個是CC3100的Code??它是MCU Base, RTOS吧?
這種處理方式不太一樣喔!, 一定有辦法做到你說的, 不過我沒實際碰過你這套code, 應該無法給你明確的建議!
張貼留言