服务端：
- R$ ?: z# O# A# _8 ]#include <sys/types.h>
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#include <sys/socket.h>
) j- z. u3 ?# d; o5 d& A#include <netinet/in.h>
- m/ K2 |+ k1 q#include <string.h>
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#include <stdio.h>
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#define SERVER_PORT 8888
- \% k: }+ l; c% l/ d4 \#define DATASIZE 100
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void udps_respon(int sockfd)
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{
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int n;
i! _; c+ e2 z& [( b% Q int addrlen;
* [# H- U5 R- G T' p' K, f# D char recvbuf[DATASIZE];
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char* sendbuf;
5 I' u! `. x" N! p; a char* client_ip;
8 |6 j! t, p( {" k% f struct sockaddr_in client_addr;
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n=recvfrom(sockfd,recvbuf,DATASIZE,0,(struct sockaddr*)&client_addr,&addrlen);
: f9 P$ I5 ~% N8 a9 A5 a& H recvbuf[n]='\0';
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client_ip=inet_ntoa(client_addr.sin_addr);
- f& ]% O7 I3 M printf("I recieved data from:'%s'.\n",client_ip);
. E' p; W2 i3 s printf("I have received '%s'.\n",recvbuf);
8 H# [* u; X1 S& b, f sendbuf="OK! You did a good job!!";
, d* j7 q9 [* G1 l& V2 x n=strlen(sendbuf);
) Y( G$ c+ t! l; g9 a sendto(sockfd,sendbuf,n,0,(struct sockaddr*)&client_addr,addrlen);
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int main(void)
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2 u/ K7 d; l8 D; F int sockfd;
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struct sockaddr_in server_addr;
; I9 i5 | l1 y0 _ if((sockfd=socket(AF_INET,SOCK_DGRAM,0))<0)
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{
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printf("Socket Error.\n");
' N9 t* b( } {& c$ Y$ k2 a exit(1);
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}
, a. D7 N: m! N bzero(&server_addr,sizeof(struct sockaddr_in));
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server_addr.sin_family=AF_INET;
+ ]0 h2 V3 Q; B$ ^% R/ S server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
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server_addr.sin_port=htons(SERVER_PORT);
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if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr_in))<0 )
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{
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printf("Bind Error.\n");
& z$ |* o- ^, B" |; F exit(1);
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udps_respon(sockfd);
1 W9 ]7 p5 ~" y3 V8 a5 b1 U' [ close(sockfd);
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( k" d/ |% b% z$ A O客户端：
% @: z$ x* U0 F9 k7 P- Z+ P#include <sys/types.h>
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#include <sys/socket.h>
8 L( Y9 G3 X+ r& y" q) G" B#include <netinet/in.h>
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#include <string.h>
5 _3 _3 t* h; ~4 ^* R; V1 d#include <stdio.h>
( F: Y0 e! _* K& S3 \8 b#include <unistd.h>
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#define IPADDR "255.255.255.255"
6 n5 P ]# W" R4 C#define PORT 8888
6 ], G' L2 ^! v# h2 T#define DATASIZE 100
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void udpc_requ(int sockfd,const struct sockaddr_in *server_addr,int addrlen)
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{
8 V) ^$ a, Y9 [0 J; ^ int n;
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int server_addrlen;
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char sendbuf[DATASIZE];
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char recvbuf[DATASIZE];
# N H) e! U" e' F: H e char* server_ip;
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struct sockaddr_in server;
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printf("
lease input string:");
( S% H) V, C ~$ @% X2 _; ` fgets(sendbuf,DATASIZE,stdin);
3 {0 ?/ y1 Z% O sendto(sockfd,sendbuf,strlen(sendbuf)-1,0,server_addr,addrlen);
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printf("I have send: %s",sendbuf);
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n=recvfrom(sockfd,recvbuf,DATASIZE,0,(struct sockaddr *)&server,&server_addrlen);
1 h5 I7 ^: E4 ~" Y" L8 p F0 | recvbuf[n]='\0';
* @6 i4 {! x4 y3 w% n: _( ]( ] server_ip=inet_ntoa(server.sin_addr);
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printf("I have recieved data from:%s.\n",server_ip);
9 s5 M0 c# A/ W! _/ F& s printf("I have recieved:'%s'.\n",recvbuf);
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/ f) k4 K( l3 b: V1 V6 g- B. wint main()
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{
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int sockfd;
. n6 e1 _, Z* r! i$ f struct sockaddr_in addr;
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if((sockfd=socket(AF_INET,SOCK_DGRAM,0))<0)
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{
! c8 s S2 r/ ?) p5 l printf("Socket Error.\n");
4 }3 g3 P9 Y# L" V/ e, _ exit(1);
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+ I; P# Z: q: k bzero(&addr,sizeof(struct sockaddr_in));
4 u; ]! p, ]5 A; r4 J& ~4 s7 ~ addr.sin_family=AF_INET;
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addr.sin_port=htons(PORT);
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if(inet_aton(IPADDR,&addr.sin_addr)<0)
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{
( F% U* d3 x$ g- [9 V0 v printf("IPADDR error.\n");
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exit(1);
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udpc_requ(sockfd,&addr,sizeof(struct sockaddr_in));
% u; ^( H8 v, _; v0 R; V) e close(sockfd);
* J- q. o/ V$ S5 Y1 ^}
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! F8 |3 {) A% [# P8 D9 j; p****************************************************************************************************
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客户端定义发送消息的ip地址为：255.255.255.255 广播地址，为什么服务端收不到信号？
. z- x0 o# l8 W# x3 u8 j% e, |( j! i小弟初学网络编程，还请各位大牛指教．
