作者s890269 (賽)
看板C_and_CPP
標題[問題] UDP發送接收
時間Tue Nov 8 23:15:50 2016
開發平台(Platform): (Ex: Win10, Linux, ...)
Win7
編譯器(Ex: GCC, clang, VC++...)+目標環境(跟開發平台不同的話需列出)
Microsoft Visual Studio C++
問題(Question)：
我最一開始有撰寫UDP Server以及UDP Client,UDP開著,client發送封包給server,
server接收到後,會發送回給client,所以client可以發送跟接收
但我最近在改寫時就發現server跟client連不到,這次的寫法是
server發送封包給client接收
但就接收不到了,應該說根本沒有連上
但我不太覺得程式碼有錯誤,因為我是參考之前成功的範例去改的
所以不知道是有程式碼以外的問題嗎?
預期的正確結果(Expected Output)：
server發送的封包client可以接收成功
出現的error都是在接收發送那裏接下來進入的if
bind或者初始的設定沒跑出error
程式碼(Code)：(請善用置底文網頁, 記得排版)
Server端
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#include <iostream>
#include <sys/types.h>
using namespace std;
#pragma comment(lib,"ws2_32.lib") //Winsock Library
#define SERVER_PORT1 8889
#define BUFLEN 1024
int _tmain(int argc, _TCHAR* argv[]){
struct sockaddr_in addrsend;
SOCKET s1;
int length_addrsend;
char buf[BUFLEN];
int sendbol;
int receivebol;
double cur_ang[3];
WSADATA wsa;
printf("\nInitializing Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0){
printf("Failed. Error Code : %d",WSAGetLastError());
}
printf("Initialized.\n");
if ((s1= socket(AF_INET, SOCK_DGRAM, 0)) <0){
perror ("socket s1 failed");
}
memset(&addrsend,'\0',sizeof(addrsend));
addrsend.sin_family = AF_INET;
addrsend.sin_addr.s_addr = htonl(INADDR_ANY);
addrsend.sin_port = htons(SERVER_PORT1);
if (bind(s1,(struct sockaddr*)&addrsend,sizeof(addrsend)) <0) {
perror ("bind s1 failed\n");
}
printf("bind done");
length_addrsend=sizeof(addrsend);
printf("Server is ready to receive !!\n");
printf("Can strike Cntrl-c to stop Server >>\n");
memset(buf,'\0', BUFLEN);
cur_ang[0]=0.5678;
cur_ang[1]=0.51278;
cur_ang[2]=0.589678;
while(1){
sprintf(buf,"%f %f %f ",cur_ang[0],cur_ang[1],cur_ang[2]);
sendbol=sendto(s1,buf,BUFLEN,0,(struct sockaddr*)&addrsend,length_addrsend);
if (sendbol<0){
perror("Could not send datagram!!\n");
continue;
}
memset(buf,'\0',BUFLEN);
}
closesocket(s1);
WSACleanup();
system("pause");
return 0;
}
Client端
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <winsock2.h>
#include <fcntl.h>
#include <string.h>
#include <iostream>
#include <cstdio>
#include <cassert>
#include <cmath>
#include <math.h>
#include <time.h>
#pragma comment(lib,"ws2_32.lib")
using namespace std;
#define SERV_PORT 8889 //receive from server
#define BUFLEN 1024
#define SERVER "127.0.0.1"
int main(int argc, char **argv){
struct sockaddr_in server;//one port
struct hostent *hp; /* holds IP address of server */
SOCKET s;
int size_server;
char data;
char buf[BUFLEN]={0};
char buf1[BUFLEN]={0};
int sendbol, receivebol;
WSADATA wsa;
//Initialise winsock
printf("\nInitializing Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0){
printf("Failed. Error Code : %d",WSAGetLastError());
}
printf("Initialized.\n");
//create socket
if ( (s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == SOCKET_ERROR){
printf("socket() failed with error code : %d" , WSAGetLastError());
}
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_addr.s_addr=inet_addr(SERVER);
server.sin_port = htons(SERV_PORT);
size_server=sizeof(server);
while(1){
receivebol=recvfrom(s,buf,BUFLEN,0,(struct sockaddr*)&server,&size_server);
if (receivebol< 0) {
printf("receive failed: %d\n" , WSAGetLastError());
}
else{
printf("bytes have been received\n");
printf("%s\n",buf);
}
}
closesocket(s);
WSACleanup();
system("pause");
return 0;
}
--
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1F：→ s890269: 會跟程式碼哪個先跑有關係嗎?我是都先跑server 11/08 23:30
2F：推 bibo9901: 你可能要先唸一下網路概論了解什麼是client/server 11/09 00:04
3F：→ bibo9901: 還有IP的意思 11/09 00:04