2007年9月9日日曜日

UDP版echoサーバ







#include<stdio.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>


#define MAX 255

void exitWithError(char *message);


int main(int argc,char *argv[])
{
int sock;
struct sockaddr_in echoServAddr;
struct sockaddr_in echoCliAddr;
unsigned int cliAddrLen;
char echoBuffer[MAX];
unsigned short echoServPort;
int recvMsgSize;


if(argc != 2){
fprintf(stderr,"Usage %s <Port>\n,argv[0]");
exit (1);
}

echoServPort = atoi(argv[1]);


if((sock = socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP)) < 0)
exitWithError("socket() error\n");


memset(&echoServAddr,0,sizeof(echoServAddr));
echoServAddr.sin_family = AF_INET;
echoServAddr.sin_addr.s_addr = htonl(INADDR_ANY);
echoServAddr.sin_port = htons(echoServPort);


if(bind(sock,(struct sockaddr *)&echoServAddr,sizeof(echoServAddr)) < 0)
exitWithError("bind() error\n");


for(;;)
{
cliAddrLen = sizeof(echoCliAddr);

if((recvMsgSize = recvfrom(sock,echoBuffer,MAX,0,(struct sockaddr *)&echoCliAddr,&cliAddrLen)) < 0)
exitWithError("recvfrom() error\n");


printf("Handling: %s\n",inet_ntoa(echoCliAddr.sin_addr));

if(sendto(sock,echoBuffer,recvMsgSize,0,(struct sockaddr *)&echoCliAddr,sizeof(echoCliAddr)) != recvMsgSize)
exitWithError("sendto() bytes error\n");

}

}

void exitWithError(char *message)
{
printf("%s\n",message);
exit(1);
}





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