私はネットワークプログラミングに非常に慣れていません。メッセージを小文字または大文字でサーバーに送信する UDP クライアント/サーバーがあります。サーバーはメッセージを受信し、ケースを切り替えて中継します。それを最初のクライアントに中継してclient2に送信する代わりに、どうすればよいかわかりません。ここに私のコードがあります。
サーバ：
/*
Simple udp server
*/
#include<stdio.h> //printf
#include<string.h> //memset
#include<stdlib.h> //exit(0);
#include<arpa/inet.h>
#include<sys/socket.h>
#include<ctype.h>
#define BUFLEN 512 //Max length of buffer
#define PORT 8888 //The port on which to listen for incoming data
void die(char *s)
{
perror(s);
exit(1);
}
int main(void)
{
struct sockaddr_in si_me, si_other, si_other2;
int s, i, slen = sizeof(si_other) , recv_len;
char buf[BUFLEN];
//create a UDP socket
if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
{
die("socket");
}
// zero out the structure
memset((char *) &si_me, 0, sizeof(si_me));
si_me.sin_family = AF_INET;
si_me.sin_port = htons(PORT);
si_me.sin_addr.s_addr = htonl(INADDR_ANY);
//bind socket to port
if( bind(s , (struct sockaddr*)&si_me, sizeof(si_me) ) == -1)
{
die("bind");
}
//keep listening for data
while(1)
{
printf("Waiting for data...");
fflush(stdout);
//try to receive some data, this is a blocking call
if ((recv_len = recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen)) == -1) // read datagram from server socket
{
die("recvfrom()");
}
//print details of the client/peer and the data received
printf("Received packet from %s:%d\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port)); printf("Data: %s\n" , buf);
//now reply to server socket/the client with the same data
if (sendto(s, buf, recv_len, 0, (struct sockaddr*) &si_other, slen) == -1)
{
die("sendto()");
}
}
close(s);
return 0;
}
クライアント:
/*
Simple udp client
*/
#include<stdio.h> //printf
#include<string.h> //memset
#include<stdlib.h> //exit(0);
#include<arpa/inet.h>
#include<sys/socket.h>
#include<ctype.h>
#define SERVER "192.x.x.x"
#define BUFLEN 512 //Max length of buffer
#define PORT 8888 //The port on which to send data
void die(char *s)
{
perror(s);
exit(1);
}
int main(void)
{
struct sockaddr_in si_other;
int s, s2, i, slen=sizeof(si_other);
char buf[BUFLEN];
char message[BUFLEN];
if ( (s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) // create a client socket
{
die("socket");
}
memset((char *) &si_other, 0, sizeof(si_other));
si_other.sin_family = AF_INET;
si_other.sin_port = htons(PORT);
if (inet_aton(SERVER , &si_other.sin_addr) == 0) // Create datagram with server IP and port.
{
fprintf(stderr, "inet_aton() failed\n");
exit(1);
}
while(1)
{
printf("Enter message : ");
gets(message);
int a;
char message2[BUFLEN];
for(a=0;a<=BUFLEN-1;a++)
{
if(message[a] >= 97 && message[a] <= 122)
message2[a] = toupper(message[a]);
else
message2[a] = tolower(message[a]);
}
if (sendto(s, message2, strlen(message2) , 0 , (struct sockaddr *) &si_other, slen)==-1)
{
die("sendto()");
}
//receive a reply and print it
//clear the buffer by filling null, it might have previously received data
memset(buf,'\0', BUFLEN);
//try to receive some data, this is a blocking call
if (recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen) == -1) // read datagram from client socket
{
die("recvfrom()");
}
puts(buf);
}
close(s);
return 0;
}