ここには、サーバーがすべてのクライアントに同時にメッセージをブロードキャストできるブロードキャストメカニズムを備えた UDP チャット用の 2 つのコードがあります。
サーバーコード...
#include<stdio.h>
#include<string.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
int main(int argc, char *argv[] )
{
struct sockaddr_in client,server;
int s,n;
char b1[100],b2[100];
s=socket(AF_INET,SOCK_DGRAM,0);
server.sin_family=AF_INET;
server.sin_port=htons(2000);
server.sin_addr.s_addr=inet_addr("127.0.0.1");
bind(s,(struct sockaddr *)&server,sizeof(server));
printf("\nServer ready,waiting for client....\n");
n=sizeof(client);
int sock; /* Socket */
struct sockaddr_in broadcastAddr; /* Broadcast address */
char *broadcastIP; /* IP broadcast address */
unsigned short broadcastPort; /* Server port */
char *sendString; /* String to broadcast */
int broadcastPermission; /* Socket opt to set permission to broadcast */
unsigned int sendStringLen; /* Length of string to broadcast */
if (argc < 4) /* Test for correct number of parameters */
{
fprintf(stderr,"Usage: %s <IP Address> <Port> <Send String>\n", argv[0]);
exit(1);
}
broadcastIP = argv[1]; /* First arg: broadcast IP address */
broadcastPort = atoi(argv[2]); /* Second arg: broadcast port */
sendString = argv[3]; /* Third arg: string to broadcast */
/* Create socket for sending/receiving datagrams */
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
broadcastPermission = 1;
while(1)
{
recvfrom(s,b1,sizeof(b1),0,(struct sockaddr *) &client,&n);
if(!(strcmp(b1,"end")))
break;
printf("\nClient:%s",b1);
printf("\nServer:");
gets(b2);
sendto(s,b2,sizeof(b2),0,(struct sockaddr *) &client,n);
broadcastPermission = 1;
setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (void *) &broadcastPermission,sizeof(broadcastPermission));
/* Construct local address structure */
//memset(&broadcastAddr, 0, sizeof(broadcastAddr)); /* Zero out structure */
broadcastAddr.sin_family = AF_INET; /* Internet address family */
broadcastAddr.sin_addr.s_addr = inet_addr(broadcastIP);/* Broadcast IP address */
broadcastAddr.sin_port = htons(broadcastPort); /* Broadcast port */
sendStringLen = strlen(sendString);
for (;;) /* Run forever */
{
/* Broadcast sendString in datagram to clients every 3 seconds*/
sendto(sock, sendString, sendStringLen, 0, (struct sockaddr *) &broadcastAddr, sizeof(broadcastAddr));
// DieWithError("sendto() sent a different number of bytes than expected");
//sleep(3); /* Avoids flooding the network */
}
}
}
クライアントコード...
#include<stdio.h>
#include<string.h>
#include<sys/stat.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#define MAXRECVSTRING 255
int main(int argc , char argv[])
{
struct sockaddr_in client,server;
int s,n;
char b1[100],b2[100];
s=socket(AF_INET,SOCK_DGRAM,0);
server.sin_family=AF_INET;
server.sin_port=htons(2000);
server.sin_addr.s_addr=inet_addr("127.0.0.1");
printf("\nClient ready....\n");
n=sizeof(server);
int sock; /* Socket */
struct sockaddr_in broadcastAddr; /* Broadcast Address */
unsigned short broadcastPort; /* Port */
char recvString[MAXRECVSTRING+1]; /* Buffer for received string */
int recvStringLen; /* Length of received string */
if (argc != 2) /* Test for correct number of arguments */
{
fprintf(stderr,"Usage: %s <Broadcast Port>\n", argv[0]);
exit(1);
}
printf("\nClient ready…11111.\n");
broadcastPort = htons(argv[1]); /* First arg: broadcast port */
printf("\nClient ready….1\n");
/* Create a best-effort datagram socket using UDP */
if(sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)<0)
printf("no sock created");
printf("\nClient ready….2\n");
while(1)
{
printf("\nClient:");
gets(b2);
sendto(s,b2,sizeof(b2),0,(struct sockaddr *) &server,n);
if(strcmp(b2,"end")==0)
break;
recvfrom(s,b1,sizeof(b1),0,NULL,NULL);
printf("\nServer:%s",b1);
broadcastAddr.sin_family = AF_INET; /* Internet address family */
broadcastAddr.sin_addr.s_addr = htonl(INADDR_ANY); /* Any incoming interface */
broadcastAddr.sin_port = htons(broadcastPort); /* Broadcast port */
/* Bind to the broadcast port */
bind(sock, (struct sockaddr *) &broadcastAddr, sizeof(broadcastAddr));
/* Receive a single datagram from the server */
recvStringLen = recvfrom(sock, recvString, MAXRECVSTRING, 0, NULL, 0);
recvString[recvStringLen] = '\0';
printf("Received: %s\n", recvString); /* Print the received string */
}
close(sock);
}
これらのコードはエラーなしで実行されますが、クライアントからサーバーに文字列を送信すると、サーバーは文字列を受信できず、その逆も同様です。
なぜこれが起こっているのかについて誰かが私を助けることができれば。
サーバーとクライアントの両方を同じシステムの異なる端末ウィンドウで実行しています..したがって、ローカルホストアドレス