2 replies to this topic

[phantom308]

I've got some code from a tutorial website (Beej's network proamming ) trying to understand how it works .got a lot out of that website !

Issue : i want to Broadcast an audio file to my listeners : which i can record and save .now here is some changes that i've made into the exsisting code but it seems like i have to convert the file into binary first and then convert it back to playback .Not sure how to do that ?????.Please see if anyone could help me do that .
Quote:
Code : Broadcasting file.

Quote

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#define SERVERPORT 4950 // the port users will be connecting to

int main(int argc,char *argv[])
{
int sockfd;
struct sockaddr_in their_addr; // connector's address information
struct hostent *he;
int numbytes;
int broadcast = 1;
FILE *fp1;
int infile[50000]; //filesize
int *mypointer
char c;
int i = 0;

mypointer = infile;

if (argc != 3) {
fprintf(stderr,"usage: broadcaster hostname message\n");
exit(1);
}

if ((he = gethostbyname(argv[1])) == NULL) { // get the host info
herror("gethostbyname");
exit(1);
}

if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
perror("socket");
exit(1);
}


if (setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &broadcast,
sizeof broadcast) == -1) {
perror("setsockopt (SO_BROADCAST)");
exit(1);
}
fp1 = fopen(argv[2],"r");
while(( c = getc(fp1)) != EOF)
{
infile[i] = c;
i = i+1;
};
their_addr.sin_family = AF_INET; // host byte order
their_addr.sin_port = htons(SERVERPORT); // short, network byte order
their_addr.sin_addr = *((struct in_addr *)he->h_addr);
memset(their_addr.sin_zero, '\0', sizeof their_addr.sin_zero);

if ((numbytes=sendto(sockfd, mypointer, i, 0,
(struct sockaddr *)&their_addr, sizeof their_addr)) == -1) {
perror("sendto");
exit(1);
}

printf("sent %d bytes to %s\n", numbytes, inet_ntoa(their_addr.sin_addr));

close(sockfd);

return 0;
}

-------------------------------------------------------------------------------------

Code :listening file

Quote

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define MYPORT 4950 // the port users will be connecting to

#define MAXBUFLEN 50000

int main(void)
{
FILE *out;
int sockfd;
struct sockaddr_in my_addr; // my address information
struct sockaddr_in their_addr; // connector's address information
socklen_t addr_len;
int numbytes;
char buf[MAXBUFLEN];

if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
perror("socket");
exit(1);
}

my_addr.sin_family = AF_INET; // host byte order
my_addr.sin_port = htons(MYPORT); // short, network byte order
my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
memset(my_addr.sin_zero, '\0', sizeof my_addr.sin_zero);

if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof my_addr) == -1) {
perror("bind");
exit(1);
}

addr_len = sizeof their_addr;
if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
(struct sockaddr *)&their_addr, &addr_len)) == -1) {
perror("recvfrom");
exit(1);
}
out = fopen("../thanga/xxxx.c","a");//save in a file
fprintf(out,"got packet from %s\n",inet_ntoa(their_addr.sin_addr));
fprintf(out,"packet is %d bytes long\n",numbytes);
buf[numbytes] = '\0';
fprintf(out,"packet contains \"%s\"\n",buf);
fclose(out);mohan

close(sockfd);

return 0;
}

-------------------------------------------------------------------------

it listens the contents from broadcasting file and saves it in a file xxxx.c but when sending and audio file it recives some garbage value....
Please advice
Thanks...

[v0id]

Datagram sockets are unreliable, and they may not arrive at the destination. And if they actually arrive, then there's a big chance that the data arrived unordered. I would rather use stream sockets. But you'll still have to watch out. If you send large chunks of data, all of it may not arrive, but fortunately you can check how many bytes were sent, and send the rest, if not all the data were sent the first time.

[TkTech]

TCP is almost always preffered over UDP. UDP is, technically, less bandwith intensive, but unlike TCP it doesn't guarantee packet delivery. UDP is handy for local networks where you can just keep sending packets and to hell with bandwith. UDP is also used in games like Wc3 where massive amounts of non-crucial traffic need to be sent rapidly.