Forked from chancyWu/send and receive a broadcast udp packet in c or objective c
Created
December 26, 2016 08:19
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#include <netinet/in.h> | |
#include <sys/socket.h> | |
#include <unistd.h> | |
#include <arpa/inet.h> | |
- (void)broadCast | |
{ | |
int socketSD = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); | |
if (socketSD <= 0) { | |
NSLog(@"Error: Could not open socket."); | |
return; | |
} | |
// set socket options enable broadcast | |
int broadcastEnable = 1; | |
int ret = setsockopt(socketSD, SOL_SOCKET, SO_BROADCAST, &broadcastEnable, sizeof(broadcastEnable)); | |
if (ret) { | |
NSLog(@"Error: Could not open set socket to broadcast mode"); | |
close(socketSD); | |
return; | |
} | |
// Configure the port and ip we want to send to | |
struct sockaddr_in broadcastAddr; | |
memset(&broadcastAddr, 0, sizeof(broadcastAddr)); | |
broadcastAddr.sin_family = AF_INET; | |
inet_pton(AF_INET, "255.255.255.255", &broadcastAddr.sin_addr); | |
broadcastAddr.sin_port = htons(8585); | |
char *request = "message from ios by c"; | |
ret = sendto(socketSD, request, strlen(request), 0, (struct sockaddr*)&broadcastAddr, sizeof(broadcastAddr)); | |
if (ret < 0) { | |
NSLog(@"Error: Could not open send broadcast."); | |
close(socketSD); | |
return; | |
} | |
close(socketSD); | |
dispatch_async(dispatch_get_global_queue(0, 0), ^{ | |
[self listenForPackets]; | |
}); | |
[_connectionSpinner show:YES]; | |
[_connectionTimer invalidate]; | |
_connectionTimer = [NSTimer scheduledTimerWithTimeInterval:3.0f target:self selector:@selector(checkConnection) userInfo:nil repeats:NO]; | |
} | |
- (void)listenForPackets | |
{ | |
int listeningSocket = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); | |
if (listeningSocket <= 0) { | |
NSLog(@"Error: listenForPackets - socket() failed."); | |
return; | |
} | |
// set timeout to 2 seconds. | |
struct timeval timeV; | |
timeV.tv_sec = 2; | |
timeV.tv_usec = 0; | |
if (setsockopt(listeningSocket, SOL_SOCKET, SO_RCVTIMEO, &timeV, sizeof(timeV)) == -1) { | |
NSLog(@"Error: listenForPackets - setsockopt failed"); | |
close(listeningSocket); | |
return; | |
} | |
// bind the port | |
struct sockaddr_in sockaddr; | |
memset(&sockaddr, 0, sizeof(sockaddr)); | |
sockaddr.sin_len = sizeof(sockaddr); | |
sockaddr.sin_family = AF_INET; | |
sockaddr.sin_port = htons(18686); | |
sockaddr.sin_addr.s_addr = htonl(INADDR_ANY); | |
int status = bind(listeningSocket, (struct sockaddr *)&sockaddr, sizeof(sockaddr)); | |
if (status == -1) { | |
close(listeningSocket); | |
NSLog(@"Error: listenForPackets - bind() failed."); | |
return; | |
} | |
// receive | |
struct sockaddr_in receiveSockaddr; | |
socklen_t receiveSockaddrLen = sizeof(receiveSockaddr); | |
size_t bufSize = 9216; | |
void *buf = malloc(bufSize); | |
ssize_t result = recvfrom(listeningSocket, buf, bufSize, 0, (struct sockaddr *)&receiveSockaddr, &receiveSockaddrLen); | |
NSData *data = nil; | |
if (result > 0) { | |
if ((size_t)result != bufSize) { | |
buf = realloc(buf, result); | |
} | |
data = [NSData dataWithBytesNoCopy:buf length:result freeWhenDone:YES]; | |
char addrBuf[INET_ADDRSTRLEN]; | |
if (inet_ntop(AF_INET, &receiveSockaddr.sin_addr, addrBuf, (size_t)sizeof(addrBuf)) == NULL) { | |
addrBuf[0] = '\0'; | |
} | |
NSString *address = [NSString stringWithCString:addrBuf encoding:NSASCIIStringEncoding]; | |
NSString *msg = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; | |
dispatch_async(dispatch_get_main_queue(), ^{ | |
[self didReceiveMessage:msg fromAddress:address]; | |
}); | |
} else { | |
free(buf); | |
} | |
close(listeningSocket); | |
} | |
- (void)didReceiveMessage:(NSString *)message fromAddress:(NSString *)address | |
{ | |
} |
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