How to create a TCP Server on the iPhone? - ios

Question

I want to create a TCP server on the iPhone. I tried to write this server using Apple's developer help, but I had no success.
I tried to listen with CoreFoundation and with POSIX Socket API but none of these worked.
Using CoreFoundation I implemented the following:
CFSocketRef myipv4cfsock = CFSocketCreate(kCFAllocatorDefault, PF_INET, SOCK_STREAM, IPPROTO_TCP,
kCFSocketAcceptCallBack, handleConnect, NULL);
struct sockaddr_in mySocket;
memset(&mySocket, 0, sizeof(sin));
mySocket.sin_len = sizeof(sin);
mySocket.sin_family = PF_INET;
mySocket.sin_port = 8000;
mySocket.sin_addr.s_addr= INADDR_ANY;
CFSocketSetAddress(myipv4cfsock, CFDataCreate(kCFAllocatorDefault, (UInt8 *)&mySocket, sizeof(mySocket)));
CFRunLoopSourceRef socketsource = CFSocketCreateRunLoopSource(kCFAllocatorDefault, myipv4cfsock, 0);
CFRunLoopAddSource(CFRunLoopGetCurrent(), socketsource, kCFRunLoopDefaultMode);
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStringRef remoteHost = CFSTR("localhost");
CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)remoteHost, 8000, &readStream, &writeStream);
NSInputStream *inputStream = (__bridge_transfer NSInputStream *)readStream;
NSOutputStream *outputStream = (__bridge_transfer NSOutputStream *)writeStream;
[inputStream setDelegate: self];
[outputStream setDelegate: self];
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[inputStream open];
[outputStream open];
Using the POSIX Socket API I implemented this:
int listenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
struct sockaddr_in socketAddr;
memset(&socketAddr, 0, sizeof(socketAddr));
socketAddr.sin_len = sizeof(sin);
socketAddr.sin_family = AF_INET;
socketAddr.sin_port = 8000;
socketAddr.sin_addr.s_addr= INADDR_ANY;
if (bind(listenSocket, (struct sockaddr *)&socketAddr, sizeof(socketAddr)) < 0)
{
NSLog(#"Error: Could not bind socket.");
}
listen(listenSocket, 10);
But then I didn't know how to handle the events with Grand Central Dispatch.
When I try to connect with some client I always get the exception "Connection refused" on client side.
Does anybody have some example code?

Answer 1

I found a solution using the POSIX Socket API.
int listenfd = 0;
struct sockaddr_in serv_addr;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(8008);
bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
_listenForConnections = true;
listen(listenfd, 10);
dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSLog(#"Waiting for connections...");
while (_listenForConnections)
{
__block int connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
NSLog(#"Connection accepted");
char buffer[1024];
bzero(buffer, 1024);
NSString *message = #"";
bool continueReading = true;
do
{
recv(connfd , buffer , 1024 , 0);
int size = strlen(buffer);
if ((buffer[size-1] == '}' && buffer[size-2] == '{'))
{
continueReading = false;
buffer[size-2] = '\0';
}
message = [NSString stringWithFormat: #"%#%s", message, buffer];
}while (continueReading);
NSLog(#"Got message from client");
char* answer = "Hello World";
write(connfd, answer, strlen(answer));
}
NSLog(#"Stop listening.");
close(listenfd);
});