(Objective-C) Transfer a File using Sockets (TLS or non-TLS)

Demonstrates how to two programs, one a socket writer and the other a socket reader, can transfer a file. The connection can be TLS or a regular non-encrypted TCP connection.

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#import <CkoBinData.h>
#import <CkoSocket.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// On the sending side, we'll load the file into a BinData object and send.
// On the receiving side, we'll read from the socket connection into a BinData, and save to a file.
// This example assumes the file is not crazy-large, and that the entire contents
// can fit into memory.  
// (If the file is too large for memory, there are other ways to send. It just involves streaming or 
// sending the file chunk-by-chunk..)

// This section of code is for the sender.
CkoBinData *bdToSend = [[CkoBinData alloc] init];
BOOL success = [bdToSend LoadFile: @"somePath/someFile.dat"];
// Assume success for the example...

CkoSocket *sndSock = [[CkoSocket alloc] init];
BOOL bUseTls = YES;
int port = 5555;
int maxWaitMs = 5000;
success = [sndSock Connect: @"some_domain_or_ip.com" port: [NSNumber numberWithInt: port] ssl: bUseTls maxWaitMs: [NSNumber numberWithInt: maxWaitMs]];
// Assume success for the example...

// Tell the receiver how many bytes are coming.
int numBytes = [bdToSend.NumBytes intValue];
BOOL bBigEndian = YES;
success = [sndSock SendInt32: [NSNumber numberWithInt: numBytes] bigEndian: bBigEndian];

// Send the file data (sends the entire contents of bdToSend).
success = [sndSock SendBd: bdToSend offset: 0 numBytes: 0];

// Get an acknowledgement.
success = [sndSock ReceiveInt32: bBigEndian];
if (success != YES) {
    NSLog(@"%@",sndSock.LastErrorText);
    return;
}

// Did the receiver get the correct number of bytes?
if ([sndSock.ReceivedInt intValue] != numBytes) {
    NSLog(@"%@",@"The receiver did not acknowledge with the correct number of bytes.");
    return;
}

NSLog(@"%@",@"File sent!");

// ------------------------------------------------------------------------------------
// The code below is for the receiving side (running on some other computer..)

CkoSocket *listenSock = [[CkoSocket alloc] init];

success = [listenSock BindAndListen: [NSNumber numberWithInt: 5555] backlog: [NSNumber numberWithInt: 25]];
if (success != YES) {
    NSLog(@"%@",listenSock.LastErrorText);
    return;
}

// Get the next incoming connection
// Wait a maximum of 20 seconds (20000 millisec)
CkoSocket *rcvSock = 0;
rcvSock = [listenSock AcceptNextConnection: [NSNumber numberWithInt: 20000]];
if (listenSock.LastMethodSuccess == NO) {
    NSLog(@"%@",listenSock.LastErrorText);
    return;
}

// The sender will first send the big-endian integer for the number of bytes
// that are forthcoming..
success = [rcvSock ReceiveInt32: bBigEndian];
if (success != YES) {
    NSLog(@"%@",rcvSock.LastErrorText);

    return;
}

int numBytesComing = [rcvSock.ReceivedInt intValue];

// Receive that many bytes..
CkoBinData *bdReceived = [[CkoBinData alloc] init];
success = [rcvSock ReceiveBdN: numBytesComing binData: bdReceived];
if (success != YES) {
    NSLog(@"%@",rcvSock.LastErrorText);

    return;
}

// Acknowledge the sender by sending back the number of bytes we received.
success = [rcvSock SendInt32: bdReceived.NumBytes bigEndian: bBigEndian];

// Close the connection.
int maxWaitMs = 20;
[rcvSock Close: [NSNumber numberWithInt: maxWaitMs]];

// Save the received data to a file.
success = [bdReceived WriteFile: @"somePath/someFile.dat"];
// Assume success for the example...

NSLog(@"%@",@"File received!");