(Tcl) 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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load ./chilkat.dll

# 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.
set bdToSend [new_CkBinData]

set success [CkBinData_LoadFile $bdToSend "somePath/someFile.dat"]
# Assume success for the example...

set sndSock [new_CkSocket]

set bUseTls 1
set port 5555
set maxWaitMs 5000
set success [CkSocket_Connect $sndSock "some_domain_or_ip.com" $port $bUseTls $maxWaitMs]
# Assume success for the example...

# Tell the receiver how many bytes are coming.
set numBytes [CkBinData_get_NumBytes $bdToSend]
set bBigEndian 1
set success [CkSocket_SendInt32 $sndSock $numBytes $bBigEndian]

# Send the file data (sends the entire contents of bdToSend).
set success [CkSocket_SendBd $sndSock $bdToSend 0 0]

# Get an acknowledgement.
set success [CkSocket_ReceiveInt32 $sndSock $bBigEndian]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $sndSock]
    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    exit
}

# Did the receiver get the correct number of bytes?
if {[CkSocket_get_ReceivedInt $sndSock] != $numBytes} then {
    puts "The receiver did not acknowledge with the correct number of bytes."
    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    exit
}

puts "File sent!"

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

set listenSock [new_CkSocket]

set success [CkSocket_BindAndListen $listenSock 5555 25]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $listenSock]
    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    delete_CkSocket $listenSock
    exit
}

# Get the next incoming connection
# Wait a maximum of 20 seconds (20000 millisec)
# rcvSock is a CkSocket

set rcvSock [CkSocket_AcceptNextConnection $listenSock 20000]
if {[CkSocket_get_LastMethodSuccess $listenSock] == 0} then {
    puts [CkSocket_lastErrorText $listenSock]
    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    delete_CkSocket $listenSock
    exit
}

# The sender will first send the big-endian integer for the number of bytes
# that are forthcoming..
set success [CkSocket_ReceiveInt32 $rcvSock $bBigEndian]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $rcvSock]
    delete_CkSocket $rcvSock

    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    delete_CkSocket $listenSock
    exit
}

set numBytesComing [CkSocket_get_ReceivedInt $rcvSock]

# Receive that many bytes..
set bdReceived [new_CkBinData]

set success [CkSocket_ReceiveBdN $rcvSock $numBytesComing $bdReceived]
if {$success != 1} then {
    puts [CkSocket_lastErrorText $rcvSock]
    delete_CkSocket $rcvSock

    delete_CkBinData $bdToSend
    delete_CkSocket $sndSock
    delete_CkSocket $listenSock
    delete_CkBinData $bdReceived
    exit
}

# Acknowledge the sender by sending back the number of bytes we received.
set success [CkSocket_SendInt32 $rcvSock [CkBinData_get_NumBytes $bdReceived] $bBigEndian]

# Close the connection.
set maxWaitMs 20
CkSocket_Close $rcvSock $maxWaitMs
delete_CkSocket $rcvSock

# Save the received data to a file.
set success [CkBinData_WriteFile $bdReceived "somePath/someFile.dat"]
# Assume success for the example...

puts "File received!"

delete_CkBinData $bdToSend
delete_CkSocket $sndSock
delete_CkSocket $listenSock
delete_CkBinData $bdReceived