Tcl

FTP Socket Buffer and Address Options

Demonstrates the SoRcvBuf, SoSndBuf, PreferIpv6, and ClientIpAddress properties.

Background: These are low-level knobs for specific situations. Larger send/receive buffers can improve throughput on high-bandwidth, high-latency links, though the defaults suit the common case. PreferIpv6 only matters when a hostname resolves to both address families, choosing which to try first. ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing connection to a particular local interface. Change any of these only with a concrete reason.

Chilkat Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

set success 0

set ftp [new_CkFtp2]

CkFtp2_put_Hostname $ftp "ftp.example.com"
CkFtp2_put_Username $ftp "myFtpLogin"

#  SoRcvBuf and SoSndBuf set the TCP socket receive/send buffer sizes.  The defaults are tuned for
#  the common case; larger values can sometimes help throughput on high-latency links.
CkFtp2_put_SoRcvBuf $ftp 4194304
CkFtp2_put_SoSndBuf $ftp 524288

#  PreferIpv6 (default 0) chooses IPv6 over IPv4 when a hostname resolves to both.
CkFtp2_put_PreferIpv6 $ftp 0

#  ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing
#  connection to a specific local interface.
CkFtp2_put_ClientIpAddress $ftp "192.168.1.50"

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
CkFtp2_put_Password $ftp "myPassword"

set success [CkFtp2_Connect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    exit
}

puts "Connected with custom socket options."

set success [CkFtp2_Disconnect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    exit
}


delete_CkFtp2 $ftp