Visual FoxPro

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.

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LOCAL lnSuccess
LOCAL loFtp

lnSuccess = 0

loFtp = CreateObject('Chilkat.Ftp2')

loFtp.Hostname = "ftp.example.com"
loFtp.Username = "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.
loFtp.SoRcvBuf = 4194304
loFtp.SoSndBuf = 524288

*  PreferIpv6 (default 0) chooses IPv6 over IPv4 when a hostname resolves to both.
loFtp.PreferIpv6 = 0

*  ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing
*  connection to a specific local interface.
loFtp.ClientIpAddress = "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.
loFtp.Password = "myPassword"

lnSuccess = loFtp.Connect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

? "Connected with custom socket options."

lnSuccess = loFtp.Disconnect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

RELEASE loFtp