PORT Command Usage in FTP and the Compact Framework
From: Paul [Paradise Solutions] (Paul_at_Don'tChuffingSpamMe.com)
Date: 01/05/05
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Date: Wed, 05 Jan 2005 10:54:24 +0000
Hi all
I recently managed to find a proven piece of code from these groups, for
using FTP on the Compact Framework. It was originally written for the
desktop but a respected name (can't remember who) said that he had got
it working on PDA by commenting out a line.
I tried it and at was great - connected to ftp site almost first time.
I now have a prblem though. The code does work 100% on the desktop, but
the PORT command always fails on the PDA. I was wondering if anyone
could shed any light on this. I currently have the PDA 'sunk' with the
desktop via a cradle and I'm attempting to connect to a an FTP server on
me local machine. Could this setup prevent the PORT command from
succeding, or are there a restricted number or ports available to use on
the PDA and my port number is too high?
I have lokoed into IPworks, but the cost is too high as their component
does 101 things.. but I only need one bit of it, so it's not cost
effective for us.
The code for setting the port is as follows (not originally written by
me, I just put it in it's own proc and added a couple of bits):
/// <summary>
/// Function to find usable IPaddress and port number for FTP return path
/// </summary>
/// <returns>
/// Arraylist[0]=Ipaddress object
/// Arraylist[1]=port number as integer
/// </returns>
public ArrayList SetPort()
{
string sOut = null;
string returnString=null;
bool bIPFound = false;
ArrayList returnValue=new ArrayList();
// get a list of IP addresses for this machine
IPHostEntry ipThis = Dns.GetHostByName(Dns.GetHostName());
Random r = new Random();
// we will try all IP addresses assigned to this machine
// the first one that the remote machine likes will be chosen
while (!bIPFound)
{
for(int i=0;i<ipThis.AddressList.Length;i++)
{
string ip = ipThis.AddressList[i].ToString().Replace(".",",");
int p1 = r.Next(20);
int p2 = r.Next(20);
p_Port = 256*p1+p2;
string sPortCom = "PORT " + ip + "," + p1.ToString() + "," +
p2.ToString();
// Port command now looks like PORT 61,45,6,34,xx,yy where
// first 4 values is your IP address and xx and yy are random numbers
// 256*xx+yy will be the port number where the remote machine will
connect
// and send data
WriteToStream(sPortCom);
sOut = m_comRead.ReadLine();
RaiseInfoEvent(sOut);
returnString = string.Concat(sOut + " - " + sPortCom +
"\r\n",returnString);
if (sOut.Substring(0,3) == "200")
{
// PORT command accepted
bIPFound = true;
returnValue.Add(ipThis.AddressList[i]);
returnValue.Add(p_Port);
break;
}
}
}
return returnValue;
}
The 'While...' is there because on the desktop I found that sometime the
command failed, but retrying succeded.
Appologies for any line wrapping.. I was sifting through it trying to
ensure no wraps, until I learnt that C# can be multi-line (I'm VB).
Any input would be useful.
Many thanks
Paul
- Next message: Daniel Moth: "Re: InputBox SIP? (was Re: "Unexpected error" strangeness...(ipaq vb.n"
- Previous message: Frederik Jensen: "Re: How do I see what events are available?"
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