Getting the IP address of a UDP client

Getting the IP address of a UDP client

[Lee Chin]

Hi
I can use getpeername to get the IP address of a client on a connected TCP socket, but when I have a UDP client that just sent me a packet, how do I get the IP address of that UDP client?

Thanks
Lee
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Getting the IP address of a UDP client

[Lee Chin]

Hi
I can use getpeername to get the IP address of a
client on a connected TCP socket, but when I have a
UDP client that just sent me a packet, how do I get
the IP address of that UDP client?

Thanks
Lee

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Re: Getting the IP address of a UDP client

[Elias Athanasopoulos]

On Fri, Jan 03, 2003 at 11:03:20AM -0800, Lee Chin wrote:
> I can use getpeername to get the IP address of a
> client on a connected TCP socket, but when I have a
> UDP client that just sent me a packet, how do I get
> the IP address of that UDP client?

Forgive me if I have misunderstood you, but do you use accept() to create
the new incoming connection? Then the second argument to accept() is
a structure, which contains the information you want.

Have a look at the man page of accept(2).

Elias

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Re: Getting the IP address of a UDP client

[Lee Chin]

Hi,
This is a UDP server ... so I do not use accept, I
simply have a server loop that does a "recv" ...

So the server does a recvfrom and then a sendto on the
same file descriptor... 

When I try to do an accept, that system call fails
because it is not a TCP socket...

Thanks
Lee
--- Elias Athanasopoulos <eathan@otenet.gr> wrote:
> On Fri, Jan 03, 2003 at 11:03:20AM -0800, Lee Chin
> wrote:
> > I can use getpeername to get the IP address of a
> > client on a connected TCP socket, but when I have
> a
> > UDP client that just sent me a packet, how do I
> get
> > the IP address of that UDP client?
> 
> Forgive me if I have misunderstood you, but do you
> use accept() to create
> the new incoming connection? Then the second
> argument to accept() is
> a structure, which contains the information you
> want.
> 
> Have a look at the man page of accept(2).
> 
> Elias
> 
> -- 
> http://gnewtellium.sourceforge.net			MP3 is not a
> crime.	


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Re: Getting the IP address of a UDP client

[Lee Chin]

Hi Mark,
I am not using recvfrom... I simply use recv

In other words, I create the server UDP socket, listen
on a port then enter into a while loop just doing a
recv.  Now the thing is, many different clients are
sending packets to the server, and I need to reply to
each of them at a later time, so I need to get their
IP addresses and store it away so I can do a sendto at
a later time

Thanks
Lee
--- Mark Hahn <hahn@physics.mcmaster.ca> wrote:
> > This is a UDP server ... so I do not use accept, I
> > simply have a server loop that does a "recv" ...
> > 
> > So the server does a recvfrom and then a sendto on
> the
> 
> if you're using recvfrom, why aren't you simply
> providing 
> a buffer for the "from" argument (and appropriate
> fromlen).
> read the fine man page!
> 


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