[lwip-users] Re: Probem sending large files using LwIP

[Tom Evans]

Louis Filasky asks:

> Anyway, I was just wondering, now it's sending all of
> my data, good start. On my client side, when I start
> sending such data which will be written into a file,
> there must be a too long time between the two sets
> of data send to the client so it believes than it
> is another file and create a new file and writes
> over the former one.
>
> Well, there is definitely something to fix on my client
> and I only see that solution, just like I can give to
> the client the size of the file to be sent and tell
> him to only write a file until that much data has
> been received. But I was wondering also if there was
> something that I haven't done to solve this
> solution on the server side:

Easy. FTP.

http://www.faqs.org/rfcs/rfc765.html
http://www.faqs.org/rfcs/rfc959.html

If that is too heavyweight for you then use TFTP.

http://www.faqs.org/rfcs/rfc783.html
http://www.faqs.org/rfcs/rfc1350.html

The above are reliable, tested, fully functional, documented and there's
lots of public domain source around.

The other big advantage is that there are servers and clients already on
EVERYTHING. You can use Linux or Windows FTP or TFTP servers, and even
if this isn't required you can test your implementation against them.

If you must "roll your own" then the usual reliable [1] way to signify
"end of file" is by closing the socket.

Note 1: More reliable that timeouts. Does have the problem that if the
network goes down during a file transfer the receiver may never close
(so you need LONG application-level timeouts to recover from this).

=== 
Tom Evans                      Software Engineer
Electronics Engineering        address@hidden
Australian Arrow Pty Ltd       www.aapl.com.au
1a Hartnett Drive, Seaford, Vic, 3198, Australia
Phone  (+61 3) 8770 2200 Extension 275
Direct (+61 3) 8770 2275
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