FpHTTPClient.Get - skip first N byte, continue download
lazarus / 38-Networking and Web Programming

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TCH · 2021-12-12 15:59

Is it possible to tell FpHTTPClient.Get to skip the first N byte? The
server keeps disconnecting before the whole file is downloaded. How
can i continue a download?

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mirce.vladimirov · 2021-12-12 17:08

Download the entire file and then take some processing steps to take
whatever bytes you need.

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TCH · 2021-12-12 17:42

I said:QuoteThe server keeps disconnecting before the whole file is
downloaded.How i am supposed to be able to download the whole file, if
i am not able to download the whole file?

The problem is: i need the entire file, but i only can download the
first N bytes.

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balazsszekely · 2021-12-12 19:33

@TCH
QuoteIs it possible to tell FpHTTPClient.Get to skip the first N byte?
The server keeps disconnecting before the whole file is downloaded.
How can i continue a download?It looks like a server issue for me,
however the attached project is capable of resuming an aborted
download, maybe you should give it a try.
On windows you need the openssl libraries, you can download it from
the following link:
  32 bit: https://packages.lazarus-
ide.org/openssl-1.0.2j-i386-win32.zip      
  64 bit: https://packages.lazarus-
ide.org/openssl-1.0.2j-x64_86-win64.zip
Put the dlls the same folder as your executable is.

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TCH · 2021-12-12 20:18

So, the solution is not to use FpHTTPClient.Get, but
FpHTTPClient.HTTPMethod('GET' ... with allowed HTTP response codes 200
and 206 (success, partial success) and do
FpHTTPClient.AddHeader('Range', 'bytes=' + IntToStr(cpos) + '-' +
IntToStr(cpos + rlen)); before each request.

It works flawlessly, thank you very much.