After having downloaded a big files from HTTP how to check if it's ok?

Are there any way to send an http request to know开发者_开发问答 for example the md5 of a file?

I need it because I have a php script that downloads a remote file from http and then writes it locally.

I would like to check if it was transfered right.

Thanks

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HTTP (in reality TCP) has internal error checking, so everything you download ist correct. The only problem you can have is an incomplete download, so check for filesize.

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Without checksum at original server, either external or inside file (like .exe), you can't. HTTP provides no such functionality.

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This isn't efficient, but you could download it twice and checksum each (with md5 or sha). If the two match, and the size matches the content-length header, it's probably correct.