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https://git.code.sf.net/p/quake/quakeforge
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6a7b316572
Vim's autoformating doesn't like our style of comments, so I have to force it to do what I want. Having to set the appropriate options every time I edit a file got to be a RPITA, so time to get the computer to do it for me :)
101 lines
3.8 KiB
Text
101 lines
3.8 KiB
Text
//unfortunately, have to wrap the docs in a C comment for doxygen
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// vim:tw=74:formatoptions-=l
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/**
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\page qw_download_spec QW Download Specification
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client has 'h' flag in "*cap" info string
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format of svc_download message:
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\verbatim
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<size (short)> <percent (byte)> ([url (string)] [newname (string)] | [data])
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\endverbatim
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size and percent are always present.
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url is present only for http redirects.
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data is present only when size is > 0 (ie, normal downloading)
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newname is present for all http redirects (but may be the empty string) or if
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the file to download has a different name to what what requested. This is so
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the client saves the downloaded file with the correct name (in QF, this is
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currently used for gzipped transfers, but there are plans to enable whole pak
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downloads (similar to RTCW and ET)).
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size is the number of data bytes in the message (if >= 0) or a special flag:
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\li -1 file not found. download aborted
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\li -2 download filename is not what was requested (in QF, this is because
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the file has been gzipped and has the .gz extension). In this case,
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newname is in the message. Currently, QF checks newname to ensure the
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only modification is the addition of an extension.
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\li -3 http redirect. url is always present and is the full url to download.
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If the download name is the same as the requested name, newname will
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be the empty string (""), otherwise it contains the new name of the
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file. See -2.
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QF \#defines for the above values:
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\verbatim
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#define DL_NOFILE -1
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#define DL_RENAME -2
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#define DL_HTTP -3
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\endverbatim
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Pseudo-code representing client side handling of svc_download
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\verbatim
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CL_ParseDownload
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{
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size = MSG_ReadShort (net_message);
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percent = MSG_ReadByte (net_message);
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if (size == DL_NOFILE) {
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abort download
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return
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}
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if (size == DL_RENAME) {
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newname = MSG_ReadString (net_message);
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if (newname is bad) {
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abort download
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return
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}
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rename file
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return
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}
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if (size == DL_HTTP) {
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url = MSG_ReadString (net_message);
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newname = MSG_ReadString (net_message);
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if (newname != "") {
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if (newname is bad) {
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abort download
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return
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}
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rename file
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}
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start http transfer
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return
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}
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normal download processing
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}
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\endverbatim
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\note While the QF quakeworld server simply appends the requested file's path
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to the given url base, with the addition of a '/' (eg, "maps/foo.map" to
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"http://server/downloads", giving "http://server/downloads/maps/foo.map"), so
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long as it is reasonable for the client to not rename the download file, there
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is no requirement for the full url to match the requested name in any manner,
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and newname can be left as empty (""). However, if the client must rename the
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file, set newname to the new name. The extension checking is done as a
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security measure.
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\note Currently, the only reason QF renames a download is if it found eg
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"maps/foo.map.gz" instead of "maps/foo.map" (2:1 to 3:1 compression on maps is
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nice). This is the basis of the extension checking the QF clients do.
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\todo [this has no bearing on the protocol itself]
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One good reason for the name being quite different is when the requested file
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is part of a pak file (and downloading the pak file is permitted), the entire
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pak file can be sent instead. QF does not yet do this, but it should be easy
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enough to implement: if file_from_pak (from FOpenFile) is set, and pak file
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downloading is permitted, do a rename (-2 for non-http, set newname in http)
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and send that instead. The client can check for a ".pak" extension in the
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rename, permit it, and then cause a rescan of the game directory in order to
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pick up the new pak file.
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*/
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