Bugs item #3585128, was opened at 2012-11-07 04:20
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Category: libcurl
Group: bad behaviour
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Chris Wilson (gcc)
Assigned to: Daniel Stenberg (bagder)
Summary: Please add support for setting IP TOS/Precedence flags

Initial Comment:
IP TOS (Precedence) flags as described in RFC 791 are really useful for building QoS routers that treat bulk and interactive traffic differently; but only if client applications actually bother to declare whether their traffic is bulk or interactive.

SSH and bittorrent do this already, but there doesn't seem to be any way to do it in curl.

You can do it with setsockopt(IP_TOS) on all platforms that support it except Windows, which disables this functionality and uses DSCP instead (unlike everyone else).

Some discussion of whether to use IPTOS_THROUGHPUT, IPTOS_PREC_PRIORITY or something else for bulk traffic:
http://lists.ibiblio.org/pipermail/bittorrent/2004-December/001060.html . I don't particularly care as long as we do *something* to mark bulk and interactive traffic differently.

Please could we add at least a flag that sets the precedence of all connections made by curl to bulk or interactive?

Even better would be heuristics to determine which mode is appropriate. My guess is that all applications of command-line curl are bulk, using libcurl to write to an output file or for any protocol except HTTP is bulk, and everything else (libcurl HTTP not to a file) is interactive.

If you accept this proposal I can try to work up a patch.

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Received on 2012-11-07