socket.setTOS

[ronag]

What is the problem this feature will solve?

Allow users to set the Type Of Service (TOS) field on a TCP socket for e.g. priority hints for kernel and switches.

What is the feature you are proposing to solve the problem?

Add a 2 new methods socket.setTOS and socket.getTOS.

What alternatives have you considered?

No response

[ronag]

Note that there is a difference between ipv4 and ipv6. Not sure how/if this can exposed in a uniform way.

[ronag]

In our ipv4 case we would like to use the following TOS values:

CS1 (TOS BYTE 0x20) = LOW PRIO
Best Effort (TOS BYTE 0x00) = NORMAL PRIO
AF11 (TOS BYTES 0x28) = HIGH PRIO

[amyssnippet]

regarding the IPv4/IPv6 uniformity, since RFC 2474 standardized the DS Field to work similarly for both IPv4 (TOS byte) and IPv6 (Traffic Class byte), could the API simply accept the 8-bit integer and handle the implementation details internally? ideally, socket.setTOS(val) would just map to setsockopt(..., IP_TOS, ...) for AF_INET and setsockopt(..., IPV6_TCLASS, ...) for AF_INET6, this keeps the user-facing API uniform since the DSCP constants (like CS1, AF11) represent the same priority intent regardless of the protocol version.

[amyssnippet]

should i work on this, or is this you already been working on?

[ronag]

Please do work on it.

[amyssnippet]

Awesome, I'm on it!

I plan to implement the C++ bindings in TCPWrap (handling IP_TOS/IPV6_TCLASS) and expose it via lib/net.js. I'll open a Draft PR once I have the basic implementation working.