1674449 - HTTP3 connection failures with low MTU

Status: RESOLVED FIXED

(Core :: Networking: HTTP, defect, P2)

Description

[Erik Karulf]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36

Steps to reproduce:

We observed failures connecting to HTTP3 enabled sites when the MTU of the network path was below the minimum required for HTTP3 on IPv4 and IPv6 (1350 and 1370 respectively). The racing feature did not gracefully handle a truncated UDP response and fall back to HTTP2, resulting in a broken connection.

Repro steps:

• Configure network MTU to something smaller than 1350, e.g. 1280
• Install Firefox Nightly
• Enable http3 in about:config
• Try connecting to a HTTP3 enabled site www.youtube.com or http3.is

Actual results:

When connecting to a HTTP3 enabled site over a network link with a small MTU, the connection would fail with the error "error: secure connection failed"

Expected results:

The connection should have gracefully degraded to HTTP2 or HTTP1.

Comment 1

[Dragana Damjanovic [:dragana]]

This should be fix by bug 1674116

Comment 2

[Dragana Damjanovic [:dragana]]

(In reply to Dragana Damjanovic [:dragana] from comment #1)

This should be fix by bug 1674116

It sis a wrong bug number (the bugs are duplicate), the bug thatt will fix this is bug 1675016.