The curl sub-command should support --http2-prior-knowledge with "https" URLs#2342
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The curl sub-command should support --http2-prior-knowledge with "https" URLs#2342
--http2-prior-knowledge with "https" URLs#2342Conversation
pkwarren
approved these changes
Aug 3, 2023
--http2-prior-knowledge with "https" URLs--http2-prior-knowledge with "https" URLs
bufdev
approved these changes
Aug 3, 2023
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Previously,
buf curlwould complain if you tried to use--http2-prior-knowledgewith secure "https" URLs.Now, the flag is accepted and the client will only use HTTP/2. This basically removes "http/1.1" from the set of supported protocols during ALPN, and if the server does not support ALPN (i.e. does not pick a protocol), it defaults to HTTP/2 (whereas it was previously defaulting to HTTP 1.1).
This can be used to work with secure servers that expect HTTP/2 but don't correctly implement ALPN to select "h2". This could be the case when using network load balancers that terminate TLS (layer 4, instead of layer 7).
I tested this locally against a server using the grpc-go runtime (it does not use "net/http" and only supports HTTP/2). I hacked the runtime so that it did not use ALPN during the TLS handshake. Without
--http2-prior-knowledge, abuf curlcommand fails since it is sending an HTTP 1.1 request to a server expecting HTTP/2. But with the flag, the request succeeds.