b7e769dc87
- For HTTPS if http2-prior-knowledge is set then only offer h2 (HTTP/2)
alpn to the server for protocol negotiation.
Prior to this change both HTTP/2 ("h2") and HTTP/1.1 ("http/1.1") were
offered for ALPN when http2-prior-knowledge was set.
CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE (tool: --http2-prior-knowledge) is
meant to send non-TLS HTTP requests HTTP/2 when it is known the server
supports them. However when HTTPS is used then it attempts to first
negotiate the connection with ALPN. In that case the user likely does
not want to offer http/1.1 to the server as an acceptable protocol.
Reported-by: kit-ty-kate@users.noreply.github.com
Fixes https://github.com/curl/curl/issues/9963
Closes https://github.com/curl/curl/pull/14266
30 lines
853 B
Markdown
30 lines
853 B
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Long: http2-prior-knowledge
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Tags: Versions
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Protocols: HTTP
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Added: 7.49.0
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Mutexed: http1.1 http1.0 http2 http3
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Requires: HTTP/2
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Help: Use HTTP 2 without HTTP/1.1 Upgrade
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Category: http
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Multi: boolean
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See-also:
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- http2
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- http3
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Example:
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- --http2-prior-knowledge $URL
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---
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# `--http2-prior-knowledge`
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Issue a non-TLS HTTP requests using HTTP/2 directly without HTTP/1.1 Upgrade.
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It requires prior knowledge that the server supports HTTP/2 straight away.
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HTTPS requests still do HTTP/2 the standard way with negotiated protocol
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version in the TLS handshake.
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Since 8.10.0 if this option is set for an HTTPS request then the application
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layer protocol version (ALPN) offered to the server is only HTTP/2. Prior to
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that both HTTP/1.1 and HTTP/2 were offered.
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