RFR: 8354276: Strict HTTP header validation

[Daniel Jeliński]

On Thu, 10 Apr 2025 12:45:40 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

>> RFC 9113 HTTP/2 mandates certain validation for HTTP headers; the HttpClient don't fully implement the described requirements.
>> 
>> This PR adds the following validation:
>> - pseudo-headers defined for requests are rejected in responses and push streams
>> - pseudo-headers defined for responses are rejected in push promises
>> - connection headers are rejected in responses and push streams
>> 
>> Connection headers are still accepted in push promises; that's because some popular server implementations were found to echo the request headers in push promises, and when the original request was a HTTP/1 upgrade, the push promise could contain one or more headers that were prohibited in HTTP/2 but allowed in HTTP/1.
>> 
>> An existing test was adapted to verify the handling of response headers. The modified test passes with this the changes in this PR, fails without them. Other tier1-3 tests continue to pass.
>
> test/jdk/java/net/httpclient/http2/BadHeadersTest.java line 83:
> 
>> 81:         of(entry(":status", "200"),  entry("hello", "DE" + ((char) 0x7F) + "L")),  // Bad byte in value
>> 82:         of(entry(":status", "200"),  entry("connection", "close")),                // Prohibited connection-specific header
>> 83:         of(entry(":status", "200"),  entry(":scheme", "https")),                   // Request pseudo-header in response
> 
> Shouldn't we instead exhaustively test against all hard-coded header collection in `ValidatingHeadersConsumer`, i.e., `PSEUDO_HEADERS` and `PROHIBITED_HEADERS`?

We could. I don't think it adds much value though.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24569#discussion_r2037385857