ServerSentEventHttpMessageReader does not respect maxInMemorySize and is always limited to 256k messages

[jacqueslemire]

Affects: 5.2.2, 5.2.1

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To reproduce:

• Create a ServerSentEventHttpMessageReader with a decoder that has maxInMemorySize > 256k.
• Call either read or readMono with 256k < len(message body) <= maxInMemorySize
• DataBufferLimitException is thrown

Expected:

• The configured buffer limit is applied and not error is thrown

The problem is that while the data decoder passed to ServerSentEventHttpMessageReader is properly configured to support a larger maxInMemorySize, that decoder is only used to decode the data part of the message. Prior to that, the SSE's body is decoded through a different decoder (private static final StringDecoder stringDecoder = StringDecoder.textPlainOnly()) which is not properly configured - nore is it accessible in any way - with the new limit.

Note that to my understanding, prior to 5.2.0 there was no limit at all imposed to the body. Now there is one (see 89d053d by @rstoyanchev) , but we have no way to adjust it.

[OLPMO]

Could you provide a minimal demo that can reproduce the problem? @jacqueslemire