HTTP/2: tighten SETTINGS validation#632
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arturobernalg merged 1 commit intoapache:masterfrom Feb 22, 2026
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Enforce RFC 9113 constraints for SETTINGS_ENABLE_PUSH and reject invalid values. Accept zero values for peer settings that may legitimately be 0. Add unit tests for client and server multiplexers.
ok2c
approved these changes
Feb 22, 2026
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This change tightens HTTP/2 SETTINGS processing and aligns config handling with RFC 9113.
RFC 9113 6.5.2 (SETTINGS_ENABLE_PUSH):
"Any value other than 0 or 1 MUST be treated as a connection error (Section 5.4.1) of type PROTOCOL_ERROR."
"A client MUST treat receipt of a SETTINGS frame with SETTINGS_ENABLE_PUSH set to 1 as a connection error (Section 5.4.1) of type PROTOCOL_ERROR."
RFC 9113 6.5.2 (SETTINGS_MAX_CONCURRENT_STREAMS):
"A value of 0 for SETTINGS_MAX_CONCURRENT_STREAMS SHOULD NOT be treated as special by endpoints."
RFC 9113 6.5.2 (SETTINGS_INITIAL_WINDOW_SIZE):
"Values above the maximum flow-control window size of 2^{31}-1 MUST be treated as a connection error (Section 5.4.1) of type FLOW_CONTROL_ERROR."
RFC 9113 6.5.2 (SETTINGS_MAX_HEADER_LIST_SIZE):
"The initial value of this setting is unlimited."