Add a setting to adjust the maximum PP header size

[maskit]

The original hard coded size is too small if PP version2 is used and the header contains many TLV fields. This adds a new setting proxy.config.proxy_protocol.max_header_size to read a larger but limited amount of data to parse PP header.

This also adds a quick check to detect whether PP header exists. The check avoids copying a large amount of data if PP is definitely unused.

A known limitation that has been there:
The code assumes that a whole PP header is received at once. If the header size is really large and the header is only partially received, ATS does not wait for the rest of the header and raises an error.

[maskit]

[approve ci rocky]

[Copilot]

Pull request overview

Adds a configurable limit for inbound PROXY protocol header parsing so ATS can accept larger PPv2 headers (e.g., with many TLVs), and documents the new record.

Changes:

• Register proxy.config.proxy_protocol.max_header_size and document it in records.yaml.
• Add proxy_protocol_detect() helper and use it to gate parsing in NetVConnection::has_proxy_protocol(IOBufferReader*).
• Adjust PPv2 parse logging when the buffer is smaller than the expected header length.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/records/RecordsConfig.cc	Adds a new config record to control max inbound PROXY protocol header size.
include/iocore/net/ProxyProtocol.h	Exposes a new proxy_protocol_detect() API.
src/iocore/net/ProxyProtocol.cc	Implements detection helper and changes PPv2 “short buffer” logging behavior.
src/iocore/net/NetVConnection.cc	Uses the new config to size the read buffer for PROXY protocol parsing.
doc/admin-guide/files/records.yaml.en.rst	Documents the new configuration option.

Comments suppressed due to low confidence (1)

src/iocore/net/NetVConnection.cc:76

• When proxy_protocol_detect(tv) succeeds, a proxy_protocol_parse() result of 0 likely means the header is incomplete (not enough bytes yet) or larger than the current max, not that the header is absent. Returning false here leaves the PROXY preface in the reader, and ProtocolProbeSessionAccept will proceed to HTTP probing with the wrong bytes at the front of the stream. Consider treating this as a “need more data” state (like the other overload does with -EAGAIN) or closing the connection with a clear diagnostic when the preface is present but parsing cannot complete.

  size_t len = proxy_protocol_parse(&this->pp_info, tv);

  if (len > 0) {
    reader->consume(len);
    return true;
  }

  return false;

[Copilot]

Pull request overview

Adds a configurable limit for PROXY protocol header parsing so ATS can support larger PROXY v2 headers (e.g., with TLVs) while keeping a default sized for PROXY v1.

Changes:

• Introduce proxy.config.proxy_protocol.max_header_size and plumb it through HttpConfig.
• Use the configured max header size when probing/parsing for PROXY protocol on accepted connections.
• Add PROXY protocol preface detection helper and document the new configuration record.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/records/RecordsConfig.cc	Registers the new proxy.config.proxy_protocol.max_header_size config record and its allowed range.
src/proxy/http/HttpConfig.cc	Loads the new config and propagates it into HttpConfigParams.
include/proxy/http/HttpConfig.h	Adds pp_hdr_max_size to HttpConfigParams.
src/proxy/ProtocolProbeSessionAccept.cc	Uses pp_hdr_max_size when checking for PROXY protocol on new connections.
include/iocore/net/NetVConnection.h	Updates NetVConnection::has_proxy_protocol(IOBufferReader*) signature to accept max_header_size.
src/iocore/net/NetVConnection.cc	Implements configurable-sized read for PROXY protocol parsing from an IOBufferReader.
include/iocore/net/ProxyProtocol.h	Declares proxy_protocol_detect() helper.
src/iocore/net/ProxyProtocol.cc	Implements proxy_protocol_detect() and adjusts logging for a PPv2 length mismatch case.
doc/admin-guide/files/records.yaml.en.rst	Documents the new PROXY protocol max header size configuration.

[Copilot]

Pull request overview

Adds a configurable maximum PROXY protocol header size, wiring it through records config and HttpConfig so the protocol probe can parse larger v2 headers (e.g., with many TLVs).

Changes:

• Introduces proxy.config.proxy_protocol.max_header_size and documents it.
• Plumbs the new config through HttpConfig/HttpConfigParams and into the protocol probe path.
• Refactors PROXY protocol detection/parsing flow to first detect preface, then parse with a configurable read size.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/records/RecordsConfig.cc	Adds the new config record for PROXY protocol max header size.
src/proxy/ProtocolProbeSessionAccept.cc	Reads the configured max header size and passes it into proxy-protocol detection/parsing.
src/proxy/http/HttpConfig.cc	Loads and propagates the new PROXY protocol header size setting into runtime params.
src/iocore/net/ProxyProtocol.cc	Adds proxy_protocol_detect() and changes logging for v2 length mismatch.
src/iocore/net/NetVConnection.cc	Updates has_proxy_protocol() to take a max header size and read more data before parsing.
include/proxy/http/HttpConfig.h	Adds pp_hdr_max_size to HttpConfigParams.
include/iocore/net/ProxyProtocol.h	Declares proxy_protocol_detect().
include/iocore/net/NetVConnection.h	Updates the has_proxy_protocol() signature to accept max header size.
doc/admin-guide/files/records.yaml.en.rst	Documents the new config variable and its intent.