[WeidiDeng]

Some behaviors of the transports used by reverse proxy rely on type assertion to an actual type to modify the behavior of the transports,

1. enabling h2c
2. enabling request buffering for fastcgi (this one is particularly ugly because it checks the transport module name)
3. overriding the scheme of the active health check requests
4. changing the host keys used in the connection pool if proxy protocol is enabled

By using interfaces, it's possible for third party transport implementations to implement them to automatically get the behaviors we want.

Assistance Disclosure

No AI was used.

[mholt]

I think I like this much better. Thank you Weidi!

[francislavoie]

Technically the newline between the comments breaks the godoc

Suggested change

	// DefaultBufferSizes enables request buffering for fastcgi if not configured.
	// This is because most fastcgi servers are php-fpm that require the content length to be set to read the body, golang
	// std has fastcgi implementation that doesn't need this value to process the body, but we can safely assume that's
	// not used.
	// http3 requests have a negative content length for GET and HEAD requests, if that header is not sent.
	// see: https://github.com/caddyserver/caddy/issues/6678#issuecomment-2472224182
	// Though it appears even if CONTENT_LENGTH is invalid, php-fpm can handle just fine if the body is empty (no Stdin records sent).
	// php-fpm will hang if there is any data in the body though, https://github.com/caddyserver/caddy/issues/5420#issuecomment-2415943516
	// TODO: better default buffering for fastcgi requests without content length, in theory a value of 1 should be enough, make it bigger anyway
	// DefaultBufferSizes enables request buffering for fastcgi if not configured.
	// This is because most fastcgi servers are php-fpm that require the content length to be set to read the body, golang
	// std has fastcgi implementation that doesn't need this value to process the body, but we can safely assume that's
	// not used.
	// http3 requests have a negative content length for GET and HEAD requests, if that header is not sent.
	// see: https://github.com/caddyserver/caddy/issues/6678#issuecomment-2472224182
	// Though it appears even if CONTENT_LENGTH is invalid, php-fpm can handle just fine if the body is empty (no Stdin records sent).
	// php-fpm will hang if there is any data in the body though, https://github.com/caddyserver/caddy/issues/5420#issuecomment-2415943516
	// TODO: better default buffering for fastcgi requests without content length, in theory a value of 1 should be enough, make it bigger anyway

[mholt]

Dangit, nice catch Francis. Thanks