add raw buffer access

http/httphi/exchange.go

@@ -119,6 +119,18 @@ func (exch *Exchange) Release() {
 	exch.used.Store(false)
 }
 
+// UnsafeRawBuffer returns the contiguous buffer being used for the request and response.
+// Writing to it will mangle the entire request header+body and/or any staged response headers.
+// Does not return the buffer used for the response first line so can be safely
+// written to and used without modifying the staged response first line.
+//
+// Staging headers will write to this buffer so use mindfully.
+// To access only the request header buffer portion use [httpraw.Header.BufferRaw] limited
+// to [httpraw.Header.BufferParsed] as returned by [Exchange.RequestHeaderRaw].
+//
+// In [Router] context, the size of this buffer is influenced directly by [RouterConfig] HeaderBufferSize fields.
+func (exch *Exchange) UnsafeRawBuffer() []byte { return exch.rawbuf }
+
 // StageHeader stages a response header field, written on the first
 // [Exchange.FlushHeader], [Exchange.WriteHeader] or [Exchange.Write].
 // Returns false and drops the field if the response buffer cannot fit it.

http/httphi/router.go

@@ -222,7 +222,7 @@ func (r *Router) awaitIdleExchangesLocked(maxWait time.Duration) error {
 // full, and an error when the router's goroutines have been torn down. On every
 // one of them conn is left untouched and unclosed for the caller to dispose of:
 // refusing connections is how a router with fixed memory applies backpressure.
-func (r *Router) Handle(conn conn) error {
+func (r *Router) Handle(conn io.ReadWriteCloser) error {
 	// Exchange acquisition and the configuration it is served with must be read
 	// under the same lock: [Router.Configure] may run concurrently.
 	r.mu.Lock()

http/httpraw/header.go

@@ -196,6 +196,10 @@ func (h *Header) BufferParsed() int {
 	return h.hbuf.off
 }
 
+// BufferRaw returns the undeerlying buffer as stored currently in memory.
+// The length of the returned buffer is the used portion. Capacity of returned slice is [Header.BufferCapacity].
+func (h *Header) BufferRaw() []byte { return h.hbuf.buf }
+
 // BufferUsed returns the raw memory used.
 //
 //	BufferUsed + BufferFree == BufferCapacity