Preserve case in WS rawHeader rule events

Author: pimterry

src/rules/websockets/websocket-handlers.ts

@@ -394,6 +394,19 @@ export class PassThroughWebSocketHandler extends PassThroughWebSocketHandlerDefi
 
         if (options.emitEventCallback) {
             const upstreamReq = (upstreamWebSocket as any as { _req: http.ClientRequest })._req;
+            // This is slower than req.getHeaders(), but gives us (roughly) the correct casing
+            // of the headers as sent. Still not perfect (loses dupe ordering) but at least it
+            // generally matches what's actually sent on the wire.
+            const rawHeaders = upstreamReq.getRawHeaderNames().map((headerName) => {
+                const value = upstreamReq.getHeader(headerName);
+                if (!value) return [];
+                if (Array.isArray(value)) {
+                    return value.map(v => [headerName, v]);
+                } else {
+                    return [[headerName, value.toString()]];
+                }
+            }).flat() as RawHeaders;
+
             options.emitEventCallback('passthrough-websocket-connect', {
                 method: upstreamReq.method,
                 protocol: upstreamReq.protocol
@@ -402,7 +415,7 @@ export class PassThroughWebSocketHandler extends PassThroughWebSocketHandlerDefi
                 hostname: upstreamReq.host,
                 port: effectivePort.toString(),
                 path: upstreamReq.path,
-                rawHeaders: objectHeadersToRaw(upstreamReq.getHeaders() as Headers),
+                rawHeaders: rawHeaders,
                 subprotocols: filteredSubprotocols
             });
         }

test/integration/subscriptions/rule-events.spec.ts

@@ -351,11 +351,11 @@ describe("Rule event subscriptions", () => {
         });
 
         // This reports the *modified* header, not the original:
-        expect(connectEvent.rawHeaders).to.deep.include(['host', `localhost:${remoteServer.port}`]);
-        expect(connectEvent.rawHeaders).to.deep.include(['sec-websocket-version', '13']);
-        expect(connectEvent.rawHeaders).to.deep.include(['sec-websocket-extensions', 'permessage-deflate; client_max_window_bits']);
-        expect(connectEvent.rawHeaders).to.deep.include(['connection', 'Upgrade']);
-        expect(connectEvent.rawHeaders).to.deep.include(['upgrade', 'websocket']);
+        expect(connectEvent.rawHeaders).to.deep.include(['Host', `localhost:${remoteServer.port}`]);
+        expect(connectEvent.rawHeaders).to.deep.include(['Sec-WebSocket-Version', '13']);
+        expect(connectEvent.rawHeaders).to.deep.include(['Sec-WebSocket-Extensions', 'permessage-deflate; client_max_window_bits']);
+        expect(connectEvent.rawHeaders).to.deep.include(['Connection', 'Upgrade']);
+        expect(connectEvent.rawHeaders).to.deep.include(['Upgrade', 'websocket']);
 
         // Make sure we want to see the upstream WS key, not the downstream one
         const upstreamWsKey = (connectEvent.rawHeaders as RawHeaders)