http2: add headersDistinct to Http2ServerRequest fixes #64060

lib/internal/http2/compat.js

@@ -71,6 +71,7 @@ const kRawTrailers = Symbol('rawTrailers');
 const kSetHeader = Symbol('setHeader');
 const kAppendHeader = Symbol('appendHeader');
 const kAborted = Symbol('aborted');
+const kHeadersDistinct = Symbol('kHeadersDistinct');
 
 let statusMessageWarned = false;
 let statusConnectionHeaderWarned = false;
@@ -323,6 +324,7 @@ class Http2ServerRequest extends Readable {
     this[kRawTrailers] = [];
     this[kStream] = stream;
     this[kAborted] = false;
+    this[kHeadersDistinct] = undefined;
     stream[kProxySocket] = null;
     stream[kRequest] = this;
 
@@ -356,6 +358,29 @@ class Http2ServerRequest extends Readable {
     return this[kHeaders];
   }
 
+  get headersDistinct() {
+  if (this[kHeadersDistinct] === undefined) {
+    const distinct = { __proto__: null };
+
+    const raw = this[kRawHeaders];
+
+    for (let i = 0; i < raw.length; i += 2) {
+      const name = String(raw[i]).toLowerCase();
+      const value = raw[i + 1];
+
+      if (distinct[name] === undefined) {
+        distinct[name] = [value];
+      } else {
+        distinct[name].push(value);
+      }
+    }
+
+    this[kHeadersDistinct] = distinct;
+  }
+
+  return this[kHeadersDistinct];
+}
+
   get rawHeaders() {
     return this[kRawHeaders];
   }

test/parallel/test-http2-compat-serverrequest-headers.js

@@ -39,6 +39,25 @@ const h2 = require('http2');
         assert.strictEqual(rawHeaders[position + 1], value);
       }
 
+      const headersDistinct = request.headersDistinct;
+
+      assert.deepStrictEqual(
+        headersDistinct,
+        {
+          __proto__: null,
+          ':path': ['/foobar'],
+          ':method': ['GET'],
+          ':scheme': ['http'],
+          ':authority': [`localhost:${port}`],
+          'foo-bar': ['abc123'],
+        }
+      );
+
+      assert.strictEqual(
+        headersDistinct,
+        request.headersDistinct
+      );
+
       request.url = '/one';
       assert.strictEqual(request.url, '/one');