http2: handle 100-continue flow & writeContinue

Adds an implementation for writeContinue based on the h2 spec & the
existing http implementation. ClientHttp2Stream now also emits
a continue event when it receives headers with :status 100.
Includes two test cases for default server continue behaviour and
for the exposed checkContinue listener.

PR-URL: https://github.com/nodejs/node/pull/15039
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/test/parallel/test-http2-compat-expect-continue-check.js b/test/parallel/test-http2-compat-expect-continue-check.js
new file mode 100644
index 0000000000..a956697b5c
--- /dev/null
+++ b/test/parallel/test-http2-compat-expect-continue-check.js
@@ -0,0 +1,81 @@
+// Flags: --expose-http2
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const assert = require('assert');
+const http2 = require('http2');
+
+const testResBody = 'other stuff!\n';
+
+// Checks the full 100-continue flow from client sending 'expect: 100-continue'
+// through server receiving it, triggering 'checkContinue' custom handler,
+// writing the rest of the request to finally the client receiving to.
+
+function handler(req, res) {
+  console.error('Server sent full response');
+
+  res.writeHead(200, {
+    'content-type': 'text/plain',
+    'abcd': '1'
+  });
+  res.end(testResBody);
+}
+
+const server = http2.createServer(
+  common.mustNotCall('Full request received before 100 Continue')
+);
+
+server.on('checkContinue', common.mustCall((req, res) => {
+  console.error('Server received Expect: 100-continue');
+
+  res.writeContinue();
+
+  // timeout so that we allow the client to receive continue first
+  setTimeout(
+    common.mustCall(() => handler(req, res)),
+    common.platformTimeout(100)
+  );
+}));
+
+server.listen(0);
+
+server.on('listening', common.mustCall(() => {
+  let body = '';
+
+  const port = server.address().port;
+  const client = http2.connect(`http://localhost:${port}`);
+  const req = client.request({
+    ':method': 'POST',
+    ':path': '/world',
+    expect: '100-continue'
+  });
+  console.error('Client sent request');
+
+  let gotContinue = false;
+  req.on('continue', common.mustCall(() => {
+    console.error('Client received 100-continue');
+    gotContinue = true;
+  }));
+
+  req.on('response', common.mustCall((headers) => {
+    console.error('Client received response headers');
+
+    assert.strictEqual(gotContinue, true);
+    assert.strictEqual(headers[':status'], 200);
+    assert.strictEqual(headers['abcd'], '1');
+  }));
+
+  req.setEncoding('utf-8');
+  req.on('data', common.mustCall((chunk) => { body += chunk; }));
+
+  req.on('end', common.mustCall(() => {
+    console.error('Client received full response');
+
+    assert.strictEqual(body, testResBody);
+
+    client.destroy();
+    server.close();
+  }));
+}));