Add simple H2 connection example

src/examples/h2-example.py

@@ -0,0 +1,89 @@
+"""Simple h2 connections
+Adapted from "Plain Sockets Example Client"
+https://python-hyper.org/projects/h2/en/stable/plain-sockets-example.html
+"""
+import socket
+import ssl
+import certifi
+
+import h2.connection
+import h2.events
+
+
+SERVER_NAME = 'localhost'
+SERVER_PORT = 443
+
+
+def make_http2_request():
+    # Create a generic socket and SSL configuration
+    socket.setdefaulttimeout(15)
+    ctx = ssl.create_default_context(cafile=certifi.where())
+    ctx.set_alpn_protocols(['h2'])
+
+    # Required to skip certificate validation
+    ctx.check_hostname = False
+    ctx.verify_mode = ssl.CERT_NONE
+
+    # Open socket and initiate TLS/SSL connection
+    s = socket.create_connection((SERVER_NAME, SERVER_PORT))
+    s = ctx.wrap_socket(s, server_hostname=SERVER_NAME)
+
+    # Create HTTP/2 connection
+    c = h2.connection.H2Connection()
+    c.initiate_connection()
+    s.sendall(c.data_to_send())
+
+    # Create and send headers
+    headers = [
+        (':method', 'GET'),
+        (':path', '/'),
+        (':authority', SERVER_NAME),
+        (':scheme', 'https'),
+    ]
+    c.send_headers(
+        stream_id=1,
+        headers=headers,
+        end_stream=True
+    )
+    s.sendall(c.data_to_send())
+
+    # Stream response body
+    body = b''
+    response_stream_ended = False
+    while not response_stream_ended:
+        # Read raw socket data
+        data = s.recv(65536 * 1024)
+        if not data:
+            break
+
+        # Feed raw data into h2 and process events
+        events = c.receive_data(data)
+        for event in events:
+            print(event)
+            if isinstance(event, h2.events.DataReceived):
+                # Update flow control
+                c.acknowledge_received_data(event.flow_controlled_length, event.stream_id)
+                # Append data to response body
+                body += event.data
+            if isinstance(event, h2.events.StreamEnded):
+                response_stream_ended = True
+                break
+
+        # Send pending data to the server
+        s.sendall(c.data_to_send())
+
+    print('Response fully received:')
+    print(body.decode())
+
+    # Close connection and socket
+    c.close_connection()
+    s.sendall(c.data_to_send())
+    s.close()
+
+
+def main():
+    make_http2_request()
+
+
+if __name__ == '__main__':
+    main()