Adding a python middleware example file

examples/middleware/echo.py

@@ -0,0 +1,76 @@
+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import sys
+import fileinput
+import binascii
+
+# Used to find end of the Headers section
+EMPTY_LINE = b'\r\n\r\n'
+
+
+def log(msg):
+    """
+    Logging to STDERR as STDOUT and STDIN used for data transfer
+    @type msg: str or byte string
+    @param msg: Message to log to STDERR
+    """
+    try:
+        msg = str(msg) + '\n'
+    except:
+        pass
+    sys.stderr.write(msg)
+    sys.stderr.flush()
+
+
+def find_end_of_headers(byte_data):
+    """
+    Finds where the header portion ends and the content portion begins.
+    @type byte_data: str or byte string
+    @param byte_data: Hex decoded req or resp string
+    """
+    return byte_data.index(EMPTY_LINE) + 4
+
+
+def process_stdin():
+    """
+    Process STDIN and output to STDOUT
+    """
+    for raw_line in fileinput.input():
+
+        line = raw_line.rstrip()
+
+        # Decode base64 encoded line
+        decoded = bytes.fromhex(line)
+
+        # Split into metadata and payload, the payload is headers + body
+        (raw_metadata, payload) = decoded.split(b'\n', 1)
+
+        # Split into headers and payload
+        headers_pos = find_end_of_headers(payload)
+        raw_headers = payload[:headers_pos]
+        raw_content = payload[headers_pos:]
+
+        log('===================================')
+        request_type_id = int(raw_metadata.split(b' ')[0])
+        log('Request type: {}'.format({
+          1: 'Request',
+          2: 'Original Request',
+          3: 'Replayed Response'
+        }[request_type_id]))
+        log('===================================')
+
+        log('Original data:')
+        log(line)
+
+        log('Decoded request:')
+        log(decoded)
+
+        encoded = binascii.hexlify(raw_metadata + b'\n' + raw_headers + raw_content).decode('ascii')
+        log('Encoded data:')
+        log(encoded)
+
+        sys.stdout.write(encoded + '\n')
+
+if __name__ == '__main__':
+    process_stdin()