replay-chunks.py: fragmentize tcp data

1 files changed, 97 insertions, 0 deletions

diff --git a/crafted-pkt/replay-chunks.py b/crafted-pkt/replay-chunks.py
new file mode 100755
index 0000000..404e2ed
--- /dev/null
+++ b/crafted-pkt/replay-chunks.py
@@ -0,0 +1,97 @@
+#!/usr/bin/env python
+#
+# Replay a communication, splitting data at a certain chunk size
+# (hard-coded to 2). This can be used to test reassembly for example.
+#
+# Copyright (C) 2014 Peter Wu <peter@lekensteyn.nl>
+
+# Usage (assuming a capture file with TCP stream 0 at loopback interface lo)
+# dumpcap -i lo -w split.pcapng
+# tshark -r old-capture.pcapng -q -z follow,tcp,raw,0 | ./replay-chunks.py
+
+import socket
+import sys
+
+state = 'init'
+
+def _is_marker(line):
+    return all(c == '=' for c in line.strip())
+
+def _dumpbytes(data):
+    return ''.join([
+        chr(x) if x >= 0x20 and x < 0x7f else '.'
+            for x in data
+    ])
+
+class FollowParser(object):
+    def __init__(self, chunk_size=2):
+        self.state = self.state_find_begin
+        self.addr = None
+        self.sock_client = None
+        self.sock_server = None
+        self.chunk_size = chunk_size
+
+    def add_data(self, data, is_reply):
+        sock = self.sock_client if is_reply else self.sock_server
+        for i in range(0, len(data), self.chunk_size):
+            sock.send(data[i:i+self.chunk_size])
+        print('{}: {}'.format('S->C' if is_reply else 'C->S', _dumpbytes(data)))
+
+    def state_find_begin(self, line):
+        if _is_marker(line):
+            self.state = self.state_find_node_1
+
+    def state_find_node_1(self, line):
+        if line.startswith('Node 1: '):
+            host, port = line.split(' ')[-1].rsplit(':', 1)
+            self.addr = (host, int(port))
+            self.state = self.state_find_data
+            self.open_sockets()
+
+    def state_find_data(self, line):
+        if _is_marker(line):
+            self.state = self.state_done
+            return
+        is_reply = line.startswith('\t')
+        data = bytearray.fromhex(line.strip())
+        self.add_data(data, is_reply)
+
+    def state_done(self, line):
+        pass
+
+    def open_sockets(self):
+        with socket.socket() as svr:
+            svr.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            svr.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+            svr.bind(self.addr)
+            svr.listen(1)
+            self.sock_client = socket.socket()
+            self.sock_client.connect(self.addr)
+            self.sock_server, remote_addr = svr.accept()
+
+    def feed_data(self, line):
+        old_state = self.state
+        self.state(line)
+        # Return old state and new state
+        return old_state, self.state
+
+    def close(self):
+        if self.sock_server:
+            self.sock_server.close()
+            self.sock_server = None
+        if self.sock_client:
+            self.sock_client.close()
+            self.sock_client = None
+
+def main():
+    parser = FollowParser()
+    try:
+        for line in sys.stdin:
+            old_state, new_state = parser.feed_data(line)
+            if new_state != old_state and old_state == parser.state_find_node_1:
+                print('Found server node: {}:{}'.format(*parser.addr))
+    finally:
+        parser.close()
+
+if __name__ == '__main__':
+    main()