feat: add proxy template origin field and implement socket utilities for log streaming

templates/tcp-block-repeated-byte-threshold.yaml

@@ -0,0 +1,54 @@
+id: tcp-block-repeated-byte-threshold
+name: Block repeated-byte flood
+protocol: tcp
+description: Closes connections that send suspiciously long runs of the same byte.
+category: tcp
+family: tcp-hardening
+tags:
+- bof
+- repeated-byte
+- tcp
+- block
+action: block
+summary: Closes connections that send suspiciously long runs of the same byte.
+behavior: Measures the longest repeated-byte run in each client message, logs the
+  byte and run length, and closes the TCP flow on threshold hit.
+source_url: https://docs.mitmproxy.org/stable/addons/examples/
+code: |
+  import logging
+
+  from mitmproxy import tcp
+
+  MAX_REPEAT = 128
+
+
+  def longest_run(data: bytes) -> tuple[int, int]:
+      best_byte = -1
+      best_run = 0
+      current_byte = -1
+      current_run = 0
+      for byte in data:
+          if byte == current_byte:
+              current_run += 1
+          else:
+              current_byte = byte
+              current_run = 1
+          if current_run > best_run:
+              best_byte = byte
+              best_run = current_run
+      return best_byte, best_run
+
+
+  def tcp_message(flow: tcp.TCPFlow) -> None:
+      message = flow.messages[-1]
+      if not message.from_client:
+          return
+      repeated_byte, run_length = longest_run(message.content)
+      if run_length > MAX_REPEAT:
+          logging.warning(
+              "[tcp-block-repeated-byte-threshold] blocked byte=0x%02x run=%d",
+              repeated_byte,
+              run_length,
+          )
+          message.drop()
+          flow.kill()