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

templates/tcp-block-non-printable-threshold.yaml

@@ -0,0 +1,42 @@
+id: tcp-block-non-printable-threshold
+name: Block binary-noise threshold
+protocol: tcp
+description: Blocks client messages with an excessive amount of non-printable bytes.
+category: tcp
+family: tcp-hardening
+tags:
+- non-printable
+- binary-noise
+- tcp
+- block
+action: block
+summary: Blocks client messages with an excessive amount of non-printable bytes.
+behavior: Treats unusually binary-heavy client payloads as suspicious, logs the ratio,
+  and closes the flow when the threshold is exceeded.
+source_url: https://docs.mitmproxy.org/stable/addons/examples/
+code: |
+  import logging
+
+  from mitmproxy import tcp
+
+  NON_PRINTABLE_RATIO = 0.35
+
+
+  def tcp_message(flow: tcp.TCPFlow) -> None:
+      message = flow.messages[-1]
+      if not message.from_client or not message.content:
+          return
+      non_printable = sum(
+          1
+          for byte in message.content
+          if byte < 0x20 and byte not in {0x09, 0x0a, 0x0d}
+      )
+      ratio = non_printable / len(message.content)
+      if ratio > NON_PRINTABLE_RATIO:
+          logging.warning(
+              "[tcp-block-non-printable-threshold] blocked ratio=%.2f size=%d",
+              ratio,
+              len(message.content),
+          )
+          message.drop()
+          flow.kill()