Rule Syntax

Whistle modifies requests and responses through simple rule configurations. The basic syntax structure is as follows:

pattern operation [includeFilter://pattern1 ... excludeFilter://patternN ...]

Rule Composition

Each rule consists of three core components:

1. Match Pattern (pattern): An expression to match request URLs, supporting various formats:

   • Domain matching: www.test.com (matches all requests to this domain, including ports)
   • Path matching: www.test.com/path
   • Regular expression: /^https?://test\.com//i
   • Wildcards: *.test.com, **.test.com/path

   Whistle supports three URL types:

   1. Tunnel Proxy: tunnel://domain[:port]
   2. WebSocket: ws[s]://domain[:port]/path/to
   3. Regular HTTP/HTTPS: http[s]://domain[:port]/path/to

2. Operation (operation), formatted as: protocol://value

   • protocol: Operation type, such as:
     • reqHeaders: Modify request headers
     • resHeaders: Modify response headers
   • value: Operation content, supporting multiple data sources:
     • Inline value: reqHeaders://x-proxy-by=whistle (directly adds a request header)
     • Local file: file://path/to/file
     • Remote resource: https://example.com/data.json
     • Preset variable: {key} (read from embedded values in Rules or Values)

   The protocol:// in operation can be omitted in the following two scenarios:

   • ip or ip:port: Equivalent to host://ip or host://ip:port
   • D:\path\to, /path/to, or {key}: Equivalent to file://D:\path\to, file:///path/to, or file://{key}

3. Filter Conditions (Optional) (includeFilter/excludeFilter)

   • Logical relationship: Multiple conditions use "OR" matching; matching any one condition makes it effective
   • Matching scope:
     • Request: URL, method (GET/POST, etc.), header fields, content, client IP
     • Response: Status code, header fields, content, server IP

Learn More

1. Match Pattern (expressions for matching request URLs) details: Pattern
2. Operation details: Operation
3. Filter details: Filters