Server Rules

CommandBox servers have a method of locking down secure URLs and or implementing any of the Undertow predicate and handlers via a nice text based language. Undertow supports a “predicate language” that allows a string to be parsed into a graph of predicates (conditions) and handlers (actions to take). Ex:

path-suffix(/box.json) -> set-error(404)

These rules can be used for any of the following:

• Security - Block paths, IPs, or users

• URL rewrites - Rewrite incoming URLs to something different

• Modifying HTTP requests on the fly - Set headers, cookies, or response codes

Much of this functionality overlaps with the existing Tuckey-based rewrites in CommandBox, but this functionality is built directly into Undertow, has a more streamlined syntax, and allows for easier ad-hoc rules to be layered into a server that allows for you to have custom rules layered on top of built in rules. It can be used to replace what Tuckey does, or added on top.

If you have Tuckey rewrites enabled AND use the Undertow predicate-based server rules, the server rules will fire BEFORE the Tuckey rewrites.

Create your Rules

Unlike custom Tuckey-based rewrites that must be placed in a single XML file, server rules can be provided ad-hoc in a variety of locations. They are combined and passed to the server in the order defined. This allows you to easily "layer" custom rules along with out-of-the-box lockdown profiles.

For maximum configuration options, the following mechanisms are supported for specifying the rules for a given server. Rules are processed in the order listed. i.e., a rule defined in your server.json is processed prior to a rule in your server.default config setting.

1. Ad-hoc rule array in server.json

2. External rules files in server.json in the order defined

3. Ad-hoc rule array in config setting server.defaults

4. External rules files in config setting server.defaults in the order defined

5. CommandBox built-in rules (web.blockCFAdmin, web.blockConfigPaths)

6. Any module listening to server interceptions can inject their rules wherever they please in the array.

server.json Rules

You can specify ad-hoc rules in the web.rules property as an array of strings in your server.json as well as specify one or more external rule files in the web.rulesFile property as an array or list of file glob patterns.

{
    "web" : {
        "rules" : [
            "path-suffix(/box.json) -> set-error(404)",
            "path-suffix(hidden.js) -> set-error(404)",
            "path-prefix(/admin/) -> ip-access-control(192.168.0.* allow)",
            "path(/sitemap.xml) -> rewrite(/sitemap.cfm)",
        "disallowed-methods(trace)"
        ],
          "rulesFile" : "../secure-rules.json"
        // Or...
          "rulesFile" : ["../security.json","../rewrites.txt","../app-headers.json"]
        // Or...
          "rulesFile" : "../rules/*.json"
    }
}

External rule files with a .json suffix will be expected to be a valid JSON file containing an array of strings. Ex:

myRuleFile.json

[
  "path-suffix(/box.json) -> set-error(404)",
  "path-suffix(hidden.js) -> set-error(404)"
]

External rule files with any extension OTHER than .json will be expected to be a raw text file with one rule per line. Emtpy lines are ignored and the rules are processed in the order defined.

myRuleFile.txt

path-suffix(/box.json) -> set-error(404)
path-suffix(hidden.js) -> set-error(404)

Rules specified directly in the server.json or in an external JSON file must be escaped for the JSON they are a part of. Using a plain text external file can help readability since no additional escaping is required for the rules.

config setting server.defaults Rules

Like all other config server defaults, they follow the same pattern as the server.json file.

config set server.defaults.web.ruleFile=/path/to/rules.json

Commenting Out Rules

You can comment out any rule (whether it's in JSON or a text file) by proceeding it with a pound sign (#).

myRuleFile.txt

# Here is a comment that will be ignored

# The following rule also won't be run
# path-suffix(hidden.js) -> set-error(404)