F5 iRule Json parser

Simple Json library for the F5 iRules language to parse and decode Json.

This library is a rewrite of the Json parser from mongoose.

It can fetch Json tokens from any valid Json by JsonPath expressions.

Supported JsonPath operators

Only the dot-notation and a subset of operators are supported.

Operator	Description
$	The root element to query. This starts all path expressions.
.<name>	Dot-notated child.
[<number>]	Array index.

Usage

Save the json.irule file as an iRule named json. Do not attach it to any virtual server. It defines only some procs that can be called by other iRules.

# Json to parse
set json "{\"object1\": {\"key\":\"value\",\"array1\":\[{\"v1\":\"mem1\",\"v2\":\"mem2\"},{\"v3\":\"mem3\"}\],\"num1\":1},\"bool2\":true}"

# Set the JsonPath expression
set path "$.object1.key"

# Get the index and length of a token described by path.
# A positive return value represents the found index, a negative value describes an error:
#   -1: Json nesting is too deep
#   -2: Invalid Json
#   -3: Key not found
#   -4: Invalid/Unsupported JsonPath expression
set len -1 ; # This variable is populated with the length of the found token.
set idx [call json::json_get { $json $path len }]

# Get the token described by path.
# - String tokens are enclosed by quotes.
# - Array tokens are enclosed by square braces.
# - Object tokens are enclosed by curly braces.
set token [call json::json_get_tok { $json $path }]

# Get the type of the token.
# This is a simply lookup of the first char of the token.
# Type can be: string, array, object, false, true, null, number or invalid
set type [call json::json_get_type { $token }]

# Decodes a string token
set decoded [call json::json_decode_str { $token }]

Test

1. Create an iFile test-json from the test-json.ifile.
2. Attach the test.irule to a Virtual Server with an associated http profile.
3. Send a http request to it.

License

(C) 2024 Juergen Mang [email protected]

SPDX-License-Identifier: GPL-2.0-only