Add functionality to parse multiple prefixes

Makefile

@@ -1,8 +1,12 @@
 render:
 			@for file in examples/xr-*.yaml; do \
+			 	echo ""; \
 				echo "Rendering $$file..."; \
 				crossplane beta render \
 					"$$file" \
 					apis/composition.yaml \
 					examples/functions.yaml; \
 			done
+
+debug:
+			go run . --insecure --debug

README.md

@@ -5,98 +5,119 @@ A [Crossplane](https://www.crossplane.io/)
 for calculating Classless Inter-Domain Routing
 ([CIDR](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing))
 numbers.
+
 A CIDR is an IP address allocation method that is used to improve
 data routing efficiency on the internet.
 
 ## Overview
 
-This composition function offers 4 HashiCorp compatible
-IP Network Functions plus one custom wrapper. Follow the
-function links for detailed explanations of the function
-semantics.
+This composition function offers 4 HashiCorp compatible IP Network Functions
+plus two custom wrappers. Follow the function links for detailed explanations of
+the function semantics.
+
 - [cidrhost](https://developer.hashicorp.com/terraform/language/functions/cidrhost)
 - [cidrnetmask](https://developer.hashicorp.com/terraform/language/functions/cidrnetmask)
 - [cidrsubnet](https://developer.hashicorp.com/terraform/language/functions/cidrsubnet)
 - [cidrsubnets](https://developer.hashicorp.com/terraform/language/functions/cidrsubnets)
 - cidrsubnetloop wraps [cidrsubnet](https://developer.hashicorp.com/terraform/language/functions/cidrsubnet)
+- multiprefixloop wraps [cidrsubnets](https://developer.hashicorp.com/terraform/language/functions/cidrsubnets)
 
 To use this function, apply the following
 [functions.yaml](examples/functions.yaml)
 to your Crossplane management cluster.
-```
+
+```bash
 cat <<EOF|kubectl apply -f -
 apiVersion: pkg.crossplane.io/v1beta1
 kind: Function
 metadata:
   name: upbound-function-cidr
 spec:
-  package: xpkg.upbound.io/upbound/function-cidr:v0.1.0
+  package: xpkg.upbound.io/upbound/function-cidr:v0.4.0
 EOF
 ```
+
 Call the function from a Crossplane composition as described below.
 
 ## Terminology
+
 The `cidrfunc` IP Network Functions have various input parameters.
 Below are brief descriptions for context.
 
 - `prefix` must be given in CIDR notation, as defined in [RFC 4632 section 3.1.](https://datatracker.ietf.org/doc/html/rfc4632#section-3.1)
-- `hostnum` is a whole number that can be represented as a binary integer with no more than the number of digits remaining in the address after the given prefix.
-- `newbits` is the number of additional bits with which to extend the prefix. For example, if given a prefix ending in /16 and a newbits value of 4, the resulting subnet address will have length /20.
-- `netnum` is a whole number that can be represented as a binary integer with no more than newbits binary digits, which will be used to populate the additional bits added to the prefix.
+- `hostnum` is a whole number that can be represented as a binary integer with
+  no more than the number of digits remaining in the address after the given
+  prefix.
+- `newbits` is the number of additional bits with which to extend the prefix.
+  For example, if given a prefix ending in /16 and a newbits value of 4, the
+  resulting subnet address will have length /20.
+- `netnum` is a whole number that can be represented as a binary integer with no
+  more than newbits binary digits, which will be used to populate the additional
+  bits added to the prefix.
 
 ## Usage
+
 Specify the `cidrfunc` calculation type in the composition function input.
+
 Valid values are as follows:
-```
+
+```yaml
 - cidrhost
 - cidrnetmask
 - cidrsubnet
 - cidrsubnets
 - cidrsubnetloop
+- multiprefixloop
 ```
-Specify a custom `outputfield` in the function input parameters
-when the output should appear at a different path
-than the respective `status.atFunction.cidr` sub field default path.
+
+Specify a custom `outputfield` in the function input parameters when the output
+should appear at a different path than the respective `status.atFunction.cidr`
+sub field default path.
 
 All `cidrfunc` IP Network Functions require a CIDR `prefix` as input.
-Provide the `prefix` directly in the
-function input or specify a `prefixfield` in the XR where
-the function shall pick up the `prefix` value.
 
-Function input field names ending in `field` indicate that
-the function shall read the field path value from the specified
-field path in the XR.
+Provide the `prefix` directly in the function input or specify a `prefixfield`
+in the XR where the function shall pick up the `prefix` value.
+
+Function input field names ending in `field` indicate that the function shall
+read the field path value from the specified field path in the XR.
 
 ### cidrhost
+
 The `cidrhost cidrfunc` requires a `hostnum` or `hostnumfield` as
 function input. `hostnum` is an integer.
 
 ### cidrnetmask
-The `cidrnetmask cidrfunc` does not require additional parameters
-beyond the `prefix`. The `prefix` can be read from an XR field
-when the `prefixField` path is specified in the function input
-instead of a `prefix` value.
+
+The `cidrnetmask cidrfunc` does not require additional parameters beyond the
+`prefix`. The `prefix` can be read from an XR field when the `prefixField` path
+is specified in the function input instead of a `prefix` value.
 
 ### cidrsubnet
-The `cidrhost cidrsubnet` reauires a `netnum` or `netnumfield`,
-and a `newbits` or `newbitsfield` as function input.
+
+The `cidrhost cidrsubnet` requires a `netnum` or `netnumfield`, and a `newbits`
+or `newbitsfield` as function input.
 
 `netNum` is an integer.
 `newBits` is one integer in an array of integers.
 
 ### cidrsubnets
-The `cidrhost cidrsubnets` reauires a `newBits`
- or `newBitsField` as function input.
+
+The `cidrhost cidrsubnets` requires a `newBits` or `newBitsField` as function
+input.
 
 `newBits` is an array of integers.
 
 ### cidrsubnetloop
+
 The `cidrhost cidrsubnetloop` reauires the following input fields.
+
 - `newBits` (integer array) or `newBitsField`
 - `netNumCount` (integer) or `netNumCountField`
 - `netNumItems` (string array) or `netNumItemsField`
 - `offset` or `offsetfield`
-** netNumCount and netNumItems are mutually exclusive **
+
+**`netNumCount` and `netNumItems` are mutually exclusive**
 
 The `cidrsubnetloop` wrapper calculates `cidrsubnet` CIDRs using
 the `prefix` and `newBits` parameters as input. It performs the
@@ -105,7 +126,27 @@ iteration from `iteration`+`offset`. The iterations are either from
 0 to `netNumCount` -1 or from 0 to number of items in `netNumItemsCount`
 or their respective values from their XR field references.
 
+### multiprefixloop
+
+This is an additional convenience function that takes a list of objects, each
+describing a cidr prefix to split and returns the result as a
+`map[string][]string` key'd on the prefix for that block.
+
+It is most useful for scenarios where your composition requires multiple cidr
+prefixes, such as splitting VPC additional CIDRs for subnet creation.
+
+The `multiprefixloop` function requires a list of inputs with each input
+containing:
+
+- `prefix` The CIDR prefix to create subnets for
+- `newBits` An integer array defining how to split the prefix
+- `offset` An optional bit size to start the subnet range after
+
+If `offset` is specified, this is prepended to the `newBits` field immediately
+before calculations and then removed after the calculation is completed.
+
 ## Testing The Function
+
 Clone the repo. Run `make debug` and in a second terminal run `make render`
-and examine the output. Corresponding compositions and XR yaml can be
-found in the `examples` folder.
+and examine the output. Corresponding compositions and XR yaml can be found in
+the `examples` folder.

apis/composition.yaml

@@ -14,10 +14,10 @@ spec:
       input:
         apiVersion: cidr.fn.crossplane.io/v1beta1
         kind: Parameters
-        cidrFunc: spec.parameters.cidrFunc
+        cidrFuncField: spec.parameters.cidrFunc
         prefixField: spec.parameters.cidrBlock
         newBitsField: spec.parameters.newBits
         netNumItemsField: spec.parameters.azs
         hostNumField: spec.parameters.hostNum
         offsetField: spec.parameters.offset
-        outputField: spec.parameters.output
+        multiPrefixField: spec.parameters.subnets

apis/definition.yaml

@@ -33,6 +33,18 @@ spec:
                         - cidrhost
                         - cidrnetmask
                         - cidrsubnetloop
+                        - multiprefixloop
+                    subnets:
+                      type: array
+                      items:
+                        type: object
+                        properties:
+                          prefix:
+                            type: string
+                          newBits:
+                            type: array
+                            items:
+                              type: integer
                     cidrBlock:
                       type: string
                     newBits:

examples/xr-cidrhost.yaml

@@ -7,4 +7,3 @@ spec:
     cidrFunc: cidrhost
     cidrBlock: 10.0.0.0/20
     hostNum: 111
-    output: status.atFunction.cidr.hostAddress

examples/xr-cidrnetmask.yaml

@@ -6,4 +6,3 @@ spec:
   parameters:
     cidrFunc: cidrnetmask
     cidrBlock: 172.16.0.0/12
-    output: status.atFunction.cidr.netmask

examples/xr-cidrsubnet.yaml

@@ -9,4 +9,3 @@ spec:
     newBits:
       - 8
     netNum: 3
-    output: status.atFunction.cidr.subnet-a

examples/xr-multicidrsubnetsloop.yaml

@@ -0,0 +1,20 @@
+apiVersion: platform.upbound.io/v1alpha1
+kind: XCIDR
+metadata:
+  name: cidr-multiprefixloop
+spec:
+  parameters:
+    cidrFunc: multiprefixloop
+    subnets:
+      - prefix: 10.0.0.0/20
+        newBits:
+        - 8
+        - 4
+        - 2
+      - prefix: 127.0.0.0/20
+        newBits: [
+          4, 4, 4,
+          4, 4, 4,
+          5, 5, 5,
+          5, 5, 5,
+        ]