Add support for late binding to IP addresses using go-sockaddr/template

vendor/github.com/hashicorp/go-sockaddr/template/Makefile

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+test::
+	go test

vendor/github.com/hashicorp/go-sockaddr/template/README.md

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+# sockaddr/template
+
+sockaddr's template library.  See
+the
+[sockaddr/template](https://godoc.org/github.com/hashicorp/go-sockaddr/template)
+docs for details on how to use this template.

vendor/github.com/hashicorp/go-sockaddr/template/doc.go

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+/*
+
+Package sockaddr/template provides a text/template interface the SockAddr helper
+functions.  The primary entry point into the sockaddr/template package is
+through its Parse() call.  For example:
+
+    import (
+      "fmt"
+
+      template "github.com/hashicorp/go-sockaddr/template"
+    )
+
+    results, err := template.Parse(`{{ GetPrivateIP }}`)
+    if err != nil {
+      fmt.Errorf("Unable to find a private IP address: %v", err)
+    }
+    fmt.Printf("My Private IP address is: %s\n", results)
+
+Below is a list of builtin template functions and details re: their usage.  It
+is possible to add additional functions by calling ParseIfAddrsTemplate
+directly.
+
+In general, the calling convention for this template library is to seed a list
+of initial interfaces via one of the Get*Interfaces() calls, then filter, sort,
+and extract the necessary attributes for use as string input.  This template
+interface is primarily geared toward resolving specific values that are only
+available at runtime, but can be defined as a heuristic for execution when a
+config file is parsed.
+
+All functions, unless noted otherwise, return an array of IfAddr structs making
+it possible to `sort`, `filter`, `limit`, seek (via the `offset` function), or
+`unique` the list.  To extract useful string information, the `attr` and `join`
+functions return a single string value.  See below for details.
+
+Important note: see the
+https://github.com/hashicorp/go-sockaddr/tree/master/cmd/sockaddr utility for
+more examples and for a CLI utility to experiment with the template syntax.
+
+`GetAllInterfaces` - Returns an exhaustive set of IfAddr structs available on
+the host.  `GetAllInterfaces` is the initial input and accessible as the initial
+"dot" in the pipeline.
+
+Example:
+
+    {{ GetAllInterfaces }}
+
+
+`GetDefaultInterfaces` - Returns one IfAddr for every IP that is on the
+interface containing the default route for the host.
+
+Example:
+
+    {{ GetDefaultInterfaces }}
+
+`GetPrivateInterfaces` - Returns one IfAddr for every forwardable IP address
+that is included in RFC 6890, is attached to the interface with the default
+route, and whose interface is marked as up.  NOTE: RFC 6890 is a more exhaustive
+version of RFC1918 because it spans IPv4 and IPv6, however it does permit the
+inclusion of likely undesired addresses such as multicast, therefore our version
+of "private" also filters out non-forwardable addresses.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "up" }}
+
+
+`GetPublicInterfaces` - Returns a list of IfAddr that do not match RFC 6890, is
+attached to the default route, and whose interface is marked as up.
+
+Example:
+
+    {{ GetPublicInterfaces | include "flags" "up" }}
+
+
+`GetPrivateIP` - Helper function that returns a string of the first IP address
+from GetPrivateInterfaces.
+
+Example:
+
+    {{ GetPrivateIP }}
+
+
+`GetPublicIP` - Helper function that returns a string of the first IP from
+GetPublicInterfaces.
+
+Example:
+
+    {{ GetPublicIP }}
+
+`GetInterfaceIP` - Helper function that returns a string of the first IP from
+the named interface.
+
+Example:
+
+    {{ GetInterfaceIP }}
+
+
+`sort` - Sorts the IfAddrs result based on its arguments.  `sort` takes one
+argument, a list of ways to sort its IfAddrs argument.  The list of sort
+criteria is comma separated (`,`):
+  - `address`, `+address`: Ascending sort of IfAddrs by Address
+  - `-address`: Descending sort of IfAddrs by Address
+  - `name`, `+name`: Ascending sort of IfAddrs by lexical ordering of interface name
+  - `-name`: Descending sort of IfAddrs by lexical ordering of interface name
+  - `port`, `+port`: Ascending sort of IfAddrs by port number
+  - `-port`: Descending sort of IfAddrs by port number
+  - `private`, `+private`: Ascending sort of IfAddrs with private addresses first
+  - `-private`: Descending sort IfAddrs with private addresses last
+  - `size`, `+size`: Ascending sort of IfAddrs by their network size as determined
+    by their netmask (larger networks first)
+  - `-size`: Descending sort of IfAddrs by their network size as determined by their
+    netmask (smaller networks first)
+  - `type`, `+type`: Ascending sort of IfAddrs by the type of the IfAddr (Unix,
+    IPv4, then IPv6)
+  - `-type`: Descending sort of IfAddrs by the type of the IfAddr (IPv6, IPv4, Unix)
+
+Example:
+
+    {{ GetPrivateInterfaces | sort "type,size,address" }}
+
+
+`exclude` and `include`: Filters IfAddrs based on the selector criteria and its
+arguments.  Both `exclude` and `include` take two arguments.  The list of
+available filtering criteria is:
+  - "address": Filter IfAddrs based on a regexp matching the string representation
+    of the address
+  - "flag","flags": Filter IfAddrs based on the list of flags specified.  Multiple
+    flags can be passed together using the pipe character (`|`) to create an inclusive
+    bitmask of flags.  The list of flags is included below.
+  - "name": Filter IfAddrs based on a regexp matching the interface name.
+  - "network": Filter IfAddrs based on whether a netowkr is included in a given
+    CIDR.  More than one CIDR can be passed in if each network is separated by
+    the pipe character (`|`).
+  - "port": Filter IfAddrs based on an exact match of the port number (number must
+    be expressed as a string)
+  - "rfc", "rfcs": Filter IfAddrs based on the matching RFC.  If more than one RFC
+    is specified, the list of RFCs can be joined together using the pipe character (`|`).
+  - "size": Filter IfAddrs based on the exact match of the mask size.
+  - "type": Filter IfAddrs based on their SockAddr type.  Multiple types can be
+    specified together by using the pipe character (`|`).  Valid types include:
+    `ip`, `ipv4`, `ipv6`, and `unix`.
+
+Example:
+
+    {{ GetPrivateInterfaces | exclude "type" "IPv6" | include "flag" "up|forwardable" }}
+
+
+`unique`: Removes duplicate entries from the IfAddrs list, assuming the list has
+already been sorted.  `unique` only takes one argument:
+  - "address": Removes duplicates with the same address
+  - "name": Removes duplicates with the same interface names
+
+Example:
+
+    {{ GetPrivateInterfaces | sort "type,address" | unique "name" }}
+
+
+`limit`: Reduces the size of the list to the specified value.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | limit 1 }}
+
+
+`offset`: Seeks into the list by the specified value.  A negative value can be
+used to seek from the end of the list.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | offset "-2" | limit 1 }}
+
+
+`attr`: Extracts a single attribute of the first member of the list and returns
+it as a string.  `attr` takes a single attribute name.  The list of available
+attributes is type-specific and shared between `join`.  See below for a list of
+supported attributes.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | attr "address" }}
+
+
+`join`: Similar to `attr`, `join` extracts all matching attributes of the list
+and returns them as a string joined by the separator, the second argument to
+`join`.  The list of available attributes is type-specific and shared between
+`join`.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | join "address" " " }}
+
+
+`exclude` and `include` flags:
+  - `broadcast`
+  - `down`: Is the interface down?
+  - `forwardable`: Is the IP forwardable?
+  - `global unicast`
+  - `interface-local multicast`
+  - `link-local multicast`
+  - `link-local unicast`
+  - `loopback`
+  - `multicast`
+  - `point-to-point`
+  - `unspecified`: Is the IfAddr the IPv6 unspecified address?
+  - `up`: Is the interface up?
+
+
+Attributes for `attr` and `join`:
+
+SockAddr Type:
+  - `string`
+  - `type`
+
+IPAddr Type:
+  - `address`
+  - `binary`
+  - `first_usable`
+  - `hex`
+  - `host`
+  - `last_usable`
+  - `mask_bits`
+  - `netmask`
+  - `network`
+  - `octets`: Decimal values per byte
+  - `port`
+  - `size`: Number of hosts in the network
+
+IPv4Addr Type:
+  - `broadcast`
+  - `uint32`: unsigned integer representation of the value
+
+IPv6Addr Type:
+  - `uint128`: unsigned integer representation of the value
+
+UnixSock Type:
+  - `path`
+
+*/
+package template

vendor/github.com/hashicorp/go-sockaddr/template/template.go

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+package template
+
+import (
+	"bytes"
+	"fmt"
+	"text/template"
+
+	"github.com/hashicorp/errwrap"
+	sockaddr "github.com/hashicorp/go-sockaddr"
+)
+
+var (
+	// SourceFuncs is a map of all top-level functions that generate
+	// sockaddr data types.
+	SourceFuncs template.FuncMap
+
+	// SortFuncs is a map of all functions used in sorting
+	SortFuncs template.FuncMap
+
+	// FilterFuncs is a map of all functions used in sorting
+	FilterFuncs template.FuncMap
+
+	// HelperFuncs is a map of all functions used in sorting
+	HelperFuncs template.FuncMap
+)
+
+func init() {
+	SourceFuncs = template.FuncMap{
+		// GetAllInterfaces - Returns an exhaustive set of IfAddr
+		// structs available on the host.  `GetAllInterfaces` is the
+		// initial input and accessible as the initial "dot" in the
+		// pipeline.
+		"GetAllInterfaces": sockaddr.GetAllInterfaces,
+
+		// GetDefaultInterfaces - Returns one IfAddr for every IP that
+		// is on the interface containing the default route for the
+		// host.
+		"GetDefaultInterfaces": sockaddr.GetDefaultInterfaces,
+
+		// GetPrivateInterfaces - Returns one IfAddr for every IP that
+		// matches RFC 6890, are attached to the interface with the
+		// default route, and are forwardable IP addresses.  NOTE: RFC
+		// 6890 is a more exhaustive version of RFC1918 because it spans
+		// IPv4 and IPv6, however it doespermit the inclusion of likely
+		// undesired addresses such as multicast, therefore our
+		// definition of a "private" address also excludes
+		// non-forwardable IP addresses (as defined by the IETF).
+		"GetPrivateInterfaces": sockaddr.GetPrivateInterfaces,
+
+		// GetPublicInterfaces - Returns a list of IfAddr that do not
+		// match RFC 6890, are attached to the default route, and are
+		// forwardable.
+		"GetPublicInterfaces": sockaddr.GetPublicInterfaces,
+	}
+
+	SortFuncs = template.FuncMap{
+		"sort": sockaddr.SortIfBy,
+	}
+
+	FilterFuncs = template.FuncMap{
+		"exclude": sockaddr.ExcludeIfs,
+		"include": sockaddr.IncludeIfs,
+	}
+
+	HelperFuncs = template.FuncMap{
+		// Misc functions that operate on IfAddrs inputs
+		"attr":   sockaddr.IfAttr,
+		"join":   sockaddr.JoinIfAddrs,
+		"limit":  sockaddr.LimitIfAddrs,
+		"offset": sockaddr.OffsetIfAddrs,
+		"unique": sockaddr.UniqueIfAddrsBy,
+
+		// Return a Private RFC 6890 IP address string that is attached
+		// to the default route and a forwardable address.
+		"GetPrivateIP": sockaddr.GetPrivateIP,
+
+		// Return a Public RFC 6890 IP address string that is attached
+		// to the default route and a forwardable address.
+		"GetPublicIP": sockaddr.GetPublicIP,
+
+		// Return the first IP address of the named interface, sorted by
+		// the largest network size.
+		"GetInterfaceIP": sockaddr.GetInterfaceIP,
+	}
+}
+
+// Parse parses input as template input using the addresses available on the
+// host, then returns the string output if there are no errors.
+func Parse(input string) (string, error) {
+	addrs, err := sockaddr.GetAllInterfaces()
+	if err != nil {
+		return "", errwrap.Wrapf("unable to query interface addresses: {{err}}", err)
+	}
+
+	return ParseIfAddrs(input, addrs)
+}
+
+// ParseIfAddrs parses input as template input using the IfAddrs inputs, then
+// returns the string output if there are no errors.
+func ParseIfAddrs(input string, ifAddrs sockaddr.IfAddrs) (string, error) {
+	return ParseIfAddrsTemplate(input, ifAddrs, template.New("sockaddr.Parse"))
+}
+
+// ParseIfAddrsTemplate parses input as template input using the IfAddrs inputs,
+// then returns the string output if there are no errors.
+func ParseIfAddrsTemplate(input string, ifAddrs sockaddr.IfAddrs, tmplIn *template.Template) (string, error) {
+	// Create a template, add the function map, and parse the text.
+	tmpl, err := tmplIn.Option("missingkey=error").
+		Funcs(SourceFuncs).
+		Funcs(SortFuncs).
+		Funcs(FilterFuncs).
+		Funcs(HelperFuncs).
+		Parse(input)
+	if err != nil {
+		return "", errwrap.Wrapf(fmt.Sprintf("unable to parse template %+q: {{err}}", input), err)
+	}
+
+	var outWriter bytes.Buffer
+	err = tmpl.Execute(&outWriter, ifAddrs)
+	if err != nil {
+		return "", errwrap.Wrapf(fmt.Sprintf("unable to execute sockaddr input %+q: {{err}}", input), err)
+	}
+
+	return outWriter.String(), nil
+}