support host port split of template functions (#1244)

docs/07.Reference/7.02.Filters.md

@@ -2097,6 +2097,9 @@ package, and extra functions defined by Easegress:
  a URL query, equivalent to the `urlquery` template function.
 * **urlQueryUnescape**: performs the inverse transformation of `urlQueryEscape`,
  decoding a URL-encoded string back to its origin form.
+* **host**: host splits a network address of the form "host:port" and return host part by using `net.SplitHostPort`.
+* **port**: port splits a network address of the form "host:port" and return port part by using `net.SplitHostPort`.
+
 
 Easegress injects existing requests/responses of the current context into
 the template engine at runtime, so we can use `.requests.<namespace>.<field>`

pkg/filters/builder/extrafuncs.go

@@ -20,6 +20,7 @@ package builder
 import (
  "encoding/json"
  "fmt"
+ "net"
  "net/http"
  "net/url"
  "strconv"
@@ -156,6 +157,16 @@ var extraFuncs = template.FuncMap{
  return username
  },
 
+ "host": func(hostPort string) string {
+ addr, _, _ := net.SplitHostPort(hostPort)
+ return addr
+ },
+
+ "port": func(hostPort string) string {
+ _, port, _ := net.SplitHostPort(hostPort)
+ return port
+ },
+
  "urlQueryUnescape": func(s string) string {
  unescapedStr, err := url.QueryUnescape(s)
  if err != nil {