GRAILS-11333: Handle already absolute URLs

grails-web-url-mappings/src/main/groovy/org/codehaus/groovy/grails/web/mapping/DefaultLinkGenerator.groovy

@@ -15,6 +15,8 @@
  */
 package org.codehaus.groovy.grails.web.mapping
 
+import java.util.regex.Pattern
+
 import grails.util.Environment
 import grails.util.GrailsNameUtils
 import grails.util.GrailsWebUtil
@@ -44,6 +46,8 @@ import org.springframework.http.HttpMethod
 @CompileStatic
 class DefaultLinkGenerator implements LinkGenerator, PluginManagerAware {
 
+    private static final Pattern absoluteUrlPattern = Pattern.compile('^[A-Za-z][A-Za-z0-9+\\-.]*:.*$')
+
     private static final Map<String, String> REST_RESOURCE_ACTION_TO_HTTP_METHOD_MAP = [
         create:"GET",
         save:"POST",
@@ -97,18 +101,19 @@ class DefaultLinkGenerator implements LinkGenerator, PluginManagerAware {
         def writer = new StringBuilder()
         // prefer URI attribute
         if (attrs.get(ATTRIBUTE_URI) != null) {
-            final base = handleAbsolute(attrs)
-            if (base != null) {
-                writer << base
-            }
-            else {
-                def cp = attrs.get(ATTRIBUTE_CONTEXT_PATH)
-                if (cp == null) cp = getContextPath()
-                if (cp != null) {
-                    writer << cp
+            def uri = attrs.get(ATTRIBUTE_URI).toString()
+            if(!isUriAbsolute(uri)){
+                final base = handleAbsolute(attrs)
+                if (base != null) {
+                    writer << base
+                }
+                else {
+                    def cp = attrs.get(ATTRIBUTE_CONTEXT_PATH)
+                    if (cp == null) cp = getContextPath()
+                    if (cp != null)
+                        writer << cp
                 }
             }
-            def uri = attrs.get(ATTRIBUTE_URI).toString()
             writer << uri
 
             def paramsAttribute = attrs.get(ATTRIBUTE_PARAMS)
@@ -364,6 +369,10 @@ class DefaultLinkGenerator implements LinkGenerator, PluginManagerAware {
         }
     }
 
+    private boolean isUriAbsolute(String uri) {
+        // not using new URI(uri).absolute in order to avoid create the URI object, which is slow
+        return absoluteUrlPattern.matcher(uri).matches()
+    }
 
     /**
      * Get the declared URL of the server from config, or guess at localhost for non-production.

grails-web-url-mappings/src/test/groovy/org/codehaus/groovy/grails/web/mapping/LinkGeneratorSpec.groovy

@@ -19,12 +19,27 @@ class LinkGeneratorSpec extends Specification {
 
     def baseUrl = "http://myserver.com/foo"
     def context = "/bar"
+    def someAbsoluteUrl = "http://www.grails.org/"
     def resource = null
     def linkParams = [:]
     def pluginManager
 
     def mainCssResource = [dir:'css', file:'main.css']
 
+    def "Test absolute link"() {
+        when:
+            linkParams.uri = someAbsoluteUrl
+            linkParams.absolute = true
+        then:
+            link == someAbsoluteUrl
+
+        when:
+            linkParams.uri = someAbsoluteUrl
+
+        then:
+            link == someAbsoluteUrl
+    }
+
     def "Test create link with root URI"() {
         when:
             linkParams.uri = '/'
@@ -307,4 +322,4 @@ class Widget {
     String toString() {
         name
     }
-}
+}