If imageprint fails due to errors like name resolution failure, also …

…inform user of that

e.g. 'Failed to download (NameResolutionFailure) from http://nonexistentdomain.com/aaa/images1.png'

MCGalaxy/Network/Utils/HttpUtil.cs

@@ -11,7 +11,7 @@
 BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 or implied. See the Licenses for the specific language governing
 permissions and limitations under the Licenses.
-*/
+ */
 using System;
 using System.Net;
 
@@ -96,49 +96,55 @@ class CustomWebClient : WebClient {
             url = url.Replace("dl.dropboxusercontent.com", "dl.dropbox.com");
         }
 
-        static string CheckHttpOrHttps(string url) {
+        static bool CheckHttpOrHttps(Player p, string url) {
             Uri uri;
             // only check valid URLs here
-            if (!url.Contains("://")) return null;
-            if (!Uri.TryCreate(url, UriKind.Absolute, out uri)) return null;
+            if (!url.Contains("://")) return true;
+            if (!Uri.TryCreate(url, UriKind.Absolute, out uri)) return true;
 
             string scheme = uri.Scheme;
-            if (scheme.CaselessEq("http") || scheme.CaselessEq("https")) return null;
-            return scheme;
+            if (scheme.CaselessEq("http") || scheme.CaselessEq("https")) return true;
+
+            p.Message("%WOnly http:// or https:// urls are supported, " +
+                      "{0} is a {1}:// url", url, scheme);
+            return false;
         }
 
         /// <summary> Prefixes a URL by http:// if needed, and converts dropbox webpages to direct links. </summary>
         /// <remarks> Ensures URL is a valid http/https URI. </remarks>
         public static Uri GetUrl(Player p, ref string url) {
             Uri uri;
-            string scheme = CheckHttpOrHttps(url);
-            if (scheme != null) {
-            	p.Message("%WOnly http:// or https:// urls are supported, " +
-            	          "{0} is a {1}:// url", url, scheme);
-            	return null;
-            }
-
+            if (!CheckHttpOrHttps(p, url)) return null;
             FilterURL(ref url);
+
             if (!Uri.TryCreate(url, UriKind.Absolute, out uri)) {
                 p.Message("%W{0} is not a valid URL.", url); return null;
             }
             return uri;
         }
 
-        static int GetHttpStatus(Exception ex) {
+        static string DescribeError(Exception ex) {
             try {
                 WebException webEx = (WebException)ex;
-                return (int)((HttpWebResponse)webEx.Response).StatusCode;
+                // prefer explicit http status error codes if possible
+                try {
+                    int status = (int)((HttpWebResponse)webEx.Response).StatusCode;
+                    return "(" + status + " error) from &f{0}";
+                } catch {
+                    return "(" + webEx.Status + ") from &f{0}";
+                }
             } catch {
-                // exception was not webexception, or couldn't get status code
-                return -1; 
+                return "from &f{0}";
             }
         }
 
         public static byte[] DownloadData(string url, Player p) {
             Uri uri = GetUrl(p, ref url);
             if (uri == null) return null;
-
+            return DownloadData(p, url, uri);
+        }
+
+        static byte[] DownloadData(Player p, string url, Uri uri) {
             byte[] data = null;
             try {
                 using (WebClient client = CreateWebClient()) {
@@ -147,18 +153,20 @@ class CustomWebClient : WebClient {
                 }
                 p.Message("Finished downloading.");
             } catch (Exception ex) {
-                int status = GetHttpStatus(ex);
                 Logger.LogError("Error downloading " + url, ex);
+                string msg = DescribeError(ex);
 
-                string msg = status == -1 ? "from &f{0}" : "({1} error) from &f{0}";
-                p.Message("%WFailed to download " + msg, url, status);
+                p.Message("%WFailed to download " + msg, url);
                 return null;
             }
             return data;
         }
 
         public static byte[] DownloadImage(string url, Player p) {
-            byte[] data = DownloadData(url, p);
+            Uri uri = GetUrl(p, ref url);
+            if (uri == null) return null;
+
+            byte[] data = DownloadData(p, url, uri);
             if (data == null) p.Message("%WThe url may need to end with its extension (such as .jpg).");
             return data;
         }