Retry failed web requests, fix install stanza error

Core/Net/Net.cs

@@ -5,10 +5,11 @@
 using System.Net;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using Autofac;
 using ChinhDo.Transactions.FileManager;
-using CKAN.Configuration;
 using log4net;
+using CKAN.Configuration;
 
 namespace CKAN
 {
@@ -21,6 +22,9 @@ public class Net
         // The user agent that we report to web sites
         public static string UserAgentString = "Mozilla/4.0 (compatible; CKAN)";
 
+        private const int MaxRetries             = 3;
+        private const int RetryDelayMilliseconds = 100;
+
         private static readonly ILog          log             = LogManager.GetLogger(typeof(Net));
 
         public static readonly Dictionary<string, Uri> ThrottledHosts = new Dictionary<string, Uri>()
@@ -211,12 +215,27 @@ public static string DownloadText(Uri url, string authToken = "", string mimeTyp
                 agent.Headers.Add("Accept", mimeType);
             }
 
-            string content = agent.DownloadString(url.OriginalString);
-            string header  = agent.ResponseHeaders.ToString();
+            for (int whichAttempt = 0; whichAttempt < MaxRetries + 1; ++whichAttempt)
+            {
+                try
+                {
+                    string content = agent.DownloadString(url.OriginalString);
+                    string header  = agent.ResponseHeaders.ToString();
 
-            log.DebugFormat("Response from {0}:\r\n\r\n{1}\r\n{2}", url, header, content);
+                    log.DebugFormat("Response from {0}:\r\n\r\n{1}\r\n{2}", url, header, content);
 
-            return content;
+                    return content;
+                }
+                catch (WebException wex) when (wex.Status != WebExceptionStatus.ProtocolError && whichAttempt < MaxRetries)
+                {
+                    log.DebugFormat("Web request failed with non-protocol error, retrying in {0} milliseconds: {1}", RetryDelayMilliseconds * whichAttempt, wex.Message);
+                    Thread.Sleep(RetryDelayMilliseconds * whichAttempt);
+                }
+            }
+            // Should never get here, because we don't catch any exceptions
+            // in the final iteration of the above for loop. They should be
+            // thrown to the calling code, or the call should succeed.
+            return null;
         }
 
         public static Uri ResolveRedirect(Uri uri)

Core/Types/CkanModule.cs

@@ -646,9 +646,16 @@ public override string ToString()
         public string DescribeInstallStanzas()
         {
             List<string> descriptions = new List<string>();
-            foreach (ModuleInstallDescriptor mid in install)
+            if (install != null)
             {
-                descriptions.Add(mid.DescribeMatch());
+                foreach (ModuleInstallDescriptor mid in install)
+                {
+                    descriptions.Add(mid.DescribeMatch());
+                }
+            }
+            else
+            {
+                descriptions.Add(ModuleInstallDescriptor.DefaultInstallStanza(identifier).DescribeMatch());
             }
             return string.Join(", ", descriptions);
         }

Core/Types/ModuleInstallDescriptor.cs

@@ -418,7 +418,8 @@ public List<InstallableFile> FindInstallableFiles(ZipFile zipfile, KSP ksp)
                 : zipfile.Cast<ZipEntry>()
                     .Select(entry => inst_pattern.Match(entry.Name.Replace('\\', '/')))
                     .Where(match => match.Success)
-                    .Min(match => match.Index);
+                    .DefaultIfEmpty()
+                    .Min(match => match?.Index);
 
             // O(N^2) solution, as we're walking the zipfile for each stanza.
             // Surely there's a better way, although this is fast enough we may not care.

Netkan/Transformers/AvcTransformer.cs

@@ -94,7 +94,7 @@ public IEnumerable<Metadata> Transform(Metadata metadata, TransformOptions opts)
                         }
                         catch (Exception e)
                         {
-                            Log.WarnFormat("Error fetching remote version file: {0}", e.Message);
+                            Log.WarnFormat("Error fetching remote version file {0}: {1}", remoteUri, e.Message);
                             Log.Debug(e);
                         }
                     }