Feature/issue 209 upstream host based routing (#216)

* from messing around at lunch...initial hacking seems to sort of work..need to think of all the test scenarios

* drunken train hacking

* docs for upstreamhost

src/Ocelot/Configuration/Builder/ReRouteBuilder.cs

@@ -10,7 +10,7 @@ namespace Ocelot.Configuration.Builder
     public class ReRouteBuilder
     {
         private AuthenticationOptions _authenticationOptions;
-        private string _loadBalancerKey;
+        private string _reRouteKey;
         private string _downstreamPathTemplate;
         private string _upstreamTemplate;
         private UpstreamPathTemplate _upstreamTemplatePattern;
@@ -36,6 +36,7 @@ namespace Ocelot.Configuration.Builder
         private List<HeaderFindAndReplace> _upstreamHeaderFindAndReplace;
         private List<HeaderFindAndReplace> _downstreamHeaderFindAndReplace;
         private readonly List<DownstreamHostAndPort> _downstreamAddresses;
+        private string _upstreamHost;
 
         public ReRouteBuilder()
         {
@@ -48,6 +49,12 @@ namespace Ocelot.Configuration.Builder
             return this;
         }
 
+        public ReRouteBuilder WithUpstreamHost(string upstreamAddresses)
+        {
+            _upstreamHost = upstreamAddresses;
+            return this;
+        }
+
         public ReRouteBuilder WithLoadBalancer(string loadBalancer)
         {
           _loadBalancer = loadBalancer;
@@ -150,9 +157,9 @@ namespace Ocelot.Configuration.Builder
             return this;
         }
        
-        public ReRouteBuilder WithReRouteKey(string loadBalancerKey)
+        public ReRouteBuilder WithReRouteKey(string reRouteKey)
         {
-            _loadBalancerKey = loadBalancerKey;
+            _reRouteKey = reRouteKey;
             return this;
         }
 
@@ -204,6 +211,7 @@ namespace Ocelot.Configuration.Builder
             return this;
         }
 
+
         public ReRoute Build()
         {
             return new ReRoute(
@@ -223,7 +231,7 @@ namespace Ocelot.Configuration.Builder
                 _fileCacheOptions, 
                 _downstreamScheme, 
                 _loadBalancer,
-                _loadBalancerKey, 
+                _reRouteKey, 
                 _useQos, 
                 _qosOptions,
                 _enableRateLimiting,
@@ -233,7 +241,8 @@ namespace Ocelot.Configuration.Builder
                 _serviceName,
                 _upstreamHeaderFindAndReplace,
                 _downstreamHeaderFindAndReplace,
-                _downstreamAddresses);
+                _downstreamAddresses,
+                _upstreamHost);
         }
     }
 }

src/Ocelot/Configuration/Creator/FileOcelotConfigurationCreator.cs

@@ -166,6 +166,7 @@ namespace Ocelot.Configuration.Creator
                 .WithUseServiceDiscovery(fileReRoute.UseServiceDiscovery)
                 .WithUpstreamHeaderFindAndReplace(hAndRs.Upstream)
                 .WithDownstreamHeaderFindAndReplace(hAndRs.Downstream)
+                .WithUpstreamHost(fileReRoute.UpstreamHost)
                 .Build();
 
             return reRoute;

src/Ocelot/Configuration/File/FileReRoute.cs

@@ -42,5 +42,6 @@ namespace Ocelot.Configuration.File
         public FileHttpHandlerOptions HttpHandlerOptions { get; set; }
         public bool UseServiceDiscovery {get;set;}
         public List<FileHostAndPort> DownstreamHostAndPorts {get;set;}
+        public string UpstreamHost { get; set; }
     }
 }

src/Ocelot/Configuration/ReRoute.cs

@@ -33,15 +33,17 @@ namespace Ocelot.Configuration
             string serviceName,
             List<HeaderFindAndReplace> upstreamHeadersFindAndReplace,
             List<HeaderFindAndReplace> downstreamHeadersFindAndReplace,
-            List<DownstreamHostAndPort> downstreamAddresses)
+            List<DownstreamHostAndPort> downstreamAddresses,
+            string upstreamHost)
         {
-            DownstreamHeadersFindAndReplace = downstreamHeadersFindAndReplace;
-            UpstreamHeadersFindAndReplace = upstreamHeadersFindAndReplace;
+            UpstreamHost = upstreamHost;
+            DownstreamHeadersFindAndReplace = downstreamHeadersFindAndReplace ?? new List<HeaderFindAndReplace>();
+            UpstreamHeadersFindAndReplace = upstreamHeadersFindAndReplace ?? new List<HeaderFindAndReplace>();
             ServiceName = serviceName;
             UseServiceDiscovery = useServiceDiscovery;
             ReRouteKey = reRouteKey;
             LoadBalancer = loadBalancer;
-            DownstreamAddresses = downstreamAddresses;
+            DownstreamAddresses = downstreamAddresses ?? new List<DownstreamHostAndPort>();
             DownstreamPathTemplate = downstreamPathTemplate;
             UpstreamPathTemplate = upstreamPathTemplate;
             UpstreamHttpMethod = upstreamHttpMethod;
@@ -53,12 +55,9 @@ namespace Ocelot.Configuration
             RequestIdKey = requestIdKey;
             IsCached = isCached;
             CacheOptions = cacheOptions;
-            ClaimsToQueries = claimsToQueries
-                ?? new List<ClaimToThing>();
-            ClaimsToClaims = claimsToClaims 
-                ?? new List<ClaimToThing>();
-            ClaimsToHeaders = claimsToHeaders 
-                ?? new List<ClaimToThing>();
+            ClaimsToQueries = claimsToQueries ?? new List<ClaimToThing>();
+            ClaimsToClaims = claimsToClaims ?? new List<ClaimToThing>();
+            ClaimsToHeaders = claimsToHeaders ?? new List<ClaimToThing>();
             DownstreamScheme = downstreamScheme;
             IsQos = isQos;
             QosOptionsOptions = qosOptions;
@@ -94,6 +93,6 @@ namespace Ocelot.Configuration
         public List<HeaderFindAndReplace> UpstreamHeadersFindAndReplace {get;private set;}
         public List<HeaderFindAndReplace> DownstreamHeadersFindAndReplace {get;private set;}
         public List<DownstreamHostAndPort> DownstreamAddresses {get;private set;}
-
+        public string UpstreamHost { get; private set; }
     }
 }

src/Ocelot/Configuration/Validator/FileConfigurationFluentValidator.cs

@@ -39,7 +39,8 @@ namespace Ocelot.Configuration.Validator
 
         private static bool IsNotDuplicateIn(FileReRoute reRoute, List<FileReRoute> reRoutes)
         {
-            var matchingReRoutes = reRoutes.Where(r => r.UpstreamPathTemplate == reRoute.UpstreamPathTemplate).ToList();
+            var matchingReRoutes = reRoutes
+                .Where(r => r.UpstreamPathTemplate == reRoute.UpstreamPathTemplate && (r.UpstreamHost != reRoute.UpstreamHost || reRoute.UpstreamHost == null)).ToList();
 
             if(matchingReRoutes.Count == 1)
             {

src/Ocelot/DownstreamRouteFinder/Finder/DownstreamRouteFinder.cs

@@ -13,44 +13,56 @@ namespace Ocelot.DownstreamRouteFinder.Finder
     public class DownstreamRouteFinder : IDownstreamRouteFinder
     {
         private readonly IUrlPathToUrlTemplateMatcher _urlMatcher;
-        private readonly IPlaceholderNameAndValueFinder __placeholderNameAndValueFinder;
+        private readonly IPlaceholderNameAndValueFinder _placeholderNameAndValueFinder;
 
         public DownstreamRouteFinder(IUrlPathToUrlTemplateMatcher urlMatcher, IPlaceholderNameAndValueFinder urlPathPlaceholderNameAndValueFinder)
         {
             _urlMatcher = urlMatcher;
-            __placeholderNameAndValueFinder = urlPathPlaceholderNameAndValueFinder;
+            _placeholderNameAndValueFinder = urlPathPlaceholderNameAndValueFinder;
         }
 
-        public Response<DownstreamRoute> FindDownstreamRoute(string path, string httpMethod, IOcelotConfiguration configuration)
+        public Response<DownstreamRoute> FindDownstreamRoute(string path, string httpMethod, IOcelotConfiguration configuration, string upstreamHost)
         {
-            var applicableReRoutes = configuration.ReRoutes.Where(r => r.UpstreamHttpMethod.Count == 0 || r.UpstreamHttpMethod.Select(x => x.Method.ToLower()).Contains(httpMethod.ToLower())).OrderByDescending(x => x.UpstreamTemplatePattern.Priority);
+            var downstreamRoutes = new List<DownstreamRoute>();
+
+            var applicableReRoutes = configuration.ReRoutes
+                .Where(r => RouteIsApplicableToThisRequest(r, httpMethod, upstreamHost))
+                .OrderByDescending(x => x.UpstreamTemplatePattern.Priority);
 
             foreach (var reRoute in applicableReRoutes)
             {
-                if (path == reRoute.UpstreamTemplatePattern.Template)
-                {
-                    return GetPlaceholderNamesAndValues(path, reRoute);
-                }
-
                 var urlMatch = _urlMatcher.Match(path, reRoute.UpstreamTemplatePattern.Template);
 
                 if (urlMatch.Data.Match)
                 {
-                    return GetPlaceholderNamesAndValues(path, reRoute);
+                    downstreamRoutes.Add(GetPlaceholderNamesAndValues(path, reRoute));
                 }
             }
-        
+
+            if (downstreamRoutes.Any())
+            {
+                var notNullOption = downstreamRoutes.FirstOrDefault(x => !string.IsNullOrEmpty(x.ReRoute.UpstreamHost));
+                var nullOption = downstreamRoutes.FirstOrDefault(x => string.IsNullOrEmpty(x.ReRoute.UpstreamHost));
+
+                return notNullOption != null ? new OkResponse<DownstreamRoute>(notNullOption) : new OkResponse<DownstreamRoute>(nullOption);
+            }
+
             return new ErrorResponse<DownstreamRoute>(new List<Error>
             {
                 new UnableToFindDownstreamRouteError()
             });
         }
 
-        private OkResponse<DownstreamRoute> GetPlaceholderNamesAndValues(string path, ReRoute reRoute)
+        private bool RouteIsApplicableToThisRequest(ReRoute reRoute, string httpMethod, string upstreamHost)
         {
-            var templatePlaceholderNameAndValues = __placeholderNameAndValueFinder.Find(path, reRoute.UpstreamPathTemplate.Value);
+            return reRoute.UpstreamHttpMethod.Count == 0 || reRoute.UpstreamHttpMethod.Select(x => x.Method.ToLower()).Contains(httpMethod.ToLower()) && !(!string.IsNullOrEmpty(reRoute.UpstreamHost) && reRoute.UpstreamHost != upstreamHost);
+        }
 
-            return new OkResponse<DownstreamRoute>(new DownstreamRoute(templatePlaceholderNameAndValues.Data, reRoute));
+        private DownstreamRoute GetPlaceholderNamesAndValues(string path, ReRoute reRoute)
+        {
+            var templatePlaceholderNameAndValues = _placeholderNameAndValueFinder.Find(path, reRoute.UpstreamPathTemplate.Value);
+
+            return new DownstreamRoute(templatePlaceholderNameAndValues.Data, reRoute);
         }
     }
-}
+}

src/Ocelot/DownstreamRouteFinder/Finder/IDownstreamRouteFinder.cs

@@ -6,6 +6,6 @@ namespace Ocelot.DownstreamRouteFinder.Finder
 {
     public interface IDownstreamRouteFinder
     {
-        Response<DownstreamRoute> FindDownstreamRoute(string upstreamUrlPath, string upstreamHttpMethod, IOcelotConfiguration configuration);
+        Response<DownstreamRoute> FindDownstreamRoute(string upstreamUrlPath, string upstreamHttpMethod, IOcelotConfiguration configuration, string upstreamHost);
     }
 }

src/Ocelot/DownstreamRouteFinder/Middleware/DownstreamRouteFinderMiddleware.cs

@@ -36,6 +36,8 @@ namespace Ocelot.DownstreamRouteFinder.Middleware
         {
             var upstreamUrlPath = context.Request.Path.ToString();
 
+            var upstreamHost = context.Request.Headers["Host"];
+
             var configuration = await _configProvider.Get(); 
             
             if(configuration.IsError)
@@ -49,7 +51,7 @@ namespace Ocelot.DownstreamRouteFinder.Middleware
 
             _logger.LogDebug("upstream url path is {upstreamUrlPath}", upstreamUrlPath);
 
-            var downstreamRoute = _downstreamRouteFinder.FindDownstreamRoute(upstreamUrlPath, context.Request.Method, configuration.Data);
+            var downstreamRoute = _downstreamRouteFinder.FindDownstreamRoute(upstreamUrlPath, context.Request.Method, configuration.Data, upstreamHost);
 
             if (downstreamRoute.IsError)
             {
@@ -66,4 +68,4 @@ namespace Ocelot.DownstreamRouteFinder.Middleware
             await _next.Invoke(context);
         }
     }
-}
+}