[TT-13507] Fix for custom domains with substring listen path (#6705)

### **User description**
Actual fix for domain matching edge case related to substring listen
paths. Fixed the sorting function for the listen paths and added some
unit tests.


Extra: httpbin service not working on macos with apple silicon; now it
does

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## Description

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## Related Issue

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issue first. -->
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## Motivation and Context

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## How This Has Been Tested

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## Types of changes

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- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
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- [ ] Refactoring or add test (improvements in base code or adds test
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- [ ] I ensured that the documentation is up to date
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___

### **PR Type**
Bug fix, Configuration changes


___

### **Description**
- Fixed the domain sorting logic in the API loader by changing the
comparison from domain length to lexicographical order to ensure correct
domain matching.
- Updated the Docker configuration for the httpbin service to specify
the platform as `linux/amd64`, addressing compatibility issues on macOS
with Apple Silicon.



___



### **Changes walkthrough** 📝
<table><thead><tr><th></th><th align="left">Relevant
files</th></tr></thead><tbody><tr><td><strong>Bug
fix</strong></td><td><table>
<tr>
  <td>
    <details>
<summary><strong>api_loader.go</strong><dd><code>Fix domain sorting
logic in API loader</code>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; </dd></summary>
<hr>

gateway/api_loader.go

<li>Modified sorting logic for API specs by domain.<br> <li> Changed
comparison from domain length to lexicographical order.<br>


</details>


  </td>
<td><a
href="https://github.com/TykTechnologies/tyk/pull/6705/files#diff-cdf0b7f176c9d18e1a314b78ddefc2cb3a94b3de66f1f360174692c915734c68">+1/-1</a>&nbsp;
&nbsp; &nbsp; </td>

</tr>
</table></td></tr><tr><td><strong>Configuration
changes</strong></td><td><table>
<tr>
  <td>
    <details>
<summary><strong>httpbin.yml</strong><dd><code>Specify platform for
httpbin service in Docker configuration</code></dd></summary>
<hr>

docker/services/httpbin.yml

- Added platform specification for httpbin service.



</details>


  </td>
<td><a
href="https://github.com/TykTechnologies/tyk/pull/6705/files#diff-1a1b1d8bf4798076a41ca5f3bba0d465dc387e58b6593adbb28a4d5fe60eb810">+1/-0</a>&nbsp;
&nbsp; &nbsp; </td>

</tr>
</table></td></tr></tr></tbody></table>

___

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docker/services/httpbin.yml

@@ -2,6 +2,7 @@
 services:
   httpbin:
     image: tykio/ci-tools:latest
+    platform: linux/amd64
     networks:
       - proxy
     ports:

gateway/api_loader.go

@@ -924,21 +924,28 @@ func (gw *Gateway) loadGraphQLPlayground(spec *APISpec, subrouter *mux.Router) {
 	})
 }
 
+func sortSpecsByListenPath(specs []*APISpec) {
+	// sort by listen path from longer to shorter, so that /foo
+	// doesn't break /foo-bar
+	sort.Slice(specs, func(i, j int) bool {
+		// we sort by the following rules:
+		// - decreasing order of listen path length
+		// - if a domain is empty it should be at the end
+		if (specs[i].Domain == "") != (specs[j].Domain == "") {
+			return specs[i].Domain != ""
+		}
+		return len(specs[i].Proxy.ListenPath) > len(specs[j].Proxy.ListenPath)
+	})
+}
+
 // Create the individual API (app) specs based on live configurations and assign middleware
 func (gw *Gateway) loadApps(specs []*APISpec) {
 	mainLog.Info("Loading API configurations.")
 
 	tmpSpecRegister := make(map[string]*APISpec)
 	tmpSpecHandles := new(sync.Map)
 
-	// sort by listen path from longer to shorter, so that /foo
-	// doesn't break /foo-bar
-	sort.Slice(specs, func(i, j int) bool {
-		if specs[i].Domain != specs[j].Domain {
-			return len(specs[i].Domain) > len(specs[j].Domain)
-		}
-		return len(specs[i].Proxy.ListenPath) > len(specs[j].Proxy.ListenPath)
-	})
+	sortSpecsByListenPath(specs)
 
 	// Create a new handler for each API spec
 	apisByListen := countApisByListenHash(specs)