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Fix Twilio request validation URL scheme mismatch #337

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Merged
ucswift merged 1 commit into from
Apr 21, 2026
Merged

Fix Twilio request validation URL scheme mismatch #337

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5 changes: 5 additions & 0 deletions Web/Resgrid.Web.Services/Startup.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,11 @@ public void ConfigureServices(IServiceCollection services)
{
options.AuthToken = NumberProviderConfig.TwilioAuthToken;
options.AllowLocal = false;
// BaseUrlOverride ensures the URL used for signature validation matches
// what Twilio used when signing the request, regardless of any scheme
// override applied by upstream middleware (e.g. http → https rewrites).
if (!string.IsNullOrWhiteSpace(Config.SystemBehaviorConfig.ResgridApiBaseUrl))
options.BaseUrlOverride = Config.SystemBehaviorConfig.ResgridApiBaseUrl;
Comment on lines +171 to +172

@coderabbitai coderabbitai Bot Apr 21, 2026

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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Find the default and any checked-in overrides. Expected: Twilio-enabled environments
# should provide a non-placeholder absolute http(s) ResgridApiBaseUrl.
rg -n -C2 'ResgridApiBaseUrl\s*='
rg -n -C2 'ResgridApiBaseUrl|RESGRID.*API.*BASE|Twilio(AuthToken|ApiUrl|Voice)' --iglob '*.json' --iglob '*.config' --iglob '*.cs'

Repository: Resgrid/Core

Length of output: 39189

Reject the placeholder Twilio base URL to prevent webhook validation failures.

The condition on line 171 is always true because SystemBehaviorConfig.ResgridApiBaseUrl defaults to https://resgridapi.local, a non-empty, non-whitespace string. When Twilio.AspNet.Core uses BaseUrlOverride for webhook signature validation, any environment with Twilio enabled but without an explicit public base URL will validate against https://resgridapi.local/api/Twilio/... instead of the actual public URL Twilio signed, causing all webhook requests to be rejected.

Replace the guard to explicitly validate that a real public URL is configured:

Proposed fix 
-			if (!string.IsNullOrWhiteSpace(Config.SystemBehaviorConfig.ResgridApiBaseUrl))
-				options.BaseUrlOverride = Config.SystemBehaviorConfig.ResgridApiBaseUrl;
+			var baseUrlOverride = Config.SystemBehaviorConfig.ResgridApiBaseUrl?.Trim();
+			if (!string.IsNullOrWhiteSpace(NumberProviderConfig.TwilioAuthToken))
+			{
+				if (string.IsNullOrWhiteSpace(baseUrlOverride) ||
+					string.Equals(baseUrlOverride, "https://resgridapi.local", StringComparison.OrdinalIgnoreCase) ||
+					!Uri.TryParse(baseUrlOverride, UriKind.Absolute, out var baseUri) ||
+					(baseUri.Scheme != Uri.UriSchemeHttp && baseUri.Scheme != Uri.UriSchemeHttps))
+				{
+					throw new InvalidOperationException("SystemBehaviorConfig.ResgridApiBaseUrl must be set to the public Twilio webhook base URL when Twilio request validation is enabled.");
+				}
+
+				options.BaseUrlOverride = baseUrlOverride.TrimEnd('/');
+			}
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@Web/Resgrid.Web.Services/Startup.cs` around lines 171 - 172, The current
guard always sets options.BaseUrlOverride because
Config.SystemBehaviorConfig.ResgridApiBaseUrl defaults to the placeholder
"https://resgridapi.local"; change the condition so BaseUrlOverride is only set
when a real public URL is configured (e.g., non-empty AND not the placeholder).
Update the Startup.cs block that references
Config.SystemBehaviorConfig.ResgridApiBaseUrl and options.BaseUrlOverride to
check that ResgridApiBaseUrl is not null/whitespace and not equal to
"https://resgridapi.local" (and optionally not localhost/127.0.0.1 variants)
before assigning options.BaseUrlOverride.

});

services.AddApiVersioning(x =>
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