Add customer request headers to audit log (#637)

Add a feature to allow end users to add data to the audit logs by way of a custom HTTP header.

src/Microsoft.Health.Fhir.Api/Configs/FhirServerConfiguration.cs

@@ -18,5 +18,7 @@ public class FhirServerConfiguration
         public virtual CorsConfiguration Cors { get; } = new CorsConfiguration();
 
         public OperationsConfiguration Operations { get; } = new OperationsConfiguration();
+
+        public AuditConfiguration Audit { get; } = new AuditConfiguration();
     }
 }

src/Microsoft.Health.Fhir.Api/Controllers/AadSmartOnFhirProxyController.cs

@@ -152,7 +152,7 @@ public ActionResult Authorize(
             }
             catch (Exception ex)
             {
-                _logger.LogWarning(ex, "Redirect URL passed to Authorize failed to resolve.");
+                _logger.LogDebug(ex, "Redirect URL passed to Authorize failed to resolve.");
             }
 
             if (!_isAadV2 && !string.IsNullOrEmpty(aud))

src/Microsoft.Health.Fhir.Api/Features/Audit/AuditConstants.cs

@@ -0,0 +1,16 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+namespace Microsoft.Health.Fhir.Api.Features.Audit
+{
+    public static class AuditConstants
+    {
+        public const string CustomAuditHeaderKeyValue = "CustomAuditHeaderCollectionKeyValue";
+
+        public const int MaximumNumberOfCustomHeaders = 10;
+
+        public const int MaximumLengthOfCustomHeader = 2048;
+    }
+}

src/Microsoft.Health.Fhir.Api/Features/Audit/AuditHeaderException.cs

@@ -0,0 +1,22 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using Microsoft.Health.Fhir.Core.Exceptions;
+
+namespace Microsoft.Health.Fhir.Api.Features.Audit
+{
+    public class AuditHeaderException : FhirException
+    {
+        public AuditHeaderException(string headerName, int size)
+            : base(string.Format(Resources.CustomAuditHeaderTooLarge, AuditConstants.MaximumLengthOfCustomHeader, headerName, size))
+        {
+        }
+
+        public AuditHeaderException(int size)
+            : base(string.Format(Resources.TooManyCustomAuditHeaders, AuditConstants.MaximumNumberOfCustomHeaders, size))
+        {
+        }
+    }
+}

src/Microsoft.Health.Fhir.Api/Features/Audit/AuditHeaderReader.cs

@@ -0,0 +1,63 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using EnsureThat;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Options;
+using Microsoft.Extensions.Primitives;
+using Microsoft.Health.Fhir.Core.Configs;
+
+namespace Microsoft.Health.Fhir.Api.Features.Audit
+{
+    public class AuditHeaderReader : IAuditHeaderReader
+    {
+        private readonly AuditConfiguration _auditConfiguration;
+
+        public AuditHeaderReader(IOptions<AuditConfiguration> auditConfiguration)
+        {
+            EnsureArg.IsNotNull(auditConfiguration?.Value, nameof(auditConfiguration));
+
+            _auditConfiguration = auditConfiguration.Value;
+        }
+
+        public IReadOnlyDictionary<string, string> Read(HttpContext httpContext)
+        {
+            EnsureArg.IsNotNull(httpContext, nameof(httpContext));
+
+            object cachedCustomHeaders;
+
+            if (httpContext.Items.TryGetValue(AuditConstants.CustomAuditHeaderKeyValue, out cachedCustomHeaders))
+            {
+                return cachedCustomHeaders as IReadOnlyDictionary<string, string>;
+            }
+
+            var customHeaders = new Dictionary<string, string>();
+
+            foreach (KeyValuePair<string, StringValues> header in httpContext.Request.Headers)
+            {
+                if (header.Key.StartsWith(_auditConfiguration.CustomAuditHeaderPrefix, StringComparison.OrdinalIgnoreCase))
+                {
+                    var headerValue = header.Value.ToString();
+                    if (headerValue.Length > AuditConstants.MaximumLengthOfCustomHeader)
+                    {
+                        throw new AuditHeaderException(header.Key, headerValue.Length);
+                    }
+
+                    customHeaders[header.Key] = headerValue;
+                }
+            }
+
+            if (customHeaders.Count > AuditConstants.MaximumNumberOfCustomHeaders)
+            {
+                throw new AuditHeaderException(customHeaders.Count);
+            }
+
+            httpContext.Items[AuditConstants.CustomAuditHeaderKeyValue] = customHeaders;
+            return customHeaders;
+        }
+    }
+}

src/Microsoft.Health.Fhir.Api/Features/Audit/AuditHelper.cs

@@ -21,12 +21,14 @@ public class AuditHelper : IAuditHelper
         private readonly IAuditEventTypeMapping _auditEventTypeMapping;
         private readonly IAuditLogger _auditLogger;
         private readonly ILogger<AuditHelper> _logger;
+        private readonly IAuditHeaderReader _auditHeaderReader;
 
         public AuditHelper(
             IFhirRequestContextAccessor fhirRequestContextAccessor,
             IAuditEventTypeMapping auditEventTypeMapping,
             IAuditLogger auditLogger,
-            ILogger<AuditHelper> logger)
+            ILogger<AuditHelper> logger,
+            IAuditHeaderReader auditHeaderReader)
         {
             EnsureArg.IsNotNull(fhirRequestContextAccessor, nameof(fhirRequestContextAccessor));
             EnsureArg.IsNotNull(auditEventTypeMapping, nameof(auditEventTypeMapping));
@@ -37,6 +39,7 @@ public AuditHelper(
             _auditEventTypeMapping = auditEventTypeMapping;
             _auditLogger = auditLogger;
             _logger = logger;
+            _auditHeaderReader = auditHeaderReader;
         }
 
         /// <inheritdoc />
@@ -74,7 +77,8 @@ private void Log(AuditAction auditAction, string controllerName, string actionNa
                     statusCode: statusCode,
                     correlationId: fhirRequestContext.CorrelationId,
                     callerIpAddress: httpContext.Connection?.RemoteIpAddress?.ToString(),
-                    callerClaims: claimsExtractor.Extract());
+                    callerClaims: claimsExtractor.Extract(),
+                    customHeaders: _auditHeaderReader.Read(httpContext));
             }
         }
     }

src/Microsoft.Health.Fhir.Api/Features/Audit/AuditLogger.cs

@@ -56,15 +56,22 @@ public void LogAudit(
             HttpStatusCode? statusCode,
             string correlationId,
             string callerIpAddress,
-            IReadOnlyCollection<KeyValuePair<string, string>> callerClaims)
+            IReadOnlyCollection<KeyValuePair<string, string>> callerClaims,
+            IReadOnlyDictionary<string, string> customerHeaders = null)
         {
             string claimsInString = null;
+            string customerHeadersInString = null;
 
             if (callerClaims != null)
             {
                 claimsInString = string.Join(";", callerClaims.Select(claim => $"{claim.Key}={claim.Value}"));
             }
 
+            if (customerHeaders != null)
+            {
+                customerHeadersInString = string.Join(";", customerHeaders.Select(header => $"{header.Key}={header.Value}"));
+            }
+
             _logger.LogInformation(
                 AuditMessageFormat,
                 auditAction,
@@ -76,7 +83,8 @@ public void LogAudit(
                 action,
                 statusCode,
                 correlationId,
-                claimsInString);
+                claimsInString,
+                customerHeadersInString);
         }
     }
 }

src/Microsoft.Health.Fhir.Api/Features/Audit/IAuditHeaderReader.cs

@@ -0,0 +1,15 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.Health.Fhir.Api.Features.Audit
+{
+    public interface IAuditHeaderReader
+    {
+        IReadOnlyDictionary<string, string> Read(HttpContext httpContext);
+    }
+}

src/Microsoft.Health.Fhir.Api/Features/Audit/IAuditLogger.cs

@@ -25,6 +25,7 @@ public interface IAuditLogger
         /// <param name="correlationId">The correlation ID.</param>
         /// <param name="callerIpAddress">The caller IP address.</param>
         /// <param name="callerClaims">The claims of the caller.</param>
+        /// <param name="customHeaders">Headers added by the caller with data to be added to the audit logs.</param>
         void LogAudit(
             AuditAction auditAction,
             string operation,
@@ -33,6 +34,7 @@ void LogAudit(
             HttpStatusCode? statusCode,
             string correlationId,
             string callerIpAddress,
-            IReadOnlyCollection<KeyValuePair<string, string>> callerClaims);
+            IReadOnlyCollection<KeyValuePair<string, string>> callerClaims,
+            IReadOnlyDictionary<string, string> customHeaders = null);
     }
 }

src/Microsoft.Health.Fhir.Api/Modules/AuditModule.cs

@@ -31,6 +31,8 @@ public void Load(IServiceCollection services)
 
             services.AddSingleton<IAuditLogger, AuditLogger>();
 
+            services.AddSingleton<IAuditHeaderReader, AuditHeaderReader>();
+
             services.Add<AuditHelper>()
                 .Singleton()
                 .AsService<IAuditHelper>();

src/Microsoft.Health.Fhir.Api/Resources.resx

@@ -123,6 +123,10 @@
   <data name="ContentTypeHeaderRequired" xml:space="preserve">
     <value>The "content-type" header is required.</value>
   </data>
+  <data name="CustomAuditHeaderTooLarge" xml:space="preserve">
+    <value>The maximum length of a custom audit header value is {0}. The supplied custom audit header '{1}' has length of {2}.</value>
+    <comment>PH0 is a constant defining the max length of a header.  PH1 is the name  of the header sent in the request.  PH2 is the length of the incoming header value.  Example: The maximum length of a custom audit header value is 2048. The supplied custom audit header 'X-MS-AZUREFHIR-AUDIT-SITE' has length of 3072.</comment>
+  </data>
   <data name="Forbidden" xml:space="preserve">
     <value>Authorization failed.</value>
   </data>
@@ -179,6 +183,10 @@
   <data name="ToggleNavigation" xml:space="preserve">
     <value>Toggle navigation</value>
   </data>
+  <data name="TooManyCustomAuditHeaders" xml:space="preserve">
+    <value>The maximum number of custom audit headers allowed is {0}. The number of custom audit headers supplied is {1}.</value>
+    <comment>PH0 is a constant defining the max number of custom headers.  PH1 is the count of custom headers sent in the request.  Example: The maximum number of custom audit headers allowed is 10. The number of custom audit headers supplied is 12.</comment>
+  </data>
   <data name="UnableToObtainOpenIdConfiguration" xml:space="preserve">
     <value>Unable to obtain OpenID configuration.</value>
   </data>

src/Microsoft.Health.Fhir.Core/Configs/AuditConfiguration.cs

@@ -0,0 +1,32 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using Microsoft.Health.Fhir.Core.Exceptions;
+
+namespace Microsoft.Health.Fhir.Core.Configs
+{
+    public class AuditConfiguration
+    {
+        private string _customAuditHeaderPrefix = "X-MS-AZUREFHIR-AUDIT-";
+
+        public string CustomAuditHeaderPrefix
+        {
+            get
+            {
+                return _customAuditHeaderPrefix;
+            }
+
+            set
+            {
+                if (string.IsNullOrEmpty(value))
+                {
+                    throw new InvalidDefinitionException(Resources.CustomHeaderPrefixCannotBeEmpty);
+                }
+
+                _customAuditHeaderPrefix = value;
+            }
+        }
+    }
+}

src/Microsoft.Health.Fhir.Core/Resources.resx

@@ -181,6 +181,9 @@
     <value>Found result with Id '{0}', which did not match the provided Id '{1}'.</value>
     <comment>{0} is an Id e.g. 123456</comment>
   </data>
+  <data name="CustomHeaderPrefixCannotBeEmpty" xml:space="preserve">
+    <value>The prefix used to identify custom audit headers cannot be empty.</value>
+  </data>
   <data name="DeleteVersionNotAllowed" xml:space="preserve">
     <value>Deleting a specific record version is not supported.</value>
   </data>