Keychain search to return all matches (#6748)

Motivation:
A registry URL (i.e., same scheme, host, and port) can have multiple entries in Keychain. Currently we only ask Keychain to return one match when doing a search, but that might not be the one we want.

Modifications:
- Have Keychain search return all matches
- Sort the matches by modification timestamp
- Return the most recently modified match

rdar://112556752

Sources/Basics/AuthorizationProvider.swift

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import struct Foundation.Data
+import struct Foundation.Date
 import struct Foundation.URL
 #if canImport(Security)
 import Security
@@ -194,7 +195,7 @@ public class KeychainAuthorizationProvider: AuthorizationProvider, Authorization
         }
 
         self.observabilityScope
-            .emit(debug: "Add/update credentials for '\(protocolHostPort)' [\(url.absoluteString)] in keychain")
+            .emit(debug: "add/update credentials for '\(protocolHostPort)' [\(url.absoluteString)] in keychain")
 
         if !persist {
             self.cache[protocolHostPort.description] = (user, password)
@@ -221,7 +222,7 @@ public class KeychainAuthorizationProvider: AuthorizationProvider, Authorization
         }
 
         self.observabilityScope
-            .emit(debug: "Remove credentials for '\(protocolHostPort)' [\(url.absoluteString)] from keychain")
+            .emit(debug: "remove credentials for '\(protocolHostPort)' [\(url.absoluteString)] from keychain")
 
         do {
             try self.delete(protocolHostPort: protocolHostPort)
@@ -241,28 +242,66 @@ public class KeychainAuthorizationProvider: AuthorizationProvider, Authorization
         }
 
         self.observabilityScope
-            .emit(debug: "Search credentials for '\(protocolHostPort)' [\(url.absoluteString)] in keychain")
+            .emit(debug: "search credentials for '\(protocolHostPort)' [\(url.absoluteString)] in keychain")
 
         do {
-            guard let existingItem = try self
-                .search(protocolHostPort: protocolHostPort) as? [String: Any],
-                let passwordData = existingItem[kSecValueData as String] as? Data,
-                let password = String(data: passwordData, encoding: String.Encoding.utf8),
-                let account = existingItem[kSecAttrAccount as String] as? String
+            guard let existingItems = try self.search(protocolHostPort: protocolHostPort) as? [[String: Any]] else {
+                throw AuthorizationProviderError
+                    .other("Failed to extract credentials for '\(protocolHostPort)' from keychain")
+            }
+
+            // Log warning if there is more than one result
+            if existingItems.count > 1 {
+                self.observabilityScope
+                    .emit(
+                        warning: "multiple (\(existingItems.count)) keychain entries found for '\(protocolHostPort)' [\(url.absoluteString)]"
+                    )
+            }
+
+            // Sort by modification timestamp
+            let sortedItems = existingItems.sorted {
+                switch (
+                    $0[kSecAttrModificationDate as String] as? Date,
+                    $1[kSecAttrModificationDate as String] as? Date
+                ) {
+                case (nil, nil):
+                    return false
+                case (_, nil):
+                    return true
+                case (nil, _):
+                    return false
+                case (.some(let left), .some(let right)):
+                    return left < right
+                }
+            }
+
+            // Return most recently modified item
+            guard let mostRecent = sortedItems.last,
+                  let created = mostRecent[kSecAttrCreationDate as String] as? Date,
+                  // Get password for this specific item
+                  let existingItem = try self.get(
+                      protocolHostPort: protocolHostPort,
+                      created: created,
+                      modified: mostRecent[kSecAttrModificationDate as String] as? Date
+                  ) as? [String: Any],
+                  let passwordData = existingItem[kSecValueData as String] as? Data,
+                  let password = String(data: passwordData, encoding: String.Encoding.utf8),
+                  let account = existingItem[kSecAttrAccount as String] as? String
             else {
                 throw AuthorizationProviderError
                     .other("Failed to extract credentials for '\(protocolHostPort)' from keychain")
             }
+
             return (user: account, password: password)
         } catch {
             switch error {
             case AuthorizationProviderError.notFound:
-                self.observabilityScope.emit(debug: "No credentials found for '\(protocolHostPort)' in keychain")
+                self.observabilityScope.emit(debug: "no credentials found for '\(protocolHostPort)' in keychain")
             case AuthorizationProviderError.other(let detail):
                 self.observabilityScope.emit(error: detail)
             default:
                 self.observabilityScope.emit(
-                    error: "Failed to find credentials for '\(protocolHostPort)' in keychain",
+                    error: "failed to find credentials for '\(protocolHostPort)' in keychain",
                     underlyingError: error
                 )
             }
@@ -331,13 +370,47 @@ public class KeychainAuthorizationProvider: AuthorizationProvider, Authorization
         var query: [String: Any] = [kSecClass as String: kSecClassInternetPassword,
                                     kSecAttrProtocol as String: protocolHostPort.protocolCFString,
                                     kSecAttrServer as String: protocolHostPort.server,
-                                    kSecMatchLimit as String: kSecMatchLimitOne,
+                                    kSecMatchLimit as String: kSecMatchLimitAll, // returns all matches
+                                    kSecReturnAttributes as String: true]
+        // https://developer.apple.com/documentation/security/keychain_services/keychain_items/searching_for_keychain_items
+        // Can't combine `kSecMatchLimitAll` and `kSecReturnData` (which contains password)
+
+        if let port = protocolHostPort.port {
+            query[kSecAttrPort as String] = port
+        }
+
+        var items: CFTypeRef?
+        // Search keychain for server's username and password, if any.
+        let status = SecItemCopyMatching(query as CFDictionary, &items)
+        guard status != errSecItemNotFound else {
+            throw AuthorizationProviderError.notFound
+        }
+        guard status == errSecSuccess else {
+            throw AuthorizationProviderError
+                .other("Failed to find credentials for '\(protocolHostPort)' in keychain: status \(status)")
+        }
+
+        return items
+    }
+
+    private func get(protocolHostPort: ProtocolHostPort, created: Date, modified: Date?) throws -> CFTypeRef? {
+        self.observabilityScope
+            .emit(debug: "read credentials for '\(protocolHostPort)', created at \(created), in keychain")
+
+        var query: [String: Any] = [kSecClass as String: kSecClassInternetPassword,
+                                    kSecAttrProtocol as String: protocolHostPort.protocolCFString,
+                                    kSecAttrServer as String: protocolHostPort.server,
+                                    kSecAttrCreationDate as String: created,
+                                    kSecMatchLimit as String: kSecMatchLimitOne, // limit to one match
                                     kSecReturnAttributes as String: true,
-                                    kSecReturnData as String: true]
+                                    kSecReturnData as String: true] // password
 
         if let port = protocolHostPort.port {
             query[kSecAttrPort as String] = port
         }
+        if let modified {
+            query[kSecAttrModificationDate as String] = modified
+        }
 
         var item: CFTypeRef?
         // Search keychain for server's username and password, if any.
@@ -414,13 +487,13 @@ public struct CompositeAuthorizationProvider: AuthorizationProvider {
             if let authentication = provider.authentication(for: url) {
                 switch provider {
                 case let provider as NetrcAuthorizationProvider:
-                    self.observabilityScope.emit(info: "Credentials for \(url) found in netrc file at \(provider.path)")
+                    self.observabilityScope.emit(info: "credentials for \(url) found in netrc file at \(provider.path)")
                 #if canImport(Security)
                 case is KeychainAuthorizationProvider:
-                    self.observabilityScope.emit(info: "Credentials for \(url) found in keychain")
+                    self.observabilityScope.emit(info: "credentials for \(url) found in keychain")
                 #endif
                 default:
-                    self.observabilityScope.emit(info: "Credentials for \(url) found in \(provider)")
+                    self.observabilityScope.emit(info: "credentials for \(url) found in \(provider)")
                 }
                 return authentication
             }