use insensitive key

library/swift/HeadersBuilder.swift

@@ -3,14 +3,37 @@ import Foundation
 private let kRestrictedPrefixes = [":", "x-envoy-mobile"]
 
 private func isRestrictedHeader(name: String) -> Bool {
-  return name == "host" || kRestrictedPrefixes.contains { name.hasPrefix($0) }
+  return name.lowercased() == "host" || kRestrictedPrefixes.contains { name.lowercased().hasPrefix($0) }
 }
 
 /// Base builder class used to construct `Headers` instances.
 /// See `{Request|Response}HeadersBuilder` for usage.
 @objcMembers
 public class HeadersBuilder: NSObject {
-  private(set) var headers: [String: [String]]
+
+  struct CaseInsensitiveKey: Hashable {
+    let name: String
+    lazy var lowercasedName: String = { self.name.lowercased() }()
+
+    static func == (lhs: CaseInsensitiveKey, rhs: CaseInsensitiveKey) -> Bool {
+      var lhs = lhs, rhs = rhs
+      return lhs.lowercasedName == rhs.lowercasedName
+    }
+
+    func hash(into hasher: inout Hasher) -> Int {
+      hasher.combine(self.name.hashValue)
+      return hasher.finalize()
+    }
+  }
+
+  private(set) var _headers: [CaseInsensitiveKey: [String]]
+
+  var headers: [String: [String]] {
+    return Dictionary(uniqueKeysWithValues: _headers.map { key, value in
+    var k = key
+     return (k.lowercasedName, value) 
+     })
+  }
 
   /// Append a value to the header name.
   ///
@@ -24,7 +47,7 @@ public class HeadersBuilder: NSObject {
       return self
     }
 
-    self.headers[name, default: []].append(value)
+    self._headers[CaseInsensitiveKey(name: name), default: []].append(value)
     return self
   }
 
@@ -40,7 +63,7 @@ public class HeadersBuilder: NSObject {
       return self
     }
 
-    self.headers[name] = value
+    self._headers[CaseInsensitiveKey(name: name)] = value
     return self
   }
 
@@ -55,7 +78,7 @@ public class HeadersBuilder: NSObject {
       return self
     }
 
-    self.headers[name] = nil
+    self._headers[CaseInsensitiveKey(name: name)] = nil
     return self
   }
 
@@ -69,22 +92,22 @@ public class HeadersBuilder: NSObject {
   /// - returns: This builder.
   @discardableResult
   func internalSet(name: String, value: [String]) -> Self {
-    self.headers[name] = value
+    self._headers[CaseInsensitiveKey(name: name)] = value
     return self
   }
 
   // Only explicitly implemented to work around a swiftinterface issue in Swift 5.1. This can be
   // removed once envoy is only built with Swift 5.2+
   public override init() {
-    self.headers = [:]
+    self._headers = [:]
     super.init()
   }
 
   /// Initialize a new builder. Subclasses should provide their own public convenience initializers.
   ///
   /// - parameter headers: The headers with which to start.
   required init(headers: [String: [String]]) {
-    self.headers = headers
+    self._headers = Dictionary(uniqueKeysWithValues: headers.map { key, value in (CaseInsensitiveKey(name: key), value) })
     super.init()
   }
 }

test/swift/HeadersBuilderTests.swift

@@ -78,4 +78,16 @@ final class HeadersBuilderTests: XCTestCase {
     let headers2 = RequestHeadersBuilder(headers: ["x-foo": ["123"], "x-bar": ["abc"]]).build()
     XCTAssert(headers1 !== headers2)
   }
+
+  // func testInitializationIsCaseSensitiveButDoesIgnoresKeysCasingWhenLookingForDuplicates() {
+  //   let headers = HeadersBuilder(headers: ["fOo": ["abc"], "foo": ["123"]])
+  //   XCTAssertEqual(["fOo": ["abc", "123"]], headers.headers)
+  // }
+
+  func testInitializationIsCaseInsensitiveOperation() {
+    let headers = HeadersBuilder(headers: ["foo": ["123"], "fOo": ["abc"]])
+    headers.set(name: "fOo", value: ["abd"])
+    headers.set(name: "foo", value: ["123"])
+    XCTAssertEqual(["foo": ["abc", "123"]], headers.headers)
+  }
 }