Correctly place the SSL channel handler in front of the PostgresChannelHandler (#527)

Author: tkrajacic

Diff for: Sources/PostgresNIO/Connection/PostgresConnection.swift

@@ -60,18 +60,18 @@ public final class PostgresConnection: @unchecked Sendable {
     func start(configuration: InternalConfiguration) -> EventLoopFuture<Void> {
         // 1. configure handlers
 
-        let configureSSLCallback: ((Channel) throws -> ())?
+        let configureSSLCallback: ((Channel, PostgresChannelHandler) throws -> ())?
 
         switch configuration.tls.base {
         case .prefer(let context), .require(let context):
-            configureSSLCallback = { channel in
+            configureSSLCallback = { channel, postgresChannelHandler in
                 channel.eventLoop.assertInEventLoop()
 
                 let sslHandler = try NIOSSLClientHandler(
                     context: context,
                     serverHostname: configuration.serverNameForTLS
                 )
-                try channel.pipeline.syncOperations.addHandler(sslHandler, position: .first)
+                try channel.pipeline.syncOperations.addHandler(sslHandler, position: .before(postgresChannelHandler))
             }
         case .disable:
             configureSSLCallback = nil

Diff for: Sources/PostgresNIO/New/PostgresChannelHandler.swift

@@ -20,7 +20,7 @@ final class PostgresChannelHandler: ChannelDuplexHandler {
     private var decoder: NIOSingleStepByteToMessageProcessor<PostgresBackendMessageDecoder>
     private var encoder: PostgresFrontendMessageEncoder!
     private let configuration: PostgresConnection.InternalConfiguration
-    private let configureSSLCallback: ((Channel) throws -> Void)?
+    private let configureSSLCallback: ((Channel, PostgresChannelHandler) throws -> Void)?
 
     private var listenState = ListenStateMachine()
     private var preparedStatementState = PreparedStatementStateMachine()
@@ -29,7 +29,7 @@ final class PostgresChannelHandler: ChannelDuplexHandler {
         configuration: PostgresConnection.InternalConfiguration,
         eventLoop: EventLoop,
         logger: Logger,
-        configureSSLCallback: ((Channel) throws -> Void)?
+        configureSSLCallback: ((Channel, PostgresChannelHandler) throws -> Void)?
     ) {
         self.state = ConnectionStateMachine(requireBackendKeyData: configuration.options.requireBackendKeyData)
         self.eventLoop = eventLoop
@@ -46,7 +46,7 @@ final class PostgresChannelHandler: ChannelDuplexHandler {
         eventLoop: EventLoop,
         state: ConnectionStateMachine = .init(.initialized),
         logger: Logger = .psqlNoOpLogger,
-        configureSSLCallback: ((Channel) throws -> Void)?
+        configureSSLCallback: ((Channel, PostgresChannelHandler) throws -> Void)?
     ) {
         self.state = state
         self.eventLoop = eventLoop
@@ -439,7 +439,7 @@ final class PostgresChannelHandler: ChannelDuplexHandler {
         // This method must only be called, if we signalized the StateMachine before that we are
         // able to setup a SSL connection.
         do {
-            try self.configureSSLCallback!(context.channel)
+            try self.configureSSLCallback!(context.channel, self)
             let action = self.state.sslHandlerAdded()
             self.run(action, with: context)
         } catch {

Diff for: Tests/PostgresNIOTests/New/PostgresChannelHandlerTests.swift

@@ -48,7 +48,7 @@ class PostgresChannelHandlerTests: XCTestCase {
         var config = self.testConnectionConfiguration()
         XCTAssertNoThrow(config.tls = .require(try NIOSSLContext(configuration: .makeClientConfiguration())))
         var addSSLCallbackIsHit = false
-        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel in
+        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel, _ in
             addSSLCallbackIsHit = true
         }
         let embedded = EmbeddedChannel(handlers: [
@@ -84,7 +84,7 @@ class PostgresChannelHandlerTests: XCTestCase {
         var config = self.testConnectionConfiguration()
         XCTAssertNoThrow(config.tls = .require(try NIOSSLContext(configuration: .makeClientConfiguration())))
         var addSSLCallbackIsHit = false
-        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel in
+        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel, _ in
             addSSLCallbackIsHit = true
         }
         let eventHandler = TestEventHandler()
@@ -114,7 +114,7 @@ class PostgresChannelHandlerTests: XCTestCase {
     func testSSLUnsupportedClosesConnection() throws {
         let config = self.testConnectionConfiguration(tls: .require(try NIOSSLContext(configuration: .makeClientConfiguration())))
 
-        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel in
+        let handler = PostgresChannelHandler(configuration: config, eventLoop: self.eventLoop) { channel, _ in
             XCTFail("This callback should never be exectuded")
             throw PSQLError.sslUnsupported
         }