mutating func receiveUserAuthRequest()

in Sources/NIOSSH/User Authentication/UserAuthenticationStateMachine.swift [114:143]

• 21 lines of code
• 7 McCabe index (conditional complexity)

    mutating func receiveUserAuthRequest(_ message: SSHMessage.UserAuthRequestMessage) throws -> EventLoopFuture<NIOSSHUserAuthenticationResponseMessage>? {
        guard message.service == Self.nextServiceName else {
            throw NIOSSHError.protocolViolation(protocolName: Self.protocolName, violation: "requested unsupported service: \(message.service)")
        }

        switch (self.delegate, self.state) {
        case (.server(let delegate), .awaitingNextRequest):
            self.state = .awaitingResponses(1)
            return self.nextAuthResponse(request: message, delegate: delegate)

        case (.server(let delegate), .awaitingResponses(let pending)):
            self.state = .awaitingResponses(pending + 1)
            return self.nextAuthResponse(request: message, delegate: delegate)

        case (.server, .idle), (.server, .awaitingServiceAcceptance):
            throw NIOSSHError.protocolViolation(protocolName: Self.protocolName, violation: "user auth request before service accepted")

        case (.server, .authenticationSucceeded):
            // We ignore messages after authentication succeeded.
            return nil

        case (.server, .authenticationFailed):
            // TODO(cory): We should be limiting the maximum number of authentication attempts.
            preconditionFailure("Servers cannot enter authentication failed")

        case (.client, _):
            // Clients may never receive user auth request messages.
            throw NIOSSHError.protocolViolation(protocolName: Self.protocolName, violation: "server sent user auth request")
        }
    }