path: root/crypto/src/tls/AlertDescription.cs

using System;

namespace Org.BouncyCastle.Tls
{
    /// <summary>RFC 5246 7.2.</summary>
    public abstract class AlertDescription
    {
        /// <summary>This message notifies the recipient that the sender will not send any more messages on this
        /// connection.</summary>
        /// <remarks>
        /// Note that as of TLS 1.1, failure to properly close a connection no longer requires that a session not be
        /// resumed. This is a change from TLS 1.0 ("The session becomes unresumable if any connection is terminated
        /// without proper close_notify messages with level equal to warning.") to conform with widespread
        /// implementation practice.
        /// </remarks>
        public const short close_notify = 0;

        /// <summary>An inappropriate message was received.</summary>
        /// <remarks>
        /// This alert is always fatal and should never be observed in communication between proper implementations.
        /// </remarks>
        public const short unexpected_message = 10;

        /// <summary>This alert is returned if a record is received with an incorrect MAC.</summary>
        /// <remarks>
        /// This alert also MUST be returned if an alert is sent because a TLSCiphertext decrypted in an invalid way:
        /// either it wasn't an even multiple of the block length, or its padding values, when checked, weren't
        /// correct. This message is always fatal and should never be observed in communication between proper
        /// implementations (except when messages were corrupted in the network).
        /// </remarks>
        public const short bad_record_mac = 20;

        /// <remarks>
        /// This alert was used in some earlier versions of TLS, and may have permitted certain attacks against the CBC
        /// mode [CBCATT]. It MUST NOT be sent by compliant implementations.
        /// </remarks>
        public const short decryption_failed = 21;

        /// <summary>A TLSCiphertext record was received that had a length more than 2^14+2048 bytes, or a record
        /// decrypted to a TLSCompressed record with more than 2^14+1024 bytes.</summary>
        /// <remarks>
        /// This message is always fatal and should never be observed in communication between proper implementations
        /// (except when messages were corrupted in the network).
        /// </remarks>
        public const short record_overflow = 22;

        /// <summary>The decompression function received improper input (e.g., data that would expand to excessive
        /// length).</summary>
        /// <remarks>
        /// This message is always fatal and should never be observed in communication between proper implementations.
        /// </remarks>
        public const short decompression_failure = 30;

        /// <summary>Reception of a handshake_failure alert message indicates that the sender was unable to negotiate
        /// an acceptable set of security parameters given the options available.</summary>
        /// <remarks>
        /// This is a fatal error.
        /// </remarks>
        public const short handshake_failure = 40;

        /// <remarks>
        /// This alert was used in SSLv3 but not any version of TLS. It MUST NOT be sent by compliant implementations.
        /// </remarks>
        public const short no_certificate = 41;

        /// <summary>A certificate was corrupt, contained signatures that did not verify correctly, etc.</summary>
        public const short bad_certificate = 42;

        /// <summary>A certificate was of an unsupported type.</summary>
        public const short unsupported_certificate = 43;

        /// <summary>A certificate was revoked by its signer.</summary>
        public const short certificate_revoked = 44;

        /// <summary>A certificate has expired or is not currently valid.</summary>
        public const short certificate_expired = 45;

        /// <summary>Some other (unspecified) issue arose in processing the certificate, rendering it unacceptable.
        /// </summary>
        public const short certificate_unknown = 46;

        /// <summary>A field in the handshake was out of range or inconsistent with other fields.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short illegal_parameter = 47;

        /// <summary>A valid certificate chain or partial chain was received, but the certificate was not accepted
        /// because the CA certificate could not be located or couldn't be matched with a known, trusted CA.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short unknown_ca = 48;

        /// <summary>A valid certificate was received, but when access control was applied, the sender decided not to
        /// proceed with negotiation.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short access_denied = 49;

        /// <summary>A message could not be decoded because some field was out of the specified range or the length of
        /// the message was incorrect.</summary>
        /// <remarks>
        /// This message is always fatal and should never be observed in communication between proper
        /// implementations (except when messages were corrupted in the network).
        /// </remarks>
        public const short decode_error = 50;

        /// <summary>A handshake cryptographic operation failed, including being unable to correctly verify a signature
        /// or validate a Finished message.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short decrypt_error = 51;

        /// <remarks>
        /// This alert was used in some earlier versions of TLS. It MUST NOT be sent by compliant implementations.
        /// </remarks>
        public const short export_restriction = 60;

        /// <summary>The protocol version the client has attempted to negotiate is recognized but not supported.
        /// </summary>
        /// <remarks>
        /// (For example, old protocol versions might be avoided for security reasons.) This message is always fatal.
        /// </remarks>
        public const short protocol_version = 70;

        /// <summary>Returned instead of handshake_failure when a negotiation has failed specifically because the
        /// server requires ciphers more secure than those supported by the client.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short insufficient_security = 71;

        /// <summary>An internal error unrelated to the peer or the correctness of the protocol (such as a memory
        /// allocation failure) makes it impossible to continue.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short internal_error = 80;

        /// <summary>This handshake is being canceled for some reason unrelated to a protocol failure.</summary>
        /// <remarks>
        /// If the user cancels an operation after the handshake is complete, just closing the connection by sending a
        /// close_notify is more appropriate. This alert should be followed by a close_notify. This message is
        /// generally a warning.
        /// </remarks>
        public const short user_canceled = 90;

        /// <summary>Sent by the client in response to a hello request or by the server in response to a client hello
        /// after initial handshaking.</summary>
        /// <remarks>
        /// Either of these would normally lead to renegotiation; when that is not appropriate, the recipient should
        /// respond with this alert. At that point, the original requester can decide whether to proceed with the
        /// connection. One case where this would be appropriate is where a server has spawned a process to satisfy a
        /// request; the process might receive security parameters (key length, authentication, etc.) at startup, and
        /// it might be difficult to communicate changes to these parameters after that point. This message is always a
        /// warning.
        /// </remarks>
        public const short no_renegotiation = 100;

        /// <summary>Sent by clients that receive an extended server hello containing an extension that they did not
        /// put in the corresponding client hello.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short unsupported_extension = 110;

        /*
         * RFC 3546
         */

        /// <summary>This alert is sent by servers who are unable to retrieve a certificate chain from the URL supplied
        /// by the client(see Section 3.3).</summary>
        /// <remarks>
        /// This message MAY be fatal - for example if client authentication is required by the server for the
        /// handshake to continue and the server is unable to retrieve the certificate chain, it may send a fatal
        /// alert.
        /// </remarks>
        public const short certificate_unobtainable = 111;

        /// <summary>This alert is sent by servers that receive a server_name extension request, but do not recognize
        /// the server name.</summary>
        /// <remarks>
        /// This message MAY be fatal.
        /// </remarks>
        public const short unrecognized_name = 112;

        /// <summary>This alert is sent by clients that receive an invalid certificate status response (see Section 3.6
        /// ).</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short bad_certificate_status_response = 113;

        /// <summary>This alert is sent by servers when a certificate hash does not match a client provided
        /// certificate_hash.</summary>
        /// <remarks>
        /// This message is always fatal.
        /// </remarks>
        public const short bad_certificate_hash_value = 114;

        /*
         * RFC 4279
         */

        /// <summary>If the server does not recognize the PSK identity, it MAY respond with an "unknown_psk_identity"
        /// alert message.</summary>
        public const short unknown_psk_identity = 115;

        /*
         * RFC 7301
         */

        /// <summary>In the event that the server supports no protocols that the client advertises, then the server
        /// SHALL respond with a fatal "no_application_protocol" alert.</summary>
        public const short no_application_protocol = 120;

        /*
         * RFC 7507
         */

        /// <summary>If TLS_FALLBACK_SCSV appears in ClientHello.cipher_suites and the highest protocol version
        /// supported by the server is higher than the version indicated in ClientHello.client_version, the server MUST
        /// respond with a fatal inappropriate_fallback alert[..].</summary>
        public const short inappropriate_fallback = 86;

        /*
         * RFC 8446
         */

        /// <summary>Sent by endpoints that receive a handshake message not containing an extension that is mandatory
        /// to send for the offered TLS version or other negotiated parameters.</summary>
        public const short missing_extension = 109;

        /// <summary>Sent by servers when a client certificate is desired but none was provided by the client.
        /// </summary>
        public const short certificate_required = 116;

        public static string GetName(short alertDescription)
        {
            switch (alertDescription)
            {
            case close_notify:
                return "close_notify";
            case unexpected_message:
                return "unexpected_message";
            case bad_record_mac:
                return "bad_record_mac";
            case decryption_failed:
                return "decryption_failed";
            case record_overflow:
                return "record_overflow";
            case decompression_failure:
                return "decompression_failure";
            case handshake_failure:
                return "handshake_failure";
            case no_certificate:
                return "no_certificate";
            case bad_certificate:
                return "bad_certificate";
            case unsupported_certificate:
                return "unsupported_certificate";
            case certificate_revoked:
                return "certificate_revoked";
            case certificate_expired:
                return "certificate_expired";
            case certificate_unknown:
                return "certificate_unknown";
            case illegal_parameter:
                return "illegal_parameter";
            case unknown_ca:
                return "unknown_ca";
            case access_denied:
                return "access_denied";
            case decode_error:
                return "decode_error";
            case decrypt_error:
                return "decrypt_error";
            case export_restriction:
                return "export_restriction";
            case protocol_version:
                return "protocol_version";
            case insufficient_security:
                return "insufficient_security";
            case internal_error:
                return "internal_error";
            case user_canceled:
                return "user_canceled";
            case no_renegotiation:
                return "no_renegotiation";
            case unsupported_extension:
                return "unsupported_extension";
            case certificate_unobtainable:
                return "certificate_unobtainable";
            case unrecognized_name:
                return "unrecognized_name";
            case bad_certificate_status_response:
                return "bad_certificate_status_response";
            case bad_certificate_hash_value:
                return "bad_certificate_hash_value";
            case unknown_psk_identity:
                return "unknown_psk_identity";
            case no_application_protocol:
                return "no_application_protocol";
            case inappropriate_fallback:
                return "inappropriate_fallback";
            case missing_extension:
                return "missing_extension";
            case certificate_required:
                return "certificate_required";
            default:
                return "UNKNOWN";
            }
        }

        public static string GetText(short alertDescription)
        {
            return GetName(alertDescription) + "(" + alertDescription + ")";
        }
    }
}