using System;

using System.Collections.Generic;

using Microsoft.Extensions.Logging;

using Npgsql.Internal;

namespace Npgsql.BackendMessages;

abstract class AuthenticationRequestMessage : IBackendMessage

{

public BackendMessageCode Code => BackendMessageCode.AuthenticationRequest;

internal abstract AuthenticationRequestType AuthRequestType { get; }

}

sealed class AuthenticationOkMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.Ok;

internal static readonly AuthenticationOkMessage Instance = new();

AuthenticationOkMessage() { }

}

sealed class AuthenticationCleartextPasswordMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.CleartextPassword;

internal static readonly AuthenticationCleartextPasswordMessage Instance = new();

AuthenticationCleartextPasswordMessage() { }

}

sealed class AuthenticationMD5PasswordMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.MD5Password;

internal byte[] Salt { get; }

internal static AuthenticationMD5PasswordMessage Load(NpgsqlReadBuffer buf)

{

var salt = new byte[4];

buf.ReadBytes(salt, 0, 4);

return new AuthenticationMD5PasswordMessage(salt);

}

AuthenticationMD5PasswordMessage(byte[] salt)

=> Salt = salt;

}

sealed class AuthenticationGSSMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.GSS;

internal static readonly AuthenticationGSSMessage Instance = new();

AuthenticationGSSMessage() { }

}

sealed class AuthenticationGSSContinueMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.GSSContinue;

internal byte[] AuthenticationData { get; }

internal static AuthenticationGSSContinueMessage Load(NpgsqlReadBuffer buf, int len)

{

len -= 4; // The AuthRequestType code

var authenticationData = new byte[len];

buf.ReadBytes(authenticationData, 0, len);

return new AuthenticationGSSContinueMessage(authenticationData);

}

AuthenticationGSSContinueMessage(byte[] authenticationData)

=> AuthenticationData = authenticationData;

}

sealed class AuthenticationSSPIMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.SSPI;

internal static readonly AuthenticationSSPIMessage Instance = new();

AuthenticationSSPIMessage() { }

}

#region SASL

sealed class AuthenticationSASLMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.SASL;

internal List<string> Mechanisms { get; } = [];

internal AuthenticationSASLMessage(NpgsqlReadBuffer buf)

{

while (buf.Buffer[buf.ReadPosition] != 0)

Mechanisms.Add(buf.ReadNullTerminatedString());

buf.ReadByte();

if (Mechanisms.Count == 0)

throw new NpgsqlException("Received AuthenticationSASL message with 0 mechanisms!");

}

}

sealed class AuthenticationSASLContinueMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.SASLContinue;

internal byte[] Payload { get; }

internal AuthenticationSASLContinueMessage(NpgsqlReadBuffer buf, int len)

{

Payload = new byte[len];

buf.ReadBytes(Payload, 0, len);

}

}

sealed class AuthenticationSCRAMServerFirstMessage

{

internal string Nonce { get; }

internal string Salt { get; }

internal int Iteration { get; }

internal static AuthenticationSCRAMServerFirstMessage Load(byte[] bytes, ILogger connectionLogger)

{

var data = NpgsqlWriteBuffer.UTF8Encoding.GetString(bytes);

string? nonce = null, salt = null;

var iteration = -1;

foreach (var part in data.Split(','))

{

if (part.StartsWith("r=", StringComparison.Ordinal))

nonce = part.Substring(2);

else if (part.StartsWith("s=", StringComparison.Ordinal))

salt = part.Substring(2);

else if (part.StartsWith("i=", StringComparison.Ordinal))

iteration = int.Parse(part.Substring(2));

else

connectionLogger.LogDebug("Unknown part in SCRAM server-first message:" + part);

}

if (nonce == null)

throw new NpgsqlException("Server nonce not received in SCRAM server-first message");

if (salt == null)

throw new NpgsqlException("Server salt not received in SCRAM server-first message");

if (iteration == -1)

throw new NpgsqlException("Server iterations not received in SCRAM server-first message");

return new AuthenticationSCRAMServerFirstMessage(nonce, salt, iteration);

}

AuthenticationSCRAMServerFirstMessage(string nonce, string salt, int iteration)

{

Nonce = nonce;

Salt = salt;

Iteration = iteration;

}

}

sealed class AuthenticationSASLFinalMessage : AuthenticationRequestMessage

{

internal override AuthenticationRequestType AuthRequestType => AuthenticationRequestType.SASLFinal;

internal byte[] Payload { get; }

internal AuthenticationSASLFinalMessage(NpgsqlReadBuffer buf, int len)

{

Payload = new byte[len];

buf.ReadBytes(Payload, 0, len);

}

}

sealed class AuthenticationSCRAMServerFinalMessage

{

internal string ServerSignature { get; }

internal static AuthenticationSCRAMServerFinalMessage Load(byte[] bytes, ILogger connectionLogger)

{

var data = NpgsqlWriteBuffer.UTF8Encoding.GetString(bytes);

string? serverSignature = null;

foreach (var part in data.Split(','))

{

if (part.StartsWith("v=", StringComparison.Ordinal))

serverSignature = part.Substring(2);

else

connectionLogger.LogDebug("Unknown part in SCRAM server-first message:" + part);

}

if (serverSignature == null)

throw new NpgsqlException("Server signature not received in SCRAM server-final message");

return new AuthenticationSCRAMServerFinalMessage(serverSignature);

}

internal AuthenticationSCRAMServerFinalMessage(string serverSignature)

=> ServerSignature = serverSignature;

}

#endregion SASL

enum AuthenticationRequestType

{

Ok = 0,

CleartextPassword = 3,

MD5Password = 5,

GSS = 7,

GSSContinue = 8,

SSPI = 9,

SASL = 10,

SASLContinue = 11,

SASLFinal = 12

}