QuickProxyNet

QuickProxyNet is a high-performance, zero-dependency C# library for connecting to servers through proxy protocols. It provides direct Stream access with minimal allocations and latency — ideal for mass proxy checking, crawlers, and any scenario where thousands of proxy connections are made in parallel.

Targets: .NET 8 / .NET 9 / .NET 10

Features

• Zero runtime dependencies — BCL only, no third-party packages
• Zero-alloc protocol logic — ArrayPool, stackalloc, Utf8Formatter, ValueTask throughout
• 5 proxy protocols — HTTP, HTTPS, SOCKS4, SOCKS4a, SOCKS5
• Static one-liner API — Proxy.ConnectAsync(uri, host, port) for mass checkers
• Structured error codes — ProxyProtocolException with ProxyErrorCode enum for programmatic error handling
• Timeout support — per-connection timeouts with ProxyErrorCode.Timeout
• Raw Stream access — full control over the tunneled connection

Installation

dotnet add package QuickProxyNet

Quick Start

One-liner (recommended for mass checking)

// Single call — no intermediate objects allocated
await using var stream = await Proxy.ConnectAsync(
    new Uri("socks5://user:pass@127.0.0.1:1080"),
    "example.com", 443,
    TimeSpan.FromSeconds(5));

Extension method on Uri

var proxy = new Uri("http://proxy.example.com:8080");
await using var stream = await proxy.ConnectThroughProxyAsync("example.com", 443);

Factory API (when you need to configure the client)

var client = ProxyClientFactory.Instance.Create(new Uri("socks5://proxy:1080"));
client.NoDelay = true;
client.ReadTimeout = 5000;

await using var stream = await client.ConnectAsync("example.com", 443);

With explicit proxy type and credentials

var creds = new NetworkCredential("user", "pass");
var client = ProxyClientFactory.Instance.Create(
    ProxyType.Socks5, "proxy.example.com", 1080, creds);

await using var stream = await client.ConnectAsync("example.com", 80,
    TimeSpan.FromSeconds(10));

Error Handling

All proxy protocol errors throw ProxyProtocolException with a specific ProxyErrorCode:

try
{
    await using var stream = await Proxy.ConnectAsync(proxyUri, host, port,
        TimeSpan.FromSeconds(5));
}
catch (ProxyProtocolException ex)
{
    switch (ex.ErrorCode)
    {
        case ProxyErrorCode.Timeout:
            // Connection timed out
            break;
        case ProxyErrorCode.ConnectionFailed:
            // Could not reach the proxy (includes proxy host:port in message)
            break;
        case ProxyErrorCode.AuthRequired:
            // Proxy requires credentials (HTTP 407)
            break;
        case ProxyErrorCode.AuthFailed:
            // Wrong username/password
            break;
        case ProxyErrorCode.InvalidResponse:
            // Proxy returned garbage
            break;
    }
    // ex.Message includes proxy host:port and target host:port
    // ex.InnerException contains the original SocketException/IOException
}

Error Codes

Code	Description
Timeout	Connection timed out
ConnectionFailed	Failed to connect to the proxy server
AuthRequired	Proxy requires authentication (HTTP 407)
AuthFailed	Authentication credentials rejected
InvalidResponse	Proxy returned an invalid/unparseable response
SocksUnexpectedVersion	SOCKS protocol version mismatch
SocksNoAuthMethod	No suitable SOCKS5 auth method
SocksBadAddressType	Unknown SOCKS5 address type
SocksIPv6NotSupported	SOCKS4 does not support IPv6
SocksNoIPv4Address	Failed to resolve host to IPv4 (SOCKS4)
SocksStringTooLong	SOCKS field exceeded 255-byte limit

Supported Proxy Types

Type	Protocol	Auth	DNS through proxy
Http	HTTP CONNECT	Basic	No
Https	HTTPS CONNECT + TLS	Basic	No
Socks4	SOCKS4	UserId	No (resolved locally)
Socks4a	SOCKS4a	UserId	Yes
Socks5	SOCKS5 (RFC 1928)	Username/Password (RFC 1929)	Yes

Configuration Options

When using the factory/client API, each client supports:

Property	Default	Description
NoDelay	true	Disable Nagle algorithm
LingerState	Linger(true, 0)	Socket linger on close
ReadTimeout	0 (infinite)	Read timeout in ms
WriteTimeout	0 (infinite)	Write timeout in ms
LocalEndPoint	null	Bind to specific local IP

License

MIT