gonnect-netstack

gonnect-netstack

This module integrates gVisor's netstack into the gonnect ecosystem, providing userspace networking with full TCP/IP stack capabilities.

[!IMPORTANT] vtun package in project was originally based on code extracted from wireguard-go. Although it has been significantly modified to fit the gonnect ecosystem, I must mention the original source to comply with the license. All credit goes to the original wireguard-go authors.

Packages

vtun

The vtun package provides a virtual tunnel built on gVisor's netstack. It acts as an L4 → L3 converter, accepting high-level dial/listen operations (TCP, UDP, ICMP) and producing a stream of raw IP packets. It implements gonnect's Network, Resolver, InterfaceNetwork, UpDown, and tun.Tun interfaces, making it a drop-in userspace network stack for gonnect applications.

• DialTCP / ListenTCP — TCP connection and listener management
• DialUDP / ListenUDP — UDP socket support
• DialPingAddr / ListenPingAddr — ICMP echo request/reply
• Built-in simple DNS resolution with configurable servers
• Wildcard address binding and automatic local address selection
• Destination-based source address routing

Source address routing

Use SourceRoutes when one VTun has multiple local addresses and the remote destination must select the source address. The route with the longest matching prefix has priority.

opts := vtun.Opts{
	LocalAddrs: []netip.Addr{
		netip.MustParseAddr("10.20.0.2"),
		netip.MustParseAddr("100.64.0.2"),
	},
	SourceRoutes: []vtun.SourceRoute{
		{
			Destination: netip.MustParsePrefix("100.64.0.0/10"),
			Source:      netip.MustParseAddr("100.64.0.2"),
		},
		{
			Destination: netip.MustParsePrefix("0.0.0.0/0"),
			Source:      netip.MustParseAddr("10.20.0.2"),
		},
	},
}

device, err := opts.Build()

The source address must be in LocalAddrs. Add an explicit 0.0.0.0/0 or ::/0 route if a configured family needs a fallback. If a family has source routes without a matching route, a new operation returns a network-unreachable error. A family without source routes keeps the legacy first-address behavior.

Call SetSourceRoutes to replace the table while the VTun is running. New flows use the new table. Existing TCP, connected UDP, and connected ICMP flows keep the source address that they selected when they connected.

spoofer

The spoofer package is the inverse of vtun. It acts as an L3 → L4 converter, accepting incoming IP packet streams (from a TUN device or any io.ReadWriteCloser) and converting them back into individual TCP/UDP connections via gVisor's forwarders. It's useful for intercepting, forwarding, or proxying traffic at the packet level.

• TCP and UDP forwarders with configurable callbacks
• Extensive TCP/IP tuning options
• Works with TUN devices or arbitrary io.ReadWriteCloser endpoints