seqs

seqs is what is commonly referred to as a userspace IP implementation. It handles:

• Ethernet protocol
• IP packet marshalling to sub-protocols:
  • ARP requests and responses
  • UDP packet handling
  • DHCP client requests and DHCP server
  • TCP connections over IP with support for multiple listeners on same port. These implement net.Conn and net.Listener interfaces. See stacks/tcpconn.go

Example of use

stack := stacks.NewPortStack(stacks.PortStackConfig{
    MAC:             MAC,
    MaxOpenPortsTCP: 1,
    MaxOpenPortsUDP: 1,
    MTU:             2048,
})
// Static IP setting.
ip := netip.AddrFrom4([4]byte{192, 168, 1, 45}) 
stack.SetAddr(ip)

// Or can request an address via DHCP.
dhcpClient := stacks.NewDHCPClient(stack, dhcp.DefaultClientPort)
err = dhcpClient.BeginRequest(stacks.DHCPRequestConfig{
    RequestedAddr: netip.AddrFrom4([4]byte{192, 168, 1, 69}),
    Xid:           0x12345678,
    Hostname:      "tinygo-pico",
})

for !dhcpClient.Done() {
    time.Sleep(time.Second / 2)
}

offeredIP := dhcpClient.Offer()
fmt.Println("got offer:", offeredIP)
stack.SetAddr(offeredIP)

How to use seqs

go mod download github.com/soypat/seqs@latest

History - Precursors to seqs

Before seqs there was:

• ether-swtch - First known instance of a (barely) working TCP/IP stack in Go working on embedded systems, circa June 2021. Could blink an Arduino UNO's LED via HTTP (!). Famously bad design, code, performance, readability.
• dgrams - Library prepared for Pico W's wifi chip. Already shows similarities with seqs. Circa May 2023.