Scott Feldman
8642886f73
According to man page accept(2), accept returns new client sockfd and remote peer ip:port. This patch corrects the Accept() prototype in the netdever interface to not take in an ip:port arg, but rather return an ip:port for remote peer. Tested with examples/net/tcpecho on wioterminal and nano-rp2040. Here's a run with wioterminal: SERVER ============ sfeldma@nuc:~/work/drivers$ tinygo flash -monitor -target wioterminal -size short -stack-size=8kb ./examples/net/tcpecho code data bss | flash ram 110876 2552 11212 | 113428 13764 Connected to /dev/ttyACM2. Press Ctrl-C to exit. Realtek rtl8720dn Wifi network device driver (rtl8720dn) Driver version : 0.0.1 RTL8720 firmware version : 2.1.2 MAC address : 2c:f7:f1:1c:9b:2f Connecting to Wifi SSID 'test'...CONNECTED DHCP-assigned IP : 10.0.0.140 DHCP-assigned subnet : 255.255.255.0 DHCP-assigned gateway : 10.0.0.1 Starting TCP server listening on :8080 Client 10.0.0.190:50000 connected Client 10.0.0.190:50000 closed CLIENT ============= nc -p 50000 10.0.0.140 8080
Table of Contents
Netdever
TinyGo's network device driver model comprises two Go interfaces: Netdever and Netlinker. This README covers Netdever.
The Netdever interface describes an L4/L3 network interface modeled after the BSD sockets. A netdev is a concrete implementation of a Netdever. See Netlinker for the L2 network interface.
A netdev can:
- Send and receive L4/L3 packets
- Resolve DNS lookups
- Get/set the device's IP address
TinyGo network drivers implement the Netdever interface, providing a BSD sockets interface to TinyGo's "net" package. net.Conn implementations (TCPConn, UDPConn, and TLSConn) use the netdev socket. For example, net.DialTCP, which returns a net.TCPConn, calls netdev.Socket() and netdev.Connect():
func DialTCP(network string, laddr, raddr *TCPAddr) (*TCPConn, error) {
fd, _ := netdev.Socket(netdev.AF_INET, netdev.SOCK_STREAM, netdev.IPPROTO_TCP)
netdev.Connect(fd, "", raddr.IP, raddr.Port)
return &TCPConn{
fd: fd,
laddr: laddr,
raddr: raddr,
}, nil
}
Setting Netdev
Before the app can use TinyGo's "net" package, the app must set the netdev using UseNetdev(). This binds the "net" package to the netdev driver. For example, setting the wifinina driver as the netdev:
nina := wifinina.New(&cfg)
netdev.UseNetdev(nina)
Netdev Driver Notes
See the wifinina and rtl8720dn for examples of netdev drivers. Here are some notes for netdev drivers.
Locking
Multiple goroutines may invoke methods on a net.Conn simultaneously, and since the net package translates net.Conn calls into netdev socket calls, it follows that multiple goroutines may invoke socket calls, so locking is required to keep socket calls from stepping on one another.
Don't hold a lock while Time.Sleep()ing waiting for a long hardware operation to finish. Unlocking while sleeping let's other goroutines make progress.
Sockfd
The netdev BSD socket interface uses a socket fd (int) to represent a socket connection (end-point). Each fd maps 1:1 to a net.Conn maps. The number of fds available is a hardware limitation. Wifinina, for example, can hand out 10 fds, representing 10 active sockets.
Testing
The netdev driver should minimally run all of the example/net examples.