mirror of
https://github.com/tinygo-org/drivers.git
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Scott Feldman
79 lines
2.4 KiB
Markdown
79 lines
2.4 KiB
Markdown
### Table of Contents
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- [Netdever](#netdever)
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- [Netdev Driver](#netdev-driver)
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- [Netdev Driver Notes](#netdev-driver-notes)
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## Netdever
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TinyGo's network device driver model comprises two Go interfaces: Netdever and
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Netlinker. This README covers Netdever.
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The Netdever interface describes an L4/L3 network interface modeled after the
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BSD sockets. A netdev is a concrete implementation of a Netdever. See
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[Netlinker](../netlink/) for the L2 network interface.
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A netdev can:
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- Send and receive L4/L3 packets
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- Resolve DNS lookups
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- Get/set the device's IP address
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TinyGo network drivers implement the Netdever interface, providing a BSD
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sockets interface to TinyGo's "net" package. net.Conn implementations
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(TCPConn, UDPConn, and TLSConn) use the netdev socket. For example,
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net.DialTCP, which returns a net.TCPConn, calls netdev.Socket() and
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netdev.Connect():
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```go
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func DialTCP(network string, laddr, raddr *TCPAddr) (*TCPConn, error) {
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fd, _ := netdev.Socket(netdev.AF_INET, netdev.SOCK_STREAM, netdev.IPPROTO_TCP)
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netdev.Connect(fd, "", raddr.IP, raddr.Port)
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return &TCPConn{
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fd: fd,
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laddr: laddr,
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raddr: raddr,
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}, nil
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}
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```
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## Setting Netdev
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Before the app can use TinyGo's "net" package, the app must set the netdev
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using UseNetdev(). This binds the "net" package to the netdev driver. For
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example, setting the wifinina driver as the netdev:
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```
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nina := wifinina.New(&cfg)
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netdev.UseNetdev(nina)
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```
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## Netdev Driver Notes
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See the wifinina and rtl8720dn for examples of netdev drivers. Here are some
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notes for netdev drivers.
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#### Locking
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Multiple goroutines may invoke methods on a net.Conn simultaneously, and since
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the net package translates net.Conn calls into netdev socket calls, it follows
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that multiple goroutines may invoke socket calls, so locking is required to
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keep socket calls from stepping on one another.
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Don't hold a lock while Time.Sleep()ing waiting for a long hardware operation to
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finish. Unlocking while sleeping let's other goroutines make progress.
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#### Sockfd
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The netdev BSD socket interface uses a socket fd (int) to represent a socket
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connection (end-point). Each fd maps 1:1 to a net.Conn maps. The number of fds
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available is a hardware limitation. Wifinina, for example, can hand out 10
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fds, representing 10 active sockets.
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#### Testing
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The netdev driver should minimally run all of the example/net examples.
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