Performing low-level network socket operations using syscalls in Go can be achieved using the syscall package. Below is an example code snippet that demonstrates how to create a TCP socket, bind it to a specific port, listen for incoming connections, and accept those connections:
package main
import (
"fmt"
"net"
"os"
"syscall"
)
const (
AF_INET = 2 // IPv4
SOCK_STREAM = 1 // TCP
SOL_SOCKET = 1 // Socket level
SO_REUSEADDR = 2 // Reuse socket address
INADDR_ANY = 0 // Listen on all available IP addresses
SOMAXCONN = 128 // Maximum queue length for incoming connections
)
func main() {
// Create a socket using the syscall.Socket function.
sockfd, err := syscall.Socket(AF_INET, SOCK_STREAM, 0)
if err != nil {
fmt.Println("Socket creation failed:", err)
return
}
// Set the SO_REUSEADDR socket option to reuse the address.
err = syscall.SetsockoptInt(sockfd, SOL_SOCKET, SO_REUSEADDR, 1)
if err != nil {
fmt.Println("Setsockopt failed:", err)
return
}
// Bind the socket to a specific IP address and port.
addr := syscall.SockaddrInet4{Port: 12345}
copy(addr.Addr[:], net.ParseIP("0.0.0.0").To4())
err = syscall.Bind(sockfd, &addr)
if err != nil {
fmt.Println("Bind failed:", err)
return
}
// Listen for incoming connections.
err = syscall.Listen(sockfd, SOMAXCONN)
if err != nil {
fmt.Println("Listen failed:", err)
return
}
fmt.Println("Listening for connections...")
for {
// Accept incoming connections.
connfd, _, err := syscall.Accept(sockfd)
if err != nil {
fmt.Println("Accept failed:", err)
return
}
// Handle the connection, e.g., read/write data, etc.
// Close the connection.
syscall.Close(connfd)
}
// Close the socket.
syscall.Close(sockfd)
}
Please note that using low-level syscalls for network operations is generally not recommended unless you have specific requirements that cannot be fulfilled using higher-level abstractions provided by the standard library.