go-smb2

The negotiation process involves creating a NegotiateRequest based on the Negotiator settings, sending it to the server, and processing the NegotiateResponse.

Key behaviors during negotiation:

1. Security Mode: Based on RequireMessageSigning, the request sets SMB2_NEGOTIATE_SIGNING_REQUIRED or SMB2_NEGOTIATE_SIGNING_ENABLED.
2. Dialect Selection: If a SpecifiedDialect is provided, the client attempts to connect using only that dialect. If the server returns a different dialect (specifically if it returns SMB2), the client may retry with SMB210.
3. Contexts: For modern dialects (like SMB 3.1.1), the negotiator handles NegotiateContext for pre-authentication integrity (e.g., SHA512) and encryption capabilities (e.g., AES128GCM).
4. Capabilities: The resulting connection inherits capabilities from the server response, such as maxTransactSize, maxReadSize, and maxWriteSize.

The go-smb2 library integrates with Go's standard os error checking. You can use os.IsNotExist(err), os.IsExist(err), and os.IsPermission(err) to inspect errors returned by filesystem operations. Additionally, you can use fs.WithContext(ctx) to perform operations with context support, allowing you to detect timeouts via os.IsTimeout(err).

package main

import (
	"context"
	"fmt"
	"net"
	"os"

	"github.com/hirochachacha/go-smb2"
)

func main() {
	conn, err := net.Dial("tcp", "SERVERNAME:445")
	if err != nil {
		panic(err)
	}
	defer conn.Close()

	d := &smb2.Dialer{
		Initiator: &smb2.NTLMInitiator{
			User:     "USERNAME",
			Password: "PASSWORD",
		},
	}

	s, err := d.Dial(conn)
	if err != nil {
		panic(err)
	}
	defer s.Logoff()

	fs, err := s.Mount("SHARENAME")
	if err != nil {
		panic(err)
	}
	defer fs.Umount()

	_, err = fs.Open("notExist.txt")

	fmt.Println(os.IsNotExist(err)) // true
	fmt.Println(os.IsExist(err))    // false

	fs.WriteFile("hello2.txt", []byte("test"), 0444)
	err = fs.WriteFile("hello2.txt", []byte("test2"), 0444)
	fmt.Println(os.IsPermission(err)) // true

	ctx, cancel := context.WithTimeout(context.Background(), 0)
	defer cancel()

	_, err = fs.WithContext(ctx).Open("hello.txt")

	fmt.Println(os.IsTimeout(err)) // true
}

To manipulate files, mount a specific share using s.Mount("SHARENAME") to obtain an fs object. You can then use standard file operations such as fs.Create(), f.Write(), f.Seek(), and fs.Remove(). Always remember to Umount() the filesystem and Logoff() the session.

package main

import (
	"io"
	"io/ioutil"
	"net"

	"github.com/hirochachacha/go-smb2"
)

func main() {
	conn, err := net.Dial("tcp", "SERVERNAME:445")
	if err != nil {
		panic(err)
	}
	defer conn.Close()

	d := &smb2.Dialer{
		Initiator: &smb2.NTLMInitiator{
			User:     "USERNAME",
			Password: "PASSWORD",
		},
	}

	s, err := d.Dial(conn)
	if err != nil {
		panic(err)
	}
	defer s.Logoff()

	fs, err := s.Mount("SHARENAME")
	if err != nil {
		panic(err)
	}
	defer fs.Umount()

	f, err := fs.Create("hello.txt")
	if err != nil {
		panic(err)
	}
	defer fs.Remove("hello.txt")
	defer f.Close()

	_, err = f.Write([]byte("Hello world!"))
	if err != nil {
		panic(err)
	}

	_, err = f.Seek(0, io.SeekStart)
	if err != nil {
		panic(err)
	}

	bs, err := ioutil.ReadAll(f)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(bs))
}

The go-smb2 filesystem object can be used with the standard io/fs package. By calling fs.DirFS("."), you can obtain an io/fs.FS compatible interface, which allows you to use iofs.Glob for pattern matching and iofs.WalkDir for recursive directory traversal.

package main

import (
	"fmt"
	"net"
	iofs "io/fs"

	"github.com/hirochachacha/go-smb2"
)

func main() {
	conn, err := net.Dial("tcp", "SERVERNAME:445")
	if err != nil {
		panic(err)
	}
	defer conn.Close()

	d := &smb2.Dialer{
		Initiator: &smb2.NTLMInitiator{
			User:     "USERNAME",
			Password: "PASSWORD",
		},
	}

	s, err := d.Dial(conn)
	if err != nil {
		panic(err)
	}
	defer s.Logoff()

	fs, err := s.Mount("SHARENAME")
	if err != nil {
		panic(err)
	}
	defer fs.Umount()

	matches, err := iofs.Glob(fs.DirFS("."), "*")
	if err != nil {
		panic(err)
	}
	for _, match := range matches {
		fmt.Println(match)
	}

	err = iofs.WalkDir(fs.DirFS("."), ".", func(path string, d iofs.DirEntry, err error) error {
		fmt.Println(path, d, err)

		return nil
	})
	if err != nil {
		panic(err)
	}
}