Go1.7.3簡單的ftp協議交互

package main

import (
    "bufio"
    "bytes"
    "errors"
    "fmt"
    "io"
    "log"
    "net"
    "os"
    "strconv"
    "strings"
)

func main() {
    f, err := NewFtp("172.18.80.247:300", "test", "123456")
    if err != nil {
        log.Println(err)
        return
    }
    defer f.Exit()
    err = f.GetFile("1.go", "命令.txt")
    if err != nil {
        log.Println(err)
    }
    err = f.PutFile("ssh", "ssh.go")
    if err != nil {
        log.Println(err)
    }
}

func NewFtp(ip, user, pass string) (*ftp, error) {
    con, err := net.Dial("tcp", ip)
    if err != nil {
        return nil, err
    }
    fmt.Fprintf(con, "USER %s\r\nPASS %s\r\n", user, pass)
    buf := bufio.NewReader(con)
    for {
        line, _, err := buf.ReadLine()
        if err != nil {
            return nil, err
        }
        if bytes.HasPrefix(line, []byte("220")) {
            continue
        }
        if bytes.HasPrefix(line, []byte("530")) {
            log.Print(string(line))
        }
        if bytes.HasPrefix(line, []byte("230")) {
            log.Printf(string(line))
            break
        }
    }
    return &ftp{con, ip}, nil
}

type ftp struct {
    con net.Conn
    ip  string
}

func (self *ftp) PutFile(lpath, rpath string) error {
    con, err := self.connection("STOR", rpath)
    if err != nil {
        return err
    }
    File, err := os.Open(lpath)
    if err != nil {
        con.Close()
        return err
    }
    io.Copy(con, File)
    con.Close()
    File.Close()

    buf := make([]byte, 1024)
    n, err := self.con.Read(buf)
    if err == nil {
        log.Print(string(buf[:n]))
    }
    return err
}

func (self *ftp) GetFile(lpath, rpath string) error {
    con, err := self.connection("RETR", rpath)
    if err != nil {
        return err
    }
    File, err := os.Create(lpath)
    if err != nil {
        con.Close()
        return err
    }
    io.Copy(File, con)
    File.Close()
    con.Close()
    buf := make([]byte, 1024)
    n, err := self.con.Read(buf)
    if err == nil {
        log.Print(string(buf[:n]))
    }
    return err
}

func (self *ftp) connection(status, Pathname string) (net.Conn, error) {
    buf := make([]byte, 1024)
    fmt.Fprintln(self.con, "PASV ")
    n, err := self.con.Read(buf)
    if err != nil {
        return nil, err
    }
    if s := string(buf[:n]); !strings.Contains(s, "227 Entering Passive Mode") {
        return nil, errors.New(s)
    }
    port := getport(buf[27 : n-3])
    con, err := net.Dial("tcp", fmt.Sprintf("%s:%d", strings.Split(self.ip, ":")[0], port))
    if err != nil {
        return nil, err
    }
    fmt.Fprintf(self.con, "%s %s\r\n", status, Pathname)
    n, err = self.con.Read(buf)
    if err != nil {
        con.Close()
        return nil, err
    }
    if !strings.Contains(string(buf[:n]), "150 Opening data channel") {
        con.Close()
        return nil, errors.New(string(buf[:n-2]))
    }
    return con, nil
}

func (self *ftp) Exit() {
    buf := make([]byte, 1024)
    fmt.Fprintln(self.con, "QUIT ")
    n, err := self.con.Read(buf)
    if err == nil {
        log.Print(string(buf[:n]))
    } else {
        log.Println(err)
    }
    if self.con != nil {
        self.con.Close()
    }
}

func getport(by []byte) int {
    s := string(by)
    list := strings.Split(s, ",")
    n1, err := strconv.Atoi(list[len(list)-2])
    if err != nil {
        return 0
    }
    n2, err := strconv.Atoi(list[len(list)-1])
    if err != nil {
        return 0
    }
    return n1*256 + n2
}