First commit.

ftp.go

@@ -0,0 +1,224 @@
+package ftp
+
+import (
+	"bufio"
+	"net"
+	"os"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+const (
+	EntryTypeFile = iota
+	EntryTypeFolder
+	EntryTypeLink
+)
+
+type ServerCon struct {
+	conn net.Conn
+	bio *bufio.Reader
+}
+
+type Response struct {
+	conn net.Conn
+	c *ServerCon
+}
+
+type Entry struct {
+	Name string
+	EntryType int
+	Size uint64
+}
+
+// Check if the last status code is equal to the given code
+// If it is the case, err is nil
+// Returns the status line for further processing
+func (c *ServerCon) checkStatus(expected int) (line string, err os.Error) {
+	line, err = c.bio.ReadString('\n')
+	if err != nil {
+		return
+	}
+	code, err := strconv.Atoi(line[:3]) // A status is 3 digits
+	if err != nil {
+		return
+	}
+	if code != expected {
+		err = os.NewError(fmt.Sprintf("%d %s", code, statusText[code]))
+		return
+	}
+	return
+}
+
+// Like send() but with formating.
+func (c *ServerCon) sendf(str string, a ...interface{}) (os.Error) {
+	return c.send([]byte(fmt.Sprintf(str, a...)))
+}
+
+// Send a raw command on the connection.
+func (c *ServerCon) send(data []byte) (os.Error) {
+	_, err := c.conn.Write(data)
+	return err
+}
+
+// Connect to a ftp server and returns a ServerCon handler.
+func Connect(host, user, password string) (*ServerCon, os.Error) {
+	conn, err := net.Dial("tcp", host)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &ServerCon{conn, bufio.NewReader(conn)}
+
+	_, err = c.checkStatus(StatusReady)
+	if err != nil {
+		c.Close()
+		return nil, err
+	}
+
+	c.sendf("USER %v\r\n", user)
+	_, err = c.checkStatus(StatusUserOK)
+	if err != nil {
+		c.Close()
+		return nil, err
+	}
+
+	c.sendf("PASS %v\r\n", password)
+	_, err = c.checkStatus(StatusLoggedIn)
+	if err != nil {
+		c.Close()
+		return nil, err
+	}
+
+	return c, nil
+}
+
+// Like Connect() but with anonymous credentials.
+func ConnectAnonymous(host string) (*ServerCon, os.Error) {
+	return Connect(host, "anonymous", "anonymous")
+}
+
+// Enter extended passive mode
+func (c *ServerCon) epsv() (port int, err os.Error) {
+	c.send([]byte("EPSV\r\n"))
+	line, err := c.checkStatus(StatusExtendedPassiveMode)
+	if err != nil {
+		return
+	}
+	start := strings.Index(line, "|||")
+	end := strings.LastIndex(line, "|")
+	if start == -1 || end == -1 {
+		err = os.NewError("Invalid EPSV response format")
+		return
+	}
+	port, err = strconv.Atoi(line[start+3 : end])
+	return
+}
+
+// Open a new data connection using extended passive mode
+func (c *ServerCon) openDataConnection() (r *Response, err os.Error) {
+	port, err := c.epsv()
+	if err != nil {
+		return
+	}
+
+	// Build the new net address string
+	a := strings.Split(c.conn.RemoteAddr().String(), ":", 2)
+	addr := fmt.Sprintf("%v:%v", a[0], port)
+
+	conn, err := net.Dial("tcp", addr)
+	if err != nil {
+		return
+	}
+
+	r = &Response{conn, c}
+	return
+}
+
+func parseListLine(line string) (*Entry, os.Error) {
+	fields := strings.Fields(line)
+	if len(fields) < 9 {
+		return nil, os.NewError("Unsupported LIST line")
+	}
+
+	e := &Entry{}
+	switch fields[0][0] {
+		case '-':
+			e.EntryType = EntryTypeFile
+		case 'd':
+			e.EntryType = EntryTypeFolder
+		case 'l':
+			e.EntryType = EntryTypeLink
+		default:
+			return nil, os.NewError("Unknown entry type")
+	}
+
+	e.Name = strings.Join(fields[8:], " ")
+	return e, nil
+}
+
+func (c *ServerCon) List() (entries []*Entry, err os.Error) {
+	r, err := c.openDataConnection()
+	if err != nil {
+		return
+	}
+	defer r.Close()
+
+	c.send([]byte("LIST\r\n"))
+	_, err = c.checkStatus(StatusAboutToSend)
+	if err != nil {
+		return
+	}
+
+	bio := bufio.NewReader(r)
+	for {
+		line, e := bio.ReadString('\n')
+		if e == os.EOF {
+			break
+		} else if e != nil {
+			return nil, e
+		}
+		entry, err := parseListLine(line)
+		if err == nil {
+			entries = append(entries, entry)
+		}
+	}
+	return
+}
+
+func (c *ServerCon) ChangeDir(path string) (err os.Error) {
+	c.sendf("CWD %s\r\n", path);
+	_, err = c.checkStatus(StatusRequestedFileActionOK)
+	return
+}
+
+func (c *ServerCon) Get(path string) (r *Response, err os.Error) {
+	r, err = c.openDataConnection()
+	if err != nil {
+		return
+	}
+
+	c.sendf("RETR %s\r\n", path)
+	_, err = c.checkStatus(StatusAboutToSend)
+	return
+}
+
+func (c *ServerCon) Close() {
+	c.send([]byte("QUIT\r\n"))
+	c.conn.Close()
+}
+
+func (r *Response) Read(buf []byte) (int, os.Error) {
+	n, err := r.conn.Read(buf)
+	if err == os.EOF {
+		_, err2 := r.c.checkStatus(StatusClosingDataConnection)
+		if err2 != nil {
+			err = err2
+		}
+	}
+	return n, err
+}
+
+func (r *Response) Close() os.Error {
+	return r.conn.Close()
+}