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client.go
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client.go
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// Copyright (C) 2017 Kale Blankenship. All rights reserved.
// This software may be modified and distributed under the terms
// of the MIT license. See the LICENSE file for details
package tftp // import "pack.ag/tftp"
import (
"fmt"
"io"
"net"
"net/url"
"strconv"
"strings"
)
// Client makes requests to a server.
type Client struct {
log *logger
net string // UDP network (ie, "udp", "udp4", "udp6")
mode TransferMode // TFTP transfer mode
opts map[string]string // Map of TFTP options (RFC2347)
retransmit int // Per-packet retransmission limit
}
// NewClient returns a configured Client.
//
// Any number of ClientOpts can be provided to modify the default client behavior.
func NewClient(opts ...ClientOpt) (*Client, error) {
// Copy default options into new map
options := map[string]string{}
for k, v := range defaultOptions {
options[k] = v
}
c := &Client{
log: newLogger("client"),
net: defaultUDPNet,
opts: options,
mode: defaultMode,
retransmit: defaultRetransmit,
}
// Apply option functions to client
for _, opt := range opts {
if err := opt(c); err != nil {
return c, err
}
}
return c, nil
}
// Get initiates a read request a server.
//
// URL is in the format tftp://[server]:[port]/[file]
func (c *Client) Get(url string) (*Response, error) {
u, err := parseURL(url)
if err != nil {
return nil, err
}
// Create connection
conn, err := newConnFromHost(c.net, c.mode, u.host)
if err != nil {
return nil, err
}
// Set retransmit
conn.retransmit = c.retransmit
// Initiate the request
if err := conn.sendReadRequest(u.file, c.opts); err != nil {
return nil, err
}
return &Response{conn: conn}, nil
}
// Put takes an io.Reader request a server.
//
// URL is in the format tftp://[server]:[port]/[file]
func (c *Client) Put(url string, r io.Reader, size int64) (err error) {
u, err := parseURL(url)
if err != nil {
return err
}
// Create connection
conn, err := newConnFromHost(c.net, c.mode, u.host)
if err != nil {
return err
}
defer func() {
cErr := conn.Close()
if err == nil {
err = cErr
}
}()
// Set retransmit
conn.retransmit = c.retransmit
// Check if tsize is enabled
if _, ok := c.opts[optTransferSize]; ok {
if size < 1 {
// If size is <1, remove the option
delete(c.opts, optTransferSize)
} else {
// Otherwise add the size as a string
c.opts[optTransferSize] = fmt.Sprint(size)
}
}
// Initiate the request
if err := conn.sendWriteRequest(u.file, c.opts); err != nil {
return err
}
// Write the data to the connections
_, err = io.Copy(conn, r)
return err
}
// parsedURL holds the result of parseURL
type parsedURL struct {
host string
file string
}
// parsedURL takes a string with the format "[server]:[port]/[file]"
// and splits it into host and file.
//
// If port is not specified, defaultPort will be used.
func parseURL(tftpURL string) (*parsedURL, error) {
if tftpURL == "" {
return nil, ErrInvalidURL
}
const kTftpPrefix = "tftp://"
if !strings.HasPrefix(tftpURL, kTftpPrefix) {
tftpURL = kTftpPrefix + tftpURL
}
u, err := url.Parse(tftpURL)
if err != nil {
return nil, err
}
file := u.RequestURI()
if u.Fragment != "" {
file = file + "#" + u.Fragment
}
p := &parsedURL{
host: u.Hostname(),
file: strings.TrimPrefix(file, "/"),
}
if p.host == "" {
return nil, ErrInvalidHostIP
}
if isNumeric(p.host) {
return nil, ErrInvalidHostIP
}
if p.file == "" {
return nil, ErrInvalidFile
}
port := u.Port()
if port == "" {
port = defaultPort
}
if !isNumeric(port) {
return nil, ErrInvalidHostIP
}
p.host = net.JoinHostPort(p.host, port)
return p, nil
}
func isNumeric(s string) bool {
_, err := strconv.Atoi(s)
return err == nil
}
// Response is an io.Reader for receiving files from a TFTP server.
type Response struct {
conn *conn
}
// Size returns the transfer size as indicated by the server in the tsize option.
//
// ErrSizeNotReceived will be returned if tsize option was not enabled.
func (r *Response) Size() (int64, error) {
if r.conn.tsize == nil {
return 0, ErrSizeNotReceived
}
return *r.conn.tsize, nil
}
func (r *Response) Read(p []byte) (int, error) {
return r.conn.Read(p)
}
// ClientOpt is a function that configures a Client.
type ClientOpt func(*Client) error
// ClientMode configures the mode.
//
// Valid options are ModeNetASCII and ModeOctet. Default is ModeNetASCII.
func ClientMode(mode TransferMode) ClientOpt {
return func(c *Client) error {
if mode != ModeNetASCII && mode != ModeOctet {
return ErrInvalidMode
}
c.mode = mode
return nil
}
}
// ClientBlocksize configures the number of data bytes that will be send in each datagram.
// Valid range is 8 to 65464.
//
// Default: 512.
func ClientBlocksize(size int) ClientOpt {
return func(c *Client) error {
if size < 8 || size > 65464 {
return ErrInvalidBlocksize
}
c.opts[optBlocksize] = strconv.Itoa(size)
return nil
}
}
// ClientTimeout configures the number of seconds to wait before resending an unacknowledged datagram.
// Valid range is 1 to 255.
//
// Default: 1.
func ClientTimeout(seconds int) ClientOpt {
return func(c *Client) error {
if seconds < 1 || seconds > 255 {
return ErrInvalidTimeout
}
c.opts[optTimeout] = strconv.Itoa(seconds)
return nil
}
}
// ClientWindowsize configures the number of datagrams that will be transmitted before needing an acknowledgement.
//
// Default: 1.
func ClientWindowsize(window int) ClientOpt {
return func(c *Client) error {
if window < 1 || window > 65535 {
return ErrInvalidWindowsize
}
c.opts[optWindowSize] = strconv.Itoa(window)
return nil
}
}
// ClientTransferSize requests for the server to send the file size before sending.
//
// Default: enabled.
func ClientTransferSize(enable bool) ClientOpt {
return func(c *Client) error {
if enable {
c.opts[optTransferSize] = "0"
} else {
delete(c.opts, optTransferSize)
}
return nil
}
}
// ClientRetransmit configures the per-packet retransmission limit for all requests.
//
// Default: 10.
func ClientRetransmit(i int) ClientOpt {
return func(c *Client) error {
if i < 0 {
return ErrInvalidRetransmit
}
c.retransmit = i
return nil
}
}