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client.go
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client.go
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package whois
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"os"
"syscall"
"time"
)
const (
// DefaultTimeout sets the maximum lifetime of whois requests.
DefaultTimeout = 30 * time.Second
// DefaultReadLimit sets the maximum bytes a client will attempt to read from a connection.
DefaultReadLimit = 1 << 20 // 1 MB
)
// Client represents a whois client. It contains an http.Client, for executing
// some whois Requests.
type Client struct {
Dial func(string, string) (net.Conn, error)
HTTPClient *http.Client
}
// DefaultClient represents a shared whois client with a default timeout, HTTP
// transport, and dialer.
var DefaultClient = NewClient(DefaultTimeout)
// NewClient creates and initializes a new Client with the specified timeout.
func NewClient(timeout time.Duration) *Client {
dial := func(network, address string) (net.Conn, error) {
deadline := time.Now().Add(timeout)
conn, err := net.DialTimeout(network, address, timeout)
if err != nil {
return nil, err
}
conn.SetDeadline(deadline)
return conn, nil
}
c := &Client{
Dial: dial,
HTTPClient: &http.Client{},
}
c.HTTPClient.Transport = &http.Transport{
Dial: c.dial,
Proxy: http.ProxyFromEnvironment,
TLSHandshakeTimeout: timeout,
ResponseHeaderTimeout: timeout,
}
return c
}
func (c *Client) dial(network, address string) (net.Conn, error) {
return c.Dial(network, address)
}
// FetchError reports the underlying error and includes the target host of the fetch operation.
type FetchError struct {
Err error
Host string
}
// Error implements the error interface.
func (f *FetchError) Error() string {
return f.Err.Error()
}
// Fetch sends the Request to a whois server.
func (c *Client) Fetch(req *Request) (*Response, error) {
if req.URL != "" {
return c.fetchHTTP(req)
}
return c.fetchWhois(req)
}
func (c *Client) fetchWhois(req *Request) (*Response, error) {
if req.Host == "" {
return nil, &FetchError{fmt.Errorf("no request host for %s", req.Query), "unknown"}
}
conn, err := c.Dial("tcp", req.Host+":43")
if err != nil {
return nil, &FetchError{err, req.Host}
}
defer conn.Close()
if _, err = conn.Write(req.Body); err != nil {
logError(err)
return nil, &FetchError{err, req.Host}
}
res := NewResponse(req.Query, req.Host)
if res.Body, err = ioutil.ReadAll(io.LimitReader(conn, DefaultReadLimit)); err != nil {
logError(err)
return nil, &FetchError{err, req.Host}
}
res.DetectContentType("")
return res, nil
}
func (c *Client) fetchHTTP(req *Request) (*Response, error) {
hreq, err := httpRequest(req)
if err != nil {
return nil, &FetchError{err, req.Host}
}
hres, err := c.HTTPClient.Do(hreq)
if err != nil {
return nil, &FetchError{err, req.Host}
}
res := NewResponse(req.Query, req.Host)
if res.Body, err = ioutil.ReadAll(io.LimitReader(hres.Body, DefaultReadLimit)); err != nil {
logError(err)
return nil, &FetchError{err, req.Host}
}
res.DetectContentType(hres.Header.Get("Content-Type"))
return res, nil
}
func httpRequest(req *Request) (*http.Request, error) {
var hreq *http.Request
var err error
// POST if non-zero Request.Body
if len(req.Body) > 0 {
hreq, err = http.NewRequest("POST", req.URL, bytes.NewReader(req.Body))
} else {
hreq, err = http.NewRequest("GET", req.URL, nil)
}
if err != nil {
return nil, err
}
// Some web whois servers require a Referer header
hreq.Header.Add("Referer", req.URL)
return hreq, nil
}
func logError(err error) {
switch t := err.(type) {
case syscall.Errno:
fmt.Fprintf(os.Stderr, "syscall.Errno %d: %s\n", t, err.Error())
case net.Error:
fmt.Fprintf(os.Stderr, "net.Error timeout=%t, temp=%t: %s\n", t.Timeout(), t.Temporary(), err.Error())
default:
fmt.Fprintf(os.Stderr, "Unknown error %v: %s\n", t, err.Error())
}
}