// New creates a new instance of Proxy. "direct" is a special case URL that simply passes data through.
func New(proxyURLString string) *Proxy {
proxy := &Proxy{
Tr: &http.Transport{
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
DialContext: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).DialContext,
IdleConnTimeout: 90 * time.Second,
Dial: net.Dial,
},
}
if proxyURLString == "direct" {
proxy.Tr.Proxy = func(req *http.Request) (*url.URL, error) { return nil, nil }
proxy.Available = func() bool { return true }
proxy.ConnectDial = nil
} else {
proxyURL := earl.ParseWithDefaults(proxyURLString, &earl.URL{Scheme: "auto"})
proxy.Tr.Proxy = func(req *http.Request) (*url.URL, error) { return proxyURL.ToNetURL(), nil }
proxy.Available = func() bool { return exec.Command("ping", "-w", "1", proxyURL.Host).Run() == nil }
proxy.ConnectDial = proxy.connectDialer(proxyURL.ToNetURL().String())
}
return proxy
}
// connectDialer establishes a connection for use with a CONNECT request
// This code is largely derived from github.com/elazarl/go-proxy
func (proxy *Proxy) connectDialer(https_proxy string) func(network, addr string) (net.Conn, error) {
u := earl.ParseWithDefaults(https_proxy, &earl.URL{Scheme: "auto", Port: "80"})
return func(network, addr string) (net.Conn, error) {
client, err := proxy.Tr.Dial(network, u.HostAndPort())
if err != nil {
return nil, fmt.Errorf("Proxy refused connection: %s", err)
}
if u.Scheme == "https" {
client = tls.Client(client, proxy.Tr.TLSClientConfig)
}
request := &http.Request{
Method: "CONNECT",
URL: &url.URL{Opaque: addr},
Host: addr,
Header: make(http.Header),
}
request.Write(client)
reader := bufio.NewReader(client)
response, err := http.ReadResponse(reader, request)
if err != nil {
client.Close()
return nil, fmt.Errorf("Error reading response from proxy: %s", err)
}
if response.StatusCode != 200 {
responseText, _ := ioutil.ReadAll(response.Body)
response.Body.Close()
client.Close()
return nil, fmt.Errorf("Proxy error: %s", string(responseText))
}
return client, nil
}
}