Import xtransport

This commit is contained in:
Frank Denis 2018-01-30 15:51:07 +01:00
parent ecaf18f614
commit 61bad01726
1 changed files with 147 additions and 0 deletions

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@ -0,0 +1,147 @@
package main
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"net/url"
"strings"
"sync"
"time"
"github.com/jedisct1/dlog"
"github.com/miekg/dns"
)
const DefaultFallbackResolver = "9.9.9.9:53"
type CachedIPs struct {
sync.RWMutex
cache map[string]string
}
type XTransport struct {
transport *http.Transport
timeout time.Duration
cachedIPs CachedIPs
fallbackResolver string
}
func NewXTransport(timeout time.Duration) *XTransport {
xTransport := XTransport{
cachedIPs: CachedIPs{cache: make(map[string]string)},
timeout: timeout,
fallbackResolver: DefaultFallbackResolver,
}
dialer := &net.Dialer{Timeout: timeout, KeepAlive: timeout, DualStack: true}
transport := &http.Transport{
DisableKeepAlives: false,
DisableCompression: true,
MaxIdleConns: 1,
IdleConnTimeout: timeout,
ResponseHeaderTimeout: timeout,
ExpectContinueTimeout: timeout,
MaxResponseHeaderBytes: 4096,
DialContext: func(ctx context.Context, network, addrStr string) (net.Conn, error) {
host := addrStr[:strings.LastIndex(addrStr, ":")]
ipOnly := host
xTransport.cachedIPs.RLock()
cachedIP := xTransport.cachedIPs.cache[host]
xTransport.cachedIPs.RUnlock()
if len(cachedIP) > 0 {
ipOnly = cachedIP
} else {
dlog.Debugf("[%s] IP address was not cached", host)
}
addrStr = ipOnly + addrStr[strings.LastIndex(addrStr, ":"):]
return dialer.DialContext(ctx, network, addrStr)
},
}
xTransport.transport = transport
return &xTransport
}
func (xTransport *XTransport) Fetch(method string, url *url.URL, accept string, contentType string, body *io.ReadCloser, timeout time.Duration) (*http.Response, time.Duration, error) {
if timeout <= 0 {
timeout = xTransport.timeout
}
client := http.Client{Transport: xTransport.transport, Timeout: timeout}
header := map[string][]string{"User-Agent": {"dnscrypt-proxy"}}
if len(accept) > 0 {
header["Accept"] = []string{accept}
}
if len(contentType) > 0 {
header["Content-Type"] = []string{contentType}
}
req := &http.Request{
Method: method,
URL: url,
Header: header,
Close: false,
}
if body != nil {
req.Body = *body
}
start := time.Now()
resp, err := client.Do(req)
rtt := time.Since(start)
if err == nil {
if resp == nil {
err = errors.New("Webserver returned an error")
} else if resp.StatusCode < 200 || resp.StatusCode > 299 {
err = fmt.Errorf("Webserver returned code %d", resp.StatusCode)
}
return resp, rtt, err
}
host := url.Host
xTransport.cachedIPs.RLock()
cachedIP := xTransport.cachedIPs.cache[host]
xTransport.cachedIPs.RUnlock()
if len(cachedIP) > 0 {
dlog.Debugf("IP for [%s] was cached to [%s], but connection failed: [%s]", host, cachedIP, err)
return resp, rtt, err
}
dnsClient := new(dns.Client)
msg := new(dns.Msg)
msg.SetQuestion(dns.Fqdn(host), dns.TypeA)
msg.SetEdns0(4096, true)
dlog.Noticef("System DNS configuration not usable yet, exceptionally resolving [%s] using fallback resolver [%s]", host, xTransport.fallbackResolver)
in, _, err := dnsClient.Exchange(msg, xTransport.fallbackResolver)
if err != nil {
return resp, rtt, err
}
if len(in.Answer) <= 0 {
return resp, rtt, fmt.Errorf("No IP found for [%s]", host)
}
foundIP := in.Answer[0].(*dns.A).A.String()
xTransport.cachedIPs.Lock()
xTransport.cachedIPs.cache[host] = foundIP
xTransport.cachedIPs.Unlock()
dlog.Debugf("[%s] IP address [%s] added to the cache", host, foundIP)
start = time.Now()
resp, err = client.Do(req)
rtt = time.Since(start)
if err == nil {
if resp == nil {
err = errors.New("Webserver returned an error")
} else if resp.StatusCode < 200 || resp.StatusCode > 299 {
err = fmt.Errorf("Webserver returned code %d", resp.StatusCode)
}
}
return resp, rtt, err
}
func (xTransport *XTransport) Get(url *url.URL, timeout time.Duration) (*http.Response, time.Duration, error) {
return xTransport.Fetch("GET", url, "", "", nil, timeout)
}
func (xTransport *XTransport) Post(url *url.URL, accept string, contentType string, body []byte, timeout time.Duration) (*http.Response, time.Duration, error) {
bc := ioutil.NopCloser(bytes.NewReader(body))
return xTransport.Fetch("POST", url, accept, contentType, &bc, timeout)
}