Update vendor

vendor/github.com/labstack/echo/middleware/proxy.go

@@ -0,0 +1,160 @@
+package middleware
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"math/rand"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync/atomic"
+	"time"
+
+	"github.com/labstack/echo"
+)
+
+// TODO: Handle TLS proxy
+
+type (
+	// ProxyConfig defines the config for Proxy middleware.
+	ProxyConfig struct {
+		// Skipper defines a function to skip middleware.
+		Skipper Skipper
+
+		// Balancer defines a load balancing technique.
+		// Required.
+		// Possible values:
+		// - RandomBalancer
+		// - RoundRobinBalancer
+		Balancer ProxyBalancer
+	}
+
+	// ProxyTarget defines the upstream target.
+	ProxyTarget struct {
+		URL *url.URL
+	}
+
+	// RandomBalancer implements a random load balancing technique.
+	RandomBalancer struct {
+		Targets []*ProxyTarget
+		random  *rand.Rand
+	}
+
+	// RoundRobinBalancer implements a round-robin load balancing technique.
+	RoundRobinBalancer struct {
+		Targets []*ProxyTarget
+		i       uint32
+	}
+
+	// ProxyBalancer defines an interface to implement a load balancing technique.
+	ProxyBalancer interface {
+		Next() *ProxyTarget
+	}
+)
+
+func proxyHTTP(t *ProxyTarget) http.Handler {
+	return httputil.NewSingleHostReverseProxy(t.URL)
+}
+
+func proxyRaw(t *ProxyTarget, c echo.Context) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		h, ok := w.(http.Hijacker)
+		if !ok {
+			c.Error(errors.New("proxy raw, not a hijacker"))
+			return
+		}
+		in, _, err := h.Hijack()
+		if err != nil {
+			c.Error(fmt.Errorf("proxy raw, hijack error=%v, url=%s", r.URL, err))
+			return
+		}
+		defer in.Close()
+
+		out, err := net.Dial("tcp", t.URL.Host)
+		if err != nil {
+			he := echo.NewHTTPError(http.StatusBadGateway, fmt.Sprintf("proxy raw, dial error=%v, url=%s", r.URL, err))
+			c.Error(he)
+			return
+		}
+		defer out.Close()
+
+		err = r.Write(out)
+		if err != nil {
+			he := echo.NewHTTPError(http.StatusBadGateway, fmt.Sprintf("proxy raw, request copy error=%v, url=%s", r.URL, err))
+			c.Error(he)
+			return
+		}
+
+		errc := make(chan error, 2)
+		cp := func(dst io.Writer, src io.Reader) {
+			_, err := io.Copy(dst, src)
+			errc <- err
+		}
+
+		go cp(out, in)
+		go cp(in, out)
+		err = <-errc
+		if err != nil && err != io.EOF {
+			c.Logger().Errorf("proxy raw, error=%v, url=%s", r.URL, err)
+		}
+	})
+}
+
+// Next randomly returns an upstream target.
+func (r *RandomBalancer) Next() *ProxyTarget {
+	if r.random == nil {
+		r.random = rand.New(rand.NewSource(int64(time.Now().Nanosecond())))
+	}
+	return r.Targets[r.random.Intn(len(r.Targets))]
+}
+
+// Next returns an upstream target using round-robin technique.
+func (r *RoundRobinBalancer) Next() *ProxyTarget {
+	r.i = r.i % uint32(len(r.Targets))
+	t := r.Targets[r.i]
+	atomic.AddUint32(&r.i, 1)
+	return t
+}
+
+// Proxy returns an HTTP/WebSocket reverse proxy middleware.
+func Proxy(config ProxyConfig) echo.MiddlewareFunc {
+	// Defaults
+	if config.Skipper == nil {
+		config.Skipper = DefaultLoggerConfig.Skipper
+	}
+	if config.Balancer == nil {
+		panic("echo: proxy middleware requires balancer")
+	}
+
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) (err error) {
+			req := c.Request()
+			res := c.Response()
+			tgt := config.Balancer.Next()
+
+			// Fix header
+			if req.Header.Get(echo.HeaderXRealIP) == "" {
+				req.Header.Set(echo.HeaderXRealIP, c.RealIP())
+			}
+			if req.Header.Get(echo.HeaderXForwardedProto) == "" {
+				req.Header.Set(echo.HeaderXForwardedProto, c.Scheme())
+			}
+			if c.IsWebSocket() && req.Header.Get(echo.HeaderXForwardedFor) == "" { // For HTTP, it is automatically set by Go HTTP reverse proxy.
+				req.Header.Set(echo.HeaderXForwardedFor, c.RealIP())
+			}
+
+			// Proxy
+			switch {
+			case c.IsWebSocket():
+				proxyRaw(tgt, c).ServeHTTP(res, req)
+			case req.Header.Get(echo.HeaderAccept) == "text/event-stream":
+			default:
+				proxyHTTP(tgt).ServeHTTP(res, req)
+			}
+
+			return
+		}
+	}
+}