traefik/pkg/server/service/proxy.go

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package service
import (
"context"
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"errors"
"io"
"net"
"net/http"
"net/http/httputil"
"net/url"
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"strings"
"time"
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"github.com/rs/zerolog/log"
"golang.org/x/net/http/httpguts"
)
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// StatusClientClosedRequest non-standard HTTP status code for client disconnection.
const StatusClientClosedRequest = 499
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// StatusClientClosedRequestText non-standard HTTP status for client disconnection.
const StatusClientClosedRequestText = "Client Closed Request"
func buildSingleHostProxy(target *url.URL, passHostHeader bool, flushInterval time.Duration, roundTripper http.RoundTripper, bufferPool httputil.BufferPool) http.Handler {
return &httputil.ReverseProxy{
Director: directorBuilder(target, passHostHeader),
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Transport: roundTripper,
FlushInterval: flushInterval,
BufferPool: bufferPool,
ErrorHandler: errorHandler,
}
}
func directorBuilder(target *url.URL, passHostHeader bool) func(req *http.Request) {
return func(outReq *http.Request) {
outReq.URL.Scheme = target.Scheme
outReq.URL.Host = target.Host
u := outReq.URL
if outReq.RequestURI != "" {
parsedURL, err := url.ParseRequestURI(outReq.RequestURI)
if err == nil {
u = parsedURL
}
}
outReq.URL.Path = u.Path
outReq.URL.RawPath = u.RawPath
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// If a plugin/middleware adds semicolons in query params, they should be urlEncoded.
outReq.URL.RawQuery = strings.ReplaceAll(u.RawQuery, ";", "&")
outReq.RequestURI = "" // Outgoing request should not have RequestURI
outReq.Proto = "HTTP/1.1"
outReq.ProtoMajor = 1
outReq.ProtoMinor = 1
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// Do not pass client Host header unless optsetter PassHostHeader is set.
if !passHostHeader {
outReq.Host = outReq.URL.Host
}
cleanWebSocketHeaders(outReq)
}
}
// cleanWebSocketHeaders Even if the websocket RFC says that headers should be case-insensitive,
// some servers need Sec-WebSocket-Key, Sec-WebSocket-Extensions, Sec-WebSocket-Accept,
// Sec-WebSocket-Protocol and Sec-WebSocket-Version to be case-sensitive.
// https://tools.ietf.org/html/rfc6455#page-20
func cleanWebSocketHeaders(req *http.Request) {
if !isWebSocketUpgrade(req) {
return
}
req.Header["Sec-WebSocket-Key"] = req.Header["Sec-Websocket-Key"]
delete(req.Header, "Sec-Websocket-Key")
req.Header["Sec-WebSocket-Extensions"] = req.Header["Sec-Websocket-Extensions"]
delete(req.Header, "Sec-Websocket-Extensions")
req.Header["Sec-WebSocket-Accept"] = req.Header["Sec-Websocket-Accept"]
delete(req.Header, "Sec-Websocket-Accept")
req.Header["Sec-WebSocket-Protocol"] = req.Header["Sec-Websocket-Protocol"]
delete(req.Header, "Sec-Websocket-Protocol")
req.Header["Sec-WebSocket-Version"] = req.Header["Sec-Websocket-Version"]
delete(req.Header, "Sec-Websocket-Version")
}
func isWebSocketUpgrade(req *http.Request) bool {
return httpguts.HeaderValuesContainsToken(req.Header["Connection"], "Upgrade") &&
strings.EqualFold(req.Header.Get("Upgrade"), "websocket")
}
func errorHandler(w http.ResponseWriter, req *http.Request, err error) {
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statusCode := computeStatusCode(err)
logger := log.Ctx(req.Context())
logger.Debug().Err(err).Msgf("%d %s", statusCode, statusText(statusCode))
w.WriteHeader(statusCode)
if _, werr := w.Write([]byte(statusText(statusCode))); werr != nil {
logger.Debug().Err(werr).Msg("Error while writing status code")
}
}
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func computeStatusCode(err error) int {
switch {
case errors.Is(err, io.EOF):
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return http.StatusBadGateway
case errors.Is(err, context.Canceled):
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return StatusClientClosedRequest
default:
var netErr net.Error
if errors.As(err, &netErr) {
if netErr.Timeout() {
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return http.StatusGatewayTimeout
}
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return http.StatusBadGateway
}
}
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return http.StatusInternalServerError
}
func statusText(statusCode int) string {
if statusCode == StatusClientClosedRequest {
return StatusClientClosedRequestText
}
return http.StatusText(statusCode)
}