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