/
util.go
136 lines (127 loc) · 3.24 KB
/
util.go
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package main
import (
"bufio"
"errors"
"fmt"
"io"
"net"
"net/http"
"strings"
)
func shouldUpgradeWebsocket(r *http.Request) bool {
connHdr := ""
connHdrs := r.Header["Connection"]
if len(connHdrs) > 0 {
connHdr = connHdrs[0]
}
upgradeWebsocket := false
if strings.ToLower(connHdr) == "upgrade" {
upgradeHdrs := r.Header["Upgrade"]
if len(upgradeHdrs) > 0 {
upgradeWebsocket = (strings.ToLower(upgradeHdrs[0]) == "websocket")
}
}
return upgradeWebsocket
}
func plumbWebsocket(w http.ResponseWriter, r *http.Request, route **Route) error {
hj, ok := w.(http.Hijacker)
if !ok {
http.Error(w, "webserver doesn't support hijacking", http.StatusInternalServerError)
return errors.New("no-hijack")
}
conn, bufrw, err := hj.Hijack()
conn2, err := net.Dial("tcp", r.URL.Host)
if err != nil {
http.Error(w, "couldn't connect to backend server", http.StatusServiceUnavailable)
return errors.New("dead-backend")
}
err = r.Write(conn2)
if err != nil {
log.Warning("writing WebSocket request to backend server failed: %v", err)
return errors.New("dead-backend")
}
CopyBidir(conn, bufrw, conn2, bufio.NewReadWriter(bufio.NewReader(conn2), bufio.NewWriter(conn2)), route)
err = conn.Close()
if err != nil {
log.Warning("Could not close stream", err)
}
err = conn2.Close()
if err != nil {
log.Warning("Could not close stream", err)
}
return nil
}
func plumbHTTP(h *requestHandler, w http.ResponseWriter, r *http.Request, route **Route) error {
resp, err := h.Transport.RoundTrip(r)
if err != nil {
w.WriteHeader(http.StatusServiceUnavailable)
fmt.Fprintf(w, "Error: %v", err)
return errors.New("dead-backend")
}
for k, v := range resp.Header {
for _, vv := range v {
w.Header().Add(k, vv)
}
}
(*route).Seen()
w.WriteHeader(resp.StatusCode)
_, err = io.Copy(w, resp.Body)
if err != nil {
log.Warning("Could not copy bytes", err)
}
err = resp.Body.Close()
if err != nil {
log.Warning("Could not close response", err)
}
return nil
}
// Copy from src buffer to destination buffer. One way.
func Copy(dest *bufio.ReadWriter, src *bufio.ReadWriter, route **Route) {
buf := make([]byte, 40*1024)
for {
n, err := src.Read(buf)
if err != nil && err != io.EOF {
//log.Error("Read failed: %v", err)
return
}
if n == 0 {
return
}
(*route).Seen()
_, err = dest.Write(buf[0:n])
if err != nil && err != io.EOF {
log.Warning("Could not write to dest", err)
}
err = dest.Flush()
if err != nil && err != io.EOF {
log.Warning("Could not flush to dest", err)
}
}
}
// CopyBidir copies the first buffer to the second and vice versa.
func CopyBidir(conn1 io.ReadWriteCloser, rw1 *bufio.ReadWriter, conn2 io.ReadWriteCloser, rw2 *bufio.ReadWriter, route **Route) {
finished := make(chan bool)
go func() {
Copy(rw2, rw1, route)
_ = conn2.Close()
finished <- true
}()
go func() {
Copy(rw1, rw2, route)
_ = conn1.Close()
finished <- true
}()
<-finished
<-finished
}
func addForwardedFor(r *http.Request) {
remoteAddr := r.RemoteAddr
idx := strings.LastIndex(remoteAddr, ":")
if idx != -1 {
remoteAddr = remoteAddr[0:idx]
if remoteAddr[0] == '[' && remoteAddr[len(remoteAddr)-1] == ']' {
remoteAddr = remoteAddr[1 : len(remoteAddr)-1]
}
}
r.Header.Add("X-Forwarded-For", remoteAddr)
}