mirror of
https://github.com/juanfont/headscale.git
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125 lines
3.9 KiB
Go
125 lines
3.9 KiB
Go
package headscale
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import (
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"encoding/base64"
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"net/http"
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"github.com/gin-gonic/gin"
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"github.com/rs/zerolog/log"
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"golang.org/x/net/http2"
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"golang.org/x/net/http2/h2c"
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"tailscale.com/control/controlbase"
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"tailscale.com/net/netutil"
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)
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const (
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errWrongConnectionUpgrade = Error("wrong connection upgrade")
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errCannotHijack = Error("cannot hijack connection")
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errNoiseHandshakeFailed = Error("noise handshake failed")
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)
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const (
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// ts2021UpgradePath is the path that the server listens on for the WebSockets upgrade.
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ts2021UpgradePath = "/ts2021"
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// upgradeHeader is the value of the Upgrade HTTP header used to
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// indicate the Tailscale control protocol.
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upgradeHeaderValue = "tailscale-control-protocol"
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// handshakeHeaderName is the HTTP request header that can
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// optionally contain base64-encoded initial handshake
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// payload, to save an RTT.
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handshakeHeaderName = "X-Tailscale-Handshake"
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)
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// NoiseUpgradeHandler is to upgrade the connection and hijack the net.Conn
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// in order to use the Noise-based TS2021 protocol. Listens in /ts2021.
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func (h *Headscale) NoiseUpgradeHandler(ctx *gin.Context) {
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log.Trace().Caller().Msgf("Noise upgrade handler for client %s", ctx.ClientIP())
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// Under normal circumpstances, we should be able to use the controlhttp.AcceptHTTP()
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// function to do this - kindly left there by the Tailscale authors for us to use.
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// (https://github.com/tailscale/tailscale/blob/main/control/controlhttp/server.go)
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//
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// However, Gin seems to be doing something funny/different with its writer (see AcceptHTTP code).
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// This causes problems when the upgrade headers are sent in AcceptHTTP.
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// So have getNoiseConnection() that is essentially an AcceptHTTP but using the native Gin methods.
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noiseConn, err := h.getNoiseConnection(ctx)
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if err != nil {
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log.Error().Err(err).Msg("noise upgrade failed")
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ctx.AbortWithError(http.StatusInternalServerError, err)
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return
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}
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server := http.Server{}
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server.Handler = h2c.NewHandler(h.noiseMux, &http2.Server{})
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server.Serve(netutil.NewOneConnListener(noiseConn, nil))
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}
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// getNoiseConnection is basically AcceptHTTP from tailscale, but more _alla_ Gin
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// TODO(juan): Figure out why we need to do this at all.
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func (h *Headscale) getNoiseConnection(ctx *gin.Context) (*controlbase.Conn, error) {
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next := ctx.GetHeader("Upgrade")
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if next == "" {
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ctx.String(http.StatusBadRequest, "missing next protocol")
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return nil, errWrongConnectionUpgrade
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}
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if next != upgradeHeaderValue {
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ctx.String(http.StatusBadRequest, "unknown next protocol")
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return nil, errWrongConnectionUpgrade
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}
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initB64 := ctx.GetHeader(handshakeHeaderName)
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if initB64 == "" {
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ctx.String(http.StatusBadRequest, "missing Tailscale handshake header")
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return nil, errWrongConnectionUpgrade
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}
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init, err := base64.StdEncoding.DecodeString(initB64)
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if err != nil {
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ctx.String(http.StatusBadRequest, "invalid tailscale handshake header")
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return nil, errWrongConnectionUpgrade
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}
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hijacker, ok := ctx.Writer.(http.Hijacker)
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if !ok {
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log.Error().Caller().Err(err).Msgf("Hijack failed")
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ctx.String(http.StatusInternalServerError, "HTTP does not support general TCP support")
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return nil, errCannotHijack
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}
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// This is what changes from the original AcceptHTTP() function.
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ctx.Header("Upgrade", upgradeHeaderValue)
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ctx.Header("Connection", "upgrade")
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ctx.Status(http.StatusSwitchingProtocols)
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ctx.Writer.WriteHeaderNow()
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// end
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netConn, conn, err := hijacker.Hijack()
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if err != nil {
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log.Error().Caller().Err(err).Msgf("Hijack failed")
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ctx.String(http.StatusInternalServerError, "HTTP does not support general TCP support")
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return nil, errCannotHijack
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}
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if err := conn.Flush(); err != nil {
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netConn.Close()
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return nil, errCannotHijack
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}
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netConn = netutil.NewDrainBufConn(netConn, conn.Reader)
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nc, err := controlbase.Server(ctx.Request.Context(), netConn, *h.noisePrivateKey, init)
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if err != nil {
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netConn.Close()
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return nil, errNoiseHandshakeFailed
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}
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return nc, nil
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}
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