commit 4d453dab2120082b00bf6e63ab4aaeeda6b8d8a3 Author: Yawning Angel <yawning@schwanenlied.me> Date: Mon Jan 21 04:31:07 2019 +0000 transports/meeklite: uTLS for ClientHello camouflage There's still some interesting oddities depending on remote server and what fingerprint is chosen, but I can watch videos online with the chosen settings and the TBB Azure bridge. Note: Despite what people are claiming in the Tor Browser bug tracker it isn't all that hard to use the built in http client with utls. And yes, the `transport.go` code does negotiate correctly in a standalone test case (apart from compatibility related oddities). --- ChangeLog | 2 + LICENSE-GPL3.txt | 674 +++++++++++++++++++++++++++++++++++++++ go.mod | 11 +- go.sum | 22 +- transports/meeklite/meek.go | 10 +- transports/meeklite/transport.go | 168 ++++++++++ 6 files changed, 870 insertions(+), 17 deletions(-) diff --git a/ChangeLog b/ChangeLog index fdcffc4..fe8f58d 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,4 +1,6 @@ Changes in version 0.0.9 - UNRELEASED: + - Various meek_lite code cleanups and bug fixes. + - Bug 29077: uTLS for ClientHello camouflage (meek_lite). Changes in version 0.0.8 - 2019-01-20: - Bug 24793: Send the correct authorization HTTP header for basic auth. diff --git a/LICENSE-GPL3.txt b/LICENSE-GPL3.txt new file mode 100644 index 0000000..f288702 --- /dev/null +++ b/LICENSE-GPL3.txt @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/> + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. By contrast, +the GNU General Public License is intended to guarantee your freedom to +share and change all versions of a program--to make sure it remains free +software for all its users. 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If not, see <https://www.gnu.org/licenses/>. + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + <program> Copyright (C) <year> <name of author> + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +<https://www.gnu.org/licenses/>. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +<https://www.gnu.org/licenses/why-not-lgpl.html>. diff --git a/go.mod b/go.mod index f676f90..50bb7eb 100644 --- a/go.mod +++ b/go.mod @@ -1,9 +1,12 @@ module gitlab.com/yawning/obfs4.git require ( - git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20180321061416-7d56ec4f381e + git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20190117054722-15f83653abbc github.com/agl/ed25519 v0.0.0-20170116200512-5312a6153412 - github.com/dchest/siphash v1.2.0 - golang.org/x/crypto v0.0.0-20181015023909-0c41d7ab0a0e - golang.org/x/net v0.0.0-20181011144130-49bb7cea24b1 + github.com/dchest/siphash v1.2.1 + github.com/refraction-networking/utls v0.0.0-20190105024908-a89e7e6da482 + golang.org/x/crypto v0.0.0-20190103213133-ff983b9c42bc + golang.org/x/net v0.0.0-20190119204137-ed066c81e75e + golang.org/x/sys v0.0.0-20190116161447-11f53e031339 // indirect + golang.org/x/text v0.3.0 // indirect ) diff --git a/go.sum b/go.sum index 94991ce..9545483 100644 --- a/go.sum +++ b/go.sum @@ -1,10 +1,16 @@ -git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20180321061416-7d56ec4f381e h1:PYcONLFUhr00kGrq7Mf14JRtoXHG7BOSKIfIha0Hu5Q= -git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20180321061416-7d56ec4f381e/go.mod h1:YT4XMSkuEXbtqlydr9+OxqFAyspUv0Gr9qhM3B++o/Q= +git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20190117054722-15f83653abbc h1:k14lBVrBVgZx22Eg5eqQshT12PAsXBfAJK3vm65D/YE= +git.torproject.org/pluggable-transports/goptlib.git v0.0.0-20190117054722-15f83653abbc/go.mod h1:YT4XMSkuEXbtqlydr9+OxqFAyspUv0Gr9qhM3B++o/Q= github.com/agl/ed25519 v0.0.0-20170116200512-5312a6153412 h1:w1UutsfOrms1J05zt7ISrnJIXKzwaspym5BTKGx93EI= github.com/agl/ed25519 v0.0.0-20170116200512-5312a6153412/go.mod h1:WPjqKcmVOxf0XSf3YxCJs6N6AOSrOx3obionmG7T0y0= -github.com/dchest/siphash v1.2.0 h1:YWOShuhvg0GqbQpMa60QlCGtEyf7O7HC1Jf0VjdQ60M= -github.com/dchest/siphash v1.2.0/go.mod h1:q+IRvb2gOSrUnYoPqHiyHXS0FOBBOdl6tONBlVnOnt4= -golang.org/x/crypto v0.0.0-20181015023909-0c41d7ab0a0e h1:IzypfodbhbnViNUO/MEh0FzCUooG97cIGfdggUrUSyU= -golang.org/x/crypto v0.0.0-20181015023909-0c41d7ab0a0e/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4= -golang.org/x/net v0.0.0-20181011144130-49bb7cea24b1 h1:Y/KGZSOdz/2r0WJ9Mkmz6NJBusp0kiNx1Cn82lzJQ6w= -golang.org/x/net v0.0.0-20181011144130-49bb7cea24b1/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4= +github.com/dchest/siphash v1.2.1 h1:4cLinnzVJDKxTCl9B01807Yiy+W7ZzVHj/KIroQRvT4= +github.com/dchest/siphash v1.2.1/go.mod h1:q+IRvb2gOSrUnYoPqHiyHXS0FOBBOdl6tONBlVnOnt4= +github.com/refraction-networking/utls v0.0.0-20190105024908-a89e7e6da482 h1:mP4Zgxxydw8ljKIA3zHWmzrTKizyULi7vQrRtxqQNmo= +github.com/refraction-networking/utls v0.0.0-20190105024908-a89e7e6da482/go.mod h1:tz9gX959MEFfFN5whTIocCLUG57WiILqtdVxI8c6Wj0= +golang.org/x/crypto v0.0.0-20190103213133-ff983b9c42bc h1:F5tKCVGp+MUAHhKp5MZtGqAlGX3+oCsiL1Q629FL90M= +golang.org/x/crypto v0.0.0-20190103213133-ff983b9c42bc/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4= +golang.org/x/net v0.0.0-20190119204137-ed066c81e75e h1:MDa3fSUp6MdYHouVmCCNz/zaH2a6CRcxY3VhT/K3C5Q= +golang.org/x/net v0.0.0-20190119204137-ed066c81e75e/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4= +golang.org/x/sys v0.0.0-20190116161447-11f53e031339 h1:g/Jesu8+QLnA0CPzF3E1pURg0Byr7i6jLoX5sqjcAh0= +golang.org/x/sys v0.0.0-20190116161447-11f53e031339/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY= +golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg= +golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= diff --git a/transports/meeklite/meek.go b/transports/meeklite/meek.go index 39a6d4b..fb6aa0d 100644 --- a/transports/meeklite/meek.go +++ b/transports/meeklite/meek.go @@ -108,9 +108,9 @@ func newClientArgs(args *pt.Args) (ca *meekClientArgs, err error) { } type meekConn struct { - args *meekClientArgs - sessionID string - transport *http.Transport + args *meekClientArgs + sessionID string + roundTripper http.RoundTripper closeOnce sync.Once workerWrChan chan []byte @@ -242,7 +242,7 @@ func (c *meekConn) roundTrip(sndBuf []byte) (recvBuf []byte, err error) { req.Header.Set("X-Session-Id", c.sessionID) req.Header.Set("User-Agent", "") - resp, err = c.transport.RoundTrip(req) + resp, err = c.roundTripper.RoundTrip(req) if err != nil { return nil, err } @@ -346,7 +346,7 @@ func newMeekConn(network, addr string, dialFn base.DialFunc, ca *meekClientArgs) conn := &meekConn{ args: ca, sessionID: id, - transport: &http.Transport{Dial: dialFn}, + roundTripper: newRoundTripper(dialFn), workerWrChan: make(chan []byte, maxChanBacklog), workerRdChan: make(chan []byte, maxChanBacklog), workerCloseChan: make(chan struct{}), diff --git a/transports/meeklite/transport.go b/transports/meeklite/transport.go new file mode 100644 index 0000000..6ccef31 --- /dev/null +++ b/transports/meeklite/transport.go @@ -0,0 +1,168 @@ +/* + * Copyright (c) 2019 Yawning Angel <yawning at schwanenlied dot me> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +package meeklite + +import ( + "crypto/tls" + "errors" + "fmt" + "net" + "net/http" + "net/url" + "strings" + "sync" + + utls "github.com/refraction-networking/utls" + "golang.org/x/net/http2" + + "gitlab.com/yawning/obfs4.git/transports/base" +) + +var errProtocolNegotiated = errors.New("meek_lite: protocol negotiated") + +type roundTripper struct { + sync.Mutex + + transport http.RoundTripper + dialFn base.DialFunc + + initConn net.Conn +} + +func (rt *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) { + // Note: This isn't protected with a lock, since the meeklite ioWorker + // serializes RoundTripper requests. + // + // This also assumes that req.URL.Host will remain constant for the + // lifetime of the roundTripper, which is a valid assumption for meeklite. + if rt.transport == nil { + if err := rt.getTransport(req); err != nil { + return nil, err + } + } + return rt.transport.RoundTrip(req) +} + +func (rt *roundTripper) getTransport(req *http.Request) error { + switch strings.ToLower(req.URL.Scheme) { + case "http": + rt.transport = &http.Transport{Dial: rt.dialFn} + return nil + case "https": + default: + return fmt.Errorf("meek_lite: invalid URL scheme: '%v'", req.URL.Scheme) + } + + _, err := rt.dialTLS("tcp", getDialTLSAddr(req.URL)) + switch err { + case errProtocolNegotiated: + case nil: + // Should never happen. + panic("meek_lite: dialTLS returned no error when determining transport") + default: + return err + } + + return nil +} + +func (rt *roundTripper) dialTLS(network, addr string) (net.Conn, error) { + // Unlike rt.transport, this is protected by a critical section + // since past the initial manual call from getTransport, the HTTP + // client will be the caller. + rt.Lock() + defer rt.Unlock() + + // If we have the connection from when we determined the HTTPS + // transport to use, return that. + if conn := rt.initConn; conn != nil { + rt.initConn = nil + return conn, nil + } + + rawConn, err := rt.dialFn(network, addr) + if err != nil { + return nil, err + } + + var host string + if host, _, err = net.SplitHostPort(addr); err != nil { + host = addr + } + + // TODO: Make this configurable. What "works" is host dependent. + // * HelloChrome_Auto - Failures in a stand alone testcase against google.com + // * HelloFirefox_Auto - Fails with the azure bridge, incompatible group. + // * HelloIOS_Auto - Seems to work. + // + // Since HelloChrome_Auto works with azure, that's what'll be used for + // now, since that's what the overwelming vast majority of people will + // use. + conn := utls.UClient(rawConn, &utls.Config{ServerName: host}, utls.HelloChrome_Auto) + if err = conn.Handshake(); err != nil { + conn.Close() + return nil, err + } + + if rt.transport != nil { + return conn, nil + } + + // No http.Transport constructed yet, create one based on the results + // of ALPN. + switch conn.ConnectionState().NegotiatedProtocol { + case http2.NextProtoTLS: + // The remote peer is speaking HTTP 2 + TLS. + rt.transport = &http2.Transport{DialTLS: rt.dialTLSHTTP2} + default: + // Assume the remote peer is speaking HTTP 1.x + TLS. + rt.transport = &http.Transport{DialTLS: rt.dialTLS} + } + + // Stash the connection just established for use servicing the + // actual request (should be near-immediate). + rt.initConn = conn + + return nil, errProtocolNegotiated +} + +func (rt *roundTripper) dialTLSHTTP2(network, addr string, cfg *tls.Config) (net.Conn, error) { + return rt.dialTLS(network, addr) +} + +func getDialTLSAddr(u *url.URL) string { + host, port, err := net.SplitHostPort(u.Host) + if err == nil { + return net.JoinHostPort(host, port) + } + + return net.JoinHostPort(u.Host, u.Scheme) +} + +func newRoundTripper(dialFn base.DialFunc) http.RoundTripper { + return &roundTripper{ + dialFn: dialFn, + } +} + +func init() { + // Attempt to increase compatibility, there's an encrypted link + // underneath, and this doesn't (shouldn't) affect the external + // fingerprint. + utls.EnableWeakCiphers() +}