From 533def6748744789ccd49c36e6cf6c924944c9c4 Mon Sep 17 00:00:00 2001
From: Sam Whited <sam@samwhited.com>
Date: Fri, 4 Mar 2022 11:55:08 -0500
Subject: obfsvpn: initial draft library API

Signed-off-by: Sam Whited <sam@samwhited.com>
---
 listener.go | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 listener.go

(limited to 'listener.go')

diff --git a/listener.go b/listener.go
new file mode 100644
index 0000000..ae81b19
--- /dev/null
+++ b/listener.go
@@ -0,0 +1,82 @@
+package obfsvpn
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"net"
+
+	pt "git.torproject.org/pluggable-transports/goptlib.git"
+	"gitlab.com/yawning/obfs4.git/common/ntor"
+	"gitlab.com/yawning/obfs4.git/transports/base"
+	"gitlab.com/yawning/obfs4.git/transports/obfs4"
+)
+
+// ListenConfig contains options for listening to an address.
+// If Seed is not set it defaults to a randomized value.
+// If StateDir is not set the current working directory is used.
+type ListenConfig struct {
+	ListenConfig net.ListenConfig
+
+	NodeID     *ntor.NodeID
+	PrivateKey *ntor.PrivateKey
+	Seed       [ntor.KeySeedLength]byte
+	StateDir   string
+}
+
+// Listen announces on the local network address.
+//
+// See func net.Dial for a description of the network and address parameters.
+func (lc *ListenConfig) Listen(ctx context.Context, network, address string) (*Listener, error) {
+	ln, err := lc.ListenConfig.Listen(ctx, network, address)
+	if err != nil {
+		return nil, err
+	}
+	args := make(pt.Args)
+	args.Add("node-id", lc.NodeID.Hex())
+	args.Add("private-key", lc.PrivateKey.Hex())
+	seed := ntor.KeySeed{}
+	if bytes.Equal(lc.Seed[:], seed[:]) {
+		_, err = rand.Read(seed[:])
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		seed = lc.Seed
+	}
+	args.Add("drbg-seed", hex.EncodeToString(seed[:]))
+	sf, err := (&obfs4.Transport{}).ServerFactory(lc.StateDir, &args)
+	if err != nil {
+		return nil, err
+	}
+	return &Listener{sf: sf, ln: ln}, nil
+}
+
+// Listener is a network listener that accepts obfuscated connections and
+// performs the ntor handshake on them.
+type Listener struct {
+	sf base.ServerFactory
+	ln net.Listener
+}
+
+// Accept waits for and returns the next connection to the listener.
+func (l *Listener) Accept() (net.Conn, error) {
+	conn, err := l.ln.Accept()
+	if err != nil {
+		return nil, err
+	}
+	conn, err = l.sf.WrapConn(conn)
+	return conn, err
+}
+
+// Close closes the listener.
+// Any blcked Accept operations will be unblocked and return errors.
+func (l *Listener) Close() error {
+	return l.ln.Close()
+}
+
+// Addr returns the listener's network address.
+func (l *Listener) Addr() net.Addr {
+	return l.ln.Addr()
+}
-- 
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