1 files changed, 97 insertions, 21 deletions
diff --git a/internal/wireguard/wireguard.go b/internal/wireguard/wireguard.go
index cc6c577..af290ea 100644
--- a/internal/wireguard/wireguard.go
+++ b/internal/wireguard/wireguard.go
@@ -2,34 +2,110 @@
 package wireguard
 
 import (
+	"errors"
 	"fmt"
-	"regexp"
+	"net"
 
-	"github.com/go-errors/errors"
+	"github.com/eduvpn/eduvpn-common/internal/wireguard/ini"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 )
 
-// GenerateKey generates a WireGuard private key using wgctrl
-// It returns an error if key generation failed.
-func GenerateKey() (wgtypes.Key, error) {
-	key, err := wgtypes.GeneratePrivateKey()
+func availableTCPPort() (int, error) {
+	tcpaddr, err := net.ResolveTCPAddr("tcp", "127.0.0.1:0")
 	if err != nil {
-		return key, errors.WrapPrefix(err, "failed generating WireGuard key", 0)
+		return -1, err
 	}
-	return key, nil
+	ltcp, err := net.ListenTCP("tcp", tcpaddr)
+	if err != nil {
+		return -1, err
+	}
+	defer ltcp.Close()
+	return ltcp.Addr().(*net.TCPAddr).Port, nil
+}
+
+func availableUDPPort() (int, error) {
+	udpaddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
+	if err != nil {
+		return -1, err
+	}
+	ludp, err := net.ListenUDP("udp", udpaddr)
+	if err != nil {
+		return -1, err
+	}
+	defer ludp.Close()
+	return ludp.LocalAddr().(*net.UDPAddr).Port, nil
+}
+
+type Proxy struct {
+	SourcePort int
+	Listen     string
+	Peer       string
+}
+
+func Config(cfg string, key *wgtypes.Key, tcp bool) (string, *Proxy, error) {
+	// the key is nil if the client does not accept WireGuard
+	if key == nil {
+		return "", nil, errors.New("the server sent us a WireGuard profile but the client does not accept WireGuard")
+	}
+
+	var tcpp int
+	var proxy string
+	var err error
+
+	if tcp {
+		tcpp, err = availableTCPPort()
+		if err != nil {
+			return "", nil, err
+		}
+		udpp, err := availableUDPPort()
+		if err != nil {
+			return "", nil, err
+		}
+		proxy = fmt.Sprintf("127.0.0.1:%d", udpp)
+	}
+
+	rcfg, peer, err := configReplace(cfg, *key, proxy)
+	if err != nil {
+		return "", nil, err
+	}
+	var retP *Proxy
+	if tcp {
+		retP = &Proxy{
+			SourcePort: tcpp,
+			Listen:     proxy,
+			Peer:       peer,
+		}
+	}
+	return rcfg, retP, nil
 }
 
-// ConfigAddKey takes the WireGuard configuration and adds the PrivateKey to the right section
-// FIXME: Instead of doing a regex replace, decide if we should use a parser.
-func ConfigAddKey(config string, key wgtypes.Key) string {
-	interfaceSection := "[Interface]"
-	InterfaceSectionEscaped := regexp.QuoteMeta(interfaceSection)
-
-	// (?m) enables multi line mode
-	// ^ match from beginning of line
-	// $ match till end of line
-	// So it matches [Interface] section exactly
-	InterfaceRe := regexp.MustCompile(fmt.Sprintf("(?m)^%s$", InterfaceSectionEscaped))
-	toReplace := fmt.Sprintf("%s\nPrivateKey = %s", interfaceSection, key.String())
-	return InterfaceRe.ReplaceAllString(config, toReplace)
+// ConfigReplace replaces the wireguard config with our private key and proxy in case of TCP
+func configReplace(cfg string, key wgtypes.Key, proxy string) (string, string, error) {
+	// first parse the config
+	secs := ini.Parse(cfg)
+	if secs.Empty() {
+		return "", "", errors.New("parsed ini is empty")
+	}
+
+	// find the interface section
+	// and set the private key
+	is, err := secs.Section("Interface")
+	if err != nil {
+		return "", "", err
+	}
+	is.AddOrReplaceKeyValue("PrivateKey", key.String())
+	peer := ""
+	if proxy != "" {
+		ps, err := secs.Section("Peer")
+		if err != nil {
+			return "", "", err
+		}
+		peer, err = ps.RemoveKey("TCPEndpoint")
+		if err != nil {
+			return "", "", err
+		}
+		ps.AddOrReplaceKeyValue("Endpoint", proxy)
+	}
+
+	return secs.String(), peer, nil
 }