chore!(amneziawg): refactor to be separate from wireguard

- amneziawg is now a VPN protocol and no longer a Wireguard implementation
- Use it with VPN_TYPE=amneziawg
- document AMNEZIAWG_* options in Dockerfile
- document amneziawg support in readme
- separate amneziawg settings and code from wireguard
- re-use code from wireguard whenever possible

internal/configuration/sources/files/amneziawg.go

@@ -0,0 +1,84 @@
+package files
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"gopkg.in/ini.v1"
+)
+
+func (s *Source) lazyLoadAmneziawgConf() AmneziawgConfig {
+	if s.cached.amneziawgLoaded {
+		return s.cached.amneziawgConf
+	}
+
+	s.cached.amneziawgLoaded = true
+	var err error
+	s.cached.amneziawgConf, err = ParseAmneziawgConf(filepath.Join(s.rootDirectory, "amneziawg", "awg0.conf"))
+	if err != nil {
+		s.warner.Warnf("skipping Amneziawg config: %s", err)
+	}
+	return s.cached.amneziawgConf
+}
+
+type AmneziawgConfig struct {
+	Wireguard WireguardConfig
+	Jc        *string
+	Jmin      *string
+	Jmax      *string
+	S1        *string
+	S2        *string
+	S3        *string
+	S4        *string
+	H1        *string
+	H2        *string
+	H3        *string
+	H4        *string
+	I1        *string
+	I2        *string
+	I3        *string
+	I4        *string
+	I5        *string
+}
+
+func ParseAmneziawgConf(path string) (config AmneziawgConfig, err error) {
+	iniFile, err := ini.InsensitiveLoad(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return AmneziawgConfig{}, nil
+		}
+		return AmneziawgConfig{}, fmt.Errorf("loading ini from reader: %w", err)
+	}
+
+	config.Wireguard, err = ParseWireguardConf(path)
+	if err != nil {
+		return AmneziawgConfig{}, err
+	}
+
+	interfaceSection, err := iniFile.GetSection("Interface")
+	if err != nil {
+		// can never happen
+		return AmneziawgConfig{}, fmt.Errorf("getting interface section: %w", err)
+	}
+
+	config.Jc = getINIKeyFromSection(interfaceSection, "Jc")
+	config.Jmin = getINIKeyFromSection(interfaceSection, "Jmin")
+	config.Jmax = getINIKeyFromSection(interfaceSection, "Jmax")
+	config.S1 = getINIKeyFromSection(interfaceSection, "S1")
+	config.S2 = getINIKeyFromSection(interfaceSection, "S2")
+	config.S3 = getINIKeyFromSection(interfaceSection, "S3")
+	config.S4 = getINIKeyFromSection(interfaceSection, "S4")
+	config.H1 = getINIKeyFromSection(interfaceSection, "H1")
+	config.H2 = getINIKeyFromSection(interfaceSection, "H2")
+	config.H3 = getINIKeyFromSection(interfaceSection, "H3")
+	config.H4 = getINIKeyFromSection(interfaceSection, "H4")
+	config.I1 = getINIKeyFromSection(interfaceSection, "I1")
+	config.I2 = getINIKeyFromSection(interfaceSection, "I2")
+	config.I3 = getINIKeyFromSection(interfaceSection, "I3")
+	config.I4 = getINIKeyFromSection(interfaceSection, "I4")
+	config.I5 = getINIKeyFromSection(interfaceSection, "I5")
+
+	return config, nil
+}