Initial implementation of mc-proxy

Layer 4 TLS SNI proxy with global firewall (IP/CIDR/GeoIP blocking),
per-listener route tables, bidirectional TCP relay with half-close
propagation, and a gRPC admin API (routes, firewall, status) with
TLS/mTLS support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-03-17 02:56:24 -07:00
commit c7024dcdf0
23 changed files with 2693 additions and 0 deletions

115
internal/config/config.go Normal file
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package config
import (
"fmt"
"os"
"time"
"github.com/pelletier/go-toml/v2"
)
type Config struct {
Listeners []Listener `toml:"listeners"`
GRPC GRPC `toml:"grpc"`
Firewall Firewall `toml:"firewall"`
Proxy Proxy `toml:"proxy"`
Log Log `toml:"log"`
}
type GRPC struct {
Addr string `toml:"addr"`
TLSCert string `toml:"tls_cert"`
TLSKey string `toml:"tls_key"`
ClientCA string `toml:"client_ca"`
}
type Listener struct {
Addr string `toml:"addr"`
Routes []Route `toml:"routes"`
}
type Route struct {
Hostname string `toml:"hostname"`
Backend string `toml:"backend"`
}
type Firewall struct {
GeoIPDB string `toml:"geoip_db"`
BlockedIPs []string `toml:"blocked_ips"`
BlockedCIDRs []string `toml:"blocked_cidrs"`
BlockedCountries []string `toml:"blocked_countries"`
}
type Proxy struct {
ConnectTimeout Duration `toml:"connect_timeout"`
IdleTimeout Duration `toml:"idle_timeout"`
ShutdownTimeout Duration `toml:"shutdown_timeout"`
}
type Log struct {
Level string `toml:"level"`
}
// Duration wraps time.Duration for TOML string unmarshalling.
type Duration struct {
time.Duration
}
func (d *Duration) UnmarshalText(text []byte) error {
var err error
d.Duration, err = time.ParseDuration(string(text))
return err
}
func Load(path string) (*Config, error) {
data, err := os.ReadFile(path)
if err != nil {
return nil, fmt.Errorf("reading config: %w", err)
}
var cfg Config
if err := toml.Unmarshal(data, &cfg); err != nil {
return nil, fmt.Errorf("parsing config: %w", err)
}
if err := cfg.validate(); err != nil {
return nil, fmt.Errorf("invalid config: %w", err)
}
return &cfg, nil
}
func (c *Config) validate() error {
if len(c.Listeners) == 0 {
return fmt.Errorf("at least one listener is required")
}
for i, l := range c.Listeners {
if l.Addr == "" {
return fmt.Errorf("listener %d: addr is required", i)
}
if len(l.Routes) == 0 {
return fmt.Errorf("listener %d (%s): at least one route is required", i, l.Addr)
}
seen := make(map[string]bool)
for j, r := range l.Routes {
if r.Hostname == "" {
return fmt.Errorf("listener %d (%s), route %d: hostname is required", i, l.Addr, j)
}
if r.Backend == "" {
return fmt.Errorf("listener %d (%s), route %d: backend is required", i, l.Addr, j)
}
if seen[r.Hostname] {
return fmt.Errorf("listener %d (%s), route %d: duplicate hostname %q", i, l.Addr, j, r.Hostname)
}
seen[r.Hostname] = true
}
}
if len(c.Firewall.BlockedCountries) > 0 && c.Firewall.GeoIPDB == "" {
return fmt.Errorf("firewall: geoip_db is required when blocked_countries is set")
}
return nil
}

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package config
import (
"os"
"path/filepath"
"testing"
)
func TestLoadValid(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[[listeners]]
addr = ":443"
[[listeners.routes]]
hostname = "example.com"
backend = "127.0.0.1:8443"
[proxy]
connect_timeout = "5s"
idle_timeout = "300s"
shutdown_timeout = "30s"
[log]
level = "info"
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
cfg, err := Load(path)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if len(cfg.Listeners) != 1 {
t.Fatalf("got %d listeners, want 1", len(cfg.Listeners))
}
if cfg.Listeners[0].Addr != ":443" {
t.Fatalf("got listener addr %q, want %q", cfg.Listeners[0].Addr, ":443")
}
if len(cfg.Listeners[0].Routes) != 1 {
t.Fatalf("got %d routes, want 1", len(cfg.Listeners[0].Routes))
}
if cfg.Listeners[0].Routes[0].Hostname != "example.com" {
t.Fatalf("got hostname %q, want %q", cfg.Listeners[0].Routes[0].Hostname, "example.com")
}
}
func TestLoadNoListeners(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[log]
level = "info"
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
_, err := Load(path)
if err == nil {
t.Fatal("expected error for missing listeners")
}
}
func TestLoadNoRoutes(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[[listeners]]
addr = ":443"
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
_, err := Load(path)
if err == nil {
t.Fatal("expected error for missing routes")
}
}
func TestLoadDuplicateHostnames(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[[listeners]]
addr = ":443"
[[listeners.routes]]
hostname = "example.com"
backend = "127.0.0.1:8443"
[[listeners.routes]]
hostname = "example.com"
backend = "127.0.0.1:9443"
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
_, err := Load(path)
if err == nil {
t.Fatal("expected error for duplicate hostnames")
}
}
func TestLoadGeoIPRequiredWithCountries(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[[listeners]]
addr = ":443"
[[listeners.routes]]
hostname = "example.com"
backend = "127.0.0.1:8443"
[firewall]
blocked_countries = ["CN"]
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
_, err := Load(path)
if err == nil {
t.Fatal("expected error for blocked_countries without geoip_db")
}
}
func TestLoadMultipleListeners(t *testing.T) {
dir := t.TempDir()
path := filepath.Join(dir, "test.toml")
data := `
[[listeners]]
addr = ":443"
[[listeners.routes]]
hostname = "public.example.com"
backend = "127.0.0.1:8443"
[[listeners]]
addr = ":8443"
[[listeners.routes]]
hostname = "internal.example.com"
backend = "127.0.0.1:9443"
`
if err := os.WriteFile(path, []byte(data), 0600); err != nil {
t.Fatalf("write config: %v", err)
}
cfg, err := Load(path)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if len(cfg.Listeners) != 2 {
t.Fatalf("got %d listeners, want 2", len(cfg.Listeners))
}
if cfg.Listeners[0].Routes[0].Hostname != "public.example.com" {
t.Fatalf("listener 0 hostname = %q, want %q", cfg.Listeners[0].Routes[0].Hostname, "public.example.com")
}
if cfg.Listeners[1].Routes[0].Hostname != "internal.example.com" {
t.Fatalf("listener 1 hostname = %q, want %q", cfg.Listeners[1].Routes[0].Hostname, "internal.example.com")
}
}
func TestDuration(t *testing.T) {
var d Duration
if err := d.UnmarshalText([]byte("5s")); err != nil {
t.Fatalf("unexpected error: %v", err)
}
if d.Duration.Seconds() != 5 {
t.Fatalf("got %v, want 5s", d.Duration)
}
}