package caddytls import ( "crypto/tls" "encoding/json" "fmt" "bitbucket.org/lightcodelabs/caddy2" "github.com/go-acme/lego/challenge/tlsalpn01" "github.com/mholt/certmagic" ) // ConnectionPolicies is an ordered group of connection policies; // the first matching policy will be used to configure TLS // connections at handshake-time. type ConnectionPolicies []*ConnectionPolicy // TLSConfig converts the group of policies to a standard-lib-compatible // TLS configuration which selects the first matching policy based on // the ClientHello. func (cp ConnectionPolicies) TLSConfig(handle caddy2.Handle) (*tls.Config, error) { // connection policy matchers for i, pol := range cp { for modName, rawMsg := range pol.MatchersRaw { val, err := caddy2.LoadModule("tls.handshake_match."+modName, rawMsg) if err != nil { return nil, fmt.Errorf("loading handshake matcher module '%s': %s", modName, err) } cp[i].Matchers = append(cp[i].Matchers, val.(ConnectionMatcher)) } cp[i].MatchersRaw = nil // allow GC to deallocate - TODO: Does this help? } // pre-build standard TLS configs so we don't have to at handshake-time for i := range cp { err := cp[i].buildStandardTLSConfig(handle) if err != nil { return nil, fmt.Errorf("connection policy %d: building standard TLS config: %s", i, err) } } return &tls.Config{ GetConfigForClient: func(hello *tls.ClientHelloInfo) (*tls.Config, error) { policyLoop: for _, pol := range cp { for _, matcher := range pol.Matchers { if !matcher.Match(hello) { continue policyLoop } } return pol.stdTLSConfig, nil } return nil, fmt.Errorf("no server TLS configuration available for ClientHello: %+v", hello) }, }, nil } // ConnectionPolicy specifies the logic for handling a TLS handshake. type ConnectionPolicy struct { MatchersRaw map[string]json.RawMessage `json:"match,omitempty"` CipherSuites []string `json:"cipher_suites,omitempty"` Curves []string `json:"curves,omitempty"` ALPN []string `json:"alpn,omitempty"` ProtocolMin string `json:"protocol_min,omitempty"` ProtocolMax string `json:"protocol_max,omitempty"` // TODO: Client auth // TODO: see if starlark could be useful here - enterprise only StarlarkHandshake string `json:"starlark_handshake,omitempty"` Matchers []ConnectionMatcher stdTLSConfig *tls.Config } func (cp *ConnectionPolicy) buildStandardTLSConfig(handle caddy2.Handle) error { tlsApp := handle.App("tls").(*TLS) cfg := &tls.Config{ NextProtos: cp.ALPN, PreferServerCipherSuites: true, GetCertificate: func(hello *tls.ClientHelloInfo) (*tls.Certificate, error) { cfgTpl, err := tlsApp.getConfigForName(hello.ServerName) if err != nil { return nil, fmt.Errorf("getting config for name %s: %v", hello.ServerName, err) } newCfg := certmagic.New(tlsApp.certCache, cfgTpl) return newCfg.GetCertificate(hello) }, MinVersion: tls.VersionTLS12, MaxVersion: tls.VersionTLS13, // TODO: Session ticket key rotation (use Storage) } // add all the cipher suites in order, without duplicates cipherSuitesAdded := make(map[uint16]struct{}) for _, csName := range cp.CipherSuites { csID := supportedCipherSuites[csName] if _, ok := cipherSuitesAdded[csID]; !ok { cipherSuitesAdded[csID] = struct{}{} cfg.CipherSuites = append(cfg.CipherSuites, csID) } } // add all the curve preferences in order, without duplicates curvesAdded := make(map[tls.CurveID]struct{}) for _, curveName := range cp.Curves { curveID := supportedCurves[curveName] if _, ok := curvesAdded[curveID]; !ok { curvesAdded[curveID] = struct{}{} cfg.CurvePreferences = append(cfg.CurvePreferences, curveID) } } // ensure ALPN includes the ACME TLS-ALPN protocol var alpnFound bool for _, a := range cp.ALPN { if a == tlsalpn01.ACMETLS1Protocol { alpnFound = true break } } if !alpnFound { cfg.NextProtos = append(cfg.NextProtos, tlsalpn01.ACMETLS1Protocol) } // min and max protocol versions if cp.ProtocolMin != "" { cfg.MinVersion = supportedProtocols[cp.ProtocolMin] } if cp.ProtocolMax != "" { cfg.MaxVersion = supportedProtocols[cp.ProtocolMax] } if cp.ProtocolMin > cp.ProtocolMax { return fmt.Errorf("protocol min (%x) cannot be greater than protocol max (%x)", cp.ProtocolMin, cp.ProtocolMax) } // TODO: client auth, and other fields cp.stdTLSConfig = cfg return nil } // ConnectionMatcher is a type which matches TLS handshakes. type ConnectionMatcher interface { Match(*tls.ClientHelloInfo) bool }