Allow conditions on challenges, and early hint deadline

examples/forgejo.yml

@@ -116,12 +116,16 @@ challenges:
   # Challenges with a redirect via Link header with rel=preload and early hints (non-JS, requires HTTP parsing, fetching and logic)
   # Works on HTTP/2 and above!
   self-preload-link:
+    # doesn't seem to work reliably on other stuff that firefox
+    # userAgent.contains("Firefox/") &&
+    condition: '"Sec-Fetch-Mode" in headers && headers["Sec-Fetch-Mode"] == "navigate"'
     mode: "preload-link"
     runtime:
       # verifies that result = key
       mode: "key"
       probability: 0.1
     parameters:
+      preload-early-hint-deadline: 3s
       key-code: 200
       key-mime: text/css
       key-content: ""

lib/challenge.go

@@ -20,6 +20,18 @@ type ChallengeInformation struct {
 	IssuedAt  *jwt.NumericDate `json:"iat,omitempty"`
 }
 
+func getRequestScheme(r *http.Request) string {
+	if proto := r.Header.Get("X-Forwarded-Proto"); proto == "http" || proto == "https" {
+		return proto
+	}
+
+	if r.TLS != nil {
+		return "https"
+	}
+
+	return "http"
+}
+
 func getRequestAddress(r *http.Request, clientHeader string) net.IP {
 	var ipStr string
 	if clientHeader != "" {

lib/challenge/state.go

@@ -7,6 +7,7 @@ import (
 	"git.gammaspectra.live/git/go-away/utils"
 	"github.com/go-jose/go-jose/v4"
 	"github.com/go-jose/go-jose/v4/jwt"
+	"github.com/google/cel-go/cel"
 	"math/rand/v2"
 	"net/http"
 	"time"
@@ -26,9 +27,10 @@ const (
 type Id int
 
 type Challenge struct {
-	Id   Id
+	Id      Id
-	Name string
+	Program cel.Program
-	Path string
+	Name    string
+	Path    string
 
 	Verify            func(key []byte, result string, r *http.Request) (bool, error)
 	VerifyProbability float64
@@ -86,6 +88,7 @@ type VerifyResult int
 const (
 	VerifyResultNONE = VerifyResult(iota)
 	VerifyResultFAIL
+	VerifyResultSKIP
 
 	// VerifyResultPASS Client just passed this challenge
 	VerifyResultPASS
@@ -95,7 +98,7 @@ const (
 )
 
 func (r VerifyResult) Ok() bool {
-	return r > VerifyResultFAIL
+	return r >= VerifyResultPASS
 }
 
 func (r VerifyResult) String() string {
@@ -104,6 +107,8 @@ func (r VerifyResult) String() string {
 		return "NONE"
 	case VerifyResultFAIL:
 		return "FAIL"
+	case VerifyResultSKIP:
+		return "SKIP"
 	case VerifyResultPASS:
 		return "PASS"
 	case VerifyResultOK:

lib/conditions.go

@@ -0,0 +1,69 @@
+package lib
+
+import (
+	"fmt"
+	"github.com/google/cel-go/cel"
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+	"net"
+)
+
+func (state *State) initConditions() (err error) {
+	state.RulesEnv, err = cel.NewEnv(
+		cel.DefaultUTCTimeZone(true),
+		cel.Variable("remoteAddress", cel.BytesType),
+		cel.Variable("host", cel.StringType),
+		cel.Variable("method", cel.StringType),
+		cel.Variable("userAgent", cel.StringType),
+		cel.Variable("path", cel.StringType),
+		cel.Variable("query", cel.MapType(cel.StringType, cel.StringType)),
+		// http.Header
+		cel.Variable("headers", cel.MapType(cel.StringType, cel.StringType)),
+		//TODO: dynamic type?
+		cel.Function("inNetwork",
+			cel.Overload("inNetwork_string_ip",
+				[]*cel.Type{cel.StringType, cel.AnyType},
+				cel.BoolType,
+				cel.BinaryBinding(func(lhs ref.Val, rhs ref.Val) ref.Val {
+					var ip net.IP
+					switch v := rhs.Value().(type) {
+					case []byte:
+						ip = v
+					case net.IP:
+						ip = v
+					case string:
+						ip = net.ParseIP(v)
+					}
+
+					if ip == nil {
+						panic(fmt.Errorf("invalid ip %v", rhs.Value()))
+					}
+
+					val, ok := lhs.Value().(string)
+					if !ok {
+						panic(fmt.Errorf("invalid value %v", lhs.Value()))
+					}
+
+					network, ok := state.Networks[val]
+					if !ok {
+						_, ipNet, err := net.ParseCIDR(val)
+						if err != nil {
+							panic("network not found")
+						}
+						return types.Bool(ipNet.Contains(ip))
+					} else {
+						ok, err := network.Contains(ip)
+						if err != nil {
+							panic(err)
+						}
+						return types.Bool(ok)
+					}
+				}),
+			),
+		),
+	)
+	if err != nil {
+		return err
+	}
+	return nil
+}

lib/http.go

@@ -159,29 +159,6 @@ func (state *State) handleRequest(w http.ResponseWriter, r *http.Request) {
 
 	start := time.Now()
 
-	//TODO better matcher! combo ast?
-	env := map[string]any{
-		"host":          host,
-		"method":        r.Method,
-		"remoteAddress": getRequestAddress(r, state.Settings.ClientIpHeader),
-		"userAgent":     r.UserAgent(),
-		"path":          r.URL.Path,
-		"query": func() map[string]string {
-			result := make(map[string]string)
-			for k, v := range r.URL.Query() {
-				result[k] = strings.Join(v, ",")
-			}
-			return result
-		}(),
-		"headers": func() map[string]string {
-			result := make(map[string]string)
-			for k, v := range r.Header {
-				result[k] = strings.Join(v, ",")
-			}
-			return result
-		}(),
-	}
-
 	state.addTiming(w, "rule-env", "Setup the rule environment", time.Since(start))
 
 	var (
@@ -211,7 +188,7 @@ func (state *State) handleRequest(w http.ResponseWriter, r *http.Request) {
 			continue
 		}
 		start = time.Now()
-		out, _, err := rule.Program.Eval(env)
+		out, _, err := rule.Program.Eval(data.ProgramEnv)
 		ruleEvalDuration += time.Since(start)
 
 		if err != nil {
@@ -230,7 +207,6 @@ func (state *State) handleRequest(w http.ResponseWriter, r *http.Request) {
 					serve()
 					return
 				case policy.RuleActionCHALLENGE, policy.RuleActionCHECK:
-
 					for _, challengeId := range rule.Challenges {
 						if result := data.Challenges[challengeId]; !result.Ok() {
 							continue
@@ -249,6 +225,11 @@ func (state *State) handleRequest(w http.ResponseWriter, r *http.Request) {
 
 					// none matched, issue first challenge in priority
 					for _, challengeId := range rule.Challenges {
+						result := data.Challenges[challengeId]
+						if result.Ok() || result == challenge.VerifyResultSKIP {
+							// skip already ok'd challenges for some reason, and also skip skipped challenges
+							continue
+						}
 						c := state.Challenges[challengeId]
 						if c.ServeChallenge != nil {
 							result := c.ServeChallenge(w, r, state.GetChallengeKeyForRequest(c.Name, data.Expires, r), data.Expires)
@@ -264,7 +245,10 @@ func (state *State) handleRequest(w http.ResponseWriter, r *http.Request) {
 								}
 								state.logger(r).Warn("challenge passed", "rule", rule.Name, "rule_hash", rule.Hash, "challenge", c.Name)
 
-								data.Challenges[c.Id] = challenge.VerifyResultOK
+								// set pass if caller didn't set one
+								if !data.Challenges[c.Id].Ok() {
+									data.Challenges[c.Id] = challenge.VerifyResultPASS
+								}
 
 								// we pass the challenge early!
 								lg.Debug("request passed", "rule", rule.Name, "rule_hash", rule.Hash, "challenge", c.Name)
@@ -425,6 +409,27 @@ func (state *State) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	_, _ = rand.Read(data.Id[:])
 	data.Challenges = make(map[challenge.Id]challenge.VerifyResult, len(state.Challenges))
 	data.Expires = time.Now().UTC().Add(DefaultValidity).Round(DefaultValidity)
+	data.ProgramEnv = map[string]any{
+		"host":          r.Host,
+		"method":        r.Method,
+		"remoteAddress": getRequestAddress(r, state.Settings.ClientIpHeader),
+		"userAgent":     r.UserAgent(),
+		"path":          r.URL.Path,
+		"query": func() map[string]string {
+			result := make(map[string]string)
+			for k, v := range r.URL.Query() {
+				result[k] = strings.Join(v, ",")
+			}
+			return result
+		}(),
+		"headers": func() map[string]string {
+			result := make(map[string]string)
+			for k, v := range r.Header {
+				result[k] = strings.Join(v, ",")
+			}
+			return result
+		}(),
+	}
 
 	for _, c := range state.Challenges {
 		key := state.GetChallengeKeyForRequest(c.Name, data.Expires, r)
@@ -433,6 +438,21 @@ func (state *State) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			// clear invalid cookie
 			utils.ClearCookie(utils.CookiePrefix+c.Name, w)
 		}
+
+		// prevent the challenge if not solved
+		if !result.Ok() && c.Program != nil {
+			out, _, err := c.Program.Eval(data.ProgramEnv)
+			// verify eligibility
+			if err != nil {
+				state.logger(r).Error(err.Error(), "challenge", c.Name)
+			} else if out != nil && out.Type() == types.BoolType {
+				if out.Equal(types.True) != types.True {
+					// skip challenge match!
+					result = challenge.VerifyResultSKIP
+					continue
+				}
+			}
+		}
 		data.Challenges[c.Id] = result
 	}
 
@@ -449,6 +469,7 @@ func RequestDataFromContext(ctx context.Context) *RequestData {
 
 type RequestData struct {
 	Id         [16]byte
+	ProgramEnv map[string]any
 	Expires    time.Time
 	Challenges map[challenge.Id]challenge.VerifyResult
 }

lib/policy/challenge.go

@@ -1,9 +1,10 @@
 package policy
 
 type Challenge struct {
-	Mode  string  `yaml:"mode"`
+	Conditions []string `yaml:"conditions"`
-	Asset *string `yaml:"asset,omitempty"`
+	Mode       string   `yaml:"mode"`
-	Url   *string `yaml:"url,omitempty"`
+	Asset      *string  `yaml:"asset,omitempty"`
+	Url        *string  `yaml:"url,omitempty"`
 
 	Parameters map[string]string `json:"parameters,omitempty"`
 	Runtime    struct {

lib/state.go

@@ -20,15 +20,12 @@ import (
 	"git.gammaspectra.live/git/go-away/utils"
 	"git.gammaspectra.live/git/go-away/utils/inline"
 	"github.com/google/cel-go/cel"
-	"github.com/google/cel-go/common/types"
-	"github.com/google/cel-go/common/types/ref"
 	"github.com/tetratelabs/wazero/api"
 	"github.com/yl2chen/cidranger"
 	"html/template"
 	"io"
 	"io/fs"
 	"log/slog"
-	"net"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
@@ -197,13 +194,56 @@ func NewState(p policy.Policy, settings StateSettings) (state *State, err error)
 
 	state.Wasm = wasm.NewRunner(true)
 
+	err = state.initConditions()
+	if err != nil {
+		return nil, err
+	}
+
+	var replacements []string
+	for k, entries := range p.Conditions {
+		ast, err := condition.FromStrings(state.RulesEnv, condition.OperatorOr, entries...)
+		if err != nil {
+			return nil, fmt.Errorf("conditions %s: error compiling conditions: %v", k, err)
+		}
+
+		cond, err := cel.AstToString(ast)
+		if err != nil {
+			return nil, fmt.Errorf("conditions %s: error printing condition: %v", k, err)
+		}
+
+		replacements = append(replacements, fmt.Sprintf("($%s)", k))
+		replacements = append(replacements, "("+cond+")")
+	}
+	conditionReplacer := strings.NewReplacer(replacements...)
+
 	state.Challenges = make(map[challenge.Id]challenge.Challenge)
 
 	idCounter := challenge.Id(1)
 
 	for challengeName, p := range p.Challenges {
+
+		// allow nesting
+		var conditions []string
+		for _, cond := range p.Conditions {
+			cond = conditionReplacer.Replace(cond)
+			conditions = append(conditions, cond)
+		}
+
+		var program cel.Program
+		if len(conditions) > 0 {
+			ast, err := condition.FromStrings(state.RulesEnv, condition.OperatorOr, conditions...)
+			if err != nil {
+				return nil, fmt.Errorf("challenge %s: error compiling conditions: %v", challengeName, err)
+			}
+			program, err = state.RulesEnv.Program(ast)
+			if err != nil {
+				return nil, fmt.Errorf("challenge %s: error compiling program: %v", challengeName, err)
+			}
+		}
+
 		c := challenge.Challenge{
 			Id:                idCounter,
+			Program:           program,
 			Name:              challengeName,
 			Path:              fmt.Sprintf("%s/challenge/%s", state.UrlPath, challengeName),
 			VerifyProbability: p.Runtime.Probability,
@@ -383,13 +423,16 @@ func NewState(p policy.Policy, settings StateSettings) (state *State, err error)
 				return challenge.ResultStop
 			}
 		case "preload-link":
-			deadline := time.Second * 5
+			deadline, _ := time.ParseDuration(p.Parameters["preload-early-hint-deadline"])
+			if deadline == 0 {
+				deadline = time.Second * 3
+			}
 
 			c.ServeChallenge = func(w http.ResponseWriter, r *http.Request, key []byte, expiry time.Time) challenge.Result {
 				// this only works on HTTP/2 and HTTP/3
 
 				if r.ProtoMajor < 2 {
-					// this can happen if we are an upgraded request
+					// this can happen if we are an upgraded request from HTTP/1.1 to HTTP/2 in H2C
 					if _, ok := w.(http.Pusher); !ok {
 						return challenge.ResultContinue
 					}
@@ -397,18 +440,19 @@ func NewState(p policy.Policy, settings StateSettings) (state *State, err error)
 
 				data := RequestDataFromContext(r.Context())
 				redirectUri := new(url.URL)
+				redirectUri.Scheme = getRequestScheme(r)
+				redirectUri.Host = r.Host
 				redirectUri.Path = c.Path + "/verify-challenge"
 
 				values := make(url.Values)
 				values.Set("result", hex.EncodeToString(key))
-				values.Set("redirect", r.URL.String())
 				values.Set("requestId", r.Header.Get("X-Away-Id"))
 
 				redirectUri.RawQuery = values.Encode()
 
-				w.Header().Set("Link", fmt.Sprintf("<%s>; rel=preload; as=style; fetchpriority=high", redirectUri.String()))
+				w.Header().Set("Link", fmt.Sprintf("<%s>; rel=\"preload\"; as=\"style\"; fetchpriority=high", redirectUri.String()))
 				defer func() {
-					// remove old header header!
+					// remove old header so it won't show on response!
 					w.Header().Del("Link")
 				}()
 				w.WriteHeader(http.StatusEarlyHints)
@@ -656,80 +700,6 @@ func NewState(p policy.Policy, settings StateSettings) (state *State, err error)
 		state.Challenges[c.Id] = c
 	}
 
-	state.RulesEnv, err = cel.NewEnv(
-		cel.DefaultUTCTimeZone(true),
-		cel.Variable("remoteAddress", cel.BytesType),
-		cel.Variable("host", cel.StringType),
-		cel.Variable("method", cel.StringType),
-		cel.Variable("userAgent", cel.StringType),
-		cel.Variable("path", cel.StringType),
-		cel.Variable("query", cel.MapType(cel.StringType, cel.StringType)),
-		// http.Header
-		cel.Variable("headers", cel.MapType(cel.StringType, cel.StringType)),
-		//TODO: dynamic type?
-		cel.Function("inNetwork",
-			cel.Overload("inNetwork_string_ip",
-				[]*cel.Type{cel.StringType, cel.AnyType},
-				cel.BoolType,
-				cel.BinaryBinding(func(lhs ref.Val, rhs ref.Val) ref.Val {
-					var ip net.IP
-					switch v := rhs.Value().(type) {
-					case []byte:
-						ip = v
-					case net.IP:
-						ip = v
-					case string:
-						ip = net.ParseIP(v)
-					}
-
-					if ip == nil {
-						panic(fmt.Errorf("invalid ip %v", rhs.Value()))
-					}
-
-					val, ok := lhs.Value().(string)
-					if !ok {
-						panic(fmt.Errorf("invalid value %v", lhs.Value()))
-					}
-
-					network, ok := state.Networks[val]
-					if !ok {
-						_, ipNet, err := net.ParseCIDR(val)
-						if err != nil {
-							panic("network not found")
-						}
-						return types.Bool(ipNet.Contains(ip))
-					} else {
-						ok, err := network.Contains(ip)
-						if err != nil {
-							panic(err)
-						}
-						return types.Bool(ok)
-					}
-				}),
-			),
-		),
-	)
-	if err != nil {
-		return nil, err
-	}
-
-	var replacements []string
-	for k, entries := range p.Conditions {
-		ast, err := condition.FromStrings(state.RulesEnv, condition.OperatorOr, entries...)
-		if err != nil {
-			return nil, fmt.Errorf("conditions %s: error compiling conditions: %v", k, err)
-		}
-
-		cond, err := cel.AstToString(ast)
-		if err != nil {
-			return nil, fmt.Errorf("conditions %s: error printing condition: %v", k, err)
-		}
-
-		replacements = append(replacements, fmt.Sprintf("($%s)", k))
-		replacements = append(replacements, "("+cond+")")
-	}
-	conditionReplacer := strings.NewReplacer(replacements...)
-
 	for _, rule := range p.Rules {
 		hasher := sha256.New()
 		hasher.Write([]byte(rule.Name))