context: add CONTEXT action to apply options on current request

README.md

@@ -88,6 +88,7 @@ In addition to the common PASS / CHALLENGE / DENY rules, go-away offers more act
 
 |  Action   | Behavior                                                                | Terminating |
 |:---------:|:------------------------------------------------------------------------|:-----------:|
+|   NONE    | Do nothing, continue. Useful for specifying on checks or challenges.    |     No      |
 |   PASS    | Passes the request to the backend immediately                           |     Yes     |
 |   DENY    | Denies the request with a descriptive page                              |     Yes     |
 |   BLOCK   | Denies the request with a response code                                 |     Yes     |
@@ -95,6 +96,7 @@ In addition to the common PASS / CHALLENGE / DENY rules, go-away offers more act
 | CHALLENGE | Issues a challenge that when passed, acts like PASS                     |     Yes     |
 |   CHECK   | Issues a challenge that when passed, continues executing rules          |     No      |
 |   PROXY   | Proxies request to a different backend, with optional path replacements |     Yes     |
+|  CONTEXT  | Modify the request context and apply different options                  |     No      |
 
 
 CHECK allows the client to be challenged but continue matching rules after these, for example, chaining a list of challenges that must be passed. 

lib/action/context.go

@@ -0,0 +1,50 @@
+package action
+
+import (
+	"git.gammaspectra.live/git/go-away/lib/challenge"
+	"git.gammaspectra.live/git/go-away/lib/policy"
+	"github.com/goccy/go-yaml"
+	"github.com/goccy/go-yaml/ast"
+	"log/slog"
+	"net/http"
+)
+
+func init() {
+	Register[policy.RuleActionCONTEXT] = func(state challenge.StateInterface, ruleName, ruleHash string, settings ast.Node) (Handler, error) {
+		params := ContextDefaultSettings
+
+		if settings != nil {
+			ymlData, err := settings.MarshalYAML()
+			if err != nil {
+				return nil, err
+			}
+			err = yaml.Unmarshal(ymlData, &params)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		return Context{
+			opts: params,
+		}, nil
+	}
+}
+
+var ContextDefaultSettings = ContextSettings{}
+
+type ContextSettings struct {
+	Settings map[string]string `yaml:"context-set"`
+}
+
+type Context struct {
+	opts ContextSettings
+}
+
+func (a Context) Handle(logger *slog.Logger, w http.ResponseWriter, r *http.Request, done func() (backend http.Handler)) (next bool, err error) {
+	data := challenge.RequestDataFromContext(r.Context())
+	for k, v := range a.opts.Settings {
+		data.SetOpt(k, v)
+	}
+
+	return false, nil
+}

lib/challenge/data.go

@@ -46,6 +46,8 @@ type RequestData struct {
 	fp     map[string]string
 	header traits.Mapper
 	query  traits.Mapper
+
+	opts map[string]string
 }
 
 func CreateRequestData(r *http.Request, state StateInterface) (*http.Request, *RequestData) {
@@ -84,6 +86,7 @@ func CreateRequestData(r *http.Request, state StateInterface) (*http.Request, *R
 
 	data.query = http_cel.NewValuesMap(q)
 	data.header = http_cel.NewMIMEMap(textproto.MIMEHeader(r.Header))
+	data.opts = make(map[string]string)
 
 	sum := sha256.New()
 	sum.Write([]byte(r.Host))
@@ -126,6 +129,18 @@ func (d *RequestData) Parent() cel.Activation {
 	return nil
 }
 
+func (d *RequestData) SetOpt(n, v string) {
+	d.opts[n] = v
+}
+
+func (d *RequestData) GetOpt(n, def string) string {
+	v, ok := d.opts[n]
+	if !ok {
+		return def
+	}
+	return v
+}
+
 func (d *RequestData) EvaluateChallenges(w http.ResponseWriter, r *http.Request) {
 	q := r.URL.Query()
 	var issuedChallenge string

lib/challenge/helper.go

@@ -19,7 +19,7 @@ func NewKeyVerifier() (verify VerifyFunc, issue func(key Key) string) {
 			if subtle.ConstantTimeCompare(key[:], expectedKey) == 1 {
 				return VerifyResultOK, nil
 			}
-			return VerifyResultFail, errors.New("invalid token")
+			return VerifyResultFail, errors.New("mismatched token")
 		}, func(key Key) string {
 			return hex.EncodeToString(key[:])
 		}

lib/policy/rule.go

@@ -26,6 +26,9 @@ const (
 
 	// RuleActionPROXY Proxies request to a backend, with optional path replacements
 	RuleActionPROXY RuleAction = "PROXY"
+
+	// RuleActionCONTEXT Changes Request Context information or properties
+	RuleActionCONTEXT RuleAction = "CONTEXT"
 )
 
 type Rule struct {