v2: Implement RegExp Vars Matcher (#2997)

* implement regexp var matcher

* use subtests pattern for tests

* be more consistent with naming: MatchVarRE -> MatchVarsRE, var_regexp -> vars_regexp

1 files changed, 69 insertions, 0 deletions

diff --git a/modules/caddyhttp/vars.go b/modules/caddyhttp/vars.go
index 1208d9c..9561d46 100644
--- a/modules/caddyhttp/vars.go
+++ b/modules/caddyhttp/vars.go
@@ -25,6 +25,7 @@ import (
 func init() {
 	caddy.RegisterModule(VarsMiddleware{})
 	caddy.RegisterModule(VarsMatcher{})
+	caddy.RegisterModule(MatchVarsRE{})
 }
 
 // VarsMiddleware is an HTTP middleware which sets variables
@@ -88,6 +89,74 @@ func (m VarsMatcher) Match(r *http.Request) bool {
 	return true
 }
 
+// MatchVarsRE matches the value of the context variables by a given regular expression.
+//
+// Upon a match, it adds placeholders to the request: `{http.regexp.name.capture_group}`
+// where `name` is the regular expression's name, and `capture_group` is either
+// the named or positional capture group from the expression itself. If no name
+// is given, then the placeholder omits the name: `{http.regexp.capture_group}`
+// (potentially leading to collisions).
+type MatchVarsRE map[string]*MatchRegexp
+
+// CaddyModule returns the Caddy module information.
+func (MatchVarsRE) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "http.matchers.vars_regexp",
+		New: func() caddy.Module { return new(MatchVarsRE) },
+	}
+}
+
+// Provision compiles m's regular expressions.
+func (m MatchVarsRE) Provision(ctx caddy.Context) error {
+	for _, rm := range m {
+		err := rm.Provision(ctx)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Match returns true if r matches m.
+func (m MatchVarsRE) Match(r *http.Request) bool {
+	vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
+	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
+	for k, rm := range m {
+		var varStr string
+		switch vv := vars[k].(type) {
+		case string:
+			varStr = vv
+		case fmt.Stringer:
+			varStr = vv.String()
+		case error:
+			varStr = vv.Error()
+		default:
+			varStr = fmt.Sprintf("%v", vv)
+		}
+		valExpanded := repl.ReplaceAll(varStr, "")
+		if match := rm.Match(valExpanded, repl); match {
+			return match
+		}
+
+		replacedVal := repl.ReplaceAll(k, "")
+		if match := rm.Match(replacedVal, repl); match {
+			return match
+		}
+	}
+	return false
+}
+
+// Validate validates m's regular expressions.
+func (m MatchVarsRE) Validate() error {
+	for _, rm := range m {
+		err := rm.Validate()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // GetVar gets a value out of the context's variable table by key.
 // If the key does not exist, the return value will be nil.
 func GetVar(ctx context.Context, key string) interface{} {