TUN-6774: Validate OriginRequest.Access to add Ingress.Middleware

We take advantage of the JWTValidator middleware and attach it to an
ingress rule based on Access configurations. We attach the Validator
directly to the ingress rules because we want to take advantage of
caching and token revert/handling that comes with go-oidc.

ingress/ingress.go

@@ -13,6 +13,7 @@ import (
 	"github.com/urfave/cli/v2"
 
 	"github.com/cloudflare/cloudflared/config"
+	"github.com/cloudflare/cloudflared/ingress/middleware"
 	"github.com/cloudflare/cloudflared/ipaccess"
 )
 
@@ -168,6 +169,28 @@ func (ing Ingress) CatchAll() *Rule {
 	return &ing.Rules[len(ing.Rules)-1]
 }
 
+func validateAccessConfiguration(cfg *config.AccessConfig) error {
+	if !cfg.Required {
+		return nil
+	}
+
+	// It is possible to set `required:true` and not have these two configured yet.
+	// But if one of them is configured, we'd validate for correctness.
+	if len(cfg.AudTag) == 0 && cfg.TeamName == "" {
+		return nil
+	}
+
+	if len(cfg.AudTag) == 0 {
+		return errors.New("access audtag cannot be empty")
+	}
+
+	if cfg.TeamName == "" {
+		return errors.New("access.TeamName cannot be blank")
+	}
+
+	return nil
+}
+
 func validateIngress(ingress []config.UnvalidatedIngressRule, defaults OriginRequestConfig) (Ingress, error) {
 	rules := make([]Rule, len(ingress))
 	for i, r := range ingress {
@@ -237,6 +260,17 @@ func validateIngress(ingress []config.UnvalidatedIngressRule, defaults OriginReq
 			}
 		}
 
+		var handlers []middleware.Handler
+		if access := r.OriginRequest.Access; access != nil {
+			if err := validateAccessConfiguration(access); err != nil {
+				return Ingress{}, err
+			}
+			if access.Required {
+				verifier := middleware.NewJWTValidator(access.TeamName, "", access.AudTag)
+				handlers = append(handlers, verifier)
+			}
+		}
+
 		if err := validateHostname(r, i, len(ingress)); err != nil {
 			return Ingress{}, err
 		}
@@ -255,6 +289,7 @@ func validateIngress(ingress []config.UnvalidatedIngressRule, defaults OriginReq
 			Hostname: r.Hostname,
 			Service:  service,
 			Path:     pathRegexp,
+			Handlers: handlers,
 			Config:   cfg,
 		}
 	}