caddypki: Refactor /pki/ admin endpoints

Remove /pki/certificates/<ca> endpoint and split into two endpoints:

- GET /pki/ca/<id> to get CA info and certs in JSON format
- GET /pki/ca/<id>/certificates to get cert in PEM chain

2 files changed, 132 insertions, 70 deletions

diff --git a/modules/caddypki/adminpki.go b/modules/caddypki/adminpki.go
index 5933bcd..a2939d1 100644
--- a/modules/caddypki/adminpki.go
+++ b/modules/caddypki/adminpki.go
@@ -16,7 +16,6 @@ package caddypki
 
 import (
 	"encoding/json"
-	"encoding/pem"
 	"fmt"
 	"net/http"
 	"strings"
@@ -26,27 +25,27 @@ import (
 )
 
 func init() {
-	caddy.RegisterModule(adminPKI{})
+	caddy.RegisterModule(adminAPI{})
 }
 
-// adminPKI is a module that serves a PKI endpoint to retrieve
+// adminAPI is a module that serves PKI endpoints to retrieve
 // information about the CAs being managed by Caddy.
-type adminPKI struct {
+type adminAPI struct {
 	ctx    caddy.Context
 	log    *zap.Logger
 	pkiApp *PKI
 }
 
 // CaddyModule returns the Caddy module information.
-func (adminPKI) CaddyModule() caddy.ModuleInfo {
+func (adminAPI) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
 		ID:  "admin.api.pki",
-		New: func() caddy.Module { return new(adminPKI) },
+		New: func() caddy.Module { return new(adminAPI) },
 	}
 }
 
-// Provision sets up the adminPKI module.
-func (a *adminPKI) Provision(ctx caddy.Context) error {
+// Provision sets up the adminAPI module.
+func (a *adminAPI) Provision(ctx caddy.Context) error {
 	a.ctx = ctx
 	a.log = ctx.Logger(a)
 
@@ -69,52 +68,128 @@ func (a *adminPKI) Provision(ctx caddy.Context) error {
 }
 
 // Routes returns the admin routes for the PKI app.
-func (a *adminPKI) Routes() []caddy.AdminRoute {
+func (a *adminAPI) Routes() []caddy.AdminRoute {
 	return []caddy.AdminRoute{
 		{
-			Pattern: adminPKICertificatesEndpoint,
-			Handler: caddy.AdminHandlerFunc(a.handleCertificates),
+			Pattern: adminPKIEndpointBase,
+			Handler: caddy.AdminHandlerFunc(a.handleAPIEndpoints),
 		},
 	}
 }
 
-// handleCertificates returns certificate information about a particular
-// CA, by its ID. If the CA ID is the default, then the CA will be
+// handleAPIEndpoints routes API requests within adminPKIEndpointBase.
+func (a *adminAPI) handleAPIEndpoints(w http.ResponseWriter, r *http.Request) error {
+	uri := strings.TrimPrefix(r.URL.Path, "/pki/")
+	parts := strings.Split(uri, "/")
+	switch {
+	case len(parts) == 2 && parts[0] == "ca" && parts[1] != "":
+		return a.handleCAInfo(w, r)
+	case len(parts) == 3 && parts[0] == "ca" && parts[1] != "" && parts[2] == "certificates":
+		return a.handleCACerts(w, r)
+	}
+	return caddy.APIError{
+		HTTPStatus: http.StatusNotFound,
+		Err:        fmt.Errorf("resource not found: %v", r.URL.Path),
+	}
+}
+
+// handleCAInfo returns cinformation about a particular
+// CA by its ID. If the CA ID is the default, then the CA will be
 // provisioned if it has not already been. Other CA IDs will return an
 // error if they have not been previously provisioned.
-func (a *adminPKI) handleCertificates(w http.ResponseWriter, r *http.Request) error {
+func (a *adminAPI) handleCAInfo(w http.ResponseWriter, r *http.Request) error {
 	if r.Method != http.MethodGet {
 		return caddy.APIError{
 			HTTPStatus: http.StatusMethodNotAllowed,
-			Err:        fmt.Errorf("method not allowed"),
+			Err:        fmt.Errorf("method not allowed: %v", r.Method),
+		}
+	}
+
+	ca, err := a.getCAFromAPIRequestPath(r)
+	if err != nil {
+		return err
+	}
+
+	rootCert, interCert, err := rootAndIntermediatePEM(ca)
+	if err != nil {
+		return caddy.APIError{
+			HTTPStatus: http.StatusInternalServerError,
+			Err:        fmt.Errorf("failed to get root and intermediate cert for CA %s: %v", ca.ID, err),
+		}
+	}
+
+	repl := ca.newReplacer()
+
+	response := caInfo{
+		ID:               ca.ID,
+		Name:             ca.Name,
+		RootCN:           repl.ReplaceAll(ca.RootCommonName, ""),
+		IntermediateCN:   repl.ReplaceAll(ca.IntermediateCommonName, ""),
+		RootCert:         string(rootCert),
+		IntermediateCert: string(interCert),
+	}
+
+	encoded, err := json.Marshal(response)
+	if err != nil {
+		return caddy.APIError{
+			HTTPStatus: http.StatusInternalServerError,
+			Err:        err,
 		}
 	}
 
-	// Prep for a JSON response
 	w.Header().Set("Content-Type", "application/json")
-	enc := json.NewEncoder(w)
+	w.Write(encoded)
 
-	idPath := r.URL.Path
+	return nil
+}
 
-	// Grab the CA ID from the request path, it should be the 4th segment
-	parts := strings.Split(idPath, "/")
-	if len(parts) < 4 || parts[3] == "" {
+// handleCACerts returns cinformation about a particular
+// CA by its ID. If the CA ID is the default, then the CA will be
+// provisioned if it has not already been. Other CA IDs will return an
+// error if they have not been previously provisioned.
+func (a *adminAPI) handleCACerts(w http.ResponseWriter, r *http.Request) error {
+	if r.Method != http.MethodGet {
 		return caddy.APIError{
-			HTTPStatus: http.StatusBadRequest,
-			Err:        fmt.Errorf("request path is missing the CA ID"),
+			HTTPStatus: http.StatusMethodNotAllowed,
+			Err:        fmt.Errorf("method not allowed: %v", r.Method),
 		}
 	}
-	if parts[0] != "" || parts[1] != "pki" || parts[2] != "certificates" {
+
+	ca, err := a.getCAFromAPIRequestPath(r)
+	if err != nil {
+		return err
+	}
+
+	rootCert, interCert, err := rootAndIntermediatePEM(ca)
+	if err != nil {
 		return caddy.APIError{
+			HTTPStatus: http.StatusInternalServerError,
+			Err:        fmt.Errorf("failed to get root and intermediate cert for CA %s: %v", ca.ID, err),
+		}
+	}
+
+	w.Header().Set("Content-Type", "application/pem-certificate-chain")
+	_, err = w.Write(interCert)
+	if err == nil {
+		w.Write(rootCert)
+	}
+
+	return nil
+}
+
+func (a *adminAPI) getCAFromAPIRequestPath(r *http.Request) (*CA, error) {
+	// Grab the CA ID from the request path, it should be the 4th segment (/pki/ca/<ca>)
+	id := strings.Split(r.URL.Path, "/")[3]
+	if id == "" {
+		return nil, caddy.APIError{
 			HTTPStatus: http.StatusBadRequest,
-			Err:        fmt.Errorf("malformed object path"),
+			Err:        fmt.Errorf("missing CA in path"),
 		}
 	}
-	id := parts[3]
 
 	// Find the CA by ID, if PKI is configured
 	var ca *CA
-	ok := false
+	var ok bool
 	if a.pkiApp != nil {
 		ca, ok = a.pkiApp.CAs[id]
 	}
@@ -127,7 +202,7 @@ func (a *adminPKI) handleCertificates(w http.ResponseWriter, r *http.Request) er
 	// if they actually requested the local CA ID.
 	if !ok {
 		if id != DefaultCAID {
-			return caddy.APIError{
+			return nil, caddy.APIError{
 				HTTPStatus: http.StatusNotFound,
 				Err:        fmt.Errorf("no certificate authority configured with id: %s", id),
 			}
@@ -138,57 +213,43 @@ func (a *adminPKI) handleCertificates(w http.ResponseWriter, r *http.Request) er
 		ca = new(CA)
 		err := ca.Provision(a.ctx, id, a.log)
 		if err != nil {
-			return caddy.APIError{
+			return nil, caddy.APIError{
 				HTTPStatus: http.StatusInternalServerError,
 				Err:        fmt.Errorf("failed to provision CA %s, %w", id, err),
 			}
 		}
 	}
 
-	// Convert the root certificate to PEM
-	rootPem := string(pem.EncodeToMemory(&pem.Block{
-		Type:  "CERTIFICATE",
-		Bytes: ca.RootCertificate().Raw,
-	}))
-
-	// Convert the intermediate certificate to PEM
-	interPem := string(pem.EncodeToMemory(&pem.Block{
-		Type:  "CERTIFICATE",
-		Bytes: ca.IntermediateCertificate().Raw,
-	}))
+	return ca, nil
+}
 
-	// Build the response
-	response := CAInfo{
-		ID:           ca.ID,
-		Name:         ca.Name,
-		Root:         rootPem,
-		Intermediate: interPem,
+func rootAndIntermediatePEM(ca *CA) (root, inter []byte, err error) {
+	root, err = pemEncodeCert(ca.RootCertificate().Raw)
+	if err != nil {
+		return
 	}
-
-	// Encode and write the JSON response
-	err := enc.Encode(response)
+	inter, err = pemEncodeCert(ca.IntermediateCertificate().Raw)
 	if err != nil {
-		return caddy.APIError{
-			HTTPStatus: http.StatusInternalServerError,
-			Err:        err,
-		}
+		return
 	}
-
-	return nil
+	return
 }
 
-// CAInfo is the response from the certificates API endpoint
-type CAInfo struct {
-	ID           string `json:"id"`
-	Name         string `json:"name"`
-	Root         string `json:"root"`
-	Intermediate string `json:"intermediate"`
+// caInfo is the response structure for the CA info API endpoint.
+type caInfo struct {
+	ID               string `json:"id"`
+	Name             string `json:"name"`
+	RootCN           string `json:"root_common_name"`
+	IntermediateCN   string `json:"intermediate_common_name"`
+	RootCert         string `json:"root_certificate"`
+	IntermediateCert string `json:"intermediate_certificate"`
 }
 
-const adminPKICertificatesEndpoint = "/pki/certificates/"
+// adminPKIEndpointBase is the base admin endpoint under which all PKI admin endpoints exist.
+const adminPKIEndpointBase = "/pki/"
 
 // Interface guards
 var (
-	_ caddy.AdminRouter = (*adminPKI)(nil)
-	_ caddy.Provisioner = (*adminPKI)(nil)
+	_ caddy.AdminRouter = (*adminAPI)(nil)
+	_ caddy.Provisioner = (*adminAPI)(nil)
 )
diff --git a/modules/caddypki/command.go b/modules/caddypki/command.go
index fa37ab0..4744c68 100644
--- a/modules/caddypki/command.go
+++ b/modules/caddypki/command.go
@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"path"
 
 	"github.com/caddyserver/caddy/v2"
 	caddycmd "github.com/caddyserver/caddy/v2/cmd"
@@ -132,7 +133,7 @@ func cmdTrust(fl caddycmd.Flags) (int, error) {
 	ca := CA{
 		log:          caddy.Log(),
 		root:         rootCert,
-		rootCertPath: adminAddr + adminPKICertificatesEndpoint + caID,
+		rootCertPath: adminAddr + path.Join(adminPKIEndpointBase, caID, "certificates"),
 	}
 
 	// Install the cert!
@@ -204,9 +205,9 @@ func cmdUntrust(fl caddycmd.Flags) (int, error) {
 	return caddy.ExitCodeSuccess, nil
 }
 
-// rootCertFromAdmin makes the API request to fetch the
+// rootCertFromAdmin makes the API request to fetch the root certificate for the named CA via admin API.
 func rootCertFromAdmin(adminAddr string, caID string) (*x509.Certificate, error) {
-	uri := adminPKICertificatesEndpoint + caID
+	uri := path.Join(adminPKIEndpointBase, caID, "certificates")
 
 	// Make the request to fetch the CA info
 	resp, err := caddycmd.AdminAPIRequest(adminAddr, http.MethodGet, uri, make(http.Header), nil)
@@ -216,14 +217,14 @@ func rootCertFromAdmin(adminAddr string, caID string) (*x509.Certificate, error)
 	defer resp.Body.Close()
 
 	// Decode the resposne
-	caInfo := new(CAInfo)
+	caInfo := new(caInfo)
 	err = json.NewDecoder(resp.Body).Decode(caInfo)
 	if err != nil {
 		return nil, fmt.Errorf("failed to decode JSON response: %v", err)
 	}
 
-	// Decode the root
-	rootBlock, _ := pem.Decode([]byte(caInfo.Root))
+	// Decode the root cert
+	rootBlock, _ := pem.Decode([]byte(caInfo.RootCert))
 	if rootBlock == nil {
 		return nil, fmt.Errorf("failed to decode root certificate: %v", err)
 	}