From d21fac6f190c1079ca247658530d465ad5867ff5 Mon Sep 17 00:00:00 2001
From: Niall Sheridan <nsheridan@gmail.com>
Date: Thu, 9 Aug 2018 20:47:50 +0100
Subject: Only request a reason from the client if the server requires it

---
 client/client.go      | 57 ++++++++++++++++++++++++++++++++++++++-------------
 client/client_test.go |  8 ++++----
 2 files changed, 47 insertions(+), 18 deletions(-)

(limited to 'client')

diff --git a/client/client.go b/client/client.go
index 58cc6bb..628783a 100644
--- a/client/client.go
+++ b/client/client.go
@@ -1,6 +1,7 @@
 package client
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/tls"
 	"encoding/base64"
@@ -10,7 +11,9 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"os"
 	"path"
+	"strings"
 	"time"
 
 	"github.com/nsheridan/cashier/lib"
@@ -19,6 +22,10 @@ import (
 	"golang.org/x/crypto/ssh/agent"
 )
 
+var (
+	errNeedsReason = errors.New("reason required")
+)
+
 // SavePublicFiles installs the public part of the cert and key.
 func SavePublicFiles(prefix string, cert *ssh.Certificate, pub ssh.PublicKey) error {
 	if prefix == "" {
@@ -77,7 +84,11 @@ func InstallCert(a agent.Agent, cert *ssh.Certificate, key Key) error {
 }
 
 // send the signing request to the CA.
-func send(s []byte, token, ca string, ValidateTLSCertificate bool) (*lib.SignResponse, error) {
+func send(sr *lib.SignRequest, token, ca string, ValidateTLSCertificate bool) (*lib.SignResponse, error) {
+	s, err := json.Marshal(sr)
+	if err != nil {
+		return nil, errors.Wrap(err, "unable to create sign request")
+	}
 	transport := &http.Transport{
 		TLSClientConfig: &tls.Config{InsecureSkipVerify: !ValidateTLSCertificate},
 	}
@@ -99,33 +110,51 @@ func send(s []byte, token, ca string, ValidateTLSCertificate bool) (*lib.SignRes
 		return nil, err
 	}
 	defer resp.Body.Close()
+	signResponse := &lib.SignResponse{}
 	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("Bad response from server: %s", resp.Status)
+		if resp.StatusCode == http.StatusForbidden && strings.HasPrefix(resp.Header.Get("X-Need-Reason"), "required") {
+			return signResponse, errNeedsReason
+		}
+		return signResponse, fmt.Errorf("bad response from server: %s", resp.Status)
 	}
-	c := &lib.SignResponse{}
-	if err := json.NewDecoder(resp.Body).Decode(c); err != nil {
+	if err := json.NewDecoder(resp.Body).Decode(signResponse); err != nil {
 		return nil, errors.Wrap(err, "unable to decode server response")
 	}
-	return c, nil
+	return signResponse, nil
+}
+
+func promptForReason() (message string) {
+	fmt.Print("Enter message: ")
+	scanner := bufio.NewScanner(os.Stdin)
+	if scanner.Scan() {
+		message = scanner.Text()
+	}
+	return message
 }
 
 // Sign sends the public key to the CA to be signed.
-func Sign(pub ssh.PublicKey, token string, message string, conf *Config) (*ssh.Certificate, error) {
+func Sign(pub ssh.PublicKey, token string, conf *Config) (*ssh.Certificate, error) {
+	var err error
 	validity, err := time.ParseDuration(conf.Validity)
 	if err != nil {
 		return nil, err
 	}
-	s, err := json.Marshal(&lib.SignRequest{
+	s := &lib.SignRequest{
 		Key:        string(lib.GetPublicKey(pub)),
 		ValidUntil: time.Now().Add(validity),
-		Message:    message,
-	})
-	if err != nil {
-		return nil, errors.Wrap(err, "unable to create sign request")
 	}
-	resp, err := send(s, token, conf.CA, conf.ValidateTLSCertificate)
-	if err != nil {
-		return nil, errors.Wrap(err, "error sending request to CA")
+	resp := &lib.SignResponse{}
+	for {
+		resp, err = send(s, token, conf.CA, conf.ValidateTLSCertificate)
+		if err == nil {
+			break
+		}
+		if err != nil && err == errNeedsReason {
+			s.Message = promptForReason()
+			continue
+		} else if err != nil {
+			return nil, errors.Wrap(err, "error sending request to CA")
+		}
 	}
 	if resp.Status != "ok" {
 		return nil, fmt.Errorf("bad response from CA: %s", resp.Response)
diff --git a/client/client_test.go b/client/client_test.go
index fddd543..2447db3 100644
--- a/client/client_test.go
+++ b/client/client_test.go
@@ -67,7 +67,7 @@ func TestSignGood(t *testing.T) {
 		fmt.Fprintln(w, string(j))
 	}))
 	defer ts.Close()
-	_, err := send([]byte(`{}`), "token", ts.URL, true)
+	_, err := send(&lib.SignRequest{}, "token", ts.URL, true)
 	if err != nil {
 		t.Error(err)
 	}
@@ -79,7 +79,7 @@ func TestSignGood(t *testing.T) {
 		CA:       ts.URL,
 		Validity: "24h",
 	}
-	cert, err := Sign(k, "token", "message", c)
+	cert, err := Sign(k, "token", c)
 	if cert == nil && err != nil {
 		t.Error(err)
 	}
@@ -95,7 +95,7 @@ func TestSignBad(t *testing.T) {
 		fmt.Fprintln(w, string(j))
 	}))
 	defer ts.Close()
-	_, err := send([]byte(`{}`), "token", ts.URL, true)
+	_, err := send(&lib.SignRequest{}, "token", ts.URL, true)
 	if err != nil {
 		t.Error(err)
 	}
@@ -107,7 +107,7 @@ func TestSignBad(t *testing.T) {
 		CA:       ts.URL,
 		Validity: "24h",
 	}
-	cert, err := Sign(k, "token", "message", c)
+	cert, err := Sign(k, "token", c)
 	if cert != nil && err == nil {
 		t.Error(err)
 	}
-- 
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