package client import ( "bufio" "bytes" "crypto/tls" "encoding/base64" "encoding/json" "encoding/pem" "fmt" "io/ioutil" "net/http" "net/url" "os" "path" "strings" "time" "github.com/nsheridan/cashier/lib" "github.com/pkg/errors" "golang.org/x/crypto/ssh" "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 == "" { return nil } pubTxt := ssh.MarshalAuthorizedKey(pub) certPubTxt := []byte(cert.Type() + " " + base64.StdEncoding.EncodeToString(cert.Marshal())) _prefix := prefix + "/id_" + cert.KeyId if err := ioutil.WriteFile(_prefix+".pub", pubTxt, 0644); err != nil { return err } err := ioutil.WriteFile(_prefix+"-cert.pub", certPubTxt, 0644) return err } // SavePrivateFiles installs the private part of the key. func SavePrivateFiles(prefix string, cert *ssh.Certificate, key Key) error { if prefix == "" { return nil } _prefix := prefix + "/id_" + cert.KeyId pemBlock, err := pemBlockForKey(key) if err != nil { return err } err = ioutil.WriteFile(_prefix, pem.EncodeToMemory(pemBlock), 0600) return err } // InstallCert adds the private key and signed certificate to the ssh agent. func InstallCert(a agent.Agent, cert *ssh.Certificate, key Key) error { t := time.Unix(int64(cert.ValidBefore), 0) lifetime := t.Sub(time.Now()).Seconds() comment := fmt.Sprintf("%s [Expires %s]", cert.KeyId, t) pubcert := agent.AddedKey{ PrivateKey: key, Certificate: cert, Comment: comment, LifetimeSecs: uint32(lifetime), } if err := a.Add(pubcert); err != nil { return errors.Wrap(err, "unable to add cert to ssh agent") } privkey := agent.AddedKey{ PrivateKey: key, Comment: comment, LifetimeSecs: uint32(lifetime), } if err := a.Add(privkey); err != nil { return errors.Wrap(err, "unable to add private key to ssh agent") } return nil } // send the signing request to the CA. 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}, } client := &http.Client{Transport: transport} u, err := url.Parse(ca) if err != nil { return nil, errors.Wrap(err, "unable to parse CA url") } u.Path = path.Join(u.Path, "/sign") req, err := http.NewRequest("POST", u.String(), bytes.NewReader(s)) if err != nil { return nil, err } req.Header.Set("Content-Type", "application/json") req.Header.Add("Accept", "application/json") req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token)) resp, err := client.Do(req) if err != nil { return nil, err } defer resp.Body.Close() signResponse := &lib.SignResponse{} if resp.StatusCode != http.StatusOK { 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) } if err := json.NewDecoder(resp.Body).Decode(signResponse); err != nil { return nil, errors.Wrap(err, "unable to decode server response") } 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, conf *Config) (*ssh.Certificate, error) { var err error validity, err := time.ParseDuration(conf.Validity) if err != nil { return nil, err } s := &lib.SignRequest{ Key: string(lib.GetPublicKey(pub)), ValidUntil: time.Now().Add(validity), } 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) } k, _, _, _, err := ssh.ParseAuthorizedKey([]byte(resp.Response)) if err != nil { return nil, errors.Wrap(err, "unable to parse response") } cert, ok := k.(*ssh.Certificate) if !ok { return nil, fmt.Errorf("did not receive a valid certificate from server") } return cert, nil }