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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")
}
client := &http.Client{
Transport: &http.Transport{
TLSClientConfig: &tls.Config{InsecureSkipVerify: !ValidateTLSCertificate},
},
Timeout: 30 * time.Second,
}
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),
Version: lib.Version,
}
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
}
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