forked from TrueCloudLab/lego
197 lines
5.1 KiB
Go
197 lines
5.1 KiB
Go
package acme
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import (
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"crypto/rand"
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"crypto/rsa"
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"crypto/tls"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/json"
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"encoding/pem"
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"errors"
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"fmt"
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"io/ioutil"
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"math/big"
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"net"
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"net/http"
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"time"
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)
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type simpleHTTPChallenge struct {
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jws *jws
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optPort string
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}
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// SimpleHTTPS checks for DNS, public IP and port bindings
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func (s *simpleHTTPChallenge) CanSolve(domain string) bool {
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// determine public ip
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resp, err := http.Get("https://icanhazip.com/")
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if err != nil {
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logger().Printf("Could not get public IP -> %v", err)
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return false
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}
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ip, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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logger().Printf("Could not get public IP -> %v", err)
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return false
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}
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ipStr := string(ip)
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// resolve domain we should solve for
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resolvedIPs, err := net.LookupHost(domain)
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if err != nil {
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logger().Printf("Could not lookup DNS A record for %s", domain)
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return false
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}
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// if the resolve does not resolve to our public ip, we can't solve.
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for _, resolvedIP := range resolvedIPs {
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if resolvedIP == ipStr {
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return true
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}
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}
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logger().Printf("SimpleHTTPS: Domain %s does not resolve to the public ip of this server. Determined ip: %s", domain, ipStr)
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return false
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}
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func (s *simpleHTTPChallenge) Solve(chlng challenge, domain string) error {
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logger().Print("Trying to solve SimpleHTTPS")
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// Generate random string for the path. The acme server will
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// access this path on the server in order to validate the request
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responseToken := getRandomString(15)
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listener, err := s.startHTTPSServer(domain, chlng.Token, responseToken)
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if err != nil {
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return fmt.Errorf("Could not start HTTPS server for challenge -> %v", err)
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}
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// Tell the server about the generated random path
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jsonBytes, err := json.Marshal(challenge{Type: chlng.Type, Path: responseToken})
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if err != nil {
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return errors.New("Failed to marshal network message...")
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}
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resp, err := s.jws.post(chlng.URI, jsonBytes)
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if err != nil {
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return fmt.Errorf("Failed to post JWS message. -> %v", err)
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}
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// After the path is sent, the ACME server will access our server.
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// Repeatedly check the server for an updated status on our request.
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var challengeResponse challenge
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loop:
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for {
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decoder := json.NewDecoder(resp.Body)
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decoder.Decode(&challengeResponse)
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switch challengeResponse.Status {
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case "valid":
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logger().Print("The server validated our request")
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listener.Close()
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break loop
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case "pending":
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break
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case "invalid":
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return errors.New("The server could not validate our request.")
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default:
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return errors.New("The server returned an unexpected state.")
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}
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time.Sleep(1 * time.Second)
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resp, err = http.Get(chlng.URI)
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}
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return nil
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}
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// Starts a temporary HTTPS server on port 443. As soon as the challenge passed validation,
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// this server will get shut down. The certificate generated here is only held in memory.
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func (s *simpleHTTPChallenge) startHTTPSServer(domain string, token string, responseToken string) (net.Listener, error) {
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// Generate a new RSA key and a self-signed certificate.
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tempPrivKey, err := generatePrivateKey(2048)
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if err != nil {
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return nil, err
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}
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tempCertPEM, err := generateCert(tempPrivKey, domain)
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if err != nil {
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return nil, err
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}
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pemBytes := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(tempPrivKey)})
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tempKeyPair, err := tls.X509KeyPair(
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tempCertPEM,
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pemBytes)
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if err != nil {
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logger().Print("error here!")
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return nil, err
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}
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tlsConf := new(tls.Config)
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tlsConf.Certificates = []tls.Certificate{tempKeyPair}
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path := "/.well-known/acme-challenge/" + responseToken
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// Allow for CLI override
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port := ":443"
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if s.optPort != "" {
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port = ":" + s.optPort
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}
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tlsListener, err := tls.Listen("tcp", port, tlsConf)
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if err != nil {
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logger().Fatalf("Could not start HTTP listener! -> %v", err)
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}
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// The handler validates the HOST header and request type.
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// For validation it then writes the token the server returned with the challenge
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http.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
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if r.Host == domain && r.Method == "GET" {
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w.Write([]byte(token))
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}
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})
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go http.Serve(tlsListener, nil)
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return tlsListener, nil
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}
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func getRandomString(length int) string {
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const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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var bytes = make([]byte, length)
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rand.Read(bytes)
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for i, b := range bytes {
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bytes[i] = alphanum[b%byte(len(alphanum))]
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}
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return string(bytes)
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}
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func generateCert(privKey *rsa.PrivateKey, domain string) ([]byte, error) {
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serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
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serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
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if err != nil {
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return nil, err
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}
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template := x509.Certificate{
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SerialNumber: serialNumber,
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Subject: pkix.Name{
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CommonName: "ACME Challenge TEMP",
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},
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NotBefore: time.Now(),
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NotAfter: time.Now().Add(365),
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KeyUsage: x509.KeyUsageKeyEncipherment,
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BasicConstraintsValid: true,
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DNSNames: []string{domain},
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}
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derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &privKey.PublicKey, privKey)
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if err != nil {
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return nil, err
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}
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return pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes}), nil
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}
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