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path: root/provider.go
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package acme

import (
	"crypto/rsa"
	"crypto/x509"
	"encoding/json"
	"errors"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"regexp"
	"strconv"
	"time"

	"github.com/mgutz/ansi"
)

// Provider ...
type Provider struct {
	Directory
	nonces chan string
}

var (
	errNoNonces      = errors.New("out of nonces")
	errTimedOut      = errors.New("timed out")
	errContentType   = errors.New("unknown content type")
	errChallengeType = errors.New("unknown challenge")
)

// Nonce implements jose nonce provider
func (p Provider) Nonce() (string, error) {
	select {
	case nonce := <-p.nonces:
		return nonce, nil
	default:
		return "", errNoNonces
	}
}

func (p Provider) nonce(r *http.Response) {
	if rn := r.Header.Get("Replay-Nonce"); rn != "" {
		p.nonces <- rn
	}
}

// NewProvider fetches directory and initializes nonce
func NewProvider(directory string) (*Provider, error) {
	p := &Provider{nonces: make(chan string, 10)}
	if _, err := p.get(directory, &p.Directory); err != nil {
		return nil, err
	}
	return p, nil
}

// Important header fields
//
// Replay-Nonce		each response, required for next request
// Link			links to next stage
// Retry-After		polling interval
// Location		next step
// Content-Location	cert

// Action		Request		Response
//
// Register		POST new-reg	201 -> reg
// Request challenges	POST new-authz	201 -> authz
// Answer challenges	POST challenge	200
// Poll for status	GET  authz	200
// Request issuance	POST new-cert	201 -> cert
// Check for new cert	GET  cert	200

// request is used for
// new-reg, new-authz, challenge, new-cert
func (p *Provider) post(uri string, s Signer, v interface{}) (*http.Response, error) {
	body, err := json.Marshal(v)
	if err != nil {
		return nil, err
	}
	log.Println(ansi.Color("POST", "red+b"), uri, string(body))

	signed, err := s.Sign(body, p)
	if err != nil {
		return nil, err
	}

	resp, err := http.Post(uri, "application/json", signed)
	if err != nil {
		return nil, err
	}
	p.nonce(resp)
	log.Println(ansi.Color("STATUS", "yellow"), resp.Status)

	switch resp.Header.Get("Content-Type") {
	case "application/problem+json":
		defer resp.Body.Close()
		return resp, parseProblem(resp)
	case "application/json":
		defer resp.Body.Close()
		return resp, json.NewDecoder(resp.Body).Decode(v)
	case "application/pkix-cert":
		return resp, nil
	default:
		return resp, errContentType
	}
}

func (p *Provider) get(uri string, v interface{}) (*http.Response, error) {
	resp, err := http.Get(uri)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	p.nonce(resp)
	return resp, json.NewDecoder(resp.Body).Decode(v)
}

func parseProblem(resp *http.Response) error {
	var p Problem
	if err := json.NewDecoder(resp.Body).Decode(&p); err != nil {
		return err
	}
	if err, ok := urnErrors[p.Type]; ok {
		p.Err = err
	}
	return p
}

type Links map[string]string

type nextStep struct {
	Link       Links
	Location   *url.URL
	RetryAfter time.Duration
}

var linksRe = regexp.MustCompile(`^<(.*)>;rel="(.*)"`)

func parseHeader(r *http.Response) nextStep {
	var ns nextStep

	if lo, err := r.Location(); err == nil {
		ns.Location = lo
	}

	ns.Link = make(Links)
	for _, li := range r.Header["Link"] {
		re := linksRe.FindStringSubmatch(li)
		if len(re) == 3 {
			ns.Link[re[2]] = re[1]
		}
	}

	if ra := r.Header.Get("Retry-After"); ra != "" {
		n, err := strconv.Atoi(ra)
		if err == nil {
			ns.RetryAfter = time.Second * time.Duration(n)
		}
	}

	log.Println(ansi.Color("NEXT", "cyan"), ns)
	return ns
}

/*
                              directory
                                  .
                                  .
      ....................................................
      .                  .                  .            .
      .                  .                  .            .
      V     "next"       V      "next"      V            V
   new-reg ---+----> new-authz ---+----> new-cert    revoke-cert
      .       |          .        |         .            ^
      .       |          .        |         .            | "revoke"
      V       |          V        |         V            |
     reg* ----+        authz -----+       cert-----------+
                        . ^                 |
                        . | "up"            | "up"
                        V |                 V
                      challenge         cert-chain
*/

func (p *Provider) Register(s Signer, c Contacts) error {
	r := &Registration{
		Resource: ResNewReg,
		Contact:  c,
	}
	resp, err := p.post(p.NewReg, s, r)
	if err != nil && err.(Problem).Err != ErrMalformed {
		return err
	}
	ns := parseHeader(resp)
	switch resp.StatusCode {
	case http.StatusConflict:
		// Query Location
		r = &Registration{Resource: ResReg}
		resp, err = p.post(ns.Location.String(), s, r)
		if err != nil {
			return err
		}
		fallthrough
	case http.StatusCreated:
		// Agree to TOS
		if tos := ns.Link["terms-of-service"]; tos != "" {
			r = &Registration{
				Resource:  ResReg,
				Contact:   c,
				Agreement: tos,
			}
			_, err = p.post(ns.Location.String(), s, r)
		}
	}
	return err
}

func pickChallenge(c []Challenge) (int, Challenge) {
	for i, ch := range c {
		if canSolve[ch.Type] {
			return i, ch
		}
	}
	return -1, Challenge{}
}

func (p *Provider) Authorize(s ThumbSigner, domain string) error {
	r := &Authorization{
		Resource:   ResNewAuthz,
		Identifier: NewIdent(domain),
	}
	resp, err := p.post(p.NewAuthz, s, r)
	if err != nil {
		return err
	}
	switch resp.StatusCode {
	case http.StatusCreated:
		n, ch := pickChallenge(r.Challenges)
		if n < 0 {
			return errors.New("can't solve any challenges")
		}

		ka, _ := KeyAuthorization(s, ch.Token)
		ans := &Challenge{
			Resource:         ResChallenge,
			Type:             ch.Type,
			KeyAuthorization: ka,
		}
		_, err = p.post(ch.URI, s, ans)

		var sol Solver

		switch ch.Type {
		case ChallengeHTTP:
			sol = &httpChallenge{Addr: "localhost:8080", Challenge: *ans}
		default:
			return errChallengeType
		}

		if err := Solve(sol, time.Minute); err != nil {
			return err
		}

		ns := parseHeader(resp)
		done := make(chan bool)
		errc := make(chan error)
		log.Println(ansi.Color("NEXT", "green"), ns)
		ticker := time.NewTicker(time.Second)
		defer ticker.Stop()
		go func() {
			for range ticker.C {
				err := p.queryStatus(ns.Location.String(), n, done)
				if err != nil {
					errc <- err
					return
				}
			}
		}()
		select {
		case <-done:
		case err = <-errc:
		case <-time.After(30 * time.Second):
			return errTimedOut
		}

	}
	return err
}

func (p *Provider) queryStatus(url string, n int, done chan bool) error {
	r := &Authorization{}
	if _, err := p.get(url, r); err != nil {
		return err
	}
	if r.Challenges[n].Status == StatusValid {
		done <- true
	}
	return nil
}

func (p *Provider) Cert(s Signer, altnames []string, key *rsa.PrivateKey) (*x509.Certificate, error) {
	csr, err := NewCSR(altnames, key)
	if err != nil {
		return nil, err
	}
	r := &CSR{
		Resource: ResNewCert,
		CSR:      csr,
	}
	resp, err := p.post(p.NewCert, s, r)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	ns := parseHeader(resp)
	log.Println(ansi.Color("NEXT", "green"), ns)
	der, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	return x509.ParseCertificate(der)
}