certificates/acme/api/handler.go
2022-02-28 16:08:00 +01:00

318 lines
11 KiB
Go

package api
import (
"context"
"crypto/tls"
"crypto/x509"
"encoding/json"
"encoding/pem"
"fmt"
"net"
"net/http"
"time"
"github.com/go-chi/chi"
"github.com/smallstep/certificates/acme"
"github.com/smallstep/certificates/api"
"github.com/smallstep/certificates/authority/provisioner"
)
func link(url, typ string) string {
return fmt.Sprintf("<%s>;rel=%q", url, typ)
}
// Clock that returns time in UTC rounded to seconds.
type Clock struct{}
// Now returns the UTC time rounded to seconds.
func (c *Clock) Now() time.Time {
return time.Now().UTC().Truncate(time.Second)
}
var clock Clock
type payloadInfo struct {
value []byte
isPostAsGet bool
isEmptyJSON bool
}
// Handler is the ACME API request handler.
type Handler struct {
db acme.DB
backdate provisioner.Duration
ca acme.CertificateAuthority
linker Linker
validateChallengeOptions *acme.ValidateChallengeOptions
prerequisitesChecker func(ctx context.Context) (bool, error)
}
// HandlerOptions required to create a new ACME API request handler.
type HandlerOptions struct {
Backdate provisioner.Duration
// DB storage backend that impements the acme.DB interface.
DB acme.DB
// DNS the host used to generate accurate ACME links. By default the authority
// will use the Host from the request, so this value will only be used if
// request.Host is empty.
DNS string
// Prefix is a URL path prefix under which the ACME api is served. This
// prefix is required to generate accurate ACME links.
// E.g. https://ca.smallstep.com/acme/my-acme-provisioner/new-account --
// "acme" is the prefix from which the ACME api is accessed.
Prefix string
CA acme.CertificateAuthority
// PrerequisitesChecker checks if all prerequisites for serving ACME are
// met by the CA configuration.
PrerequisitesChecker func(ctx context.Context) (bool, error)
}
// NewHandler returns a new ACME API handler.
func NewHandler(ops HandlerOptions) api.RouterHandler {
transport := &http.Transport{
TLSClientConfig: &tls.Config{
InsecureSkipVerify: true,
},
}
client := http.Client{
Timeout: 30 * time.Second,
Transport: transport,
}
dialer := &net.Dialer{
Timeout: 30 * time.Second,
}
prerequisitesChecker := func(ctx context.Context) (bool, error) {
// by default all prerequisites are met
return true, nil
}
if ops.PrerequisitesChecker != nil {
prerequisitesChecker = ops.PrerequisitesChecker
}
return &Handler{
ca: ops.CA,
db: ops.DB,
backdate: ops.Backdate,
linker: NewLinker(ops.DNS, ops.Prefix),
validateChallengeOptions: &acme.ValidateChallengeOptions{
HTTPGet: client.Get,
LookupTxt: net.LookupTXT,
TLSDial: func(network, addr string, config *tls.Config) (*tls.Conn, error) {
return tls.DialWithDialer(dialer, network, addr, config)
},
},
prerequisitesChecker: prerequisitesChecker,
}
}
// Route traffic and implement the Router interface.
func (h *Handler) Route(r api.Router) {
getPath := h.linker.GetUnescapedPathSuffix
// Standard ACME API
r.MethodFunc("GET", getPath(NewNonceLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.checkPrerequisites(h.addNonce(h.addDirLink(h.GetNonce))))))
r.MethodFunc("HEAD", getPath(NewNonceLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.checkPrerequisites(h.addNonce(h.addDirLink(h.GetNonce))))))
r.MethodFunc("GET", getPath(DirectoryLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.checkPrerequisites(h.GetDirectory))))
r.MethodFunc("HEAD", getPath(DirectoryLinkType, "{provisionerID}"), h.baseURLFromRequest(h.lookupProvisioner(h.checkPrerequisites(h.GetDirectory))))
validatingMiddleware := func(next nextHTTP) nextHTTP {
return h.baseURLFromRequest(h.lookupProvisioner(h.checkPrerequisites(h.addNonce(h.addDirLink(h.verifyContentType(h.parseJWS(h.validateJWS(next))))))))
}
extractPayloadByJWK := func(next nextHTTP) nextHTTP {
return validatingMiddleware(h.extractJWK(h.verifyAndExtractJWSPayload(next)))
}
extractPayloadByKid := func(next nextHTTP) nextHTTP {
return validatingMiddleware(h.lookupJWK(h.verifyAndExtractJWSPayload(next)))
}
extractPayloadByKidOrJWK := func(next nextHTTP) nextHTTP {
return validatingMiddleware(h.extractOrLookupJWK(h.verifyAndExtractJWSPayload(next)))
}
r.MethodFunc("POST", getPath(NewAccountLinkType, "{provisionerID}"), extractPayloadByJWK(h.NewAccount))
r.MethodFunc("POST", getPath(AccountLinkType, "{provisionerID}", "{accID}"), extractPayloadByKid(h.GetOrUpdateAccount))
r.MethodFunc("POST", getPath(KeyChangeLinkType, "{provisionerID}", "{accID}"), extractPayloadByKid(h.NotImplemented))
r.MethodFunc("POST", getPath(NewOrderLinkType, "{provisionerID}"), extractPayloadByKid(h.NewOrder))
r.MethodFunc("POST", getPath(OrderLinkType, "{provisionerID}", "{ordID}"), extractPayloadByKid(h.isPostAsGet(h.GetOrder)))
r.MethodFunc("POST", getPath(OrdersByAccountLinkType, "{provisionerID}", "{accID}"), extractPayloadByKid(h.isPostAsGet(h.GetOrdersByAccountID)))
r.MethodFunc("POST", getPath(FinalizeLinkType, "{provisionerID}", "{ordID}"), extractPayloadByKid(h.FinalizeOrder))
r.MethodFunc("POST", getPath(AuthzLinkType, "{provisionerID}", "{authzID}"), extractPayloadByKid(h.isPostAsGet(h.GetAuthorization)))
r.MethodFunc("POST", getPath(ChallengeLinkType, "{provisionerID}", "{authzID}", "{chID}"), extractPayloadByKid(h.GetChallenge))
r.MethodFunc("POST", getPath(CertificateLinkType, "{provisionerID}", "{certID}"), extractPayloadByKid(h.isPostAsGet(h.GetCertificate)))
r.MethodFunc("POST", getPath(RevokeCertLinkType, "{provisionerID}"), extractPayloadByKidOrJWK(h.RevokeCert))
}
// GetNonce just sets the right header since a Nonce is added to each response
// by middleware by default.
func (h *Handler) GetNonce(w http.ResponseWriter, r *http.Request) {
if r.Method == "HEAD" {
w.WriteHeader(http.StatusOK)
} else {
w.WriteHeader(http.StatusNoContent)
}
}
type Meta struct {
TermsOfService string `json:"termsOfService,omitempty"`
Website string `json:"website,omitempty"`
CaaIdentities []string `json:"caaIdentities,omitempty"`
ExternalAccountRequired bool `json:"externalAccountRequired,omitempty"`
}
// Directory represents an ACME directory for configuring clients.
type Directory struct {
NewNonce string `json:"newNonce"`
NewAccount string `json:"newAccount"`
NewOrder string `json:"newOrder"`
RevokeCert string `json:"revokeCert"`
KeyChange string `json:"keyChange"`
Meta Meta `json:"meta"`
}
// ToLog enables response logging for the Directory type.
func (d *Directory) ToLog() (interface{}, error) {
b, err := json.Marshal(d)
if err != nil {
return nil, acme.WrapErrorISE(err, "error marshaling directory for logging")
}
return string(b), nil
}
// GetDirectory is the ACME resource for returning a directory configuration
// for client configuration.
func (h *Handler) GetDirectory(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
acmeProv, err := acmeProvisionerFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
api.JSON(w, &Directory{
NewNonce: h.linker.GetLink(ctx, NewNonceLinkType),
NewAccount: h.linker.GetLink(ctx, NewAccountLinkType),
NewOrder: h.linker.GetLink(ctx, NewOrderLinkType),
RevokeCert: h.linker.GetLink(ctx, RevokeCertLinkType),
KeyChange: h.linker.GetLink(ctx, KeyChangeLinkType),
Meta: Meta{
ExternalAccountRequired: acmeProv.RequireEAB,
},
})
}
// NotImplemented returns a 501 and is generally a placeholder for functionality which
// MAY be added at some point in the future but is not in any way a guarantee of such.
func (h *Handler) NotImplemented(w http.ResponseWriter, r *http.Request) {
api.WriteError(w, acme.NewError(acme.ErrorNotImplementedType, "this API is not implemented"))
}
// GetAuthorization ACME api for retrieving an Authz.
func (h *Handler) GetAuthorization(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
acc, err := accountFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
az, err := h.db.GetAuthorization(ctx, chi.URLParam(r, "authzID"))
if err != nil {
api.WriteError(w, acme.WrapErrorISE(err, "error retrieving authorization"))
return
}
if acc.ID != az.AccountID {
api.WriteError(w, acme.NewError(acme.ErrorUnauthorizedType,
"account '%s' does not own authorization '%s'", acc.ID, az.ID))
return
}
if err = az.UpdateStatus(ctx, h.db); err != nil {
api.WriteError(w, acme.WrapErrorISE(err, "error updating authorization status"))
return
}
h.linker.LinkAuthorization(ctx, az)
w.Header().Set("Location", h.linker.GetLink(ctx, AuthzLinkType, az.ID))
api.JSON(w, az)
}
// GetChallenge ACME api for retrieving a Challenge.
func (h *Handler) GetChallenge(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
acc, err := accountFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
// Just verify that the payload was set, since we're not strictly adhering
// to ACME V2 spec for reasons specified below.
_, err = payloadFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
// NOTE: We should be checking ^^^ that the request is either a POST-as-GET, or
// that the payload is an empty JSON block ({}). However, older ACME clients
// still send a vestigial body (rather than an empty JSON block) and
// strict enforcement would render these clients broken. For the time being
// we'll just ignore the body.
azID := chi.URLParam(r, "authzID")
ch, err := h.db.GetChallenge(ctx, chi.URLParam(r, "chID"), azID)
if err != nil {
api.WriteError(w, acme.WrapErrorISE(err, "error retrieving challenge"))
return
}
ch.AuthorizationID = azID
if acc.ID != ch.AccountID {
api.WriteError(w, acme.NewError(acme.ErrorUnauthorizedType,
"account '%s' does not own challenge '%s'", acc.ID, ch.ID))
return
}
jwk, err := jwkFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
if err = ch.Validate(ctx, h.db, jwk, h.validateChallengeOptions); err != nil {
api.WriteError(w, acme.WrapErrorISE(err, "error validating challenge"))
return
}
h.linker.LinkChallenge(ctx, ch, azID)
w.Header().Add("Link", link(h.linker.GetLink(ctx, AuthzLinkType, azID), "up"))
w.Header().Set("Location", h.linker.GetLink(ctx, ChallengeLinkType, azID, ch.ID))
api.JSON(w, ch)
}
// GetCertificate ACME api for retrieving a Certificate.
func (h *Handler) GetCertificate(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
acc, err := accountFromContext(ctx)
if err != nil {
api.WriteError(w, err)
return
}
certID := chi.URLParam(r, "certID")
cert, err := h.db.GetCertificate(ctx, certID)
if err != nil {
api.WriteError(w, acme.WrapErrorISE(err, "error retrieving certificate"))
return
}
if cert.AccountID != acc.ID {
api.WriteError(w, acme.NewError(acme.ErrorUnauthorizedType,
"account '%s' does not own certificate '%s'", acc.ID, certID))
return
}
var certBytes []byte
for _, c := range append([]*x509.Certificate{cert.Leaf}, cert.Intermediates...) {
certBytes = append(certBytes, pem.EncodeToMemory(&pem.Block{
Type: "CERTIFICATE",
Bytes: c.Raw,
})...)
}
api.LogCertificate(w, cert.Leaf)
w.Header().Set("Content-Type", "application/pem-certificate-chain; charset=utf-8")
w.Write(certBytes)
}