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sig.go
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sig.go
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/*
Copyright 2011 Google Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// Package signhandler implements the HTTP interface to signing and verifying
// Camlistore JSON blobs.
package signhandler
import (
"fmt"
"log"
"net/http"
"strings"
"sync"
"camlistore.org/pkg/blob"
"camlistore.org/pkg/blobserver"
"camlistore.org/pkg/blobserver/gethandler"
"camlistore.org/pkg/blobserver/memory"
"camlistore.org/pkg/httputil"
"camlistore.org/pkg/jsonconfig"
"camlistore.org/pkg/jsonsign"
"camlistore.org/pkg/osutil"
"camlistore.org/pkg/schema"
"camlistore.org/third_party/code.google.com/p/go.crypto/openpgp"
)
const kMaxJSONLength = 1024 * 1024
type Handler struct {
// Optional path to non-standard secret gpg keyring file
secretRing string
pubKey string // armored
pubKeyBlobRef blob.Ref
pubKeyFetcher blob.Fetcher
pubKeyBlobRefServeSuffix string // "camli/sha1-xxxx"
pubKeyHandler http.Handler
pubKeyDest blobserver.Storage // Where our public key is published
pubKeyUploadMu sync.RWMutex
pubKeyUploaded bool
entity *openpgp.Entity
signer *schema.Signer
}
func (h *Handler) Signer() *schema.Signer { return h.signer }
func (h *Handler) secretRingPath() string {
if h.secretRing != "" {
return h.secretRing
}
return osutil.SecretRingFile()
}
func init() {
blobserver.RegisterHandlerConstructor("jsonsign", newJSONSignFromConfig)
}
func newJSONSignFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (http.Handler, error) {
var (
// either a short form ("26F5ABDA") or one the longer forms.
keyId = conf.RequiredString("keyId")
pubKeyDestPrefix = conf.OptionalString("publicKeyDest", "")
secretRing = conf.OptionalString("secretRing", "")
)
if err := conf.Validate(); err != nil {
return nil, err
}
h := &Handler{
secretRing: secretRing,
}
var err error
h.entity, err = jsonsign.EntityFromSecring(keyId, h.secretRingPath())
if err != nil {
return nil, err
}
h.pubKey, err = jsonsign.ArmoredPublicKey(h.entity)
ms := &memory.Storage{}
h.pubKeyBlobRef = blob.SHA1FromString(h.pubKey)
if _, err := ms.ReceiveBlob(h.pubKeyBlobRef, strings.NewReader(h.pubKey)); err != nil {
return nil, fmt.Errorf("could not store pub key blob: %v", err)
}
h.pubKeyFetcher = ms
if pubKeyDestPrefix != "" {
sto, err := ld.GetStorage(pubKeyDestPrefix)
if err != nil {
return nil, err
}
h.pubKeyDest = sto
}
h.pubKeyBlobRefServeSuffix = "camli/" + h.pubKeyBlobRef.String()
h.pubKeyHandler = &gethandler.Handler{
Fetcher: ms,
}
h.signer, err = schema.NewSigner(h.pubKeyBlobRef, strings.NewReader(h.pubKey), h.entity)
if err != nil {
return nil, err
}
return h, nil
}
func (h *Handler) uploadPublicKey() error {
h.pubKeyUploadMu.RLock()
if h.pubKeyUploaded {
h.pubKeyUploadMu.RUnlock()
return nil
}
h.pubKeyUploadMu.RUnlock()
sto := h.pubKeyDest
h.pubKeyUploadMu.Lock()
defer h.pubKeyUploadMu.Unlock()
if h.pubKeyUploaded {
return nil
}
_, err := blobserver.StatBlob(sto, h.pubKeyBlobRef)
if err == nil {
h.pubKeyUploaded = true
return nil
}
_, err = blobserver.Receive(sto, h.pubKeyBlobRef, strings.NewReader(h.pubKey))
h.pubKeyUploaded = (err == nil)
return err
}
func (h *Handler) DiscoveryMap(base string) map[string]interface{} {
m := map[string]interface{}{
"publicKeyId": h.entity.PrimaryKey.KeyIdString(),
"signHandler": base + "camli/sig/sign",
"verifyHandler": base + "camli/sig/verify",
}
if h.pubKeyBlobRef.Valid() {
m["publicKeyBlobRef"] = h.pubKeyBlobRef.String()
m["publicKey"] = base + h.pubKeyBlobRefServeSuffix
}
return m
}
func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
base := httputil.PathBase(req)
subPath := httputil.PathSuffix(req)
switch req.Method {
case "GET", "HEAD":
switch subPath {
case "":
http.Redirect(rw, req, base+"camli/sig/discovery", http.StatusFound)
return
case h.pubKeyBlobRefServeSuffix:
h.pubKeyHandler.ServeHTTP(rw, req)
return
case "camli/sig/sign":
fallthrough
case "camli/sig/verify":
http.Error(rw, "POST required", 400)
return
case "camli/sig/discovery":
httputil.ReturnJSON(rw, h.DiscoveryMap(base))
return
}
case "POST":
switch subPath {
case "camli/sig/sign":
h.handleSign(rw, req)
return
case "camli/sig/verify":
h.handleVerify(rw, req)
return
}
}
http.Error(rw, "Unsupported path or method.", http.StatusBadRequest)
}
func (h *Handler) handleVerify(rw http.ResponseWriter, req *http.Request) {
req.ParseForm()
sjson := req.FormValue("sjson")
if sjson == "" {
http.Error(rw, "missing \"sjson\" parameter", http.StatusBadRequest)
return
}
m := make(map[string]interface{})
// TODO: use a different fetcher here that checks memory, disk,
// the internet, etc.
fetcher := h.pubKeyFetcher
vreq := jsonsign.NewVerificationRequest(sjson, fetcher)
if vreq.Verify() {
m["signatureValid"] = 1
m["signerKeyId"] = vreq.SignerKeyId
m["verifiedData"] = vreq.PayloadMap
} else {
errStr := vreq.Err.Error()
m["signatureValid"] = 0
m["errorMessage"] = errStr
}
rw.WriteHeader(http.StatusOK) // no HTTP response code fun, error info in JSON
httputil.ReturnJSON(rw, m)
}
func (h *Handler) handleSign(rw http.ResponseWriter, req *http.Request) {
req.ParseForm()
badReq := func(s string) {
http.Error(rw, s, http.StatusBadRequest)
log.Printf("bad request: %s", s)
return
}
jsonStr := req.FormValue("json")
if jsonStr == "" {
badReq("missing \"json\" parameter")
return
}
if len(jsonStr) > kMaxJSONLength {
badReq("parameter \"json\" too large")
return
}
sreq := &jsonsign.SignRequest{
UnsignedJSON: jsonStr,
Fetcher: h.pubKeyFetcher,
ServerMode: true,
SecretKeyringPath: h.secretRing,
}
signedJSON, err := sreq.Sign()
if err != nil {
// TODO: some aren't really a "bad request"
badReq(fmt.Sprintf("%v", err))
return
}
if err := h.uploadPublicKey(); err != nil {
log.Printf("signing handler failed to upload public key: %v", err)
}
rw.Write([]byte(signedJSON))
}
func (h *Handler) Sign(bb *schema.Builder) (string, error) {
bb.SetSigner(h.pubKeyBlobRef)
unsigned, err := bb.JSON()
if err != nil {
return "", err
}
sreq := &jsonsign.SignRequest{
UnsignedJSON: unsigned,
Fetcher: h.pubKeyFetcher,
ServerMode: true,
SecretKeyringPath: h.secretRing,
}
claimTime, err := bb.Blob().ClaimDate()
if err != nil {
if !schema.IsMissingField(err) {
return "", err
}
} else {
sreq.SignatureTime = claimTime
}
if err := h.uploadPublicKey(); err != nil {
log.Printf("signing handler failed to upload public key: %v", err)
}
return sreq.Sign()
}