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fetch.go
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fetch.go
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// Copyright 2017 CoreOS 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 internal
import (
"fmt"
"io"
"io/ioutil"
"net/http"
"os"
"path/filepath"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/crypto/openpgp"
)
// FetchAddon fetches and verifies a torcx addon. It returns
// the path to the downloaded file if successful, or error
func (a *App) FetchAddon(loc *Location) (string, error) {
if existing := a.tryFindExisting(loc.Version); existing != "" {
logrus.Infof("Found identical package at %s, skipping download", existing)
return existing, nil
}
logrus.Infof("fetching addon at %s", loc.URL)
tmpfile, err := ioutil.TempFile("", loc.Version.filename())
if err != nil {
return "", errors.Wrapf(err, "could not create temporary addon")
}
defer tmpfile.Close()
logrus.Debugf("GET %s > %s", loc.URL, tmpfile.Name())
err = fetchURL(loc.URL, tmpfile)
if err != nil {
os.Remove(tmpfile.Name())
return "", errors.Wrapf(err, "failed to fetch addon")
}
if err := tmpfile.Sync(); err != nil {
os.Remove(tmpfile.Name())
return "", errors.Wrapf(err, "failed to write addon")
}
// Seek the fp back to 0 and validate the downloaded file
if _, err := tmpfile.Seek(0, 0); err != nil {
os.Remove(tmpfile.Name())
return "", errors.Wrapf(err, "failed to seek tmpfile")
}
ok, err := loc.Version.ValidateHash(tmpfile)
if err != nil {
os.Remove(tmpfile.Name())
return "", errors.Wrapf(err, "failure during download hash validation")
}
if !ok {
os.Remove(tmpfile.Name())
return "", errors.New("Signature validation failed")
}
return tmpfile.Name(), nil
}
// fetchURL fetches a URL to a given destination
func fetchURL(url string, dst io.Writer) error {
var resp *http.Response
var err error
err = retry(5, 60, func() error {
var e error
resp, e = http.Get(url)
return e
})
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return errors.Errorf("failed to download %q: %s", url, resp.Status)
}
_, err = io.Copy(dst, resp.Body)
if err != nil {
return err
}
return nil
}
// verify will make sure a downloaded addon is signed by a key in the keyring.
// It assumes the signature is available at "$url.asc".
func (a *App) gpgVerify(data, sig io.Reader) error {
if a.Conf.NoVerifySig {
logrus.Warn("signature verification disabled, skipping")
return nil
}
// Get the keyring
keyring, err := a.openKeyring()
if err != nil {
return errors.Wrap(err, "failed to open keyring")
}
logrus.Debugf("Opened keyring with %d keys", len(keyring))
// Validate
signer, err := openpgp.CheckArmoredDetachedSignature(keyring, data, sig)
if err != nil {
return errors.Wrap(err, "failed to validate signature")
}
logrus.Debugf("good signature from %s", signer.PrimaryKey.KeyIdString())
return nil
}
// openKeying returns the parsed keyring file.
func (a *App) openKeyring() (openpgp.EntityList, error) {
if a.Conf.GpgKeyringPath == "" {
return nil, fmt.Errorf("no gpg keyring specified")
}
fp, err := os.Open(a.Conf.GpgKeyringPath)
if err != nil {
return nil, err
}
defer fp.Close()
return openpgp.ReadArmoredKeyRing(fp)
}
// findOnDisk is a simple shortcut that can find packages already downloaded.
// Since we know the hash of the package we want, we can check to see if we
// already have it. If the correct file is found, copy it to a temporary file.
// Returns empty string if not found or an error occurred
func (a *App) tryFindExisting(v *PackageVersion) string {
scan_dirs := []string{
"/usr/share/torcx/store",
a.Conf.torcxStoreDir,
}
wantName := v.filename()
foundPath := ""
for _, dir := range scan_dirs {
filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if info.IsDir() {
return nil
}
if info.Name() != wantName {
return nil
}
fp, err := os.Open(path)
if err != nil {
return err
}
ok, _ := v.ValidateHash(fp)
if ok {
foundPath = path
return filepath.SkipDir
}
return nil
})
}
return foundPath
}