status-go/ipfs/ipfs.go

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package ipfs
import (
"context"
"errors"
"io/ioutil"
"net/http"
"os"
"path/filepath"
"sync"
"time"
"github.com/ipfs/go-cid"
"github.com/multiformats/go-multibase"
"github.com/wealdtech/go-multicodec"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/log"
)
const infuraAPIURL = "https://ipfs.infura.io:5001/api/v0/cat?arg="
const maxRequestsPerSecond = 3
type taskResponse struct {
err error
response []byte
}
type taskRequest struct {
cid string
download bool
doneChan chan taskResponse
}
type Downloader struct {
ctx context.Context
cancel func()
ipfsDir string
wg sync.WaitGroup
rateLimiterChan chan taskRequest
inputTaskChan chan taskRequest
client *http.Client
quit chan struct{}
}
func NewDownloader(rootDir string) *Downloader {
ipfsDir := filepath.Clean(filepath.Join(rootDir, "./ipfs"))
if err := os.MkdirAll(ipfsDir, 0700); err != nil {
panic("could not create IPFSDir")
}
ctx, cancel := context.WithCancel(context.TODO())
d := &Downloader{
ctx: ctx,
cancel: cancel,
ipfsDir: ipfsDir,
rateLimiterChan: make(chan taskRequest, maxRequestsPerSecond),
inputTaskChan: make(chan taskRequest, 1000),
wg: sync.WaitGroup{},
client: &http.Client{
Timeout: time.Second * 5,
},
quit: make(chan struct{}, 1),
}
go d.taskDispatcher()
go d.worker()
return d
}
func (d *Downloader) Stop() {
close(d.quit)
d.cancel()
d.wg.Wait()
close(d.inputTaskChan)
close(d.rateLimiterChan)
}
func (d *Downloader) worker() {
for request := range d.rateLimiterChan {
resp, err := d.download(request.cid, request.download)
request.doneChan <- taskResponse{
err: err,
response: resp,
}
}
}
func (d *Downloader) taskDispatcher() {
ticker := time.NewTicker(time.Second / maxRequestsPerSecond)
defer ticker.Stop()
for {
<-ticker.C
request, ok := <-d.inputTaskChan
if !ok {
return
}
d.rateLimiterChan <- request
}
}
func hashToCid(hash []byte) (string, error) {
// contract response includes a contenthash, which needs to be decoded to reveal
// an IPFS identifier. Once decoded, download the content from IPFS. This content
// is in EDN format, ie https://ipfs.infura.io/ipfs/QmWVVLwVKCwkVNjYJrRzQWREVvEk917PhbHYAUhA1gECTM
// and it also needs to be decoded in to a nim type
data, codec, err := multicodec.RemoveCodec(hash)
if err != nil {
return "", err
}
codecName, err := multicodec.Name(codec)
if err != nil {
return "", err
}
if codecName != "ipfs-ns" {
return "", errors.New("codecName is not ipfs-ns")
}
thisCID, err := cid.Parse(data)
if err != nil {
return "", err
}
return thisCID.StringOfBase(multibase.Base32)
}
func decodeStringHash(input string) (string, error) {
hash, err := hexutil.Decode("0x" + input)
if err != nil {
return "", err
}
cid, err := hashToCid(hash)
if err != nil {
return "", err
}
return cid, nil
}
// Get checks if an IPFS image exists and returns it from cache
// otherwise downloads it from INFURA's ipfs gateway
func (d *Downloader) Get(hash string, download bool) ([]byte, error) {
cid, err := decodeStringHash(hash)
if err != nil {
return nil, err
}
exists, content, err := d.exists(cid)
if err != nil {
return nil, err
}
if exists {
return content, nil
}
doneChan := make(chan taskResponse, 1)
d.wg.Add(1)
d.inputTaskChan <- taskRequest{
cid: cid,
download: download,
doneChan: doneChan,
}
done := <-doneChan
close(doneChan)
d.wg.Done()
return done.response, done.err
}
func (d *Downloader) exists(cid string) (bool, []byte, error) {
path := filepath.Join(d.ipfsDir, cid)
_, err := os.Stat(path)
if err == nil {
fileContent, err := os.ReadFile(path)
return true, fileContent, err
}
return false, nil, nil
}
func (d *Downloader) download(cid string, download bool) ([]byte, error) {
path := filepath.Join(d.ipfsDir, cid)
req, err := http.NewRequest(http.MethodPost, infuraAPIURL+cid, nil)
if err != nil {
return nil, err
}
req = req.WithContext(d.ctx)
resp, err := d.client.Do(req)
if err != nil {
return nil, err
}
defer func() {
if err := resp.Body.Close(); err != nil {
log.Error("failed to close the stickerpack request body", "err", err)
}
}()
if resp.StatusCode < 200 || resp.StatusCode > 299 {
log.Error("could not load data for", "cid", cid, "code", resp.StatusCode)
return nil, errors.New("could not load ipfs data")
}
fileContent, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, err
}
if download {
// #nosec G306
err = os.WriteFile(path, fileContent, 0700)
if err != nil {
return nil, err
}
}
return fileContent, nil
}