func fetch(src blob.StreamingFetcher, br blob.Ref) (r io.ReadCloser, err error) {
if *flagVerbose {
log.Printf("Fetching %s", br.String())
}
r, _, err = src.FetchStreaming(br)
if err != nil {
return nil, fmt.Errorf("Failed to fetch %s: %s", br, err)
}
return r, err
}
// Unauthenticated user. Be paranoid.
func handleGetViaSharing(conn http.ResponseWriter, req *http.Request,
blobRef blob.Ref, fetcher blob.StreamingFetcher) error {
if !httputil.IsGet(req) {
return &shareError{code: invalidMethod, response: badRequest, message: "Invalid method"}
}
viaPathOkay := false
startTime := time.Now()
defer func() {
if !viaPathOkay {
// Insert a delay, to hide timing attacks probing
// for the existence of blobs.
sleep := fetchFailureDelay - (time.Now().Sub(startTime))
time.Sleep(sleep)
}
}()
viaBlobs := make([]blob.Ref, 0)
if via := req.FormValue("via"); via != "" {
for _, vs := range strings.Split(via, ",") {
if br, ok := blob.Parse(vs); ok {
viaBlobs = append(viaBlobs, br)
} else {
return &shareError{code: invalidVia, response: badRequest, message: "Malformed blobref in via param"}
}
}
}
fetchChain := make([]blob.Ref, 0)
fetchChain = append(fetchChain, viaBlobs...)
fetchChain = append(fetchChain, blobRef)
isTransitive := false
for i, br := range fetchChain {
switch i {
case 0:
file, size, err := fetcher.FetchStreaming(br)
if err != nil {
return unauthorized(shareFetchFailed, "Fetch chain 0 of %s failed: %v", br, err)
}
defer file.Close()
if size > schema.MaxSchemaBlobSize {
return unauthorized(shareBlobTooLarge, "Fetch chain 0 of %s too large", br)
}
blob, err := schema.BlobFromReader(br, file)
if err != nil {
return unauthorized(shareReadFailed, "Can't create a blob from %v: %v", br, err)
}
share, ok := blob.AsShare()
if !ok {
return unauthorized(shareBlobInvalid, "Fetch chain 0 of %s wasn't a valid Share", br)
}
if share.IsExpired() {
return unauthorized(shareExpired, "Share is expired")
}
if len(fetchChain) > 1 && fetchChain[1].String() != share.Target().String() {
return unauthorized(shareTargetInvalid,
"Fetch chain 0->1 (%s -> %q) unauthorized, expected hop to %q",
br, fetchChain[1], share.Target())
}
isTransitive = share.IsTransitive()
if len(fetchChain) > 2 && !isTransitive {
return unauthorized(shareNotTransitive, "Share is not transitive")
}
case len(fetchChain) - 1:
// Last one is fine (as long as its path up to here has been proven, and it's
// not the first thing in the chain)
continue
default:
file, _, err := fetcher.FetchStreaming(br)
if err != nil {
return unauthorized(viaChainFetchFailed, "Fetch chain %d of %s failed: %v", i, br, err)
}
defer file.Close()
lr := io.LimitReader(file, schema.MaxSchemaBlobSize)
slurpBytes, err := ioutil.ReadAll(lr)
if err != nil {
return unauthorized(viaChainReadFailed,
"Fetch chain %d of %s failed in slurp: %v", i, br, err)
}
saught := fetchChain[i+1].String()
if bytes.Index(slurpBytes, []byte(saught)) == -1 {
return unauthorized(viaChainInvalidLink,
"Fetch chain %d of %s failed; no reference to %s", i, br, saught)
}
}
}
if assemble, _ := strconv.ParseBool(req.FormValue("assemble")); assemble {
if !isTransitive {
return unauthorized(assembleNonTransitive, "Cannot assemble non-transitive share")
}
dh := &DownloadHandler{
Fetcher: fetcher,
// TODO(aa): It would be nice to specify a local cache here, as the UI handler does.
}
dh.ServeHTTP(conn, req, blobRef)
} else {
gethandler.ServeBlobRef(conn, req, blobRef, fetcher)
}
viaPathOkay = true
return nil
}
// Unauthenticated user. Be paranoid.
func handleGetViaSharing(conn http.ResponseWriter, req *http.Request,
blobRef blob.Ref, fetcher blob.StreamingFetcher) {
if req.Method != "GET" && req.Method != "HEAD" {
httputil.BadRequestError(conn, "Invalid method")
return
}
viaPathOkay := false
startTime := time.Now()
defer func() {
if !viaPathOkay {
// Insert a delay, to hide timing attacks probing
// for the existence of blobs.
sleep := fetchFailureDelay - (time.Now().Sub(startTime))
time.Sleep(sleep)
}
}()
viaBlobs := make([]blob.Ref, 0)
if via := req.FormValue("via"); via != "" {
for _, vs := range strings.Split(via, ",") {
if br, ok := blob.Parse(vs); ok {
viaBlobs = append(viaBlobs, br)
} else {
httputil.BadRequestError(conn, "Malformed blobref in via param")
return
}
}
}
fetchChain := make([]blob.Ref, 0)
fetchChain = append(fetchChain, viaBlobs...)
fetchChain = append(fetchChain, blobRef)
for i, br := range fetchChain {
switch i {
case 0:
file, size, err := fetcher.FetchStreaming(br)
if err != nil {
log.Printf("Fetch chain 0 of %s failed: %v", br.String(), err)
auth.SendUnauthorized(conn, req)
return
}
defer file.Close()
if size > schema.MaxSchemaBlobSize {
log.Printf("Fetch chain 0 of %s too large", br.String())
auth.SendUnauthorized(conn, req)
return
}
blob, err := schema.BlobFromReader(br, file)
if err != nil {
log.Printf("Can't create a blob from %v: %v", br.String(), err)
auth.SendUnauthorized(conn, req)
return
}
share, ok := blob.AsShare()
if !ok {
log.Printf("Fetch chain 0 of %s wasn't a valid Share", br.String())
auth.SendUnauthorized(conn, req)
return
}
if len(fetchChain) > 1 && fetchChain[1].String() != share.Target().String() {
log.Printf("Fetch chain 0->1 (%s -> %q) unauthorized, expected hop to %q",
br.String(), fetchChain[1].String(), share.Target().String())
auth.SendUnauthorized(conn, req)
return
}
case len(fetchChain) - 1:
// Last one is fine (as long as its path up to here has been proven, and it's
// not the first thing in the chain)
continue
default:
file, _, err := fetcher.FetchStreaming(br)
if err != nil {
log.Printf("Fetch chain %d of %s failed: %v", i, br.String(), err)
auth.SendUnauthorized(conn, req)
return
}
defer file.Close()
lr := io.LimitReader(file, schema.MaxSchemaBlobSize)
slurpBytes, err := ioutil.ReadAll(lr)
if err != nil {
log.Printf("Fetch chain %d of %s failed in slurp: %v", i, br.String(), err)
auth.SendUnauthorized(conn, req)
return
}
saught := fetchChain[i+1].String()
if bytes.IndexAny(slurpBytes, saught) == -1 {
log.Printf("Fetch chain %d of %s failed; no reference to %s",
i, br.String(), saught)
auth.SendUnauthorized(conn, req)
return
}
}
}
viaPathOkay = true
gethandler.ServeBlobRef(conn, req, blobRef, fetcher)
}