path: root/swarm/api/api.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package api

//go:generate mimegen --types=./../../cmd/swarm/mimegen/mime.types --package=api --out=gen_mime.go
//go:generate gofmt -s -w gen_mime.go

import (
    "archive/tar"
    "context"
    "crypto/ecdsa"
    "encoding/hex"
    "errors"
    "fmt"
    "io"
    "math/big"
    "net/http"
    "path"
    "strings"

    "bytes"
    "mime"
    "path/filepath"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/contracts/ens"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/metrics"
    "github.com/ethereum/go-ethereum/swarm/log"
    "github.com/ethereum/go-ethereum/swarm/spancontext"
    "github.com/ethereum/go-ethereum/swarm/storage"
    "github.com/ethereum/go-ethereum/swarm/storage/feed"
    "github.com/ethereum/go-ethereum/swarm/storage/feed/lookup"

    opentracing "github.com/opentracing/opentracing-go"
)

var (
    apiResolveCount        = metrics.NewRegisteredCounter("api.resolve.count", nil)
    apiResolveFail         = metrics.NewRegisteredCounter("api.resolve.fail", nil)
    apiPutCount            = metrics.NewRegisteredCounter("api.put.count", nil)
    apiPutFail             = metrics.NewRegisteredCounter("api.put.fail", nil)
    apiGetCount            = metrics.NewRegisteredCounter("api.get.count", nil)
    apiGetNotFound         = metrics.NewRegisteredCounter("api.get.notfound", nil)
    apiGetHTTP300          = metrics.NewRegisteredCounter("api.get.http.300", nil)
    apiManifestUpdateCount = metrics.NewRegisteredCounter("api.manifestupdate.count", nil)
    apiManifestUpdateFail  = metrics.NewRegisteredCounter("api.manifestupdate.fail", nil)
    apiManifestListCount   = metrics.NewRegisteredCounter("api.manifestlist.count", nil)
    apiManifestListFail    = metrics.NewRegisteredCounter("api.manifestlist.fail", nil)
    apiDeleteCount         = metrics.NewRegisteredCounter("api.delete.count", nil)
    apiDeleteFail          = metrics.NewRegisteredCounter("api.delete.fail", nil)
    apiGetTarCount         = metrics.NewRegisteredCounter("api.gettar.count", nil)
    apiGetTarFail          = metrics.NewRegisteredCounter("api.gettar.fail", nil)
    apiUploadTarCount      = metrics.NewRegisteredCounter("api.uploadtar.count", nil)
    apiUploadTarFail       = metrics.NewRegisteredCounter("api.uploadtar.fail", nil)
    apiModifyCount         = metrics.NewRegisteredCounter("api.modify.count", nil)
    apiModifyFail          = metrics.NewRegisteredCounter("api.modify.fail", nil)
    apiAddFileCount        = metrics.NewRegisteredCounter("api.addfile.count", nil)
    apiAddFileFail         = metrics.NewRegisteredCounter("api.addfile.fail", nil)
    apiRmFileCount         = metrics.NewRegisteredCounter("api.removefile.count", nil)
    apiRmFileFail          = metrics.NewRegisteredCounter("api.removefile.fail", nil)
    apiAppendFileCount     = metrics.NewRegisteredCounter("api.appendfile.count", nil)
    apiAppendFileFail      = metrics.NewRegisteredCounter("api.appendfile.fail", nil)
    apiGetInvalid          = metrics.NewRegisteredCounter("api.get.invalid", nil)
)

// Resolver interface resolve a domain name to a hash using ENS
type Resolver interface {
    Resolve(string) (common.Hash, error)
}

// ResolveValidator is used to validate the contained Resolver
type ResolveValidator interface {
    Resolver
    Owner(node [32]byte) (common.Address, error)
    HeaderByNumber(context.Context, *big.Int) (*types.Header, error)
}

// NoResolverError is returned by MultiResolver.Resolve if no resolver
// can be found for the address.
type NoResolverError struct {
    TLD string
}

// NewNoResolverError creates a NoResolverError for the given top level domain
func NewNoResolverError(tld string) *NoResolverError {
    return &NoResolverError{TLD: tld}
}

// Error NoResolverError implements error
func (e *NoResolverError) Error() string {
    if e.TLD == "" {
        return "no ENS resolver"
    }
    return fmt.Sprintf("no ENS endpoint configured to resolve .%s TLD names", e.TLD)
}

// MultiResolver is used to resolve URL addresses based on their TLDs.
// Each TLD can have multiple resolvers, and the resolution from the
// first one in the sequence will be returned.
type MultiResolver struct {
    resolvers map[string][]ResolveValidator
    nameHash  func(string) common.Hash
}

// MultiResolverOption sets options for MultiResolver and is used as
// arguments for its constructor.
type MultiResolverOption func(*MultiResolver)

// MultiResolverOptionWithResolver adds a Resolver to a list of resolvers
// for a specific TLD. If TLD is an empty string, the resolver will be added
// to the list of default resolver, the ones that will be used for resolution
// of addresses which do not have their TLD resolver specified.
func MultiResolverOptionWithResolver(r ResolveValidator, tld string) MultiResolverOption {
    return func(m *MultiResolver) {
        m.resolvers[tld] = append(m.resolvers[tld], r)
    }
}

// NewMultiResolver creates a new instance of MultiResolver.
func NewMultiResolver(opts ...MultiResolverOption) (m *MultiResolver) {
    m = &MultiResolver{
        resolvers: make(map[string][]ResolveValidator),
        nameHash:  ens.EnsNode,
    }
    for _, o := range opts {
        o(m)
    }
    return m
}

// Resolve resolves address by choosing a Resolver by TLD.
// If there are more default Resolvers, or for a specific TLD,
// the Hash from the first one which does not return error
// will be returned.
func (m *MultiResolver) Resolve(addr string) (h common.Hash, err error) {
    rs, err := m.getResolveValidator(addr)
    if err != nil {
        return h, err
    }
    for _, r := range rs {
        h, err = r.Resolve(addr)
        if err == nil {
            return
        }
    }
    return
}

// getResolveValidator uses the hostname to retrieve the resolver associated with the top level domain
func (m *MultiResolver) getResolveValidator(name string) ([]ResolveValidator, error) {
    rs := m.resolvers[""]
    tld := path.Ext(name)
    if tld != "" {
        tld = tld[1:]
        rstld, ok := m.resolvers[tld]
        if ok {
            return rstld, nil
        }
    }
    if len(rs) == 0 {
        return rs, NewNoResolverError(tld)
    }
    return rs, nil
}

/*
API implements webserver/file system related content storage and retrieval
on top of the FileStore
it is the public interface of the FileStore which is included in the ethereum stack
*/
type API struct {
    feed      *feed.Handler
    fileStore *storage.FileStore
    dns       Resolver
    Decryptor func(context.Context, string) DecryptFunc
}

// NewAPI the api constructor initialises a new API instance.
func NewAPI(fileStore *storage.FileStore, dns Resolver, feedHandler *feed.Handler, pk *ecdsa.PrivateKey) (self *API) {
    self = &API{
        fileStore: fileStore,
        dns:       dns,
        feed:      feedHandler,
        Decryptor: func(ctx context.Context, credentials string) DecryptFunc {
            return self.doDecrypt(ctx, credentials, pk)
        },
    }
    return
}

// Retrieve FileStore reader API
func (a *API) Retrieve(ctx context.Context, addr storage.Address) (reader storage.LazySectionReader, isEncrypted bool) {
    return a.fileStore.Retrieve(ctx, addr)
}

// Store wraps the Store API call of the embedded FileStore
func (a *API) Store(ctx context.Context, data io.Reader, size int64, toEncrypt bool) (addr storage.Address, wait func(ctx context.Context) error, err error) {
    log.Debug("api.store", "size", size)
    return a.fileStore.Store(ctx, data, size, toEncrypt)
}

// Resolve a name into a content-addressed hash
// where address could be an ENS name, or a content addressed hash
func (a *API) Resolve(ctx context.Context, address string) (storage.Address, error) {
    // if DNS is not configured, return an error
    if a.dns == nil {
        if hashMatcher.MatchString(address) {
            return common.Hex2Bytes(address), nil
        }
        apiResolveFail.Inc(1)
        return nil, fmt.Errorf("no DNS to resolve name: %q", address)
    }
    // try and resolve the address
    resolved, err := a.dns.Resolve(address)
    if err != nil {
        if hashMatcher.MatchString(address) {
            return common.Hex2Bytes(address), nil
        }
        return nil, err
    }
    return resolved[:], nil
}

// Resolve resolves a URI to an Address using the MultiResolver.
func (a *API) ResolveURI(ctx context.Context, uri *URI, credentials string) (storage.Address, error) {
    apiResolveCount.Inc(1)
    log.Trace("resolving", "uri", uri.Addr)

    var sp opentracing.Span
    ctx, sp = spancontext.StartSpan(
        ctx,
        "api.resolve")
    defer sp.Finish()

    // if the URI is immutable, check if the address looks like a hash
    if uri.Immutable() {
        key := uri.Address()
        if key == nil {
            return nil, fmt.Errorf("immutable address not a content hash: %q", uri.Addr)
        }
        return key, nil
    }

    addr, err := a.Resolve(ctx, uri.Addr)
    if err != nil {
        return nil, err
    }

    if uri.Path == "" {
        return addr, nil
    }
    walker, err := a.NewManifestWalker(ctx, addr, a.Decryptor(ctx, credentials), nil)
    if err != nil {
        return nil, err
    }
    var entry *ManifestEntry
    walker.Walk(func(e *ManifestEntry) error {
        // if the entry matches the path, set entry and stop
        // the walk
        if e.Path == uri.Path {
            entry = e
            // return an error to cancel the walk
            return errors.New("found")
        }
        // ignore non-manifest files
        if e.ContentType != ManifestType {
            return nil
        }
        // if the manifest's path is a prefix of the
        // requested path, recurse into it by returning
        // nil and continuing the walk
        if strings.HasPrefix(uri.Path, e.Path) {
            return nil
        }
        return ErrSkipManifest
    })
    if entry == nil {
        return nil, errors.New("not found")
    }
    addr = storage.Address(common.Hex2Bytes(entry.Hash))
    return addr, nil
}

// Put provides singleton manifest creation on top of FileStore store
func (a *API) Put(ctx context.Context, content string, contentType string, toEncrypt bool) (k storage.Address, wait func(context.Context) error, err error) {
    apiPutCount.Inc(1)
    r := strings.NewReader(content)
    key, waitContent, err := a.fileStore.Store(ctx, r, int64(len(content)), toEncrypt)
    if err != nil {
        apiPutFail.Inc(1)
        return nil, nil, err
    }
    manifest := fmt.Sprintf(`{"entries":[{"hash":"%v","contentType":"%s"}]}`, key, contentType)
    r = strings.NewReader(manifest)
    key, waitManifest, err := a.fileStore.Store(ctx, r, int64(len(manifest)), toEncrypt)
    if err != nil {
        apiPutFail.Inc(1)
        return nil, nil, err
    }
    return key, func(ctx context.Context) error {
        err := waitContent(ctx)
        if err != nil {
            return err
        }
        return waitManifest(ctx)
    }, nil
}

// Get uses iterative manifest retrieval and prefix matching
// to resolve basePath to content using FileStore retrieve
// it returns a section reader, mimeType, status, the key of the actual content and an error
func (a *API) Get(ctx context.Context, decrypt DecryptFunc, manifestAddr storage.Address, path string) (reader storage.LazySectionReader, mimeType string, status int, contentAddr storage.Address, err error) {
    log.Debug("api.get", "key", manifestAddr, "path", path)
    apiGetCount.Inc(1)
    trie, err := loadManifest(ctx, a.fileStore, manifestAddr, nil, decrypt)
    if err != nil {
        apiGetNotFound.Inc(1)
        status = http.StatusNotFound
        return nil, "", http.StatusNotFound, nil, err
    }

    log.Debug("trie getting entry", "key", manifestAddr, "path", path)
    entry, _ := trie.getEntry(path)

    if entry != nil {
        log.Debug("trie got entry", "key", manifestAddr, "path", path, "entry.Hash", entry.Hash)

        if entry.ContentType == ManifestType {
            log.Debug("entry is manifest", "key", manifestAddr, "new key", entry.Hash)
            adr, err := hex.DecodeString(entry.Hash)
            if err != nil {
                return nil, "", 0, nil, err
            }
            return a.Get(ctx, decrypt, adr, entry.Path)
        }

        // we need to do some extra work if this is a Swarm feed manifest
        if entry.ContentType == FeedContentType {
            if entry.Feed == nil {
                return reader, mimeType, status, nil, fmt.Errorf("Cannot decode Feed in manifest")
            }
            _, err := a.feed.Lookup(ctx, feed.NewQueryLatest(entry.Feed, lookup.NoClue))
            if err != nil {
                apiGetNotFound.Inc(1)
                status = http.StatusNotFound
                log.Debug(fmt.Sprintf("get feed update content error: %v", err))
                return reader, mimeType, status, nil, err
            }
            // get the data of the update
            _, contentAddr, err := a.feed.GetContent(entry.Feed)
            if err != nil {
                apiGetNotFound.Inc(1)
                status = http.StatusNotFound
                log.Warn(fmt.Sprintf("get feed update content error: %v", err))
                return reader, mimeType, status, nil, err
            }

            // extract content hash
            if len(contentAddr) != storage.AddressLength {
                apiGetInvalid.Inc(1)
                status = http.StatusUnprocessableEntity
                errorMessage := fmt.Sprintf("invalid swarm hash in feed update. Expected %d bytes. Got %d", storage.AddressLength, len(contentAddr))
                log.Warn(errorMessage)
                return reader, mimeType, status, nil, errors.New(errorMessage)
            }
            manifestAddr = storage.Address(contentAddr)
            log.Trace("feed update contains swarm hash", "key", manifestAddr)

            // get the manifest the swarm hash points to
            trie, err := loadManifest(ctx, a.fileStore, manifestAddr, nil, NOOPDecrypt)
            if err != nil {
                apiGetNotFound.Inc(1)
                status = http.StatusNotFound
                log.Warn(fmt.Sprintf("loadManifestTrie (feed update) error: %v", err))
                return reader, mimeType, status, nil, err
            }

            // finally, get the manifest entry
            // it will always be the entry on path ""
            entry, _ = trie.getEntry(path)
            if entry == nil {
                status = http.StatusNotFound
                apiGetNotFound.Inc(1)
                err = fmt.Errorf("manifest (feed update) entry for '%s' not found", path)
                log.Trace("manifest (feed update) entry not found", "key", manifestAddr, "path", path)
                return reader, mimeType, status, nil, err
            }
        }

        // regardless of feed update manifests or normal manifests we will converge at this point
        // get the key the manifest entry points to and serve it if it's unambiguous
        contentAddr = common.Hex2Bytes(entry.Hash)
        status = entry.Status
        if status == http.StatusMultipleChoices {
            apiGetHTTP300.Inc(1)
            return nil, entry.ContentType, status, contentAddr, err
        }
        mimeType = entry.ContentType
        log.Debug("content lookup key", "key", contentAddr, "mimetype", mimeType)
        reader, _ = a.fileStore.Retrieve(ctx, contentAddr)
    } else {
        // no entry found
        status = http.StatusNotFound
        apiGetNotFound.Inc(1)
        err = fmt.Errorf("Not found: could not find resource '%s'", path)
        log.Trace("manifest entry not found", "key", contentAddr, "path", path)
    }
    return
}

func (a *API) Delete(ctx context.Context, addr string, path string) (storage.Address, error) {
    apiDeleteCount.Inc(1)
    uri, err := Parse("bzz:/" + addr)
    if err != nil {
        apiDeleteFail.Inc(1)
        return nil, err
    }
    key, err := a.ResolveURI(ctx, uri, EMPTY_CREDENTIALS)

    if err != nil {
        return nil, err
    }
    newKey, err := a.UpdateManifest(ctx, key, func(mw *ManifestWriter) error {
        log.Debug(fmt.Sprintf("removing %s from manifest %s", path, key.Log()))
        return mw.RemoveEntry(path)
    })
    if err != nil {
        apiDeleteFail.Inc(1)
        return nil, err
    }

    return newKey, nil
}

// GetDirectoryTar fetches a requested directory as a tarstream
// it returns an io.Reader and an error. Do not forget to Close() the returned ReadCloser
func (a *API) GetDirectoryTar(ctx context.Context, decrypt DecryptFunc, uri *URI) (io.ReadCloser, error) {
    apiGetTarCount.Inc(1)
    addr, err := a.Resolve(ctx, uri.Addr)
    if err != nil {
        return nil, err
    }
    walker, err := a.NewManifestWalker(ctx, addr, decrypt, nil)
    if err != nil {
        apiGetTarFail.Inc(1)
        return nil, err
    }

    piper, pipew := io.Pipe()

    tw := tar.NewWriter(pipew)

    go func() {
        err := walker.Walk(func(entry *ManifestEntry) error {
            // ignore manifests (walk will recurse into them)
            if entry.ContentType == ManifestType {
                return nil
            }

            // retrieve the entry's key and size
            reader, _ := a.Retrieve(ctx, storage.Address(common.Hex2Bytes(entry.Hash)))
            size, err := reader.Size(ctx, nil)
            if err != nil {
                return err
            }

            // write a tar header for the entry
            hdr := &tar.Header{
                Name:    entry.Path,
                Mode:    entry.Mode,
                Size:    size,
                ModTime: entry.ModTime,
                Xattrs: map[string]string{
                    "user.swarm.content-type": entry.ContentType,
                },
            }

            if err := tw.WriteHeader(hdr); err != nil {
                return err
            }

            // copy the file into the tar stream
            n, err := io.Copy(tw, io.LimitReader(reader, hdr.Size))
            if err != nil {
                return err
            } else if n != size {
                return fmt.Errorf("error writing %s: expected %d bytes but sent %d", entry.Path, size, n)
            }

            return nil
        })
        // close tar writer before closing pipew
        // to flush remaining data to pipew
        // regardless of error value
        tw.Close()
        if err != nil {
            apiGetTarFail.Inc(1)
            pipew.CloseWithError(err)
        } else {
            pipew.Close()
        }
    }()

    return piper, nil
}

// GetManifestList lists the manifest entries for the specified address and prefix
// and returns it as a ManifestList
func (a *API) GetManifestList(ctx context.Context, decryptor DecryptFunc, addr storage.Address, prefix string) (list ManifestList, err error) {
    apiManifestListCount.Inc(1)
    walker, err := a.NewManifestWalker(ctx, addr, decryptor, nil)
    if err != nil {
        apiManifestListFail.Inc(1)
        return ManifestList{}, err
    }

    err = walker.Walk(func(entry *ManifestEntry) error {
        // handle non-manifest files
        if entry.ContentType != ManifestType {
            // ignore the file if it doesn't have the specified prefix
            if !strings.HasPrefix(entry.Path, prefix) {
                return nil
            }

            // if the path after the prefix contains a slash, add a
            // common prefix to the list, otherwise add the entry
            suffix := strings.TrimPrefix(entry.Path, prefix)
            if index := strings.Index(suffix, "/"); index > -1 {
                list.CommonPrefixes = append(list.CommonPrefixes, prefix+suffix[:index+1])
                return nil
            }
            if entry.Path == "" {
                entry.Path = "/"
            }
            list.Entries = append(list.Entries, entry)
            return nil
        }

        // if the manifest's path is a prefix of the specified prefix
        // then just recurse into the manifest by returning nil and
        // continuing the walk
        if strings.HasPrefix(prefix, entry.Path) {
            return nil
        }

        // if the manifest's path has the specified prefix, then if the
        // path after the prefix contains a slash, add a common prefix
        // to the list and skip the manifest, otherwise recurse into
        // the manifest by returning nil and continuing the walk
        if strings.HasPrefix(entry.Path, prefix) {
            suffix := strings.TrimPrefix(entry.Path, prefix)
            if index := strings.Index(suffix, "/"); index > -1 {
                list.CommonPrefixes = append(list.CommonPrefixes, prefix+suffix[:index+1])
                return ErrSkipManifest
            }
            return nil
        }

        // the manifest neither has the prefix or needs recursing in to
        // so just skip it
        return ErrSkipManifest
    })

    if err != nil {
        apiManifestListFail.Inc(1)
        return ManifestList{}, err
    }

    return list, nil
}

func (a *API) UpdateManifest(ctx context.Context, addr storage.Address, update func(mw *ManifestWriter) error) (storage.Address, error) {
    apiManifestUpdateCount.Inc(1)
    mw, err := a.NewManifestWriter(ctx, addr, nil)
    if err != nil {
        apiManifestUpdateFail.Inc(1)
        return nil, err
    }

    if err := update(mw); err != nil {
        apiManifestUpdateFail.Inc(1)
        return nil, err
    }

    addr, err = mw.Store()
    if err != nil {
        apiManifestUpdateFail.Inc(1)
        return nil, err
    }
    log.Debug(fmt.Sprintf("generated manifest %s", addr))
    return addr, nil
}

// Modify loads manifest and checks the content hash before recalculating and storing the manifest.
func (a *API) Modify(ctx context.Context, addr storage.Address, path, contentHash, contentType string) (storage.Address, error) {
    apiModifyCount.Inc(1)
    quitC := make(chan bool)
    trie, err := loadManifest(ctx, a.fileStore, addr, quitC, NOOPDecrypt)
    if err != nil {
        apiModifyFail.Inc(1)
        return nil, err
    }
    if contentHash != "" {
        entry := newManifestTrieEntry(&ManifestEntry{
            Path:        path,
            ContentType: contentType,
        }, nil)
        entry.Hash = contentHash
        trie.addEntry(entry, quitC)
    } else {
        trie.deleteEntry(path, quitC)
    }

    if err := trie.recalcAndStore(); err != nil {
        apiModifyFail.Inc(1)
        return nil, err
    }
    return trie.ref, nil
}

// AddFile creates a new manifest entry, adds it to swarm, then adds a file to swarm.
func (a *API) AddFile(ctx context.Context, mhash, path, fname string, content []byte, nameresolver bool) (storage.Address, string, error) {
    apiAddFileCount.Inc(1)

    uri, err := Parse("bzz:/" + mhash)
    if err != nil {
        apiAddFileFail.Inc(1)
        return nil, "", err
    }
    mkey, err := a.ResolveURI(ctx, uri, EMPTY_CREDENTIALS)
    if err != nil {
        apiAddFileFail.Inc(1)
        return nil, "", err
    }

    // trim the root dir we added
    if path[:1] == "/" {
        path = path[1:]
    }

    entry := &ManifestEntry{
        Path:        filepath.Join(path, fname),
        ContentType: mime.TypeByExtension(filepath.Ext(fname)),
        Mode:        0700,
        Size:        int64(len(content)),
        ModTime:     time.Now(),
    }

    mw, err := a.NewManifestWriter(ctx, mkey, nil)
    if err != nil {
        apiAddFileFail.Inc(1)
        return nil, "", err
    }

    fkey, err := mw.AddEntry(ctx, bytes.NewReader(content), entry)
    if err != nil {
        apiAddFileFail.Inc(1)
        return nil, "", err
    }

    newMkey, err := mw.Store()
    if err != nil {
        apiAddFileFail.Inc(1)
        return nil, "", err

    }

    return fkey, newMkey.String(), nil
}

func (a *API) UploadTar(ctx context.Context, bodyReader io.ReadCloser, manifestPath, defaultPath string, mw *ManifestWriter) (storage.Address, error) {
    apiUploadTarCount.Inc(1)
    var contentKey storage.Address
    tr := tar.NewReader(bodyReader)
    defer bodyReader.Close()
    var defaultPathFound bool
    for {
        hdr, err := tr.Next()
        if err == io.EOF {
            break
        } else if err != nil {
            apiUploadTarFail.Inc(1)
            return nil, fmt.Errorf("error reading tar stream: %s", err)
        }

        // only store regular files
        if !hdr.FileInfo().Mode().IsRegular() {
            continue
        }

        // add the entry under the path from the request
        manifestPath := path.Join(manifestPath, hdr.Name)
        contentType := hdr.Xattrs["user.swarm.content-type"]
        if contentType == "" {
            contentType = mime.TypeByExtension(filepath.Ext(hdr.Name))
        }
        //DetectContentType("")
        entry := &ManifestEntry{
            Path:        manifestPath,
            ContentType: contentType,
            Mode:        hdr.Mode,
            Size:        hdr.Size,
            ModTime:     hdr.ModTime,
        }
        contentKey, err = mw.AddEntry(ctx, tr, entry)
        if err != nil {
            apiUploadTarFail.Inc(1)
            return nil, fmt.Errorf("error adding manifest entry from tar stream: %s", err)
        }
        if hdr.Name == defaultPath {
            contentType := hdr.Xattrs["user.swarm.content-type"]
            if contentType == "" {
                contentType = mime.TypeByExtension(filepath.Ext(hdr.Name))
            }

            entry := &ManifestEntry{
                Hash:        contentKey.Hex(),
                Path:        "", // default entry
                ContentType: contentType,
                Mode:        hdr.Mode,
                Size:        hdr.Size,
                ModTime:     hdr.ModTime,
            }
            contentKey, err = mw.AddEntry(ctx, nil, entry)
            if err != nil {
                apiUploadTarFail.Inc(1)
                return nil, fmt.Errorf("error adding default manifest entry from tar stream: %s", err)
            }
            defaultPathFound = true
        }
    }
    if defaultPath != "" && !defaultPathFound {
        return contentKey, fmt.Errorf("default path %q not found", defaultPath)
    }
    return contentKey, nil
}

// RemoveFile removes a file entry in a manifest.
func (a *API) RemoveFile(ctx context.Context, mhash string, path string, fname string, nameresolver bool) (string, error) {
    apiRmFileCount.Inc(1)

    uri, err := Parse("bzz:/" + mhash)
    if err != nil {
        apiRmFileFail.Inc(1)
        return "", err
    }
    mkey, err := a.ResolveURI(ctx, uri, EMPTY_CREDENTIALS)
    if err != nil {
        apiRmFileFail.Inc(1)
        return "", err
    }

    // trim the root dir we added
    if path[:1] == "/" {
        path = path[1:]
    }

    mw, err := a.NewManifestWriter(ctx, mkey, nil)
    if err != nil {
        apiRmFileFail.Inc(1)
        return "", err
    }

    err = mw.RemoveEntry(filepath.Join(path, fname))
    if err != nil {
        apiRmFileFail.Inc(1)
        return "", err
    }

    newMkey, err := mw.Store()
    if err != nil {
        apiRmFileFail.Inc(1)
        return "", err

    }

    return newMkey.String(), nil
}

// AppendFile removes old manifest, appends file entry to new manifest and adds it to Swarm.
func (a *API) AppendFile(ctx context.Context, mhash, path, fname string, existingSize int64, content []byte, oldAddr storage.Address, offset int64, addSize int64, nameresolver bool) (storage.Address, string, error) {
    apiAppendFileCount.Inc(1)

    buffSize := offset + addSize
    if buffSize < existingSize {
        buffSize = existingSize
    }

    buf := make([]byte, buffSize)

    oldReader, _ := a.Retrieve(ctx, oldAddr)
    io.ReadAtLeast(oldReader, buf, int(offset))

    newReader := bytes.NewReader(content)
    io.ReadAtLeast(newReader, buf[offset:], int(addSize))

    if buffSize < existingSize {
        io.ReadAtLeast(oldReader, buf[addSize:], int(buffSize))
    }

    combinedReader := bytes.NewReader(buf)
    totalSize := int64(len(buf))

    // TODO(jmozah): to append using pyramid chunker when it is ready
    //oldReader := a.Retrieve(oldKey)
    //newReader := bytes.NewReader(content)
    //combinedReader := io.MultiReader(oldReader, newReader)

    uri, err := Parse("bzz:/" + mhash)
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err
    }
    mkey, err := a.ResolveURI(ctx, uri, EMPTY_CREDENTIALS)
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err
    }

    // trim the root dir we added
    if path[:1] == "/" {
        path = path[1:]
    }

    mw, err := a.NewManifestWriter(ctx, mkey, nil)
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err
    }

    err = mw.RemoveEntry(filepath.Join(path, fname))
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err
    }

    entry := &ManifestEntry{
        Path:        filepath.Join(path, fname),
        ContentType: mime.TypeByExtension(filepath.Ext(fname)),
        Mode:        0700,
        Size:        totalSize,
        ModTime:     time.Now(),
    }

    fkey, err := mw.AddEntry(ctx, io.Reader(combinedReader), entry)
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err
    }

    newMkey, err := mw.Store()
    if err != nil {
        apiAppendFileFail.Inc(1)
        return nil, "", err

    }

    return fkey, newMkey.String(), nil
}

// BuildDirectoryTree used by swarmfs_unix
func (a *API) BuildDirectoryTree(ctx context.Context, mhash string, nameresolver bool) (addr storage.Address, manifestEntryMap map[string]*manifestTrieEntry, err error) {

    uri, err := Parse("bzz:/" + mhash)
    if err != nil {
        return nil, nil, err
    }
    addr, err = a.Resolve(ctx, uri.Addr)
    if err != nil {
        return nil, nil, err
    }

    quitC := make(chan bool)
    rootTrie, err := loadManifest(ctx, a.fileStore, addr, quitC, NOOPDecrypt)
    if err != nil {
        return nil, nil, fmt.Errorf("can't load manifest %v: %v", addr.String(), err)
    }

    manifestEntryMap = map[string]*manifestTrieEntry{}
    err = rootTrie.listWithPrefix(uri.Path, quitC, func(entry *manifestTrieEntry, suffix string) {
        manifestEntryMap[suffix] = entry
    })

    if err != nil {
        return nil, nil, fmt.Errorf("list with prefix failed %v: %v", addr.String(), err)
    }
    return addr, manifestEntryMap, nil
}

// FeedsLookup finds Swarm feeds updates at specific points in time, or the latest update
func (a *API) FeedsLookup(ctx context.Context, query *feed.Query) ([]byte, error) {
    _, err := a.feed.Lookup(ctx, query)
    if err != nil {
        return nil, err
    }
    var data []byte
    _, data, err = a.feed.GetContent(&query.Feed)
    if err != nil {
        return nil, err
    }
    return data, nil
}

// FeedsNewRequest creates a Request object to update a specific feed
func (a *API) FeedsNewRequest(ctx context.Context, feed *feed.Feed) (*feed.Request, error) {
    return a.feed.NewRequest(ctx, feed)
}

// FeedsUpdate publishes a new update on the given feed
func (a *API) FeedsUpdate(ctx context.Context, request *feed.Request) (storage.Address, error) {
    return a.feed.Update(ctx, request)
}

// ErrCannotLoadFeedManifest is returned when looking up a feeds manifest fails
var ErrCannotLoadFeedManifest = errors.New("Cannot load feed manifest")

// ErrNotAFeedManifest is returned when the address provided returned something other than a valid manifest
var ErrNotAFeedManifest = errors.New("Not a feed manifest")

// ResolveFeedManifest retrieves the Swarm feed manifest for the given address, and returns the referenced Feed.
func (a *API) ResolveFeedManifest(ctx context.Context, addr storage.Address) (*feed.Feed, error) {
    trie, err := loadManifest(ctx, a.fileStore, addr, nil, NOOPDecrypt)
    if err != nil {
        return nil, ErrCannotLoadFeedManifest
    }

    entry, _ := trie.getEntry("")
    if entry.ContentType != FeedContentType {
        return nil, ErrNotAFeedManifest
    }

    return entry.Feed, nil
}

// ErrCannotResolveFeedURI is returned when the ENS resolver is not able to translate a name to a Swarm feed
var ErrCannotResolveFeedURI = errors.New("Cannot resolve Feed URI")

// ErrCannotResolveFeed is returned when values provided are not enough or invalid to recreate a
// feed out of them.
var ErrCannotResolveFeed = errors.New("Cannot resolve Feed")

// ResolveFeed attempts to extract feed information out of the manifest, if provided
// If not, it attempts to extract the feed out of a set of key-value pairs
func (a *API) ResolveFeed(ctx context.Context, uri *URI, values feed.Values) (*feed.Feed, error) {
    var fd *feed.Feed
    var err error
    if uri.Addr != "" {
        // resolve the content key.
        manifestAddr := uri.Address()
        if manifestAddr == nil {
            manifestAddr, err = a.Resolve(ctx, uri.Addr)
            if err != nil {
                return nil, ErrCannotResolveFeedURI
            }
        }

        // get the Swarm feed from the manifest
        fd, err = a.ResolveFeedManifest(ctx, manifestAddr)
        if err != nil {
            return nil, err
        }
        log.Debug("handle.get.feed: resolved", "manifestkey", manifestAddr, "feed", fd.Hex())
    } else {
        var f feed.Feed
        if err := f.FromValues(values); err != nil {
            return nil, ErrCannotResolveFeed

        }
        fd = &f
    }
    return fd, nil
}

// MimeOctetStream default value of http Content-Type header
const MimeOctetStream = "application/octet-stream"

// DetectContentType by file file extension, or fallback to content sniff
func DetectContentType(fileName string, f io.ReadSeeker) (string, error) {
    ctype := mime.TypeByExtension(filepath.Ext(fileName))
    if ctype != "" {
        return ctype, nil
    }

    // save/rollback to get content probe from begin of file
    currentPosition, err := f.Seek(0, io.SeekCurrent)
    if err != nil {
        return MimeOctetStream, fmt.Errorf("seeker can't seek, %s", err)
    }

    // read a chunk to decide between utf-8 text and binary
    var buf [512]byte
    n, _ := f.Read(buf[:])
    ctype = http.DetectContentType(buf[:n])

    _, err = f.Seek(currentPosition, io.SeekStart) // rewind to output whole file
    if err != nil {
        return MimeOctetStream, fmt.Errorf("seeker can't seek, %s", err)
    }

    return ctype, nil
}