HTTP: add handlers to allow object creation and modification

core/corehttp/gateway_handler.go

 package corehttp
 
 import (
+	"fmt"
 	"html/template"
 	"io"
 	"net/http"
@@ -17,6 +18,7 @@ import (
 	dag "github.com/jbenet/go-ipfs/merkledag"
 	path "github.com/jbenet/go-ipfs/path"
 	"github.com/jbenet/go-ipfs/routing"
+	ufs "github.com/jbenet/go-ipfs/unixfs"
 	uio "github.com/jbenet/go-ipfs/unixfs/io"
 	u "github.com/jbenet/go-ipfs/util"
 )
@@ -101,6 +103,10 @@ func (i *gatewayHandler) NewDagFromReader(r io.Reader) (*dag.Node, error) {
 		r, i.node.DAG, i.node.Pinning.GetManual(), chunk.DefaultSplitter)
 }
 
+func NewDagEmptyDir() *dag.Node {
+	return &dag.Node{Data: ufs.FolderPBData()}
+}
+
 func (i *gatewayHandler) AddNodeToDAG(nd *dag.Node) (u.Key, error) {
 	return i.node.DAG.Add(nd)
 }
@@ -110,6 +116,33 @@ func (i *gatewayHandler) NewDagReader(nd *dag.Node) (uio.ReadSeekCloser, error)
 }
 
 func (i *gatewayHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method == "POST" {
+		i.postHandler(w, r)
+		return
+	}
+
+	if r.Method == "PUT" {
+		i.putHandler(w, r)
+		return
+	}
+
+	if r.Method == "DELETE" {
+		i.deleteHandler(w, r)
+		return
+	}
+
+	if r.Method == "GET" {
+		i.getHandler(w, r)
+		return
+	}
+
+	errmsg := "Method " + r.Method + " not allowed: " + "bad request for " + r.URL.Path
+	w.WriteHeader(http.StatusBadRequest)
+	w.Write([]byte(errmsg))
+	log.Error(errmsg)
+}
+
+func (i *gatewayHandler) getHandler(w http.ResponseWriter, r *http.Request) {
 	ctx, cancel := context.WithCancel(i.node.Context())
 	defer cancel()
 
@@ -209,23 +242,180 @@ func (i *gatewayHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 func (i *gatewayHandler) postHandler(w http.ResponseWriter, r *http.Request) {
 	nd, err := i.NewDagFromReader(r.Body)
 	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		log.Error(err)
-		w.Write([]byte(err.Error()))
+		internalWebError(w, err)
 		return
 	}
 
 	k, err := i.AddNodeToDAG(nd)
 	if err != nil {
-		w.WriteHeader(http.StatusInternalServerError)
-		log.Error(err)
+		internalWebError(w, err)
+		return
+	}
+
+	h := mh.Multihash(k).B58String()
+	w.Header().Set("IPFS-Hash", h)
+	http.Redirect(w, r, IpfsPathPrefix+h, http.StatusCreated)
+}
+
+func (i *gatewayHandler) putEmptyDirHandler(w http.ResponseWriter, r *http.Request) {
+	newnode := NewDagEmptyDir()
+
+	key, err := i.node.DAG.Add(newnode)
+	if err != nil {
+		webError(w, "Could not recursively add new node", err, http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("IPFS-Hash", key.String())
+	http.Redirect(w, r, IpfsPathPrefix+key.String()+"/", http.StatusCreated)
+}
+
+func (i *gatewayHandler) putHandler(w http.ResponseWriter, r *http.Request) {
+	urlPath := r.URL.Path
+	pathext := urlPath[5:]
+	var err error
+	if urlPath == IpfsPathPrefix + "QmUNLLsPACCz1vLxQVkXqqLX5R1X345qqfHbsf67hvA3Nn/" {
+		i.putEmptyDirHandler(w, r)
+		return
+	}
+
+	var newnode *dag.Node
+	if pathext[len(pathext)-1] == '/' {
+		newnode = NewDagEmptyDir()
+	} else {
+		newnode, err = i.NewDagFromReader(r.Body)
+		if err != nil {
+			webError(w, "Could not create DAG from request", err, http.StatusInternalServerError)
+			return
+		}
+	}
+
+	h, components, err := path.SplitAbsPath(path.Path(urlPath))
+	if err != nil {
+		webError(w, "Could not split path", err, http.StatusInternalServerError)
+		return
+	}
+
+	if len(components) < 1 {
+		err = fmt.Errorf("Cannot override existing object")
+		w.WriteHeader(http.StatusBadRequest)
 		w.Write([]byte(err.Error()))
+		log.Error("%s", err)
+		return
+	}
+
+	rootnd, err := i.node.Resolver.DAG.Get(u.Key(h))
+	if err != nil {
+		webError(w, "Could not resolve root object", err, http.StatusBadRequest)
+		return
+	}
+
+	// resolving path components into merkledag nodes. if a component does not
+	// resolve, create empty directories (which will be linked and populated below.)
+	path_nodes, err := i.node.Resolver.ResolveLinks(rootnd, components[:len(components)-1])
+	if _, ok := err.(path.ErrNoLink); ok {
+		// Create empty directories, links will be made further down the code
+		for len(path_nodes) < len(components) {
+			path_nodes = append(path_nodes, NewDagEmptyDir())
+		}
+	} else if err != nil {
+		webError(w, "Could not resolve parent object", err, http.StatusBadRequest)
+		return
+	}
+
+	for i := len(path_nodes) - 1; i >= 0; i-- {
+		newnode, err = path_nodes[i].UpdateNodeLink(components[i], newnode)
+		if err != nil {
+			webError(w, "Could not update node links", err, http.StatusInternalServerError)
+			return
+		}
+	}
+
+	err = i.node.DAG.AddRecursive(newnode)
+	if err != nil {
+		webError(w, "Could not add recursively new node", err, http.StatusInternalServerError)
+		return
+	}
+
+	// Redirect to new path
+	key, err := newnode.Key()
+	if err != nil {
+		webError(w, "Could not get key of new node", err, http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("IPFS-Hash", key.String())
+	http.Redirect(w, r, IpfsPathPrefix+key.String()+"/"+strings.Join(components, "/"), http.StatusCreated)
+}
+
+func (i *gatewayHandler) deleteHandler(w http.ResponseWriter, r *http.Request) {
+	urlPath := r.URL.Path
+	h, components, err := path.SplitAbsPath(path.Path(urlPath))
+	if err != nil {
+		webError(w, "Could not split path", err, http.StatusInternalServerError)
+		return
+	}
+
+	rootnd, err := i.node.Resolver.DAG.Get(u.Key(h))
+	if err != nil {
+		webError(w, "Could not resolve root object", err, http.StatusBadRequest)
 		return
 	}
 
-	//TODO: return json representation of list instead
-	w.WriteHeader(http.StatusCreated)
-	w.Write([]byte(mh.Multihash(k).B58String()))
+	path_nodes, err := i.node.Resolver.ResolveLinks(rootnd, components[:len(components)-1])
+	if err != nil {
+		webError(w, "Could not resolve parent object", err, http.StatusBadRequest)
+		return
+	}
+
+	err = path_nodes[len(path_nodes)-1].RemoveNodeLink(components[len(components)-1])
+	if err != nil {
+		webError(w, "Could not delete link", err, http.StatusBadRequest)
+		return
+	}
+
+	newnode := path_nodes[len(path_nodes)-1]
+	for i := len(path_nodes) - 2; i >= 0; i-- {
+		newnode, err = path_nodes[i].UpdateNodeLink(components[i], newnode)
+		if err != nil {
+			webError(w, "Could not update node links", err, http.StatusInternalServerError)
+			return
+		}
+	}
+
+	err = i.node.DAG.AddRecursive(newnode)
+	if err != nil {
+		webError(w, "Could not add recursively new node", err, http.StatusInternalServerError)
+		return
+	}
+
+	// Redirect to new path
+	key, err := newnode.Key()
+	if err != nil {
+		webError(w, "Could not get key of new node", err, http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("IPFS-Hash", key.String())
+	http.Redirect(w, r, IpfsPathPrefix+key.String()+"/"+strings.Join(components[:len(components)-1], "/"), http.StatusCreated)
+}
+
+func webError(w http.ResponseWriter, message string, err error, defaultCode int) {
+	if _, ok := err.(path.ErrNoLink); ok {
+		webErrorWithCode(w, message, err, http.StatusNotFound)
+	} else if err == routing.ErrNotFound {
+		webErrorWithCode(w, message, err, http.StatusNotFound)
+	} else if err == context.DeadlineExceeded {
+		webErrorWithCode(w, message, err, http.StatusRequestTimeout)
+	} else {
+		webErrorWithCode(w, message, err, defaultCode)
+	}
+}
+
+func webErrorWithCode(w http.ResponseWriter, message string, err error, code int) {
+	w.WriteHeader(code)
+	log.Errorf("%s: %s", message, err)
+	w.Write([]byte(message + ": " + err.Error()))
 }
 
 // return a 500 error and log

fuse/ipns/ipns_unix.go

@@ -292,13 +292,13 @@ func (s *Node) Attr() fuse.Attr {
 // Lookup performs a lookup under this node.
 func (s *Node) Lookup(name string, intr fs.Intr) (fs.Node, fuse.Error) {
 	log.Debugf("ipns: node[%s] Lookup '%s'", s.name, name)
-	nd, err := s.Ipfs.Resolver.ResolveLinks(s.Nd, []string{name})
+	nodes, err := s.Ipfs.Resolver.ResolveLinks(s.Nd, []string{name})
 	if err != nil {
 		// todo: make this error more versatile.
 		return nil, fuse.ENOENT
 	}
 
-	return s.makeChild(name, nd), nil
+	return s.makeChild(name, nodes[len(nodes)-1]), nil
 }
 
 func (n *Node) makeChild(name string, node *mdag.Node) *Node {
@@ -650,12 +650,11 @@ func (n *Node) Rename(req *fuse.RenameRequest, newDir fs.Node, intr fs.Intr) fus
 // Updates the child of this node, specified by name to the given newnode
 func (n *Node) update(name string, newnode *mdag.Node) error {
 	log.Debugf("update '%s' in '%s'", name, n.name)
-	nnode := n.Nd.Copy()
-	err := nnode.RemoveNodeLink(name)
+
+	nnode, err := n.Nd.UpdateNodeLink(name, newnode)
 	if err != nil {
 		return err
 	}
-	nnode.AddNodeLink(name, newnode)
 
 	if n.parent != nil {
 		err := n.parent.update(n.name, nnode)

fuse/readonly/readonly_unix.go

@@ -118,13 +118,13 @@ func (s *Node) Attr() fuse.Attr {
 // Lookup performs a lookup under this node.
 func (s *Node) Lookup(name string, intr fs.Intr) (fs.Node, fuse.Error) {
 	log.Debugf("Lookup '%s'", name)
-	nd, err := s.Ipfs.Resolver.ResolveLinks(s.Nd, []string{name})
+	nodes, err := s.Ipfs.Resolver.ResolveLinks(s.Nd, []string{name})
 	if err != nil {
 		// todo: make this error more versatile.
 		return nil, fuse.ENOENT
 	}
 
-	return &Node{Ipfs: s.Ipfs, Nd: nd}, nil
+	return &Node{Ipfs: s.Ipfs, Nd: nodes[len(nodes)-1]}, nil
 }
 
 // ReadDir reads the link structure as directory entries

merkledag/node.go

@@ -134,6 +134,16 @@ func (n *Node) Copy() *Node {
 	return nnode
 }
 
+// UpdateNodeLink return a copy of the node with the link name set to point to
+// that. If a link of the same name existed, it is removed.
+func (n *Node) UpdateNodeLink(name string, that *Node) (*Node, error) {
+	newnode := n.Copy()
+	err := newnode.RemoveNodeLink(name)
+	err = nil // ignore error
+	err = newnode.AddNodeLink(name, that)
+	return newnode, err
+}
+
 // Size returns the total size of the data addressed by node,
 // including the total sizes of references.
 func (n *Node) Size() (uint64, error) {

path/resolver.go

@@ -11,16 +11,26 @@ import (
 
 var log = u.Logger("path")
 
+// ErrNoLink is returned when a link is not found in a path
+type ErrNoLink struct {
+	name string
+	node mh.Multihash
+}
+
+func (e ErrNoLink) Error() string {
+	return fmt.Sprintf("no link named %q under %s", e.name, e.node.B58String())
+}
+
 // Resolver provides path resolution to IPFS
 // It has a pointer to a DAGService, which is uses to resolve nodes.
 type Resolver struct {
 	DAG merkledag.DAGService
 }
 
-// ResolvePath fetches the node for given path. It uses the first
-// path component as a hash (key) of the first node, then resolves
-// all other components walking the links, with ResolveLinks.
-func (s *Resolver) ResolvePath(fpath Path) (*merkledag.Node, error) {
+// SplitAbsPath clean up and split fpath. It extracts the first component (which
+// must be a Multihash) and return it separately.
+func SplitAbsPath(fpath Path) (mh.Multihash, []string, error) {
+
 	log.Debugf("Resolve: '%s'", fpath)
 
 	parts := fpath.Segments()
@@ -30,13 +40,36 @@ func (s *Resolver) ResolvePath(fpath Path) (*merkledag.Node, error) {
 
 	// if nothing, bail.
 	if len(parts) == 0 {
-		return nil, fmt.Errorf("ipfs path must contain at least one component")
+		return nil, nil, fmt.Errorf("ipfs path must contain at least one component")
 	}
 
 	// first element in the path is a b58 hash (for now)
 	h, err := mh.FromB58String(parts[0])
 	if err != nil {
 		log.Debug("given path element is not a base58 string.\n")
+		return nil, nil, err
+	}
+
+	return h, parts[1:], nil
+}
+
+// ResolvePath fetches the node for given path. It returns the last item
+// returned by ResolvePathComponents.
+func (s *Resolver) ResolvePath(fpath Path) (*merkledag.Node, error) {
+	nodes, err := s.ResolvePathComponents(fpath)
+	if err != nil || nodes == nil {
+		return nil, err
+	} else {
+		return nodes[len(nodes)-1], err
+	}
+}
+
+// ResolvePathComponents fetches the nodes for each segment of the given path.
+// It uses the first path component as a hash (key) of the first node, then
+// resolves all other components walking the links, with ResolveLinks.
+func (s *Resolver) ResolvePathComponents(fpath Path) ([]*merkledag.Node, error) {
+	h, parts, err := SplitAbsPath(fpath)
+	if err != nil {
 		return nil, err
 	}
 
@@ -46,19 +79,22 @@ func (s *Resolver) ResolvePath(fpath Path) (*merkledag.Node, error) {
 		return nil, err
 	}
 
-	return s.ResolveLinks(nd, parts[1:])
+	return s.ResolveLinks(nd, parts)
 }
 
 // ResolveLinks iteratively resolves names by walking the link hierarchy.
 // Every node is fetched from the DAGService, resolving the next name.
-// Returns the last node found.
+// Returns the list of nodes forming the path, starting with ndd. This list is
+// guaranteed never to be empty.
 //
 // ResolveLinks(nd, []string{"foo", "bar", "baz"})
 // would retrieve "baz" in ("bar" in ("foo" in nd.Links).Links).Links
 func (s *Resolver) ResolveLinks(ndd *merkledag.Node, names []string) (
-	nd *merkledag.Node, err error) {
+	result []*merkledag.Node, err error) {
 
-	nd = ndd // dup arg workaround
+	result = make([]*merkledag.Node, 0, len(names)+1)
+	result = append(result, ndd)
+	nd := ndd // dup arg workaround
 
 	// for each of the path components
 	for _, name := range names {
@@ -75,21 +111,22 @@ func (s *Resolver) ResolveLinks(ndd *merkledag.Node, names []string) (
 		}
 
 		if next == "" {
-			h1, _ := nd.Multihash()
-			h2 := h1.B58String()
-			return nil, fmt.Errorf("no link named %q under %s", name, h2)
+			n, _ := nd.Multihash()
+			return result, ErrNoLink{name: name, node: n}
 		}
 
 		if nlink.Node == nil {
 			// fetch object for link and assign to nd
 			nd, err = s.DAG.Get(next)
 			if err != nil {
-				return nd, err
+				return append(result, nd), err
 			}
 			nlink.Node = nd
 		} else {
 			nd = nlink.Node
 		}
+
+		result = append(result, nlink.Node)
 	}
 	return
 }

util/util.go

@@ -144,3 +144,19 @@ func (m MultiErr) Error() string {
 	}
 	return s
 }
+
+func Partition(subject string, sep string) (string, string, string) {
+	if i := strings.Index(subject, sep); i != -1 {
+		return subject[:i], subject[i : i+len(sep)], subject[i+len(sep):]
+	} else {
+		return subject, "", ""
+	}
+}
+
+func RPartition(subject string, sep string) (string, string, string) {
+	if i := strings.LastIndex(subject, sep); i != -1 {
+		return subject[:i], subject[i : i+len(sep)], subject[i+len(sep):]
+	} else {
+		return subject, "", ""
+	}
+}