//Store will store a file located at path in the DHT (under key) by
//contacting the node at addr
func Store(key [sha256.Size]byte, path string, addr string) error {
//do a lookup of the key
ipaddr, err := chord.Lookup(key, addr)
file, err := os.Open(path)
checkError(err)
if err != nil {
fmt.Printf("error here (0)\n")
return err
}
defer file.Close()
document := make([]byte, 4096)
n, err := file.Read(document)
checkError(err)
if err != nil {
fmt.Printf("error here (1)\n")
return err
}
//create message to send to target ip
msg := getstoreMsg(key, document[:n])
//send message TODO: check reply for errors
_, err = chord.Send(msg, ipaddr)
if err != nil {
fmt.Printf("error here (2)\n")
}
return err
}
//Notify is part of the ChordApp interface and will update the
//application by moving files if its predecessor changes
func (fs *FileSystem) Notify(id [sha256.Size]byte, myid [sha256.Size]byte, addr string) {
fmt.Printf("Predecessor changed to %s.\n", addr)
dir, err := os.Open(fs.home)
defer dir.Close()
checkError(err)
if err != nil {
return
}
names, err := dir.Readdirnames(0)
checkError(err)
if err != nil {
return
}
for _, name := range names {
var key [sha256.Size]byte
decoded, err := base32.StdEncoding.DecodeString(name)
if err != nil {
//fmt.Printf("file was not encoded.\n")
continue
}
copy(key[:], decoded[:sha256.Size])
if chord.InRange(id, key, myid) {
//transfer file.
fs.cache[name] = true
file, err := os.Open(fmt.Sprintf("%s/%s", fs.home, name))
checkError(err)
if err != nil {
checkError(err)
}
defer file.Close()
document := make([]byte, 4096)
n, err := file.Read(document)
checkError(err)
if err != nil {
checkError(err)
}
//create message to send to target ip
msg := getstoreMsg(key, document[:n])
//send message TODO: check reply for errors
_, err = chord.Send(msg, addr)
if err != nil {
checkError(err)
}
fmt.Printf("Relocated file %s to node %s.\n", name, addr)
}
}
//TODO: exchange mirrored files
}
//Fetch will retrieve a file with key specified by key from the DHT and
//save it to path by contacting the node at addr
func Fetch(key [sha256.Size]byte, path string, addr string) error {
ipaddr, err := chord.Lookup(key, addr)
if err != nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
//create message to send to target ip
msg := getfetchMsg(key)
reply, err := chord.Send(msg, ipaddr)
if err != nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
reply, err = parseHeader(reply)
if err != nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
if reply == nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
document, err := parseDoc(reply)
if err != nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
if document == nil {
name := base32.StdEncoding.EncodeToString(key[:])
err = &FSError{ipaddr, name, err}
fmt.Printf("%s.\n", err.Error())
return err
}
file, err := os.Create(path)
checkError(err)
if err != nil {
return err
}
defer file.Close()
_, err = file.Write(document)
checkError(err)
if err != nil {
return err
}
return err
}