// Rcreate is used to respond to a succesful create request. With 9P, creating
// a file also opens the file for I/O. Once Rcreate returns, future read
// and write requests to the file handle will pass through rwc. The value
// rwc must meet the same criteria listed for the Ropen method of a Topen
// request.
func (t Tcreate) Rcreate(rwc interface{}, err error) {
var (
f styxfile.Interface
)
if err != nil {
t.Rerror("%s", err)
return
}
if dir, ok := rwc.(Directory); t.Mode.IsDir() && ok {
f = styxfile.NewDir(dir, path.Join(t.Path(), t.Name), t.session.conn.qidpool)
} else {
f, err = styxfile.New(rwc)
}
if err != nil {
t.session.conn.srv.logf("create %s failed: %s", t.Name, err)
t.Rerror("create failed")
return
}
file := file{name: path.Join(t.Path(), t.Name), rwc: f}
// fid for parent directory is now the fid for the new file,
// so there is no increase in references to this session.
t.session.files.Put(t.fid, file)
qtype := styxfile.QidType(styxfile.Mode9P(t.Mode))
qid := t.session.conn.qid(file.name, qtype)
t.session.unhandled = false
if t.session.conn.clearTag(t.tag) {
t.session.conn.Rcreate(t.tag, qid, 0)
}
}
// NOTE(droyo) consider a scenario where a malicious actor connects
// to the server that repeatedly spams Tauth requests. It can quickly
// use up resources on the server. Consider the following measures:
//
// - rate-limiting Tauth requests
// - Setting a per-connection session limit
// - close connections that have not established a session in N seconds
func (c *conn) handleTauth(cx context.Context, m styxproto.Tauth) bool {
defer c.Flush()
if c.srv.Auth == nil {
c.clearTag(m.Tag())
c.Rerror(m.Tag(), "%s", errNotSupported)
return true
}
if _, ok := c.sessionFid.Get(m.Afid()); ok {
c.clearTag(m.Tag())
c.Rerror(m.Tag(), "fid %x in use", m.Afid())
return true
}
client, server := net.Pipe()
ch := &Channel{
Context: c.cx,
ReadWriteCloser: server,
}
rwc, err := styxfile.New(client)
if err != nil {
// This should never happen
panic(err)
}
s := newSession(c, m)
go func() {
s.authC <- c.srv.Auth(ch, s.User, s.Access)
close(s.authC)
}()
c.sessionFid.Put(m.Afid(), s)
s.files.Put(m.Afid(), file{rwc: rwc, auth: true})
s.IncRef()
return true
}
// The Ropen method signals to the client that a file has succesfully
// been opened and is ready for I/O. After Ropen returns, future reads
// and writes to the opened file handle will pass through rwc.
//
// The value rwc must implement some of the interfaces in the io package
// for reading and writing. If the type implements io.Seeker or io.ReaderAt
// and io.WriterAt, clients may read or write at arbitrary offsets within
// the file. Types that only implement Read or Write operations will return
// errors on writes and reads, respectively.
//
// If rwc implements the Stat method of os.File, that will be used to
// answer Tstat requests. Otherwise, the styx package will assemble Rstat
// responses out of default values merged with any methods rwc provides
// from the os.FileInfo interface.
//
// If a file does not implement any of the Read or Write interfaces in
// the io package, A generic error is returned to the client, and a message
// will be written to the server's ErrorLog.
func (t Topen) Ropen(rwc interface{}, err error) {
var (
file file
f styxfile.Interface
)
if err != nil {
t.Rerror("%s", err)
return
}
// The type of the file (regular or directory) will have been
// established in a previous Twalk request.
qid := t.session.conn.qid(t.Path(), 0)
mode := styxfile.ModeOS(uint32(qid.Type()) << 24)
if dir, ok := rwc.(Directory); ok && mode.IsDir() {
f = styxfile.NewDir(dir, t.Path(), t.session.conn.qidpool)
} else {
f, err = styxfile.New(rwc)
}
if err != nil {
t.session.conn.srv.logf("%s open %s failed: %s", t.path, err)
// Don't want to expose too many implementation details
// to clients.
t.Rerror("open failed")
return
}
t.session.files.Update(t.fid, &file, func() {
file.rwc = f
})
t.session.unhandled = false
if t.session.conn.clearTag(t.tag) {
t.session.conn.Ropen(t.tag, qid, 0)
}
}