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.,ruby: enable accept to be called as TsnetAccept & fix gem #24

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14 changes: 8 additions & 6 deletions ruby/lib/tailscale.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -39,8 +39,7 @@ module Libtailscale
attach_function :TsnetSetLogFD, [:int, :int], :int
attach_function :TsnetDial, [:int, :string, :string, :pointer], :int, blocking: true
attach_function :TsnetListen, [:int, :string, :string, :pointer], :int
attach_function :close, [:int], :int
attach_function :tailscale_accept, [:int, :pointer], :int, blocking: true
attach_function :TsnetAccept, [:int, :pointer], :int, blocking: true
attach_function :TsnetErrmsg, [:int, :pointer, :size_t], :int
attach_function :TsnetLoopback, [:int, :pointer, :size_t, :pointer, :pointer], :int
end
Expand Down Expand Up @@ -86,15 +85,19 @@ def initialize(ts, listener)
# write.
def accept
@ts.assert_open
lio = IO.for_fd(@listener)
until IO.select([lio]).first.any?
@ts.assert_open
Comment on lines +88 to +90
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IO.for_fd defaults to autoclose=true; the temporary lio created here can be garbage-collected after accept returns, which would close the underlying listener FD unexpectedly. Use IO.for_fd(@Listener, autoclose: false) (or store a persistent IO wrapper on the Listener instance and close it in #close) so GC can’t close the listener.

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Comment on lines +89 to +90
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This until IO.select([lio]).first.any? loop is effectively a single blocking call because IO.select has no timeout; the body won’t re-run to re-check assert_open. Either pass a small timeout to IO.select and loop, or remove the loop and just do a single select (or go back to a fully blocking accept call) to avoid misleading control flow.

Suggested change
until IO.select([lio]).first.any?
@ts.assert_open
loop do
# Wait briefly for the listener to become readable so we can
# periodically re-check that the server is still open.
readable, = IO.select([lio], nil, nil, 0.1)
@ts.assert_open
break if readable && !readable.empty?

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end
conn = FFI::MemoryPointer.new(:int)
Error.check(@ts, Libtailscale::tailscale_accept(@listener, conn))
Error.check(@ts, Libtailscale::TsnetAccept(@listener, conn))
IO::new(conn.read_int)
end

# Close the listener.
def close
@ts.assert_open
Error.check(@ts, Libtailscale::close(@listener))
IO.for_fd(@listener).close
end
end

Expand Down Expand Up @@ -229,8 +232,7 @@ def set_log_fd(log_fd)
end

# Dial a network address. +network+ is one of "tcp" or "udp". +addr+ is the
# remote address to connect to. This method blocks until the connection is
# established.
# remote address to connect to. This method blocks until the connection is established.
def dial(network, addr)
assert_open
conn = FFI::MemoryPointer.new(:int)
Expand Down
26 changes: 25 additions & 1 deletion ruby/test/tailscale/test_tailscale.rb
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Expand Up @@ -23,6 +23,7 @@ def test_that_it_has_a_version_number
def test_listen_sorta_works
ts = newts
ts.up
wait_status_running ts
s = ts.listen("tcp", ":1999")
s.close
ts.close
Expand All @@ -31,18 +32,41 @@ def test_listen_sorta_works
def test_dial_sorta_works
ts = newts
ts.up
wait_status_running ts
c = ts.dial("udp", "100.100.100.100:53")
c.close
ts.close
end

def test_listen_accept_dial_close
ts = newts
ts.up
wait_status_running ts
hn = ts.local_api.status["Self"]["TailscaleIPs"][0]
s = ts.listen "tcp", "#{hn}:1999"
c = ts.dial "tcp", "#{hn}:1999"
ss = s.accept
c.write "hello"
assert_equal "hello", ss.read(5)
ss.write "world"
assert_equal "world", c.read(5)
ss.close
c.close
ts.close
end
Comment on lines +41 to +56
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Indentation in this new test method is inconsistent with the rest of the file (2-space indentation). Reformat the body to match the surrounding style to keep the test file readable.

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def wait_status_running ts
while ts.local_api.status["BackendState"] != "Running"
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wait_status_running can loop forever if the backend never reaches "Running", which can hang the test suite. Add a timeout/deadline (and possibly a short backoff) and fail the test with a helpful message when exceeded.

Suggested change
while ts.local_api.status["BackendState"] != "Running"
timeout_seconds = 30
deadline = Time.now + timeout_seconds
loop do
status = ts.local_api.status
return if status["BackendState"] == "Running"
if Time.now > deadline
flunk "BackendState did not reach 'Running' within #{timeout_seconds} seconds. Last status: #{status.inspect}"
end

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sleep 0.01
end
end

def newts
t = Tailscale::new
unless ENV["VERBOSE"]
logfd = IO.sysopen("/dev/null", "w+")
t.set_log_fd(logfd)
end

t.set_ephemeral(1)
t.set_dir(@tmpdir)
t.set_control_url($testcontrol_url)
Expand Down
23 changes: 2 additions & 21 deletions tailscale.c
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Expand Up @@ -22,6 +22,7 @@ extern int TsnetSetLogFD(int sd, int fd);
extern int TsnetGetIps(int sd, char *buf, size_t buflen);
extern int TsnetGetRemoteAddr(int listener, int conn, char *buf, size_t buflen);
extern int TsnetListen(int sd, char* net, char* addr, int* listenerOut);
extern int TsnetAccept(int ld, int* connOut);
extern int TsnetLoopback(int sd, char* addrOut, size_t addrLen, char* proxyOut, char* localOut);
extern int TsnetEnableFunnelToLocalhostPlaintextHttp1(int sd, int localhostPort);

Expand Down Expand Up @@ -50,27 +51,7 @@ int tailscale_listen(tailscale sd, const char* network, const char* addr, tailsc
}

int tailscale_accept(tailscale_listener ld, tailscale_conn* conn_out) {
struct msghdr msg = {0};

char mbuf[256];
struct iovec io = { .iov_base = mbuf, .iov_len = sizeof(mbuf) };
msg.msg_iov = &io;
msg.msg_iovlen = 1;

char cbuf[256];
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);

if (recvmsg(ld, &msg, 0) == -1) {
return -1;
}

struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
unsigned char* data = CMSG_DATA(cmsg);

int fd = *(int*)data;
*conn_out = fd;
return 0;
return TsnetAccept(ld, (int*)conn_out);
}

int tailscale_getremoteaddr(tailscale_listener l, tailscale_conn conn, char* buf, size_t buflen) {
Expand Down
36 changes: 36 additions & 0 deletions tailscale.go
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Expand Up @@ -20,6 +20,7 @@ import (
"syscall"
"unsafe"

"golang.org/x/sys/unix"
"tailscale.com/hostinfo"
"tailscale.com/ipn"
"tailscale.com/tsnet"
Expand Down Expand Up @@ -292,6 +293,41 @@ func TsnetListen(sd C.int, network, addr *C.char, listenerOut *C.int) C.int {
return 0
}

//export TsnetAccept
func TsnetAccept(listenerFd C.int, connOut *C.int) C.int {
listeners.mu.Lock()
ln := listeners.m[listenerFd]
listeners.mu.Unlock()

if ln == nil {
return C.EBADF
}

buf := make([]byte, unix.CmsgLen(int(unsafe.Sizeof((C.int)(0)))))
_, oobn, _, _, err := syscall.Recvmsg(int(listenerFd), nil, buf, 0)
if err != nil {
return ln.s.recErr(err)
}

scms, err := syscall.ParseSocketControlMessage(buf[:oobn])
if err != nil {
return ln.s.recErr(err)
}
if len(scms) != 1 {
return ln.s.recErr(fmt.Errorf("libtailscale: got %d control messages, want 1", len(scms)))
}
fds, err := syscall.ParseUnixRights(&scms[0])
Comment on lines +306 to +319
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The control-message buffer is sized with unix.CmsgLen, which is the length value for a cmsghdr, not the space needed for receiving ancillary data. This can lead to truncated SCM_RIGHTS data and failed accepts on some platforms. Allocate the OOB buffer with unix.CmsgSpace(sizeof(int)) (or syscall.CmsgSpace) and check recvmsg flags for MSG_CTRUNC/MSG_TRUNC before parsing.

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if err != nil {
return ln.s.recErr(err)
}
if len(fds) != 1 {
return ln.s.recErr(fmt.Errorf("libtailscale: got %d FDs, want 1", len(fds)))
}
*connOut = (C.int)(fds[0])

return 0
}

func newConn(s *server, netConn net.Conn, connOut *C.int) error {
fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
if err != nil {
Expand Down
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