golang app as xinetd service

[Ted Toth]

I'm trying to run a Go http server app out of xinetd. Since xinetd passes the connected socket to the child as stdin I wrote the following:

        fi, _ := os.Stdin.Stat() // get the FileInfo struct describing the standard input.

if (fi.Mode() & os.ModeSocket) == 0 {

fmt.Printf("stdin is a socket")

} else {

fmt.Printf("stdin is not a socket")

}

listener, err := net.FileListener(os.Stdin)

if err != nil {

fmt.Printf("net.FileListener(os.Stdin) failed: %v\n", err)

return

}

err = http.Serve(listener, router)

if err != nil {

fmt.Printf("http.Serve(listener, router) failed: %v\n", err)

return

}

However when I run:

wget http://localhost:10349

I get back:

stdin is not a socket

http.Serve(listener, router) failed: accept tcp 192.168.10.10: accept: invalid argument

How can I get an http server to use stdin as it's socket connection?

Ted

[Ted Toth]

stdin is a socket my test was wrong should be:

if (fi.Mode() & os.ModeSocket) == 1 {

Also I looked at the fcgi code and I'm doing basically the same thing it does if given a nil Listener.

[Ted Toth]

strace of accept error:

23045 write(3, "\0\0\0\32\0\0Z\5\0\0\0\7contactdbws: stdin", 30 <unfinished ...>

23046 select(0, NULL, NULL, NULL, {0, 20} <unfinished ...>

23045 <... write resumed> )             = 30

23045 select(4, [3], NULL, NULL, {0, 0}) = 0 (Timeout)

23045 write(3, "\0\0\0\37\0\0Z\5\0\0\0\7contactdbws: Srwxrwx"..., 35) = 35

23045 fcntl(0, F_DUPFD_CLOEXEC, 0)      = 4

23045 fcntl(4, F_GETFL)                 = 0x2 (flags O_RDWR)

23045 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0

23045 getsockopt(4, SOL_SOCKET, SO_TYPE, [1], [4]) = 0

23045 getsockname(4, {sa_family=AF_INET, sin_port=htons(10349), sin_addr=inet_addr("192.168.10.10")}, [16]) = 0

23045 getpeername(4, {sa_family=AF_INET, sin_port=htons(49196), sin_addr=inet_addr("192.168.10.10")}, [16]) = 0

23045 epoll_create1(O_CLOEXEC)          = 5

23045 epoll_ctl(5, EPOLL_CTL_ADD, 4, {EPOLLIN|EPOLLOUT|EPOLLET|0x2000, {u32=4108432872, u64=139882603329000}}) = 0

23045 write(1, "*net.TCPListener\n", 17) = 17

23045 accept4(4, 0xc820101998, [112], SOCK_CLOEXEC|SOCK_NONBLOCK) = -1 EINVAL (Invalid argument)

23045 accept(4, 0xc8201019a8, [112])    = -1 EINVAL (Invalid argument)

23045 epoll_ctl(5, EPOLL_CTL_DEL, 4, {0, {u32=0, u64=0}}) = 0

23045 close(4)                          = 0

23045 write(1, "http.Serve(listener, router) fai"..., 94) = -1 ECONNRESET (Connection reset by peer)

23045 exit_group(0)                     = ?

[Giulio Iotti]

On Tuesday, September 15, 2015 at 5:20:13 PM UTC+3, Ted Toth wrote:

I'm trying to run a Go http server app out of xinetd. Since xinetd passes the connected socket to the child as stdin I wrote the following:

        fi, _ := os.Stdin.Stat() // get the FileInfo struct describing the standard input.

Why _? Please dump this error too.

 

if (fi.Mode() & os.ModeSocket) == 0 {

I think it should be:

   if fi.Mode()&os.ModeSocket == os.ModeSocket {

As for the real problem you are having, I need more info. Your FileListener tries to use TCP: is that what you configured xinitd to use? Show conf.

-- 

Giulio Iotti

 

[Ted Toth]

xinetd configuration

service contactdbws

{

        disable         = no

        only_from       = localhost comms 127.0.0.1

protocol = tcp

        socket_type     = stream

        wait            = no

        flags           = LABELED IPv4

        user            = contactdbws

        group           = jcdx

        instances       = 50

        per_source      = 50

        cps             = 600 1

        server          = /opt/jcdx/bin/contactdbws

}

I changed the Stat call to return any error and there is none.

I also changed the code to print the mode string from the FileInfo:

fmt.Printf( fi.Mode().String())

which is Srwxrwxrwx i.e. it's a socket.

[Matt Harden]

If you set wait = yes in your xinetd service, it may work.

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[Ted Toth]

I opened a bug with a simplified example:

https://github.com/golang/go/issues/12646