Patchwork [v5,2/4] qemu-socket: change inet_connect() to to support nonblock socket

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Submitter Amos Kong
Date March 22, 2012, 3:52 a.m.
Message ID <20120322035245.2431.59699.stgit@dhcp-8-167.nay.redhat.com>
Download mbox | patch
Permalink /patch/148157/
State New
Headers show

Comments

Amos Kong - March 22, 2012, 3:52 a.m.
Change inet_connect(const char *str, int socktype) to
inet_connect(const char *str, bool block),
socktype is unused, block is used to assign if set socket
to block/nonblock.

Retry to connect when -EINTR/-EWOULDBLOCK is got.
Connect's successful for nonblock socket when following
errors are got:
  -EINPROGRESS
  -WSAEALREADY/-WSAEINVAL (win32)

Add a bool entry(block) for dummy_opts to tag block type.

Use set_socket_error() to set real errno, set errno to
EINVAL for parse error.

Change nbd, vnc to use new interface.

Signed-off-by: Amos Kong <akong@redhat.com>
---
 nbd.c          |    2 +-
 qemu-sockets.c |   66 +++++++++++++++++++++++++++++++++++++++++++-------------
 qemu_socket.h  |    2 +-
 ui/vnc.c       |    2 +-
 4 files changed, 54 insertions(+), 18 deletions(-)
Orit Wasserman - March 27, 2012, 3:29 p.m.
On 03/22/2012 05:52 AM, Amos Kong wrote:
> Change inet_connect(const char *str, int socktype) to
> inet_connect(const char *str, bool block),
> socktype is unused, block is used to assign if set socket
> to block/nonblock.
> 
> Retry to connect when -EINTR/-EWOULDBLOCK is got.
> Connect's successful for nonblock socket when following
> errors are got:
>   -EINPROGRESS
>   -WSAEALREADY/-WSAEINVAL (win32)
> 
> Add a bool entry(block) for dummy_opts to tag block type.
> 
> Use set_socket_error() to set real errno, set errno to
> EINVAL for parse error.
> 
> Change nbd, vnc to use new interface.
> 
> Signed-off-by: Amos Kong <akong@redhat.com>
> ---
>  nbd.c          |    2 +-
>  qemu-sockets.c |   66 +++++++++++++++++++++++++++++++++++++++++++-------------
>  qemu_socket.h  |    2 +-
>  ui/vnc.c       |    2 +-
>  4 files changed, 54 insertions(+), 18 deletions(-)
> 
> diff --git a/nbd.c b/nbd.c
> index 567e94e..3618344 100644
> --- a/nbd.c
> +++ b/nbd.c
> @@ -146,7 +146,7 @@ int tcp_socket_outgoing(const char *address, uint16_t port)
>  
>  int tcp_socket_outgoing_spec(const char *address_and_port)
>  {
> -    return inet_connect(address_and_port, SOCK_STREAM);
> +    return inet_connect(address_and_port, true);
>  }
>  
>  int tcp_socket_incoming(const char *address, uint16_t port)
> diff --git a/qemu-sockets.c b/qemu-sockets.c
> index 6bcb8e3..908479e 100644
> --- a/qemu-sockets.c
> +++ b/qemu-sockets.c
> @@ -51,6 +51,9 @@ static QemuOptsList dummy_opts = {
>          },{
>              .name = "ipv6",
>              .type = QEMU_OPT_BOOL,
> +        },{
> +            .name = "block",
> +            .type = QEMU_OPT_BOOL,
>          },
>          { /* end if list */ }
>      },
> @@ -201,7 +204,8 @@ int inet_connect_opts(QemuOpts *opts)
>      const char *port;
>      char uaddr[INET6_ADDRSTRLEN+1];
>      char uport[33];
> -    int sock,rc;
> +    int sock, rc, err;
> +    bool block;
>  
>      memset(&ai,0, sizeof(ai));
>      ai.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
> @@ -210,9 +214,11 @@ int inet_connect_opts(QemuOpts *opts)
>  
>      addr = qemu_opt_get(opts, "host");
>      port = qemu_opt_get(opts, "port");
> +    block = qemu_opt_get_bool(opts, "block", 0);
>      if (addr == NULL || port == NULL) {
>          fprintf(stderr, "inet_connect: host and/or port not specified\n");
> -        return -1;
> +        err = -EINVAL;
> +        goto err;

I would call set_socket_error with -EINVAL and than return -1;

>      }
>  
>      if (qemu_opt_get_bool(opts, "ipv4", 0))
> @@ -224,7 +230,8 @@ int inet_connect_opts(QemuOpts *opts)
>      if (0 != (rc = getaddrinfo(addr, port, &ai, &res))) {
>          fprintf(stderr,"getaddrinfo(%s,%s): %s\n", addr, port,
>                  gai_strerror(rc));
> -	return -1;
> +        err = -EINVAL;
> +        goto err;

I would call set_socket_error with EINVAL and than return -1;

>      }
>  
>      for (e = res; e != NULL; e = e->ai_next) {
> @@ -241,21 +248,44 @@ int inet_connect_opts(QemuOpts *opts)
>              continue;
>          }
>          setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(void*)&on,sizeof(on));
> -
> +        if (!block) {
> +            socket_set_nonblock(sock);
> +        }
>          /* connect to peer */
> -        if (connect(sock,e->ai_addr,e->ai_addrlen) < 0) {
> -            if (NULL == e->ai_next)
> -                fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __FUNCTION__,
> -                        inet_strfamily(e->ai_family),
> -                        e->ai_canonname, uaddr, uport, strerror(errno));
> -            closesocket(sock);
> -            continue;
> +        do {
> +            err = 0;
> +            if (connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
> +                err = -socket_error();
> +            }
> +        } while (err == -EINTR || err == -EWOULDBLOCK);
> +

this is only relevant for non blocking socket
it should look something like this :

while ( (rc = connect(sock, e->ai_addr, e->ai_addrlen)) < 0 && !block &&
	(socket_error() == EINTR || socket_error() == -EWOULDBLOCK))
	
> +        if (err >= 0) {
> +            goto success;
> +        } else if (!block && err == -EINPROGRESS) {
> +            goto success;
> +#ifdef _WIN32
> +        } else if (!block && (err == -WSAEALREADY || err == -WSAEINVAL)) {
> +            goto success;
> +#endif

I prefer to check for error the code should look:

	if (rc < 0 &&  (block ||
#ifdef _WIN32
	   (socket_error() != WSAEALREADY && socket_error() != -WSAEINVAL)) {
#else
	(socket_error() != EINPROGRESS)) {
#endif
	   if (NULL == e->ai_next)  
               fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __func__,
                   inet_strfamily(e->ai_family),
                  e->ai_canonname, uaddr, uport, strerror(errno));
	   closesocket(sock);
	   continue;
	} 
...

Orit
>          }
> -        freeaddrinfo(res);
> -        return sock;
> +
> +        if (NULL == e->ai_next) {
> +            fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __func__,
> +                    inet_strfamily(e->ai_family),
> +                    e->ai_canonname, uaddr, uport, strerror(errno));
> +        }
> +        closesocket(sock);
>      }
>      freeaddrinfo(res);
> +
> +err:
> +    set_socket_error(-err);
>      return -1;
> +
> +success:
> +    freeaddrinfo(res);
> +    set_socket_error(-err);
> +    return sock;
>  }
>  
>  int inet_dgram_opts(QemuOpts *opts)
> @@ -449,14 +479,20 @@ int inet_listen(const char *str, char *ostr, int olen,
>      return sock;
>  }
>  
> -int inet_connect(const char *str, int socktype)
> +int inet_connect(const char *str, bool block)
>  {
>      QemuOpts *opts;
>      int sock = -1;
>  
>      opts = qemu_opts_create(&dummy_opts, NULL, 0);
> -    if (inet_parse(opts, str) == 0)
> +    if (inet_parse(opts, str) == 0) {
> +        if (block) {
> +            qemu_opt_set(opts, "block", "on");
> +        }
>          sock = inet_connect_opts(opts);
> +    } else {
> +        set_socket_error(EINVAL);
> +    }
>      qemu_opts_del(opts);
>      return sock;
>  }
> diff --git a/qemu_socket.h b/qemu_socket.h
> index a4c5170..f86cd3f 100644
> --- a/qemu_socket.h
> +++ b/qemu_socket.h
> @@ -47,7 +47,7 @@ int inet_listen_opts(QemuOpts *opts, int port_offset);
>  int inet_listen(const char *str, char *ostr, int olen,
>                  int socktype, int port_offset);
>  int inet_connect_opts(QemuOpts *opts);
> -int inet_connect(const char *str, int socktype);
> +int inet_connect(const char *str, bool block);
>  int inet_dgram_opts(QemuOpts *opts);
>  const char *inet_strfamily(int family);
>  
> diff --git a/ui/vnc.c b/ui/vnc.c
> index deb9ecd..4a96153 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -3068,7 +3068,7 @@ int vnc_display_open(DisplayState *ds, const char *display)
>          if (strncmp(display, "unix:", 5) == 0)
>              vs->lsock = unix_connect(display+5);
>          else
> -            vs->lsock = inet_connect(display, SOCK_STREAM);
> +            vs->lsock = inet_connect(display, true);
>          if (-1 == vs->lsock) {
>              g_free(vs->display);
>              vs->display = NULL;
> 
>
Amos Kong - March 27, 2012, 4:14 p.m.
----- Original Message -----
> On 03/22/2012 05:52 AM, Amos Kong wrote:
> > Change inet_connect(const char *str, int socktype) to
> > inet_connect(const char *str, bool block),
> > socktype is unused, block is used to assign if set socket
> > to block/nonblock.
> > 
> > Retry to connect when -EINTR/-EWOULDBLOCK is got.
> > Connect's successful for nonblock socket when following
> > errors are got:
> >   -EINPROGRESS
> >   -WSAEALREADY/-WSAEINVAL (win32)
> > 
> > Add a bool entry(block) for dummy_opts to tag block type.
> > 
> > Use set_socket_error() to set real errno, set errno to
> > EINVAL for parse error.
> > 
> > Change nbd, vnc to use new interface.
> > 
> > Signed-off-by: Amos Kong <akong@redhat.com>
> > ---
> >  nbd.c          |    2 +-
> >  qemu-sockets.c |   66
> >  +++++++++++++++++++++++++++++++++++++++++++-------------
> >  qemu_socket.h  |    2 +-
> >  ui/vnc.c       |    2 +-
> >  4 files changed, 54 insertions(+), 18 deletions(-)
> > 
> > diff --git a/nbd.c b/nbd.c
> > index 567e94e..3618344 100644
> > --- a/nbd.c
> > +++ b/nbd.c
> > @@ -146,7 +146,7 @@ int tcp_socket_outgoing(const char *address,
> > uint16_t port)
> >  
> >  int tcp_socket_outgoing_spec(const char *address_and_port)
> >  {
> > -    return inet_connect(address_and_port, SOCK_STREAM);
> > +    return inet_connect(address_and_port, true);
> >  }
> >  
> >  int tcp_socket_incoming(const char *address, uint16_t port)
> > diff --git a/qemu-sockets.c b/qemu-sockets.c
> > index 6bcb8e3..908479e 100644
> > --- a/qemu-sockets.c
> > +++ b/qemu-sockets.c
> > @@ -51,6 +51,9 @@ static QemuOptsList dummy_opts = {
> >          },{
> >              .name = "ipv6",
> >              .type = QEMU_OPT_BOOL,
> > +        },{
> > +            .name = "block",
> > +            .type = QEMU_OPT_BOOL,
> >          },
> >          { /* end if list */ }
> >      },
> > @@ -201,7 +204,8 @@ int inet_connect_opts(QemuOpts *opts)
> >      const char *port;
> >      char uaddr[INET6_ADDRSTRLEN+1];
> >      char uport[33];
> > -    int sock,rc;
> > +    int sock, rc, err;
> > +    bool block;
> >  
> >      memset(&ai,0, sizeof(ai));
> >      ai.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
> > @@ -210,9 +214,11 @@ int inet_connect_opts(QemuOpts *opts)
> >  
> >      addr = qemu_opt_get(opts, "host");
> >      port = qemu_opt_get(opts, "port");
> > +    block = qemu_opt_get_bool(opts, "block", 0);
> >      if (addr == NULL || port == NULL) {
> >          fprintf(stderr, "inet_connect: host and/or port not
> >          specified\n");
> > -        return -1;
> > +        err = -EINVAL;
> > +        goto err;
> 
> I would call set_socket_error with -EINVAL and than return -1;

Hi Orit,

This is what I did.
restore "-EINVAL" to 'err', set_socket_error(-err), then return -1


> >      }
> >  
> >      if (qemu_opt_get_bool(opts, "ipv4", 0))
> > @@ -224,7 +230,8 @@ int inet_connect_opts(QemuOpts *opts)
> >      if (0 != (rc = getaddrinfo(addr, port, &ai, &res))) {
> >          fprintf(stderr,"getaddrinfo(%s,%s): %s\n", addr, port,
> >                  gai_strerror(rc));
> > -	return -1;
> > +        err = -EINVAL;
> > +        goto err;
> 
> I would call set_socket_error with EINVAL and than return -1;
> 
> >      }
> >  
> >      for (e = res; e != NULL; e = e->ai_next) {
> > @@ -241,21 +248,44 @@ int inet_connect_opts(QemuOpts *opts)
> >              continue;
> >          }
> >          setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(void*)&on,sizeof(on));
> > -
> > +        if (!block) {
> > +            socket_set_nonblock(sock);
> > +        }
> >          /* connect to peer */
> > -        if (connect(sock,e->ai_addr,e->ai_addrlen) < 0) {
> > -            if (NULL == e->ai_next)
> > -                fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n",
> > __FUNCTION__,
> > -                        inet_strfamily(e->ai_family),
> > -                        e->ai_canonname, uaddr, uport,
> > strerror(errno));
> > -            closesocket(sock);
> > -            continue;
> > +        do {
> > +            err = 0;
> > +            if (connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
> > +                err = -socket_error();
> > +            }
> > +        } while (err == -EINTR || err == -EWOULDBLOCK);
> > +
> 
> this is only relevant for non blocking socket

For blocking socket, if connect() is interrupted by a signal
that is caught while blocked waiting to establish a connection,
connect() shall fail and set errno to [EINTR]
So just re-connect when EINTR/EWOULDBLOCK are set.

http://marc.info/?l=kvm&m=133238606300535&w=2


> it should look something like this :
> 
> while ( (rc = connect(sock, e->ai_addr, e->ai_addrlen)) < 0 && !block
> &&
> 	(socket_error() == EINTR || socket_error() == -EWOULDBLOCK))


  while ( (rc = connect(sock, e->ai_addr, e->ai_addrlen)) < 0  &&
  	(socket_error() == EINTR || socket_error() == EWOULDBLOCK))
        ;
 	
> > +        if (err >= 0) {
> > +            goto success;
> > +        } else if (!block && err == -EINPROGRESS) {
> > +            goto success;
> > +#ifdef _WIN32
> > +        } else if (!block && (err == -WSAEALREADY || err ==
> > -WSAEINVAL)) {
> > +            goto success;
> > +#endif
> 
> I prefer to check for error the code should look:
>
> 	if (rc < 0 &&  (block ||
> #ifdef _WIN32
> 	   (socket_error() != WSAEALREADY && socket_error() != -WSAEINVAL))
> 	   {
> #else
> 	(socket_error() != EINPROGRESS)) {
> #endif
> 	   if (NULL == e->ai_next)
>                fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n",
>                __func__,
>                    inet_strfamily(e->ai_family),
>                   e->ai_canonname, uaddr, uport, strerror(errno));
> 	   closesocket(sock);
> 	   continue;
> 	}
> ...
> 
> Orit
> >          }
> > -        freeaddrinfo(res);
> > -        return sock;
> > +
> > +        if (NULL == e->ai_next) {
> > +            fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n",
> > __func__,
> > +                    inet_strfamily(e->ai_family),
> > +                    e->ai_canonname, uaddr, uport,
> > strerror(errno));
> > +        }
> > +        closesocket(sock);
> >      }
> >      freeaddrinfo(res);


> > +
> > +err:
> > +    set_socket_error(-err);
> >      return -1;


> > +
> > +success:
> > +    freeaddrinfo(res);
> > +    set_socket_error(-err);
> > +    return sock;
> >  }
> >  
> >  int inet_dgram_opts(QemuOpts *opts)
> > @@ -449,14 +479,20 @@ int inet_listen(const char *str, char *ostr,
> > int olen,
> >      return sock;
> >  }
> >  
> > -int inet_connect(const char *str, int socktype)
> > +int inet_connect(const char *str, bool block)
> >  {
> >      QemuOpts *opts;
> >      int sock = -1;
> >  
> >      opts = qemu_opts_create(&dummy_opts, NULL, 0);
> > -    if (inet_parse(opts, str) == 0)
> > +    if (inet_parse(opts, str) == 0) {
> > +        if (block) {
> > +            qemu_opt_set(opts, "block", "on");
> > +        }
> >          sock = inet_connect_opts(opts);
> > +    } else {
> > +        set_socket_error(EINVAL);
> > +    }
> >      qemu_opts_del(opts);
> >      return sock;
> >  }
> > diff --git a/qemu_socket.h b/qemu_socket.h
> > index a4c5170..f86cd3f 100644
> > --- a/qemu_socket.h
> > +++ b/qemu_socket.h
> > @@ -47,7 +47,7 @@ int inet_listen_opts(QemuOpts *opts, int
> > port_offset);
> >  int inet_listen(const char *str, char *ostr, int olen,
> >                  int socktype, int port_offset);
> >  int inet_connect_opts(QemuOpts *opts);
> > -int inet_connect(const char *str, int socktype);
> > +int inet_connect(const char *str, bool block);
> >  int inet_dgram_opts(QemuOpts *opts);
> >  const char *inet_strfamily(int family);
> >  
> > diff --git a/ui/vnc.c b/ui/vnc.c
> > index deb9ecd..4a96153 100644
> > --- a/ui/vnc.c
> > +++ b/ui/vnc.c
> > @@ -3068,7 +3068,7 @@ int vnc_display_open(DisplayState *ds, const
> > char *display)
> >          if (strncmp(display, "unix:", 5) == 0)
> >              vs->lsock = unix_connect(display+5);
> >          else
> > -            vs->lsock = inet_connect(display, SOCK_STREAM);
> > +            vs->lsock = inet_connect(display, true);
> >          if (-1 == vs->lsock) {
> >              g_free(vs->display);
> >              vs->display = NULL;
> > 
> > 
> 
> --
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
Amos Kong - March 28, 2012, 2:36 a.m.
----- Original Message -----
> ----- Original Message -----
> > On 03/22/2012 05:52 AM, Amos Kong wrote:
> > > Change inet_connect(const char *str, int socktype) to
> > > inet_connect(const char *str, bool block),
> > > socktype is unused, block is used to assign if set socket
> > > to block/nonblock.



> > > Retry to connect when -EINTR/-EWOULDBLOCK is got.
> > > Connect's successful for nonblock socket when following
> > > errors are got:
> > >   -EINPROGRESS
> > >   -WSAEALREADY/-WSAEINVAL (win32)


      Retry to connect when -EINTR(win32 & posix)/-EWOULDBLOCK(only win32) is got.
      Connect's successful for nonblock socket when following
      errors are got:
          -EINPROGRESS
          -WSAEALREADY(win32)


Discussed with <mdroth> in IRC.
For win32, need to re-connect when EWOULDBLOCK is got.
(http://msdn.microsoft.com/en-us/library/windows/desktop/ms740668(v=vs.85).aspx)

For posix, it's safe to treat it as fail, otherwise, 
it might hang qemu on the order of seconds. (man 2 connect : EAGAIN)

For non-blocking socket, EINPROGRESS maybe got in (win32 & posix),
but WSAEALREADY can only be got after re-connecting 
(EWOULDBLOCK is got in first connecting)

Please correct me if something is wrong, thanks.

...

> > >      for (e = res; e != NULL; e = e->ai_next) {
> > > @@ -241,21 +248,44 @@ int inet_connect_opts(QemuOpts *opts)
> > >              continue;
> > >          }
> > >          setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(void*)&on,sizeof(on));
> > > -
> > > +        if (!block) {
> > > +            socket_set_nonblock(sock);
> > > +        }
> > >          /* connect to peer */
> > > -        if (connect(sock,e->ai_addr,e->ai_addrlen) < 0) {
> > > -            if (NULL == e->ai_next)
> > > -                fprintf(stderr, "%s: connect(%s,%s,%s,%s):
> > > %s\n",
> > > __FUNCTION__,
> > > -                        inet_strfamily(e->ai_family),
> > > -                        e->ai_canonname, uaddr, uport,
> > > strerror(errno));
> > > -            closesocket(sock);
> > > -            continue;
> > > +        do {
> > > +            err = 0;
> > > +            if (connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
> > > +                err = -socket_error();
> > > +            }
> > > +        } while (err == -EINTR || err == -EWOULDBLOCK);
> > > +
> > 
> > this is only relevant for non blocking socket
> 
> For blocking socket, if connect() is interrupted by a signal
> that is caught while blocked waiting to establish a connection,
> connect() shall fail and set errno to [EINTR]
> So just re-connect when EINTR/EWOULDBLOCK are set.
> 
> http://marc.info/?l=kvm&m=133238606300535&w=2
> 
> 
> > it should look something like this :
> > 
> > while ( (rc = connect(sock, e->ai_addr, e->ai_addrlen)) < 0 &&
> > !block
> > &&
> > 	(socket_error() == EINTR || socket_error() == -EWOULDBLOCK))
> 
> 
>   while ( (rc = connect(sock, e->ai_addr, e->ai_addrlen)) < 0  &&
>   	(socket_error() == EINTR || socket_error() == EWOULDBLOCK))
>         ;


        do {
                err = 0;
                if (rc = connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
                        err = -socket_error();
                }
#ifndef _WIN32
        } while (err == -EINTR || err == -EWOULDBLOCK);
#else
        } while (err == -EINTR);
#endif

        if (rc >= 0) {
                goto success;
        } else if (!block && err == -EINPROGRESS) {
                goto success;
#ifndef _WIN32
        } else if (!block && err == -WSAEALREADY) {
                goto success;
#endif
        }


> > > +        if (err >= 0) {
> > > +            goto success;
> > > +        } else if (!block && err == -EINPROGRESS) {
> > > +            goto success;
> > > +#ifdef _WIN32
> > > +        } else if (!block && (err == -WSAEALREADY || err ==
> > > -WSAEINVAL)) {
> > > +            goto success;
> > > +#endif
> > 
> > I prefer to check for error the code should look:
> >
> > 	if (rc < 0 &&  (block ||
> > #ifdef _WIN32
> > 	   (socket_error() != WSAEALREADY && socket_error() !=
> > 	   -WSAEINVAL))
> > 	   {
> > #else
> > 	(socket_error() != EINPROGRESS)) {
> > #endif
> > 	   if (NULL == e->ai_next)
> >                fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n",
> >                __func__,
> >                    inet_strfamily(e->ai_family),
> >                   e->ai_canonname, uaddr, uport, strerror(errno));
> > 	   closesocket(sock);
> > 	   continue;
> > 	}
> > ...
> > 
> > Orit
> > >          }
> > > -        freeaddrinfo(res);
> > > -        return sock;
> > > +
> > > +        if (NULL == e->ai_next) {
> > > +            fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n",
> > > __func__,
> > > +                    inet_strfamily(e->ai_family),
> > > +                    e->ai_canonname, uaddr, uport,
> > > strerror(errno));
> > > +        }
> > > +        closesocket(sock);
> > >      }
> > >      freeaddrinfo(res);
> 
> 
> > > +
> > > +err:
> > > +    set_socket_error(-err);
> > >      return -1;
> 
> 
> > > +
> > > +success:
> > > +    freeaddrinfo(res);
> > > +    set_socket_error(-err);
> > > +    return sock;
> > >  }

...

Patch

diff --git a/nbd.c b/nbd.c
index 567e94e..3618344 100644
--- a/nbd.c
+++ b/nbd.c
@@ -146,7 +146,7 @@  int tcp_socket_outgoing(const char *address, uint16_t port)
 
 int tcp_socket_outgoing_spec(const char *address_and_port)
 {
-    return inet_connect(address_and_port, SOCK_STREAM);
+    return inet_connect(address_and_port, true);
 }
 
 int tcp_socket_incoming(const char *address, uint16_t port)
diff --git a/qemu-sockets.c b/qemu-sockets.c
index 6bcb8e3..908479e 100644
--- a/qemu-sockets.c
+++ b/qemu-sockets.c
@@ -51,6 +51,9 @@  static QemuOptsList dummy_opts = {
         },{
             .name = "ipv6",
             .type = QEMU_OPT_BOOL,
+        },{
+            .name = "block",
+            .type = QEMU_OPT_BOOL,
         },
         { /* end if list */ }
     },
@@ -201,7 +204,8 @@  int inet_connect_opts(QemuOpts *opts)
     const char *port;
     char uaddr[INET6_ADDRSTRLEN+1];
     char uport[33];
-    int sock,rc;
+    int sock, rc, err;
+    bool block;
 
     memset(&ai,0, sizeof(ai));
     ai.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
@@ -210,9 +214,11 @@  int inet_connect_opts(QemuOpts *opts)
 
     addr = qemu_opt_get(opts, "host");
     port = qemu_opt_get(opts, "port");
+    block = qemu_opt_get_bool(opts, "block", 0);
     if (addr == NULL || port == NULL) {
         fprintf(stderr, "inet_connect: host and/or port not specified\n");
-        return -1;
+        err = -EINVAL;
+        goto err;
     }
 
     if (qemu_opt_get_bool(opts, "ipv4", 0))
@@ -224,7 +230,8 @@  int inet_connect_opts(QemuOpts *opts)
     if (0 != (rc = getaddrinfo(addr, port, &ai, &res))) {
         fprintf(stderr,"getaddrinfo(%s,%s): %s\n", addr, port,
                 gai_strerror(rc));
-	return -1;
+        err = -EINVAL;
+        goto err;
     }
 
     for (e = res; e != NULL; e = e->ai_next) {
@@ -241,21 +248,44 @@  int inet_connect_opts(QemuOpts *opts)
             continue;
         }
         setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,(void*)&on,sizeof(on));
-
+        if (!block) {
+            socket_set_nonblock(sock);
+        }
         /* connect to peer */
-        if (connect(sock,e->ai_addr,e->ai_addrlen) < 0) {
-            if (NULL == e->ai_next)
-                fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __FUNCTION__,
-                        inet_strfamily(e->ai_family),
-                        e->ai_canonname, uaddr, uport, strerror(errno));
-            closesocket(sock);
-            continue;
+        do {
+            err = 0;
+            if (connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
+                err = -socket_error();
+            }
+        } while (err == -EINTR || err == -EWOULDBLOCK);
+
+        if (err >= 0) {
+            goto success;
+        } else if (!block && err == -EINPROGRESS) {
+            goto success;
+#ifdef _WIN32
+        } else if (!block && (err == -WSAEALREADY || err == -WSAEINVAL)) {
+            goto success;
+#endif
         }
-        freeaddrinfo(res);
-        return sock;
+
+        if (NULL == e->ai_next) {
+            fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __func__,
+                    inet_strfamily(e->ai_family),
+                    e->ai_canonname, uaddr, uport, strerror(errno));
+        }
+        closesocket(sock);
     }
     freeaddrinfo(res);
+
+err:
+    set_socket_error(-err);
     return -1;
+
+success:
+    freeaddrinfo(res);
+    set_socket_error(-err);
+    return sock;
 }
 
 int inet_dgram_opts(QemuOpts *opts)
@@ -449,14 +479,20 @@  int inet_listen(const char *str, char *ostr, int olen,
     return sock;
 }
 
-int inet_connect(const char *str, int socktype)
+int inet_connect(const char *str, bool block)
 {
     QemuOpts *opts;
     int sock = -1;
 
     opts = qemu_opts_create(&dummy_opts, NULL, 0);
-    if (inet_parse(opts, str) == 0)
+    if (inet_parse(opts, str) == 0) {
+        if (block) {
+            qemu_opt_set(opts, "block", "on");
+        }
         sock = inet_connect_opts(opts);
+    } else {
+        set_socket_error(EINVAL);
+    }
     qemu_opts_del(opts);
     return sock;
 }
diff --git a/qemu_socket.h b/qemu_socket.h
index a4c5170..f86cd3f 100644
--- a/qemu_socket.h
+++ b/qemu_socket.h
@@ -47,7 +47,7 @@  int inet_listen_opts(QemuOpts *opts, int port_offset);
 int inet_listen(const char *str, char *ostr, int olen,
                 int socktype, int port_offset);
 int inet_connect_opts(QemuOpts *opts);
-int inet_connect(const char *str, int socktype);
+int inet_connect(const char *str, bool block);
 int inet_dgram_opts(QemuOpts *opts);
 const char *inet_strfamily(int family);
 
diff --git a/ui/vnc.c b/ui/vnc.c
index deb9ecd..4a96153 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -3068,7 +3068,7 @@  int vnc_display_open(DisplayState *ds, const char *display)
         if (strncmp(display, "unix:", 5) == 0)
             vs->lsock = unix_connect(display+5);
         else
-            vs->lsock = inet_connect(display, SOCK_STREAM);
+            vs->lsock = inet_connect(display, true);
         if (-1 == vs->lsock) {
             g_free(vs->display);
             vs->display = NULL;