Re: [Qemu-devel] [PATCH v5 2/4] qemu-socket: change inet_connect() to to support nonblock socket

[Amos Kong]

----- 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 <address@hidden>
> > ---
> >  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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