Patchwork [v7,2/4] sockets: change inet_connect() to support nonblock socket

Add a bool argument to inet_connect() to assign if set socket
to block/nonblock, and delete original argument 'socktype'
that is unused.
Add a new argument to inet_connect()/inet_connect_opts(),
to pass back connect error by error class.

Retry to connect when -EINTR is got. Connect's successful
for nonblock socket when following errors are got, user
should wait for connecting by select():
  -EINPROGRESS
  -EWOULDBLOCK
  -WSAEALREADY (win32)

Change nbd, vnc to use new interface.

Signed-off-by: Amos Kong <akong@redhat.com>
---
 nbd.c          |    2 +-
 qemu-char.c    |    2 +-
 qemu-sockets.c |   46 +++++++++++++++++++++++++++++++++++++++-------
 qemu_socket.h  |    6 ++++--
 ui/vnc.c       |    2 +-
 5 files changed, 46 insertions(+), 12 deletions(-)

On Thu, Apr 19, 2012 at 03:11:34PM +0800, Amos Kong wrote:
> Add a bool argument to inet_connect() to assign if set socket
> to block/nonblock, and delete original argument 'socktype'
> that is unused.
> Add a new argument to inet_connect()/inet_connect_opts(),
> to pass back connect error by error class.
> 
> Retry to connect when -EINTR is got. Connect's successful
> for nonblock socket when following errors are got, user
> should wait for connecting by select():
>   -EINPROGRESS
>   -EWOULDBLOCK
>   -WSAEALREADY (win32)
> 
> Change nbd, vnc to use new interface.
> 
> Signed-off-by: Amos Kong <akong@redhat.com>
> ---
>  nbd.c          |    2 +-
>  qemu-char.c    |    2 +-
>  qemu-sockets.c |   46 +++++++++++++++++++++++++++++++++++++++-------
>  qemu_socket.h  |    6 ++++--
>  ui/vnc.c       |    2 +-
>  5 files changed, 46 insertions(+), 12 deletions(-)
> 
> diff --git a/nbd.c b/nbd.c
> index 406e555..bb71f00 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, NULL);
>  }
> 
>  int tcp_socket_incoming(const char *address, uint16_t port)
> diff --git a/qemu-char.c b/qemu-char.c
> index 74c60e1..aeee2e8 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2444,7 +2444,7 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
>          if (is_listen) {
>              fd = inet_listen_opts(opts, 0);
>          } else {
> -            fd = inet_connect_opts(opts);
> +            fd = inet_connect_opts(opts, NULL);
>          }
>      }
>      if (fd < 0) {
> diff --git a/qemu-sockets.c b/qemu-sockets.c
> index 6bcb8e3..a761ef6 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 */ }
>      },
> @@ -194,14 +197,15 @@ listen:
>      return slisten;
>  }
> 
> -int inet_connect_opts(QemuOpts *opts)
> +int inet_connect_opts(QemuOpts *opts, Error **errp)
>  {
>      struct addrinfo ai,*res,*e;
>      const char *addr;
>      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;
> @@ -210,8 +214,10 @@ 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");
> +        error_set(errp, QERR_SOCKET_CREATE_FAILED);
>          return -1;
>      }
> 
> @@ -224,6 +230,7 @@ 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));
> +        error_set(errp, QERR_SOCKET_CREATE_FAILED);
>  	return -1;
>      }
> 
> @@ -241,19 +248,38 @@ 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) {
> +        do {
> +            err = 0;
> +            if (connect(sock, e->ai_addr, e->ai_addrlen) < 0) {
> +                err = -socket_error();
> +            }
> +        } while (err == -EINTR);
> +
> +        if (!block && (err == -EINPROGRESS || err == -EWOULDBLOCK

I don't think EWOULDBLOCK is synonymous with EINPROGRESS, in the past I
think we decided EWOULDBLOCK should just generate an error. Orit's
comments were regarding WIN32 only, where WSAEWOULDBLOCK *is* synonymous
with EINPROGRESS. But I don't think map strictly to EWOULDBLOCK.

So I'd let just let EWOULDBLOCK fall through to CONNECT_FAILED path, and add
a check for WSAEWOULDBLOCK to your WSAEALREADY check below.

> +  #ifdef _WIN32
> +                       ||  err == -WASALREADY)) {

That should be WSAEALREADY.

> +  #else
> +            )) {

This is a bit hard to read. I'd rather be redundant and just write out
the whole if statement for both the _WIN32 and !_WIN32 cases

> +  #endif
> +            error_set(errp, QERR_SOCKET_CONNECT_IN_PROGRESS);
> +        }
> +        if (err < 0 && !error_is_type(*errp, QERR_SOCKET_CONNECT_IN_PROGRESS)) {
>              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);
> +            sock = -1;
>              continue;
>          }
>          freeaddrinfo(res);
>          return sock;
>      }
> +    error_set(errp, QERR_SOCKET_CONNECT_FAILED);
>      freeaddrinfo(res);
>      return -1;
>  }
> @@ -449,14 +475,20 @@ 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, Error **errp)
>  {
>      QemuOpts *opts;
>      int sock = -1;
> 
>      opts = qemu_opts_create(&dummy_opts, NULL, 0);
> -    if (inet_parse(opts, str) == 0)
> -        sock = inet_connect_opts(opts);
> +    if (inet_parse(opts, str) == 0) {
> +        if (block) {
> +            qemu_opt_set(opts, "block", "on");
> +        }
> +        sock = inet_connect_opts(opts, errp);
> +    } else {
> +        error_set(errp, QERR_SOCKET_CREATE_FAILED);
> +    }
>      qemu_opts_del(opts);
>      return sock;
>  }
> diff --git a/qemu_socket.h b/qemu_socket.h
> index a5d0a84..26998ef 100644
> --- a/qemu_socket.h
> +++ b/qemu_socket.h
> @@ -27,6 +27,8 @@ int inet_aton(const char *cp, struct in_addr *ia);
>  #endif /* !_WIN32 */
> 
>  #include "qemu-option.h"
> +#include "error.h"
> +#include "qerror.h"
> 
>  /* misc helpers */
>  int qemu_socket(int domain, int type, int protocol);
> @@ -40,8 +42,8 @@ int send_all(int fd, const void *buf, int len1);
>  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_opts(QemuOpts *opts, Error **errp);
> +int inet_connect(const char *str, bool block, Error **errp);
>  int inet_dgram_opts(QemuOpts *opts);
>  const char *inet_strfamily(int family);
> 
> diff --git a/ui/vnc.c b/ui/vnc.c
> index deb9ecd..3ae7704 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, NULL);
>          if (-1 == vs->lsock) {
>              g_free(vs->display);
>              vs->display = NULL;
>