InfoMagic Internet Tools 1995 April/Internet Tools.iso/dos_win/winsock/FAQ

Text File | 1994-09-05 | 15.4 KB | 379 lines

           Frequently Asked Questions About
             Windows Sockets Version 1.1
                  6 Sep 1994

  This FAQ has been put together by Mark Towfiq, with much-appreciated
assistance from Jay Allard, Bruce Backman, Paul Brooks, Mark Fisher,
Martin Hall, Simon Hewison, Mike Morse, Bob Quinn, Ed Schwalenberg,
J. Daniel Smith, Bill Tang, Dave Treadwell, and Fred Whiteside.  If
you have any modifications to this FAQ, send them to
[e-mail], and I will fold them into the next revision.

  First of all, the questions:

1.    What is Windows Sockets?
2.    What is the latest version?
3.    When is the next rev of the specification?  Why not sooner?
4.    Where can I get a/the WINSOCK.DLL?
5.    Why isn't there just one WINSOCK.DLL?  Do I need a TCP/IP already to
      use it?
6.    Where can I contact Windows Sockets application and implementation
      vendors?  (include list of address, phone contacts)
7.    Where can I get sample apps and tests?
8.    Will Windows Sockets be in _____?
8.1.  Will Windows Sockets be in Windows NT?
8.2.  Will Windows Sockets be in Windows for Workgroups?
8.3.  Will Windows Sockets be in DOS?
8.4.  Will Windows Sockets be in Unix?
8.5.  Will Windows Sockets be in Win32s?
9.    What about standard APIs for ____?
9.1.  What about standard APIs for FTP?
9.2.  What about standard APIs for Telnet?
9.3.  What about standard APIs for SNMP?
9.4.  What about standard APIs for RPC?
9.5.  What about standard APIs for TLI/XTI?
10.   Does Windows Sockets work over protocols other than TCP/IP?
11.   Why no SOCK_RAW?
12.   Why isn't it possible to share sockets between tasks?
13.1. How do I get my IP address?
13.2. Why no SIOCGIFADDR?
14.   When should I use blocking vs. nonblocking sockets?
15.   What about other socket options that BSD supports?  Ioctls?
16.   How can I get the local username?
17.   Do I need to initialize the WSAData structure before calling
      WSAStartup?
18.   If I write a Windows Sockets program for DOS, will I be able to
      communicate with a Sockets program on UNIX?
19.   Is it possible to create sockets that map to a dll rather than an
      application?  I have tried a WSAStartup() as part of my LibMain, but
      the sockets that are created are owned by the application, not by the
      DLL. It would be desirable for me to have some of the sockets that
      are opened have "A Global (DLL wide) Scope".
20.   A *Class* of questions that could be answered are related to porting
      extant BSD applications to Windows Sockets: "How to I implement the
      xxxx function call in my Windows Sockets application?" (e.g. fcntl(),
      readv(), etc).
21.   Is there a Pascal/Visual Basic/Visual Cobol header file for Windows
      Sockets?
----------------------------------------------------------------------
1.  What is Windows Sockets?

Answer: The Windows Sockets specification defines a network programming
interface for Microsoft Windows which is based on the "socket" paradigm
popularized in the Berkeley Software Distribution (BSD) from the University
of California at Berkeley.  It encompasses both familiar Berkeley socket
style routines and a set of Windows-specific extensions designed to allow
the programmer to take advantage of the message-driven nature of Windows.

The Windows Sockets Specification is intended to provide a single API to
which application developers can program and multiple network software
vendors can conform.  Furthermore, in the context of a particular version
of Microsoft Windows, it defines a binary interface (ABI) such that an
application written to the Windows Sockets API can work with a conformant
protocol implementation from any network software vendor.  This
specification thus defines the library calls and associated semantics to
which an application developer can program and which a network software
vendor can implement.

Network software which conforms to this Windows Sockets specification will
be considered "Windows Sockets Compliant".  Suppliers of interfaces which
are "Windows Sockets Compliant" shall be referred to as "Windows Sockets
Suppliers".  To be Windows Sockets Compliant, a vendor must implement 100%
of this Windows Sockets specification.

Applications which are capable of operating with any "Windows Sockets
Compliant" protocol implementation will be considered as having a "Windows
Sockets Interface" and will be referred to as "Windows Sockets
Applications".

2.  What is the latest version?

Answer: The latest version of the specification is 1.1.

3.  When is the next rev of the specification?

Answer: The next rev. (2.0) is actively being worked on.  You may want
to subscribe to any of the Windows Sockets 2.0 mailing lists:

    From: Dave B. Andersen, Intel Architecture Labs
    Subject: Winsock 2 mailing lists

    For those of you that have not otherwise been notified,
    a set of mailing lists have been set up for Winsock 2
    discussions.  These are located on mailbag.intel.com.

    To get a list of the mailing list names and to learn how
    to subscribe, send email to [e-mail].
    Leave the subject blank, and include the following
    commands on separate lines in the body:
        lists
        help

    The majordomo program will respond with email that provides
    the requested information.

    I would encourage all of you to subscribe to the list(s) of
    your choice so that we can continue in earnest the work of
    defining Winsock version 2.

4.  Where can I get a/the WINSOCK.DLL?

Answer: You can most probably get one from the same place you got your
TCP/IP software from.

5.  Why isn't there just one WINSOCK.DLL?  Do I need a TCP/IP already
    to use it?

Answer: The Windows Sockets specification defines the top level of the DLL,
the part which is called by user programs.  The method a given WINSOCK.DLL
will use to access TCP/IP (or NetWare, or AppleTalk, or DECNet ...) depends
on the networking package you have installed, and therefore must vary.  A
WINSOCK.DLL is therefore just an interface to whatever existing protocol
you already have installed.  An illustration would help:

       +---------------------------------+
       |  WinSock compliant application  |
       +---------------------------------+
       +---------------------------------+ <--- WinSock API
       |       Windows Sockets DLL       |
       +---------------------------------+
       +---------------------------------+ <--- Protocol Stack API
       |   Protocol Stack (e.g. TCP/IP)  | (typically proprietary)
       +---------------------------------+
       +---------------------------------+ <--- Hardware Driver API
       |        Hardware Driver          |   (Packet Driver, NDIS, ODI,
       +---------------------------------+    or proprietary)
       +---------------------------------+ <--- Hardware Interface
       |   Network (hardware) Interface  |    (hardware specific)
       +---------------------------------+
                       |
                       +----> network

6.  Where can I contact Windows Sockets application and implementation
vendors?  (include list of address, phone contacts)

Answer:

    Date: Tue, 6 Apr 93 12:53:37 PDT
    From: [e-mail] (Bill Tang)
    To: [e-mail]
    Subject: vendor list (long)

    Thanks to all that responded to my previous inquiry of vendor
    implementations. I am posting a summary and will keep the list updated
    if I receive more information.
    -------------------------------------------------------------------------
    SUMMARY
    -------------------------------------------------------------------------
    Company            Shipping?   Notes
    -------------------------------------------------------------------------
    3Com Corp            Yes
    Beame & Whiteside        Yes
    Bristol Technology        Yes        Unix Winsock part of Wind/U product.
                        [phone] or [e-mail]
    Distinct Corp        Yes
    FTP Software        Yes        DLL available from
                        vax.ftp.com:/pub/winsockapi
    Frontier Tech        Yes
    IBM                Yes
    JSB Corporation        Yes
    Lan Design            Yes
    Lanera Corp            Yes
    Microdyne            Yes
    Microsoft(W NT 32b)        Yes
    Microsoft(W NT 16b)        Yes
    Microsoft(W 3.x 16b)    ???
    NetManage            Yes
    Network Research        ???
    Novell            Yes        DLL available from
                        ftp.novell.com:
                        /pub/lanworkplace/lwp4dos/WinSock
    Persoft            Yes        Contact Rhonda Harris at
                        [e-mail]
                        or [phone].
    Spry            Yes
    SunSelect            Yes
    Ungermann Bass        Yes
    Walker Richer Quinn        Yes
    Wollongong            Yes

7.  Where can I get sample applications and tests?

Answer: Files and information related to the Windows Sockets API are
available via FTP (user: "anonymous", password: your e-mail address)
on the host SunSite.UNC.EDU, in /pub/micro/pc-stuff/ms-windows/winsock.
Note: if you do not have FTP access to the Internet, send a message
with the word "help" in the body to either [e-mail], or
[e-mail] (in the UK mail to [e-mail]), to
obtain information about the FTP to Mail service there.

8.  Will Windows Sockets be in _____?

8.1.  Will Windows Sockets be in Windows NT?

Answer: Yes.  In 16 and 32-bit versions.

8.2.  Will Windows Sockets be in Windows for Workgroups?

Answer: Yes.

8.3.  Will Windows Sockets be in DOS?

Answer: Paul Brooks of TurboSoft ([e-mail]) tells me:

    As for a Windows Sockets for DOS - we have a library that is
    pretty much complete. The goal was to produce a DOS library and
    Binary API which would allow developers to code applications using
    the Windows Sockets 1.1 spec. and have it run exactly the same
    under DOS as Windows - blocking and non-blocking modes,
    Asynchronous calls, the works. Apart from some AsyncGetXXXbyYYY
    calls the rest works, although it is not possible to capture all
    the Windows-specific semantics of some areas.

I am sure you can contact him for more information.  JSB also has a
standardized Berkeley Sockets API for DOS which provides access to all
TCP/IP implementations.

8.4.  Will Windows Sockets be in UNIX?

Answer: Because the syntax and semantics of the Winsock specification
differ enough from standard BSD sockets, UNIX Winsock implementations
are now appearing.

8.5.  Will Windows Sockets be in Win32-S?

Answer: Yes, Win32s 1.1 contains a thunking layer that converts 32-bit
Windows Sockets calls to 16-bit Windows Sockets.  It should work on
top of any 16-bit WINSOCK.DLL.

9.  What about standard APIs for ____?

9.1.  What about standard APIs for FTP?

Answer: Not yet.

9.2 What about standard APIs for Telnet?

Answer: Not yet.

9.3 What about standard APIs for SNMP?

Answer: In the works.  Send e-mail to [e-mail] with
"subscribe winsnmp" in the body of the message to join the list.

9.4 What about standard APIs for RPC?

Answer: Microsoft will be providing an implementation of DCE RPC.  Also in
the works is the definition of a standard implementation of ONC RPC (known
as RPC for Windows) which will be made available by multiple vendors.  To
contribute to the discussion, send email to [e-mail].

9.5 What about standard APIs for TLI/XTI?

Answer: No, not yet.  Vendors chose to do Windows Sockets because of the
sockets application and knowledge base, however anyone out there is free to
try a Windows TLI/XTI Specification.

10.  Does Windows Sockets work over protocols other than TCP/IP?

Answer: Yes, it does.  For example, DEC PathWorks v5.0 supplies both
TCP/IP and DECNet via WinSock, and Windows NT includes mechanisms for
multiple protocol support in Windows Sockets, both 32-bit and 16-bit.

11.  Why no SOCK_RAW?

Answer: SOCK_RAW is optionally implemented by many major Windows Sockets
vendors.  It is not mandated now because: 1) not every stack vendor can
supply a complete SOCK_RAW interface, and 2) we did not have time to define
the minimal subset every vendor could provide (e.g. maybe just ICMP).

12.  Why isn't it possible to share sockets between tasks?

Answer: The real answer is that it wasn't considered sufficiently important
for 1.1, but is high on the list for inclusion in 2.0.

13.1.  How do I get my IP address?

Answer: Do a gethostbyname() on the output from gethostname().

13.2.  Why no SIOCGIFADDR?

Answer: It was not included because there were concerns it could not be
supported across platforms.  It may be included in version 2.0 of the spec.

14.  When should I use blocking vs. non-blocking sockets?

Answer: Try to use non-blocking sockets whenever possible; certainly if you
are coding a Windows application from scratch.  Blocking sockets should
only be used when trying to maintain portability between UNIX/MS-DOS and
Windows.

15.  What about other socket options that BSD supports?  Ioctls?

Answer: Some vendors may support them.  Do not rely on ones not explicitly
mentioned in the specification, however.

16.  How can I get the local username?

Answer: Based on a suggestion from Simon Hewison
([e-mail]), one idea is to call WNetGetUser()
in the NETWORK.DRV.  If a vendor has supplied a NETWORK.DRV then this
will work, if not you can just use some other method.  Thus you could
write a bit of code thus:

    WNetGetUser(szNetUserId,sizeof(szNetUserId);
    if (strlen(szNetUserId)==0) {
        /* call some other method of getting
           userid, eg. the lan manager call NetWkstaGetInfo */
    }

  Information on this API call is in the Windows Device Driver Adaption
Guide.

17.  Do I need to initialize the WSAData structure before calling
WSAStartup?

Answer: No, WSAStartup does not retrieve the contents of the WSAData
structure pointed to, it fills it in.

18.  If I write a Windows Sockets program, will I be able to communicate
with a Sockets program on UNIX or any other non Windows platform?

Answer: Absolutely!  This common question is the result of confusing
protocols with the APIs; communicating programs need not have been
created with the same APIs, as long as they are using the same
(transport & network) protocols.

19.  Is it possible to create sockets that map to a dll rather than an
application?  I have tried a WSAStartup() as part of my LibMain, but the
sockets that are created are owned by the application, not by the DLL. It
would be desirable for me to have some of the sockets that are opened have
"A Global (DLL wide) Scope".

Answer: The way this situation has been dealt with by developers is to have
your DLL create a "helper process" which will perform all Windows Sockets
operations on behalf of your applications (thereby having all sockets owned
by the helper process' task).

20.  A *Class* of questions that could be answered are related to porting
extant BSD applications to Windows Sockets: "How to I implement the xxxx
function call in my Windows Sockets application?" (e.g. fcntl(), readv(),
etc).

Answer: In general, you will have to code such functions yourself, although
it would not hurt to suggest them for the next revision of the
specification as well.

21.  Is there a Pascal/Visual Basic/Visual Cobol header file for Windows
Sockets?

Answer: The Pascal and Visual Basic forms are already in the FTP
archive.  Look there for any other header files that people may have
developed so far.  It should be pointed out that not all the Winsock
functions can be called from Visual Basic and the subset that can be
called are not really enough for a true app (for example, you can't
call gethostbyname()).  To use Winsock from VB requires a translation
DLL that will probably have to be written in C.  To date, there is no
public domain implementation, although several vendors have announced
toolkits for Winsock for VB.