Re: PB 4.1 - how to FTP without WinInet library ?

From: John Spaith [MS] (jspaith_at_ONLINE.microsoft.com)
Date: 02/16/04 

Date: Mon, 16 Feb 2004 15:55:04 -0800

Though it's not related to this problem, you want to be careful with 'CHAR
pBuffer[4000]' in any event. Individual functions with stacks > 4KB on
WinCE can cause real problems if you exhaust the stack space. Normally if
you run out of stack the system generates an exception, but if it's >4KB
system may not catch it and you can really trounce things badly and have no
idea what went wrong.

With regards to the dwBytesRead not being equal to the bytes that you set, I
don't know what Wininet's behavior is in this case. For httplite, however,
I simply call Winsock recv() and read in as much data as I can - up to the
size of the buffer passed me. I do not call recv() multiple times if there
is more buffer left to fill up. It's possible that on a slow link that <
4KB of data was available to be read in this scenario. So for httplite at
least, checking when the bytes returned = 0 is the safe approach.

There is not a max buffer size that httplite supports. It will take what
you give it and pretty much pass that directly to recv(). 

-- 
John Spaith
Software Design Engineer, Windows CE
Microsoft Corporation
This posting is provided "AS IS" with no warranties, and confers no rights.
You assume all risk for your use. © 2003 Microsoft Corporation. All rights
reserved.
"sergei" <anonymous@discussions.microsoft.com> wrote in message
news:163301c3f49a$fc25c320$3501280a@phx.gbl...
Hi John,
I've done some testing using your example using our CE 4.1
image, which is equipped with Httplite dll. Your exact
example works as it was designed, though I have some
concern, which may help to nail down the problem.
In the code you check for success of function
InternetReadFile() and then also check for another
condition
...
if (dwBytesRead == 0) {
...
comparing it with 0. I have made slight modification of
this test condition to compare actual bytes read with
bytes requested, and not with zero. Like in below
...
if(dwBytesRead!=cBufferSize)
{
// all done ??
            break;
};
...
what I have found then is the situation when while
InternetReadFile() returns success, the dwBytesRead!
=cBufferSize. The key in my tests was the buffer size used
with Httplite function InternetReadFile().
It works when CHAR pBuffer[1000] and it does not when it
is CHAR pBuffer[4000].
Maybe this will not confirm the problem of or a feature of
Httplite DLL in your test scenario.
Please let me know if this would be confirmed or not, so I
could change the code to be sure what the maximum buffer
size supported is.
Best regards
Sergei
>-----Original Message-----
>Sergei,
>
>Even though httplite isn't officially supported, I do fix
bugs in it when we
>find out about them.  I wrote a small program to simulate
what you were
>doing here to try and reproduce and fix this problem.
However I could not
>reproduce the issues you were seeing.  I am running my
program on a CEPC x86
>debug, CE 5.0.  FTP Server I am communicating with is IIS
5.1 on WinXP.
>Httplite hasn't changed that much between CE 5.0 & 4.1
and I don't think
>that anything in underlying net stack would be this
broken in CE 4.1 to
>cause you problems.
>
>Here is my code, if it helps out any.  I couldn't figure
out what you were
>doing the FindFirstFile on so I guessed, though this
shouldn't be the root
>of the problems.
>
>If you cannot get this code to work on your platform I'm
afraid I can't help
>you much more.  If you can get it going enjoy.  Also in
the event you get it
>working, if you can track down what the difference
between my code and yours
>that is causing problems and let me know what it is, I
may be able to fix it
>in a future httplite.
>
>Good luck!
>
>int
>WINAPI
>WinMain(HINSTANCE hInstance,
>  HINSTANCE hPrevInstance,
>  LPWSTR    lpCmdLine,
>  int       nCmdShow)
>{
> HINTERNET hFtp = InternetOpenW
(NULL,INTERNET_OPEN_TYPE_DIRECT,NULL,NULL,0);
> if (hFtp == 0) {
>  wprintf(L"InternetOpen failed, GLE=0x%
08x\r\n",GetLastError());
>  return 0;
> }
>
> HINTERNET hConn =
>InternetConnectW
(hFtp,cszHostName,INTERNET_INVALID_PORT_NUMBER,
>
>L"anonymous",L"abcd",INTERNET_SERVICE_FTP,
>
INTERNET_FLAG_PASSIVE,0);
> if (hConn == 0) {
>  wprintf(L"InternetConnect failed, GLE=0x%
08x\r\n",GetLastError());
>  return 0;
> }
>
> WIN32_FIND_DATA findData;
>
> HINTERNET hFindFile = FtpFindFirstFileW
(hConn,L"temp.txt",&findData,0,0);
> if (hFindFile == 0)  {
>  wprintf(L"FtpFindFirstFileW failed, GLE=0x%
08x\r\n",GetLastError());
>  return 0;
> }
>
> HINTERNET hOpen =
>FtpOpenFileW
(hConn,L"temp.txt",GENERIC_READ,FTP_TRANSFER_TYPE_BINARY |
>INTERNET_FLAG_RELOAD,0);
> if (hFindFile == 0)  {
>  wprintf(L"FtpOpenFileW failed, GLE=0x%
08x\r\n",GetLastError());
>  return 0;
> }
>
> DWORD dwTotalBytes = 0;
>
> while (1) {
>  CHAR pBuffer[1000];
>  DWORD cBufferSize = sizeof(pBuffer);
>  DWORD dwBytesRead = 0;
>
>  if (! InternetReadFile(hOpen, pBuffer, cBufferSize,
&dwBytesRead)) {
>   wprintf(L"InternetReadFile failed, GLE=0x%
08x\r\n",GetLastError());
>   return 0;
>  }
>
>  dwTotalBytes += dwBytesRead;
>
>  if (dwBytesRead == 0) {
>   wprintf(L"InternetReadFile returned 0 bytes.  Total
Bytes read =
>%d\r\n",dwTotalBytes);
>   return 0;
>  }
> }
>}
>
>
>-- 
>John Spaith
>Software Design Engineer, Windows CE
>Microsoft Corporation
>
>This posting is provided "AS IS" with no warranties, and
confers no rights.
>You assume all risk for your use. © 2003 Microsoft
Corporation. All rights
>reserved.
>
>"SergeiR" <anonymous@discussions.microsoft.com> wrote in
message
>news:bb2c01c3ecb9$77e706c0$a401280a@phx.gbl...
>Hi John!
>
>Thanks for the prompt reply. The source code in the
>suggested ftpupdate.cpp file is quite similar to mine, but
>with the difference in creating of new, temporary file on
>disk first.
>
>We can't do that due to the fact that there is lack of
>that disk space on CF on that small device. So I went with
>the version similar to what ftpudate.cpp does, but with no
>temporary file, just read block after block from FTP
>server into a memory buffer, and then, if all went okay,
>write file to CF (or overwrite is that's the case).
>
>And this my approach works fine with WinInet. So maybe
>Httplite is somewhat different and this doesn't work.
>
>At this moment we don't know yet if management will choose
>to pursue this direction further and troubleshoot the
>problem with Httplite dll, or divert to another direction
>and choose an alternative method ( without FTP).
>
>Best regards
>Sergei
>
>>-----Original Message-----
>>Hi,
>>
>>I've looked over your code below and I can't see what's
>causing the
>>problems.  As Mark said, unfortunately HttpLite is
>officially unsupported.
>>In the future we do planning on actually supporting and
>documenting it, but
>>we can't presently.
>>
>>However, we have an application named FtpUpdate that
>downloads new images to
>>CE devices that uses the FTP functionality of httplite.
>It is shipped in
>>Platform Builder in %_WINCEROOT%
>\public\wceshellfe\oak\FTPUpdate.  The only
>>suggestion I can give you would be to check out the FTP
>specific source code
>>in this dir and try to and copy and paste it into your
>program and hope that
>>that code path makes everything just work.
>>
>>Hope this helps and good luck!
>>
>>-- 
>>John Spaith
>>Software Design Engineer, Windows CE
>>Microsoft Corporation
>>
>>This posting is provided "AS IS" with no warranties, and
>confers no rights.
>>You assume all risk for your use. © 2003 Microsoft
>Corporation. All rights
>>reserved.
>>
>><anonymous@discussions.microsoft.com> wrote in message
>>news:a95f01c3ebe2$f128b920$a501280a@phx.gbl...
>>> Hi Mark !
>>>
>>> Thanks a lot for the tip! It really saves lots of work.
>>>
>>> I have followed your directions, and quite succeded,
>>> but ...
>>>
>>> So let me check with you whether or not I have made it
>>> through.
>>>
>>> a) my code comments out #include "wininet.h" and
replace
>>> it with #include "dubinet.h"
>>>
>>> b)inside dubinet.h file, located at
>>> C:\WINCE410\PUBLIC\COMMON\OAK\INC
>>>
>>> I look for a line with "CESYSGEN IF DUBINET_DUBFTP" and
>>> for another line with " "
>>>
>>> and they are
>>>
>>> 1173 : // @CESYSGEN IF DUBINET_DUBFTP
>>> 1437 : // @CESYSGEN ENDIF
>>>
>>> so they are both commented out ! Well, delete them
>anyway
>>> as you direct.
>>>
>>> c) go to the cesysgen.bat file for my project in
>>> C:\WINCE410\PUBLIC\EmCORE_minimal\WINCE410
>\Geode\oak\MISC
>>> and insert the two lines in the beginning of it, i.e.
>line
>>> numbers are 54 and 55
>>>
>>> d)do a full command line rebuild, followed by a
>>> RebuildPlatform command from PB 4.1
>>>
>>> e) observe the appearance of the httplite.dll in the
>>> Release build of the project !
>>>
>>> Looks great ! It is just 69kbytes, very good !
>>>
>>> f) test the newly build dll.
>>>
>>> Well, things went wrong here ...
>>>
>>> LoadLibrary(httplite.dll) - success
>>> InternetOpenW()- success
>>> InternetConnectW(hInet, v_szServerName,
>>>
>>> INTERNET_INVALID_PORT_NUMBER,
>>> m_tszLoginName, // LPCTSTR lpszUserName
>>>
>>> m_tszPassword, // LPCTSTR lpszPassword
>>>                             INTERNET_SERVICE_FTP,
>>>
>>> INTERNET_FLAG_PASSIVE, 0)) - sucess
>>>
>>> FtpFindFirstFileW(hFTP, v_szSourceName, &FindFileData,
>>>
>>> INTERNET_FLAG_NO_CACHE_WRITE, 0) - success
>>> FtpOpenFileW(hFTP, v_szSourceName, GENERIC_READ,
>>>                          FTP_TRANSFER_TYPE_BINARY |
>>> INTERNET_FLAG_RELOAD,
>>>                          0) - susccess
>>> InternetReadFile(hOpen, pBuffer, cBufferSize,
>>>
>>> &dwBytesRead) - returns success several
>>> times, but after several blocks downloaded the number
of
>>> bytes read is not what was requested. GetLastError()
>>> returns 0 ... It only gets a small portion of a
file ...
>>>
>>> can't find where the problem is. Mark, did all the
>>> functions from Httplite.dll work well for you ?
>>>
>>> I have no problems using exact same code with
>Wininet.dll.
>>> Should the code be different for httplite.dll ??
>>>
>>> Best regards
>>> Sergei
>>>
>>> >-----Original Message-----
>>> >Hey Sergei.  Don't go implementing a whole new FTP
>client
>>> just yet.
>>> >
>>> >We had the same problem.  We have a headless
>>> configuration, and we made
>>> >heavy use of WinInet in a 2.11 platform.  When we
moved
>>> to 2.12, WinInet
>>> >became part of IE.  Luckily, we found that the
>>> functionality was still
>>> >available through "dubinet."  Unfortunately, "dubinet"
>>> went away with CE
>>> >3.0.
>>> >
>>> >Luckily, it looks like all of that functionality came
>>> back in httplite in CE
>>> >4.0, and we're actively using it in a product running
>CE
>>> 4.20.  We haven't
>>> >had any problems with it yet.  The only thing we had
to
>>> do, at the
>>> >recommendation of a Microsoft developer, was make a
>>> slight modification to
>>> >the file "\public\common\oak\inc\dubinet.h."  You need
>to
>>> remove the two
>>> >"CESYSGEN IF DUBINET_DUBFTP" tags, or you won't get
>>> proper prototypes for
>>> >the FTP functionality.  Then, we just added the two
>>> following lines to our
>>> >cesysgen.bat file:
>>> >
>>> >set __SYSGEN_HTTPLITE=1
>>> >set __SYSGEN_HTTPLITE_FTP=1
>>> >
>>> >Rebuild, link the "httplite.lib" import library to our
>>> app, include
>>> >"dubinet.h", and we were rolling.
>>> >
>>> >I know the modifications to the public\common file
>suck,
>>> but we couldn't
>>> >find a better way, short of redefining all of those
>>> prototypes ourselves.
>>> >Try it.  It works.
>>> >
>>> >Mark Murawski
>>> >Vocollect, Inc.
>>> >
>>> >"sergeir" <anonymous@discussions.microsoft.com> wrote
>in
>>> message
>>> >news:945401c3eaf2$f6b3ce70$a101280a@phx.gbl...
>>> >> Thanks Maxim for the idea. Unless there is another
>>> >> solution found ( either some handcraft play around
PB
>>> or a
>>> >> third party library), we could think about it.
>>> >>
>>> >> You mean by using ws2.dll ( and .lib), right ?
>>> >>
>>> >> Anyone who are using CE httplite library please
>advise !
>>> >>
>>> >>
>>> >> Sincerely
>>> >> Sergei
>>> >>
>>> >> >Implement the FTP protocol yourself on top of
>sockets -
>>> >> not this huge a task,
>>> >> >provided you will need a subset only.
>>> >> >Get the appropriate RFC and start coding.
>>> >> >
>>> >> >-- 
>>> >> >Maxim Shatskih, Windows DDK MVP
>>> >> >StorageCraft Corporation
>>> >> >maxim@storagecraft.com
>>> >> >http://www.storagecraft.com
>>> >>
>>> >>
>>> >> >-----Original Message-----
>>> >> >> Is there another way to still use FTP simple
>>> functions
>>> >> >> available but do not include this huge
>WinInet.DLL in
>>> >> the
>>> >> >> image ?
>>> >>
>>> >
>>> >
>>> >.
>>> >
>>
>>
>>.
>>
>
>
>.
>

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