Amiga Plus 2004 #9

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A SMB file system wrapper for AmigaOS, using the AmiTCP V3 API ============================================================== 1. What is it? This document briefly describes the SMBFS program, which implements an SMB file system for AmigaOS. This file system can be used to access files made available by file servers which implement the SMB protocol, such as 'Microsoft Windows' or any other platform which supports the free 'Samba' product. These files can be accessed using shell commands such as 'List', the Workbench or utilities such as 'Directory Opus' as if the file server were a local disk drive. 2. What do you need to get started? You need a TCP/IP stack that supports the AmiTCP V3 API, such as 'Miami', the original free 'AmiTCP 3.0' release, 'AmiTCP 4.x', 'Miami Deluxe' or 'AmiTCP Genesis' and the obligatory networking gear. All these items need to be in good shape and properly configured. Most important, you need a computer which exports file sharing services using the SMB protocol. It often helps to have 'Samba' installed on your Amiga, too, as this can aid in tracking down bugs and obtaining information which SMBFS cannot obtain all by itself. Last but not least, you need to be proficient in configuring and using the TCP/IP stack; networking knowledge is definitely assumed. SMBFS requires AmigaOS 2.04 or higher to work. 3. Preparations You need to know which computer's files you want to share using the SMBFS file system. That computer must be known by name, it is not sufficient just to know its IP address. If you know the IP address but cannot refer to the host by its name then SMBFS will not work. In that case, make sure that you add a host name entry referring to the IP address to your TCP/IP stack's host database (e.g. the "AmiTCP:bin/hosts" file or the corresponding page in the stack's configuration user interface). The name of the computer to connect to must not be too long. If it is longer than 16 characters, SMBFS will not work properly. You need to know which service you want to connect to on the target computer. You can find out which services are available on a certain computer by using the Samba 'smbclient' program. For example, if you were to query the services offered by a machine called 'sourcery' you could enter the following: samba:bin/smbclient -L sourcery And you might get the following information: added interface ip=192.168.0.1 bcast=192.168.0.255 nmask=255.255.255.0 Password: Domain=[ARBEITSGRUPPE] OS=[AmigaOS] Server=[Samba 2.0.7] Sharename Type Comment --------- ---- ------- All Disk All volumes in the system IPC$ IPC IPC Service (Amiga 3000UX) olsen Disk Home Directories Server Comment --------- ------- SOURCERY Amiga 3000UX Workgroup Master --------- ------- ARBEITSGRUPPE SOURCERY The share name to connect to would be "ALL" in this case. You need to know which login name and which password are required to connect to the shared resource, and you need to know the name of the workgroup or domain the file server is a member of. 4. Starting and stopping the file system SMBFS is an uncommon kind of file system in that you do not use the 'Mount' command to mount it. In fact, SMBFS is a shell program which can be launched from the shell, using command line parameters to tell it which resources should be used. But you can also start it from Workbench: in this case you would have to put the program's command line options into icon tool types. By now you should have assembled the following information: - Name of the computer to connect to; this would be the file server - Name of the shared SMB resource to connect to - Login name and password That's basically everything you need to know to continue -- unless something goes wrong, but more on that lateron. Now you can start the file system. For example, to connect to the file server called 'sourcery' and the shared 'all' resource it exports, with that computer being a member of the workgroup 'Arbeitsgruppe', using the login name 'PCGuest' and not providing any password you would enter the following: Run >NIL: SMBFS Workgroup=Arbeitsgruppe User=PCGuest Service=//sourcery/all This would cause a new device by the name of "SMBFS:" to be mounted, showing all files and directories the 'sourcery' server makes available for sharing. How do you 'unmount' the file system? That's very easy, just check the output of the 'Status' shell command. You might get the following output: Process 1: Loaded as command: TURBOTEXT Process 2: Loaded as command: Work:Tools/Blowup Process 3: Loaded as command: Work:Tools/Sashimi Process 4: Loaded as command: Work:CyberTools/CyberGuard Process 5: Loaded as command: Work:Tools/OpenDevicePatch Process 6: Loaded as command: CED Process 7: Loaded as command: Workbench Process 8: Loaded as command: Status Process 9: No command loaded Process 10: Loaded as command: SMBFS '//sourcery/all' Look at the last line describing process number 10: it shows the name of the file system program SMBFS and the name of the SMB share it is connected to. To stop this file system and effectively unmount it, use the shell 'Break' command; in this case you would enter "Break 10" to stop the file system. Note that the program may not terminate immediately; it may have to wait until the last client has released all resources referring to the file system. You may have to send more than one "Break" command to stop the program. 5. Startup options The SMBFS program supports a number of command line options, as will be described below. The command template looks like this: DOMAIN=WORKGROUP/K,USER=USERNAME/K,PASSWORD/K,CHANGECASE/S, CASE=CASESENSITIVE/S,OMITHIDDEN/S,QUIET/S,CLIENT=CLIENTNAME/K, SERVER=SERVERNAME/K,DEVICE=DEVICENAME/K,VOLUME=VOLUMENAME/K, CACHE=CACHESIZE/N/K,DEBUGLEVEL=DEBUG/N/K,TZ=TIMEZONEOFFSET/N/K, TRANSLATE=TRANSLATIONFILE/K,SERVICE/A The individual options serve the following purposes: DOMAIN=WORKGROUP/K You must specify the name of the work group or domain which the file server to connect to is a member of. The name of this workgroup or domain must not be longer than 16 characters. The name you provide will be translated to all upper case characters. You need not provide for a work group or domain name on the command line. Alternatively, you may configure an environment variable whose contents will be used instead. The variable could be set up like this: SetEnv smbfs_workgroup <name of domain or workgroup> Copy ENV:smbfs_workgroup ENVARC: You may also use the 'smbfs_domain' environment varilable in place of the 'smbfs_workgroup' variable. The two are aliases for one another, but smbfs will read only one of the two. USER=USERNAME/K To connect to an SMB share you must authenticate yourself by providing a user name. With this program the user name is optional; if you do not provide one, SMBFS will use the default, which is "GUEST". The user name must not be longer than 64 characters. The name you provide will be translated to all upper case characters. You need not provide for a user name on the command line. Alternatively, you may configure an environment variable whose contents will be used instead. The variable could be set up like this: SetEnv smbfs_username <your user name> Copy ENV:smbfs_username ENVARC: You may also use the 'smbfs_user' environment varilable in place of the 'smbfs_username' variable. The two are aliases for one another, but smbfs will read only one of the two. PASSWORD/K As part of the authentication process required to make the connection to an SMB share, you must provide for a user name and a password. The password is optional; if you do not provide one, an empty password will be transmitted. The password must not be longer than 64 characters. You need not provide for a password on the command line. Alternatively, you may configure an environment variable whose contents will be used instead. The variable could be set up like this: SetEnv smbfs_password <your password> Copy ENV:smbfs_password ENVARC: Keep in mind that passwords like these really should not be exposed by storing them in environment variables. But then the protocol smbfs uses is almost as insecure as it gets anyway. The authentication process only works if the machine you are connecting to knows about the user name and password you want to use. As of this writing, smbfs cannot be used for authenticating against a password server that is not the same machine as the one from which you wish to import a share. CHANGECASE/S By default the password will not be changed to all upper case characters. If this is required, you should either provide the password in this form or resort to this option, which will cause it to be translated to all upper case characters. CASE=CASESENSITIVE/S Some file servers treat file and directory names differently which differ only in whether they are written using upper/lower case characters. For these servers you should activate the CASESENSITIVE switch to treat those files properly. There is a catch though: the AmigaDOS file naming scheme does not follow this model and you may run into problems when you are trying to use it. By default, the file system does not treat file and directory names differently which only differ with respect to the case of letters. OMITHIDDEN/S When requesting a directory listing, the server may return some files and directories tagged as being hidden. By default this file system will report these 'hidden' entries anyway, but you can request specifically that what is intended to be hidden should be omitted from directory listings, too. Note that even though a file may be hidden you should still be able to open and examine it. QUIET/S When started from Shell, SMBFS will print a message as soon as the connection to the file server has been established. If you do not want to see that message displayed, use the QUIET parameter. Also, no such message will appear if the program has been started to run in the background. CLIENT=CLIENTNAME/K SMBFS will attempt to connect to the file server by providing the name of the computer you connect from. In some cases this may be undesirable as the computer's name differs from what the file server expects. You can use the CLIENT parameter to tell SMBFS under which name it should announce itself to the server. This parameter is optional and will be translated to all upper case characters; it cannot be longer than 16 characters. SERVER=SERVERNAME/K SMBFS will attempt to connect to the file server by providing the name you specified using the SERVICE command line parameter. In some cases this may be undesirable as the server's name differs from what you specified as the share name. You can use the SERVER parameter to tell SMBFS under which name it should contact the server. This parameter is optional and will be translated to all upper case characters; it cannot be longer than 16 characters. DEVICE=DEVICENAME/K VOLUME=VOLUMENAME/K The SMBFS program can announce itself as an AmigaDOS file system by using one of two different methods. The first method involves announcing itself only as a file system device. This should be sufficient in most cases but has a drawback in that the device will not be usable from Workbench since the file system will not appear as a disk icon. You tell SMBFS to use a specific device name by using the DEVICE command line parameter, e.g. "DEVICE=SMBFS:". Note that device names must be unique, i.e. there must be no other device by the same name in the system; SMBFS will report an error and exit if it finds one. The second method involves announcing itself as a volume. This has the benefit of making the file system usable from Workbench since a disk icon will appear for it. You tell SMBFS to use a specific volume name by using the VOLUME command line parameter, e.g. "VOLUME=Sourcery:". Both methods have advantages and drawbacks. The drawback of the VOLUME method is that it may deadlock the native Amiga Samba port as soon as the file system is mounted. The drawback of the DEVICE method is that the file system will not be usable from Workbench. If you wish, you can combine both methods; this is the approach most other file systems use. And in fact, when you tell SMBFS to add a volume it will also add a device to go along with it. The VOLUME and DEVICE keywords are optional; if you omit both, SMBFS will pretend that you had used the "DEVICE=SMBFS:" parameter. CACHE=CACHESIZE/N/K The file system attempts to optimize accesses to the file server when directory contents are being scanned. These contents are buffered in a directory cache which by default will hold 170 entries. Since each entry will require about 255 bytes of storage, the entire 170 entry cache will occupy more than 40K bytes of memory. You may want to change this requirement, by making the cache smaller or larger using the CACHESIZE parameter. The size of the directory cache cannot be smaller than 10 entries. DEBUGLEVEL=DEBUG/N/K By default SMBFS operates in silent mode. It does not report what it is doing, it just tries to respond to file system requests. To obtain debugging output you may want to use the DEBUG option and specify a debug level greater than 0. The larger the number you specify the more debugging output will be created. Note that all debugging output will be produced using the operating system's debug output functionality which requires that you have a capturing program like 'Sashimi' running in the background. TZ=TIMEZONEOFFSET/N/K By default the file system will use the current Locale settings to translate between the local time and the time used by the SMB server. For some configurations, however, this is impractical since the server's time zone is not configured properly. For these rare cases you may want to hard code a certain time zone offset using the 'TIMEZONEOFFSET' options. The number you provide must be the number of minutes to add to the local time in order to translate it into the corresponding GMT value. For example, in central Europe using CET, you would use "TZ=-60" since CET is one hour ahead of GMT. TRANSLATE=TRANSLATIONFILE/K The Amiga and the file server SMBFS connects to may not share the same character set. International characters used in file names on either side may not come out correctly on the other side. To remedy this problem, you can resort to file name translation. How the individual names are to be translated is determined by the contents of a file name translation table file such as the ones that ship with Workbench in the "L:FileSystem_Trans" drawer. The first 256 bytes of each such file must consist of the mapping of Amiga characters to the different character set, and the second 256 characters must describe a mapping back from the different character set to the Amiga. In most cases the "L:FileSystem_Trans/INTL.crossdos" translation table file should be sufficient. To specify which file contains the translation tables to use you would use the TRANSLATIONFILE parameter. SERVICE/A This is the last parameter to be specified on the command line. It should refer to the file server you want to connect to and the resource it exports, e.g. a file system. This parameter must start with two slashes which must be immediately followed by the file server's name, which must be followed by the resource to connect to. For now no special characters are allowed in the name of the service as no translation is performed like would be the case for file names on the volume. The same parameters are also used when starting SMBFS from Workbench. SMBFS will examine its icon tool types and use these in place of the shell command line. 6. Known problems The design of smbfs follows the original file system concept behind the code which the 'Sharity-Light' file system is based upon. And that is a Unix file system which differs from Amiga specific file systems in many ways which can lead to problems which are discussed briefly below: - Single threaded design This means that it is not possible for several programs to fairly share the use of the file system. For example, a program that posts a long read request can tie up the file system almost exclusively for itself, and while it is busy all other clients will have to wait. Same goes for directory scanning. - Poor scalability This is associated with the single threaded design. When several programs are accessing the file system at the same time, overhead and unfair sharing of resources will drastically reduce the performance of the file system. - Separation of file data and metadata This means that the core of the file system treats the contents of a directory and the data attached to each file inside that directory as something different. This is a common concept with Unix file systems, but it is very different with Amiga file systems. In smbfs this data separation can cause problems when deleting files from a directory while that directory is being scanned, such as how this is being done by the 'Delete' shell command. The effects of these problems are that a directory may not be deleted even though it is empty or that for the same directory the same file may be reported twice in the listing. While there are no easy solutions for any of these problems, it does not mean that smbfs is unusable. You just have to be more careful when you use the file system. For example, if a directory's contents cannot be deleted due to one of the problems mentioned above, you might want to retry later. It should be noted that the problems described above are not inherent to the original file system design. It's just that transferring that design to an Amiga file system created the problems. 7. Credits This file system is based upon prior work by Paal-Kr. Engstad, Volker Lendecke, Mark A. Shand, Donald J. Becker, Rick Sladkey, Fred N. van Kempen, Eric Kasten and Rudolf Koenig. It is a direct descendant of the 'Sharity-Light' file system written by Christian Starkjohann. The password encryption code was lifted from the Samba package. It was written by Andrew Tridgell and the Samba Team. 8. Author The 'Sharity-Light' source code was adapted and wrapped into an AmigaOS layer by Olaf `Olsen' Barthel. If you wish to contact me, please send e-mail to the following address: olsen@sourcery.han.de Or, alternatively, you might want to contact me via my postal address: Olaf Barthel Gneisenaustr. 43 D-31275 Lehrte Federal Republic of Germany If you want to submit a bug report or an enhancement request, please enclose sufficient information to allow me to make sense of the problem. That includes debugging logs produced using the DEBUG option. 9. Source code SMBFS is distributed under the terms of the GNU General Public License (version 2). The source code should have accompanied this program; if it hasn't, please contact the author for a copy. The program was compiled using the SAS/C 6.58 compiler, with the Miami SDK providing for the TCP/IP stack API header files.