Synchronet Source Code

Availability

• Anonymous FTP access to the most recent released source (very old at this time) is available at:
  • vert.synchro.net
  • ftp.synchro.net
  • cvs.synchro.net
  Anonymous CVS access to the entire development source and modification history is available at cvs.synchro.net:/cvsroot/sbbs:
  • cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs login
    (just hit return, no password is necessary)
  • cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs checkout src
  • For just the Version 3 source files, use:
    cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs checkout src/sbbs3
  • or web-based CVS access at cvs.synchro.net/cgi-bin/cvsweb.cgi
• Step-by-step instructions on how to download, build, and run the current source code on Unix (Linux, FreeBSD, and OpenBSD), see http://synchro.net/docs/sbbsunix.txt

History (as of October 2000)

The Beginning

Version 1

Version 2

A binary configuration file format (.cnf) was introduced in v2 to speed up the loading of configuration files and improve extensibility.

Although a 32-bit console-mode OS/2 version of Synchronet v2 was released in 1995, it retained the same multi-node design as its DOS counterpart and required a separate instance of the program for each node. It was also during the active development life of Synchronet v2 that I began to release 32-bit extended DOS (DPMI), OS/2, and Win32 flavors of many of the utilities included with Synchronet.

Synchronet v2 remained commercial software until it was released as Freeware in early 1997 and the source code was documented, packaged, and released to the Public Domain later that same year (the Digital Dynamics' copyright was officially relinquished at this time). In December of 1999, I released a public beta of v2.30c for DOS and OS/2 (in binary form) that fixed a few millennium bugs and introduced some of the minor features I had incorporated thus far in my development of Synchronet v3.

Version 3

Today (October 2000)

This is not to suggest that only Unix/Linux sysops would potentially benefit from Synchronet becoming an open-source project. It's just that Unix users are traditionally more likely to be willing (and able) to mess with the source code, and hence, more likely to submit useful modifications to the project. In addition, development tools (i.e. C/C++ compiler, Make utility, CVS, etc) are usually included free with Unix-like operating systems, while they are not typically as readily available to Windows users.

So I created a revision control database (repository) using CVS and checked-in the v2.3 and v3 source code trees along with all the various menus, text files, and documents included in Synchronet distributions. I chose CVS as the revision control system because it is free software and is the tool of choice among most free/open-source software developers. I would've preferred to use one of the commercial revision control systems I've become accustomed to using in my professional development career, but their price and status as proprietary software would have potentially deterred valued open-source developers from contributing to the project.

I also copyrighted all of the source code (as Rob Swindell) and put the majority of the v3 source code files under the GNU General Public License to protect them from inclusion in proprietary projects. I put the XSDK and SMBLIB modules under the GNU Lesser General Public License, which allows them to be linked with proprietary projects.

The CVS Repository (cvs.synchro.net:/cvsroot/sbbs)

Modifications

Presumably, you are reading this file because you want access to the source code. And you want access to the source code because you plan on making modifications (or maybe you just want to verify there aren't any "back doors"). In any case, if and when you make useful modifications to the source code, you are encouraged to submit those changes to mods@synchro.net for possible inclusion in a future Synchronet release. Frequent contributors may become official co-developers and be given direct read/write access to the CVS repository by me, the maintainer of the project.

Custom Modifications

If you are modifying the code for use on a single BBS and do not wish to give those modifications to anyone else, you have that right. To make synchronization of your version with the official Synchronet releases easier, it is highly recommended that you predefine a preprocessor symbol (e.g. MYMODS) and then wrap your modifications in a conditional compilation statement. Example:

#ifdef MYMODS
    bprintf("You are experiencing my custom modification.\r\n");
#endif

If you are changing existing lines of code, it is recommended that you include both the original and modified versions in your source and use conditional compilation statements to determine which version will be used. Example:

#ifdef MYMODS
	i = j/100;
#else /* Original code */
	i = j/50;
#endif	

This allows you to easily "undo" your modifications for testing purposes (by simply undefining MYMODS) as well as clearly marking, for future reference, which parts of the code were modified by you.

Coding Style

If you'd like to submit your modifications for possible inclusion in a future Synchronet release, it would be beneficial if the programming style was consistent with the style of the existing code base. Consistency of style helps improve readability and maintainability of the source code.

Prior to Synchronet v3, I used a form of "condensed" K&R style to get as much code in an 80x25 character display as possible while maintaining some degree of readability. 

Example (K&R style):

main()
{
    char line[MAXLINE];
    int found = 0;

    while (getline(line, MAXLINE) > 0)
	if (strindex(line, pattern) >= 0) {
	    printf("%s", line);
	    found++;
	}
    return found;
}

Example (Synchronet v2 style):

main()
{
    char line[MAXLINE];
    int  found=0;

while(getline(line,MAXLINE)>0)
    if(strindex(line,pattern)>=0) {
	printf("%s",line);
	found++; }
return(found);
}

As you've probably noticed, in the Synchronet v2 style, the body of the function is not indented and the closing curly brace is not on its own line. Additionally, unnecessary white-space characters have been removed from within the body of the expressions. While the above examples do not demonstrate the potential advantages of compressing white-space in a C coding style, you can imagine how the limitations of an 80 column display could make heavily nested expressions difficult without resulting to such measures.

In Synchronet v3, I've taken advantage of modern GUI text editors capable of displaying more than 80 characters on a line and have  "uncompressed" the style to a degree:

Example (Synchronet v3 style):

main()
{
    char line[MAXLINE];
    int  found=0;

    while(getline(line,MAXLINE)>0)
        if(strindex(line,pattern)>=0) {
	    printf("%s",line);
	    found++; 
	}
    return(found);
}

Now the body of the function is indented and the closing curly brace has been placed on its own line (as in the K&R style), but the unnecessary white-space characters remain compressed (eliminated from the body of the expressions). You may still find v2 style closing braces in some of the v3 source files, but indentation and all other style elements should be consistent with the v3 style shown above.

Style Guidelines

1. Use the Synchronet v3 indentation, white-space, and brace style (as described above).
2. Configure your text editor for 4 space tab stops and keep the physical tabs in the files (do not replace them with spaces).
3. Use the Synchronet copyright comment block (including the PT/SC headers) when creating new source files.
4. Do not extend lines beyond column 100.
5. Add comments around or near any code you add or modify explaining the rationale behind the modification.
6. Use descriptive symbol (function and variable) and pre-processor macro names.
7. Use symbol and macro naming styles consistent with those already used in the project/source file you are modifying.
8. Do not use unnecessary global variables (use class members or function parameters to pass values).
9. Use return types and variable types consistent with the data to be stored or returned (e.g. use bool/BOOL for true/false type values).
10. Do not embed important numeric constants in your code; use macros (e.g. #define SPECIAL_VALUE 128) or configurable variables instead.

Backwards Compatibility

There are two very important areas of compatibility that must be maintained when modifying the code:

1. Data and configuration file compatibility with older Synchronet versions (v2+)
2. Builds for other compilers and platforms

On the first point, you must take care not to alter structure definitions or file formats that will cause the resulting file not to operate in a compatible way with Synchronet v2. If you need additional data storage, try to use unused or reserved elements, bit-fields, or data fields in existing structure or file definitions (without changing the overall size of the structure or data record) or create auxiliary data files that contain the additional required data. All binary words and double-words are to be stored in little endian (Intel) byte-order and there are currently no provisions in the source code to account for byte-order translations on big endian systems.

On the second point, it is critical that you do not add system calls or system-dependant functionality in a non-portable fashion. If you are adding code that is only supported on a specific platform and when built with a specific compiler or run-time library, be sure to wrap that code in  conditional compilation statements that test for the appropriate pre-processor definitions. In addition, take care to add error conditions, warnings, or alternate behavior when the code is built on an unsupported platform or with an unsupported tool. For example:

#if defined(__MSDOS__)
	mswait(1);
#elif defined(__OS2__)
	DosSleep(1);
#elif defined (_WIN32)
	Sleep(1);
#else
	#error "No Sleep Function for target platform!"
#endif

Portability

To maintain as much compiler and platform compatibility as possible, do not unnecessarily restrict code portions to a specific Unix-like operating system (Linux for example) when the code will (or should) compile with most Unix-like operating systems. For example:

#if defined(__unix__)
	this_code_for_any_unix_variant;
#endif

#if defined(__linux__)
	this_code_only_for_linux;
#endif

Also, be sure to separate compiler dependancies from platform dependancies. For example:

#if defined(__GNUC__)
	this_code_only_for_gcc;
#else
	this_code_for_all_others;
#endif

Please use the following pre-processor symbols to determine the target platform:

Please use the following pre-processor symbols to determine the compiler:

Little-endian/80386-class target CPUs are assumed, so no testing for CPU-type is required at this time.

Submissions

When you've created a modification that you think other Synchronet sysops or users may find useful, you are encouraged to submit this modification to mods@synchro.net. Modifications should be submitted in the Unix diff format. Currently, I am the sole judge of which submissions will be merged into the code base and which ones will not. If I determine that a submission should not be merged into the code base for any reason, I will make my best effort to explain to the submitting developer the reasons why and offer advice on how to remedy the situation, if at all possible.