No, lists.infradead.org doesn't run on BSD

So days earlier, I was reading through mails forwarded by linux-riscv@lists.infradead.org as usual, and occasionally opened the RAW mbox file (an easy action in mutt, just press e). Examining the RFC 822 header, I found there're some strange extension fields starting with X-CRM114 like

X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3
X-CRM114-CacheID: sfid-20250923_043801_252533_90EC9209
X-CRM114-Status: GOOD (  11.31  )

and string TRE 0.8.0 (BSD) in field X-CRM114-Version caught my eyes. As a Linux distribution maintainer, BSD instantly reminded me of distribution names. And it is definitely a little very striking to see Linux's mailing list running on BSD systems.

So I was excited to dig the string further

CRM114 really doesn't sound like a technology or something. Thus I searched it in Duckduckgo, and the first result was Wikipedia's page CRM 114 (fictional device). Although I was not looking for something fictional art works, I still opened the page and saw a statement of disambiguation,

For the computer program, see CRM114 (program).

So CRM114 (program) is likely the origin of these extension RFC 822 fields. And I considered its name originates from the fictional film, which is confirmed by the page later.

So I learnt CRM114 is a spam e-mail filter. It makes much sense that such an anti-spam program had scanned the e-mail I read, permitted it, and left some fields.

But STFW, I didn't find any materials describing the exact meaning of X-CRM114-Version, thus it really looked like the time to read through the code.

So I was trying to get CRM114's source

It was a little hard, since as indicated by 20100106 part in field X-CRM114-Version, it seems a project that hasn't been maintained for more than a decade. Searching CRM114 source yielded no useful information.

But while I was looking for some description of X-CRM114-Version, I ocassionally opened its manpage hosted by Debian. As you could see, Debian requires original source of the package to be provided along with its control scripts, which makes it very likely a place that I could get a recent enough version (20100106, exactly matching X-CRM114-Version produced by lists.infradead.org) of CRM114's source.

So I was reading through the code of CRM114

grep -R X-CRM114-Version . resulted in many lines, and I was most interested in ones with suffix .crm. Some looks like RAW content, and I noticed one interesting result in paolo_ov2.crm,

X-CRM114-Version: 20050415.BlameTheIRS ( TRE 0.7.2 (GPL) ) MF-A10FFB4C\n

an alternative value of string "BSD" in X-CRM114-Version isn't Linux, but instead, GPL. Now I realized it's probably a license identifier, instead of indicaion of the host system. But I wanted to make sure.

Aside from ones looking like RAW RFC 822 content, I chose mailfilter.crm, which refers to X-CRM114-Version in form of

call /:mungmail_add:/ [X-CRM114-Version: :*:_crm_version: MF-:*:_pgm_hash: ]
# syscall (:*:_dw:) (:_dw:) /formail -A "X-CRM114-Version: :*:_crm_version: MF-:*:_pgm_hash: " -A "X-CRM114-Status: Good  ( :*:pr: \)"/
call /:mungmail_add:/ [X-CRM114-Version: :*:_crm_version: MF-:*:_pgm_hash: [:*:pr:]]

So I turned to grep _crm_version, it's referred in crm_var_hash_table.c as

  //   put the version string in as a variable.
  {
    char verstr[1025];
    verstr[0] = 0;
    strcat (verstr, VERSION);
    strcat (verstr, " ( ");
    strcat (verstr, crm_regversion());
    strcat (verstr, " )");
    crm_set_temp_var (":_crm_version:", verstr);
  };

So it became more clear, .crm files are some types of scripts, which may make use of variables, and _crm_version is a preset variable that contains the string I found earlier.

You see, the interesting part of X-CRM114-Version is inside a pair of braces, so crm_regversion is what I was really looking for. It's defined as

char *crm_regversion ()
{
  return (tre_version());
};

I was pretty sure I had seen tre when looking for CRM114's source tarball in Debian's package tracker. And yes, Debian describes it as

regexp matching library with approximate matching

So I was grepping a regex engine

I was able to find the definition of tre_version() in lib/tre-compile.c, it looks like

char *
tre_version(void)
{
  static char str[256];
  char *version;

  if (str[0] == 0)
    {
      (void) tre_config(TRE_CONFIG_VERSION, &version);
      (void) snprintf(str, sizeof(str), "TRE %s (BSD)", version);
    }
  return str;
}

so the string BSD in X-CRM114-Version definitely has nothing to do with the host OS.

In the NEWS file of TRE, I found an entry mentioning TRE used to licensed under LGPL, not BSD,

Version 0.7.6
  - The license is changed from LGPL to a BSD-style license.  The new
    license is essentially the same as the "2 clause" BSD-style
    license used in NetBSD.  See the file LICENSE for details.

which also explains the TRE 0.7.2 (GPL) string I had seen earlier. TRE 0.7.2 was still licensed under LGPL. I am (not) really sorry for the bad title.

So doesn't lists.infradead.org run on BSD?

Honestly saying, I don't know, even after spending my breakfast time grepping through all these decade-old source tarballs.

The good news is that, at least the X-CRM114-Version field doesn't provide any information on the host system.

The bad news is that, I haven't had any clues that lists.infradead.org runs on Linux, not Windoge, *BSD or MacOS, either.

As a Linux kernel developer, I really hopes it's Linux. Or it'll really be a breaking news.