From: Walter Alejandro Iglesias <wai@roquesor.com>
Subject: Re: mail(1) patches (UPDATE)
To: tech@openbsd.org
Date: Wed, 7 Aug 2024 10:39:35 +0200

Yesterday I ran into a problem that I didn't remember, that under Linux
gethostname() returns only the hostname.  This means that the diff below
as well as the second from the three versions I posted before, since the
idea was to make them portable, are useless.

So, to generate Message-ID and Date headers, OpenSMTP uses "hand
written" functions.  Using libc (strftime()) wasn't convenient in this
case because of OpenBSD limitation with locales.  Is detecting UTF-8
characters a different case in this matter?  This is what I was
suggested to use instead of my hand written UTF-8 parser:

  https://marc.info/?l=openbsd-tech&m=169530140424607&w=2

But mblen(3) also depends on locales.  So far, at least under Linux,
using mblen(3) I got the same behavior that under OpenBSD but given my
short experience as a C programmer, hence my limited knowledge of the
"context", contrary to my hand written function which I'm sure is 100%
portable and do NOT depend on locales, I'm not sure to which extent I
can trust on the "portability" of the code using mblen(3).

At least, this is how things look from my ignorant point of view.

Years ago I used to write web applications in PHP for my clients.  I
didn't use already written functions, I wrote my own code, trying to use
the most basics.  To filter user input I wrote my own regular
expressions.  This way my applications were secure, portable and *I
didn't have to rewrite them for each new version of PHP*.  I understand
that this worked for me because I worked alone, and that PHP is not C,
but the analogy is still valid to some extent.


> 
> 
> Index: extern.h
> ===================================================================
> RCS file: /cvs/src/usr.bin/mail/extern.h,v
> diff -u -p -r1.30 extern.h
> --- extern.h	21 May 2024 05:00:48 -0000	1.30
> +++ extern.h	6 Aug 2024 06:51:15 -0000
> @@ -176,6 +176,7 @@ void	 mesedit(FILE *, int);
>  void	 mespipe(FILE *, char *);
>  int	 messize(void *);
>  int	 metamess(int, int);
> +const char* month(int num);
>  int	 more(void *);
>  int	 newfileinfo(int);
>  int	 next(void *);
> @@ -253,7 +254,9 @@ void	 vfree(char *);
>  int	 visual(void *);
>  int	 wait_child(pid_t);
>  int	 wait_command(int);
> +const char* wday(int num);
>  int	 writeback(FILE *);
> +const char* zone(int num);
>  
>  extern char *__progname;
>  extern char *tmpdir;
> Index: send.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/mail/send.c,v
> diff -u -p -r1.26 send.c
> --- send.c	8 Mar 2023 04:43:11 -0000	1.26
> +++ send.c	6 Aug 2024 06:51:15 -0000
> @@ -516,15 +516,28 @@ puthead(struct header *hp, FILE *fo, int
>  {
>  	int gotcha;
>  	char *from;
> +	time_t t = time(NULL);
> +	struct tm lt = *localtime(&t);
> +	char host[1024];
> +	int h = gethostname(host, 1023);
>  
>  	gotcha = 0;
>  	from = hp->h_from ? hp->h_from : value("from");
>  	if (from != NULL)
>  		fprintf(fo, "From: %s\n", from), gotcha++;
> +	if (fo != stdout)
> +		fprintf(fo, "Date: %s, %d %s %d %02d:%02d:%02d %s\n",
> +		    wday(lt.tm_wday), lt.tm_mday, month(lt.tm_mon),
> +		    lt.tm_year + 1900, lt.tm_hour, lt.tm_min, lt.tm_sec,
> +		    zone(lt.tm_gmtoff)), gotcha++;
>  	if (hp->h_to != NULL && w & GTO)
>  		fmt("To:", hp->h_to, fo, w&GCOMMA), gotcha++;
>  	if (hp->h_subject != NULL && w & GSUBJECT)
>  		fprintf(fo, "Subject: %s\n", hp->h_subject), gotcha++;
> +	if (fo != stdout && h == 0)
> +		fprintf(fo, "Message-ID: <%d%02d%02d.%02d%02d%02d@%s>\n",
> +		    lt.tm_year + 1900, lt.tm_mon + 1, lt.tm_mday, lt.tm_hour,
> +		    lt.tm_min, lt.tm_sec, host), gotcha++;
>  	if (hp->h_cc != NULL && w & GCC)
>  		fmt("Cc:", hp->h_cc, fo, w&GCOMMA), gotcha++;
>  	if (hp->h_bcc != NULL && w & GBCC)
> Index: util.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/mail/util.c,v
> diff -u -p -r1.2 util.c
> --- util.c	26 Dec 2022 19:16:01 -0000	1.2
> +++ util.c	6 Aug 2024 06:51:15 -0000
> @@ -641,3 +641,34 @@ clearnew(void)
>  		}
>  	}
>  }
> +
> +const char*
> +wday(int num)
> +{
> +	const char *week[] = {"Sun", "Mon", "Tue", "Wed", "Thu",
> +	    "Fri", "Sat"};
> +	return(week[num]);
> +}
> +
> +const char*
> +month(int num)
> +{
> +	const char *month[] = {"Jan","Feb","Mar","Apr","May","Jun",
> +	    "Jul","Aug","Sep","Oct","Nov","Dec"};
> +	return(month[num]);
> +}
> +
> +const char*
> +zone(int num)
> +{
> +	static char buf[6];
> +	size_t r;
> +
> +	r = snprintf(buf, sizeof(buf), "%c%02d%02d", num >= 0 ? '+' : '-',
> +	    abs((int)num / 3600), abs((int)num % 3600) / 60);
> +
> +	if (r < 0 || r >= sizeof(buf))
> +		errx(1, "zone: snprintf");
> +
> +	return(buf);
> +}
> 


-- 
Walter