# include <stdio.h>
# include <ctype.h>
# include <pwd.h>
# include "delivermail.h"

/*
**  ALIAS -- Compute aliases.
**
**	Scans the file /usr/lib/mailaliases for a set of aliases.
**	If found, it arranges to deliver to them by inserting the
**	new names onto the SendQ queue.
**
**	Parameters:
**		none
**
**	Returns:
**		none
**
**	Side Effects:
**		Aliases found on SendQ are removed and put onto
**		AliasQ; replacements are added to SendQ.  This is
**		done until no such replacement occurs.
**
**	Defined Constants:
**		MAXRCRSN -- the maximum recursion depth.
**		ALIASFILE -- the pathname of the alias file.
**
**	Requires:
**		fopen (stdio)
**		fgets (stdio)
**		rewind (stdio)
**		isspace (sys)
**		printf (sys)
**		deliver
**
**	Called By:
**		deliver
**
**	Files:
**		/usr/lib/mailaliases -- the mail aliases.
**
**	Notes:
**		If NoAlias (the "-n" flag) is set, no aliasing is
**			done.
**
**	Deficiencies:
**		It should complain about names that are aliased to
**			nothing.
**		It is unsophisticated about line overflows.
**		It should probably take either the ARPANET sndmsg
**			format for aliases, or read Mail files and
**			pick out 'alias' commands.
**
**	History:
**		12/27/79 -- written.
*/


# define ALIASFILE	"/usr/lib/mailaliases"
# define MAXRCRSN	10


alias()
{
	register addrq *q;
	FILE *af;
	char line[MAXLINE+1];
	register char *p;
	register char *u;
	extern int errno;
	int didalias;
	int gotmatch;

	if (NoAlias)
		return (0);
	if (Debug)
		printf("--- alias ---\n");

	/* open alias file if not already open */
	if (Debug && (af = fopen("mailaliases", "r")) != NULL)
		printf(" [using local alias file]\n");
	else if ((af = fopen(ALIASFILE, "r")) == NULL)
	{
		if (Debug)
			printf("Can't open %s\n", ALIASFILE);
		errno = 0;
		return;
	}

	/*
	**  Scan alias file.
	**	If we find any user that any line matches any user, we
	**	will send to the line rather than to the user.
	*/

	didalias = TRUE;
	while (didalias)
	{
		didalias = FALSE;
		gotmatch = FALSE;
		rewind(af);
		while (fgets(line, sizeof line, af) != NULL)
		{
			/* check for continuation lines */
			if (isspace(line[0]))
			{
				if (gotmatch)
				{
					if (Debug)
						printf("   ... also aliased to %s", line);
					sendto(line);
				}
				continue;
			}
			gotmatch = FALSE;
			/* comments begin with `#' */
			if (line[0] == '#')
				continue;
			p = NULL;
			for (q = &SendQ; (q = nxtinq(q)) != NULL; )
			{
				if ((p = matchalias(valueq(q), line)) != NULL)
					break;
			}

			if (p != NULL)
			{
				/*
				**  Match on Alias.
				**	Deliver to the target list.
				**	Remove the alias from the send queue
				**	  and put it on the Alias queue.
				*/

				if (Debug)
					printf("%s aliased to %s", valueq(q), p);
				tkoffq(q, &SendQ);
				putonq(q, &AliasQ);
				didalias++;
				gotmatch++;
				sendto(p);
			}
		}
	}
	fclose(af);
}
/*
**  MATCHALIAS -- Match name against alias.
**
**	The alias is a full alias line, in the format:
**		pseudonym:name1,name2,name3,...
**	This routine just matches against the pseudonym.
**
**	Parameters:
**		user -- the user to match against.
**		line -- the alias line.
**
**	Returns:
**		A pointer to the first character after the colon on
**			a match.
**		NULL otherwise.
**
**	Side Effects:
**		none
**
**	Requires:
**		none
**
**	Called By:
**		alias
**
**	History:
**		1/11/80 -- broken from alias
*/

matchalias(user, line)
	register char *user;
	register char *line;
{
	for (; *user != '\0' && *line == *user; line++, user++)
		continue;
	while (isspace(*line))
		line++;
	if (*user == '\0' && *line == ':')
		return (++line);
	return (NULL);
}
/*
**  FORWARD -- Try to forward mail
**
**	This is similar but not identical to aliasing.  Local
**	users may put a file ".userinfo" in their home directory
**	saying what account(s) they would like their mail
**	forwarded to.  This file looks a lot like ARPANET
**	mail headers, i.e., each line is
**		field-name: value
**	This routine is looking for the field "forward-to".
**
**	Parameters:
**		user -- the name of the user who's mail we
**			would like to forward to.
**
**	Returns:
**		NULL -- we arranged to forward this somewhere,
**			so don't send it yourself.
**		else -- send it to whoever this returns.
**
**	Side Effects:
**		New names are added to SendQ.
**
**	Requires:
**		setpwent (sys)
**		getpwname (sys)
**		strcpy (sys)
**		strcat (sys)
**		fopen (sys)
**		fgets (sys)
**		matchhdr
**		sendto
**		fclose (sys)
**
**	Called By:
**		recipient
**
**	History:
**		1/23/80 -- written.
*/

char *
forward(user)
	char *user;
{
	register struct passwd *pw;
	char buf[MAXLINE];
	register char *p;
	register FILE *uf;
	extern struct passwd *getpwnam();
	extern char *matchhdr();

	/*
	**  Find and open the user's .userinfo file.
	*/

	setpwent();
	if ((pw = getpwnam(user)) == NULL)
		return (user);
	strcpy(buf, pw->pw_dir);
	strcat(buf, "/.userinfo");
	if ((uf = fopen(buf, "r")) == NULL)
		return (user);
	
	/*
	**  Look for forward-to: field.
	*/

	while (fgets(buf, sizeof buf, uf) != NULL)
	{
		if ((p = matchhdr(buf, "forward-to")) == NULL)
			continue;
		
		/*
		**  We have a foward entry.
		**	Send to the list
		*/

		fclose(uf);
		if (Debug)
			printf("--%s", buf);
		sendto(p);
		return (NULL);
	}

	/*
	**  No match -- send to the original user.
	*/

	fclose(uf);
	return (user);
}