/*++
 * NAME
 *	quote_821_local 3
 * SUMMARY
 *	quote local part of address
 * SYNOPSIS
 *	#include "quote_821_local.h"
 *
 *	VSTRING	*quote_821_local(dst, src)
 *	VSTRING	*dst;
 *	char	*src;
 *
 *	VSTRING	*quote_821_local_flags(dst, src, flags)
 *	VSTRING	*dst;
 *	const char *src;
 *	int	flags;
 * DESCRIPTION
 *	quote_821_local() quotes the local part of a mailbox address and
 *	returns a result that can be used in SMTP commands as specified
 *	by RFC 821. It implements an 8-bit clean version of RFC 821.
 *
 *	quote_821_local_flags() provides finer control.
 *
 *	Arguments:
 * .IP dst
 *	The result.
 * .IP src
 *	The input address.
 * .IP flags
 *	Bit-wise OR of zero or more of the following.
 * .RS
 * .IP QUOTE_FLAG_8BITCLEAN
 *	In violation with RFCs, treat 8-bit text as ordinary text.
 * .IP QUOTE_FLAG_EXPOSE_AT
 *	In violation with RFCs, treat `@' as an ordinary character.
 * .IP QUOTE_FLAG_APPEND
 *	Append to the result buffer, instead of overwriting it.
 * .RE
 * STANDARDS
 *	RFC 821 (SMTP protocol)
 * BUGS
 *	The code assumes that the domain is RFC 821 clean.
 * LICENSE
 * .ad
 * .fi
 *	The Secure Mailer license must be distributed with this software.
 * AUTHOR(S)
 *	Wietse Venema
 *	IBM T.J. Watson Research
 *	P.O. Box 704
 *	Yorktown Heights, NY 10598, USA
 *--*/

/* System library. */

#include "acl_stdafx.hpp"
#include <string.h>
#include <ctype.h>

/* Utility library. */

#include "stdlib/acl_vstring.h"

/* Global library. */

#include "quote_821_local.hpp"

/* Application-specific. */

#define YES	1
#define	NO	0

/* is_821_dot_string - is this local-part an rfc 821 dot-string? */

static int is_821_dot_string(const char *local_part, const char *end, int flags)
{
	const char *cp;
	int     ch;

	/*
	 * Detect any deviations from the definition of dot-string. We could use
	 * lookup tables to speed up some of the work, but hey, how large can a
	 * local-part be anyway?
	 */
	if (local_part == end || local_part[0] == 0 || local_part[0] == '.')
		return (NO);
	for (cp = local_part; cp < end && (ch = *(const unsigned char *) cp) != 0; cp++) {
		if (ch == '.' && cp[1] == '.')
			return (NO);
		if (ch > 127 && !(flags & QUOTE_FLAG_8BITCLEAN))
			return (NO);
		if (ch == ' ')
			return (NO);
		if (ACL_ISCNTRL(ch))
			return (NO);
		if (ch == '<' || ch == '>'
			|| ch == '(' || ch == ')'
			|| ch == '[' || ch == ']'
			|| ch == '\\' || ch == ','
			|| ch == ';' || ch == ':'
			|| (ch == '@' && !(flags & QUOTE_FLAG_EXPOSE_AT)) || ch == '"')
		{
			return (NO);
		}
	}
	if (cp[-1] == '.')
		return (NO);
	return (YES);
}

/* make_821_quoted_string - make quoted-string from local-part */

static ACL_VSTRING *make_821_quoted_string(ACL_VSTRING *dst, const char *local_part,
		const char *end, int flags)
{
	const char *cp;
	int     ch;

	/*
	 * Put quotes around the result, and prepend a backslash to characters
	 * that need quoting when they occur in a quoted-string.
	 */
	ACL_VSTRING_ADDCH(dst, '"');
	for (cp = local_part; cp < end && (ch = *(const unsigned char *) cp) != 0; cp++) {
		if ((ch > 127 && !(flags & QUOTE_FLAG_8BITCLEAN))
			|| ch == '\r' || ch == '\n' || ch == '"' || ch == '\\')
		{
			ACL_VSTRING_ADDCH(dst, '\\');
		}
		ACL_VSTRING_ADDCH(dst, ch);
	}
	ACL_VSTRING_ADDCH(dst, '"');
	ACL_VSTRING_TERMINATE(dst);
	return (dst);
}

/* quote_821_local_flags - quote local part of address according to rfc 821 */

ACL_VSTRING *quote_821_local_flags(ACL_VSTRING *dst, const char *addr, int flags)
{
	const char   *at;

	/*
	 * According to RFC 821, a local-part is a dot-string or a quoted-string.
	 * We first see if the local-part is a dot-string. If it is not, we turn
	 * it into a quoted-string. Anything else would be too painful.
	 */
	if ((at = strrchr(addr, '@')) == 0)		/* just in case */
		at = addr + strlen(addr);		/* should not happen */
	if ((flags & QUOTE_FLAG_APPEND) == 0)
		ACL_VSTRING_RESET(dst);
	if (is_821_dot_string(addr, at, flags)) {
		return (acl_vstring_strcat(dst, addr));
	} else {
		make_821_quoted_string(dst, addr, at, flags & QUOTE_FLAG_8BITCLEAN);
		return (acl_vstring_strcat(dst, at));
	}
}

#ifdef TEST

/*
 * Test program for local-part quoting as per rfc 821
 */
#include <stdlib.h>
#include <vstream.h>
#include <vstring_vstream.h>
#include "quote_821_local.h"

int     main(void)
{
	VSTRING *src = vstring_alloc(100);
	VSTRING *dst = vstring_alloc(100);

	while (vstring_fgets_nonl(src, VSTREAM_IN)) {
		vstream_fprintf(VSTREAM_OUT, "%s\n",
			vstring_str(quote_821_local(dst, vstring_str(src))));
		vstream_fflush(VSTREAM_OUT);
	}
	exit(0);
}

#endif
