/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

/*
 * $Id: 1e33cb9863f065d3b053804f3ab6c033658d0fec $
 *
 * @file xlat.c
 * @brief String expansion ("translation"). Implements %Attribute -> value
 *
 * @copyright 2000,2006  The FreeRADIUS server project
 * @copyright 2000  Alan DeKok <aland@ox.org>
 */

RCSID("$Id: 1e33cb9863f065d3b053804f3ab6c033658d0fec $")

#include	<freeradius-devel/radiusd.h>
#include	<freeradius-devel/parser.h>
#include	<freeradius-devel/rad_assert.h>
#include	<freeradius-devel/base64.h>

#include	<ctype.h>
#include	<limits.h>

typedef struct xlat_t {
	char			name[MAX_STRING_LEN];	//!< Name of the xlat expansion.
	int			length;			//!< Length of name.
	void			*instance;		//!< Module instance passed to xlat and escape functions.
	RAD_XLAT_FUNC		func;			//!< xlat function.
	RADIUS_ESCAPE_STRING	escape;			//!< Escape function to apply to dynamic input to func.
	bool			internal;		//!< If true, cannot be redefined.
} xlat_t;

typedef enum {
	XLAT_LITERAL,		//!< Literal string
	XLAT_PERCENT,		//!< Literal string with %v
	XLAT_MODULE,		//!< xlat module
	XLAT_VIRTUAL,		//!< virtual attribute
	XLAT_ATTRIBUTE,		//!< xlat attribute
#ifdef HAVE_REGEX_H
	XLAT_REGEX,		//!< regex reference
#endif
	XLAT_ALTERNATE		//!< xlat conditional syntax :-
} xlat_state_t;

#define XLAT_ATTR_NUMBER 65536	//!< The number of times this attribute appears in a list.
#define XLAT_ATTR_CONCAT 65537	//!< All instance of this attribute should be concatenated into a string.

struct xlat_exp {
	char const *fmt;	//!< The format string.
	size_t len;		//!< Length of the format string.

	DICT_ATTR const *da;	//!< the name of the dictionary attribute

	int num;		//!< attribute number
	int tag;		//!< attribute tag
	pair_lists_t list;	//!< list of which attribute
	request_refs_t ref;	//!< outer / this / ...

	xlat_state_t type;	//!< type of this expansion
	xlat_exp_t *next;	//!< Next in the list.

	xlat_exp_t *child;	//!< Nested expansion.
	xlat_exp_t *alternate;	//!< Alternative expansion if this one expanded to a zero length string.

	xlat_t const *xlat;	//!< The xlat expansion to expand format with.
};

typedef struct xlat_out {
	char const *out;	//!< Output data.
	size_t len;		//!< Length of the output string.
} xlat_out_t;

static rbtree_t *xlat_root = NULL;

#ifdef WITH_UNLANG
static char const * const xlat_foreach_names[] = {"Foreach-Variable-0",
						  "Foreach-Variable-1",
						  "Foreach-Variable-2",
						  "Foreach-Variable-3",
						  "Foreach-Variable-4",
						  "Foreach-Variable-5",
						  "Foreach-Variable-6",
						  "Foreach-Variable-7",
						  "Foreach-Variable-8",
						  "Foreach-Variable-9",
						  NULL};
#endif

#if REQUEST_MAX_REGEX > 8
#error Please fix the following line
#endif
static int xlat_inst[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };	/* up to 8 for regex */

char const *radiusd_short_version = RADIUSD_VERSION_STRING;

/** Print length of its RHS.
 *
 */
static ssize_t xlat_strlen(UNUSED void *instance, UNUSED REQUEST *request,
			   char const *fmt, char *out, size_t outlen)
{
	snprintf(out, outlen, "%u", (unsigned int) strlen(fmt));
	return strlen(out);
}

/** Print the size of the attribute in bytes.
 *
 */
static ssize_t xlat_length(UNUSED void *instance, UNUSED REQUEST *request,
			   char const *fmt, char *out, size_t outlen)
{
	VALUE_PAIR *vp;
	while (isspace((int) *fmt)) fmt++;

	if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) {
		*out = '\0';
		return 0;
	}

	snprintf(out, outlen, "%zu", vp->length);
	return strlen(out);
}

/** Print data as integer, not as VALUE.
 *
 */
static ssize_t xlat_integer(UNUSED void *instance, REQUEST *request,
			    char const *fmt, char *out, size_t outlen)
{
	VALUE_PAIR 	*vp;

	uint64_t 	int64 = 0;	/* Needs to be initialised to zero */
	uint32_t	int32 = 0;	/* Needs to be initialised to zero */

	while (isspace((int) *fmt)) fmt++;

	if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) {
		*out = '\0';
		return 0;
	}

	switch (vp->da->type) {
	case PW_TYPE_OCTETS:
	case PW_TYPE_STRING:
		if (vp->length > 8) {
			break;
		}

		if (vp->length > 4) {
			memcpy(&int64, vp->vp_octets, vp->length);
			return snprintf(out, outlen, "%" PRIu64, htonll(int64));
		}

		memcpy(&int32, vp->vp_octets, vp->length);
		return snprintf(out, outlen, "%i", htonl(int32));

	case PW_TYPE_INTEGER64:
		return snprintf(out, outlen, "%" PRIu64, vp->vp_integer64);

	/*
	 *	IP addresses are treated specially, as parsing functions assume the value
	 *	is bigendian and will convert it for us.
	 */
	case PW_TYPE_IPADDR:
		return snprintf(out, outlen, "%u", htonl(vp->vp_ipaddr));

	case PW_TYPE_IPV4PREFIX:
		return snprintf(out, outlen, "%u", htonl((*(uint32_t *)(vp->vp_ipv4prefix + 2))));

	case PW_TYPE_INTEGER:
	case PW_TYPE_DATE:
	case PW_TYPE_BYTE:
	case PW_TYPE_SHORT:
		return snprintf(out, outlen, "%u", vp->vp_integer);

	/*
	 *	Ethernet is weird... It's network related, so we assume to it should be
	 *	bigendian.
	 */
	case PW_TYPE_ETHERNET:
		memcpy(&int64, &vp->vp_ether, vp->length);
		return snprintf(out, outlen, "%" PRIu64, htonll(int64));

	case PW_TYPE_SIGNED:
		return snprintf(out, outlen, "%i", vp->vp_signed);

	case PW_TYPE_IPV6ADDR:
		return fr_prints_uint128(out, outlen, ntohlll(*(uint128_t const *) &vp->vp_ipv6addr));

	case PW_TYPE_IPV6PREFIX:
		return fr_prints_uint128(out, outlen, ntohlll(*(uint128_t const *) &(vp->vp_ipv6prefix[2])));

	default:
		break;
	}

	REDEBUG("Type '%s' of length %zu cannot be converted to integer",
		fr_int2str(dict_attr_types, vp->da->type, "???"), vp->length);
	*out = '\0';

	return -1;
}

/** Print data as hex, not as VALUE.
 *
 */
static ssize_t xlat_hex(UNUSED void *instance, REQUEST *request,
			char const *fmt, char *out, size_t outlen)
{
	size_t i;
	VALUE_PAIR *vp;
	uint8_t const *p;
	ssize_t	ret;
	size_t	len;

	while (isspace((int) *fmt)) fmt++;

	if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) {
		*out = '\0';
		return -1;
	}

	ret = rad_vp2data(&p, vp);
	if (ret < 0) {
		return ret;
	}
	len = (size_t) ret;

	/*
	 *	Don't truncate the data.
	 */
	if ((ret < 0 ) || (outlen < (len * 2))) {
		*out = 0;
		return 0;
	}

	for (i = 0; i < len; i++) {
		snprintf(out + 2*i, 3, "%02x", p[i]);
	}

	return len * 2;
}

/** Print out attribute info
 *
 * Prints out all instances of a current attribute, or all attributes in a list.
 *
 * At higher debugging levels, also prints out alternative decodings of the same
 * value. This is helpful to determine types for unknown attributes of long
 * passed vendors, or just crazy/broken NAS.
 *
 * It's also useful for exposing issues in the packet decoding functions, as in
 * some cases they get fed random garbage data.
 *
 * This expands to a zero length string.
 */
static ssize_t xlat_debug_attr(UNUSED void *instance, REQUEST *request, char const *fmt,
			       char *out, UNUSED size_t outlen)
{
	VALUE_PAIR *vp, **vps;
	REQUEST *current;
	value_pair_tmpl_t vpt;
	vp_cursor_t cursor;
	char buffer[1024];

	if (!RDEBUG_ENABLED2) {
		*out = '\0';
		return -1;
	}

	while (isspace((int) *fmt)) fmt++;

	if (radius_parse_attr(&vpt, fmt, REQUEST_CURRENT, PAIR_LIST_REQUEST) < 0) {
		RDEBUG("%s", fr_strerror());
		return -1;
	}

	current = request;
	if (radius_request(&current, vpt.vpt_request) < 0) return -2;

	vps = radius_list(current, vpt.vpt_list);
	if (!vps) {
		return -2;
	}

	RIDEBUG("Attributes matching \"%s\"", fmt);
	vp = fr_cursor_init(&cursor, vps);

	if (vpt.vpt_da) {
		vp = fr_cursor_next_by_da(&cursor, vpt.vpt_da, TAG_ANY);
	}
	while (vp) {
		DICT_ATTR *dac = NULL;
		DICT_VENDOR *dv;

		vp_prints_value(buffer, sizeof(buffer), vp, '\'');

		if (vp->da->flags.has_tag) {
			RIDEBUG2("\t%s:%s:%i %s %s",
				fr_int2str(pair_lists, vpt.vpt_list, "<INVALID>"),
				vp->da->name,
				vp->tag,
				fr_int2str(fr_tokens, vp->op, "<INVALID>"),
				buffer);
		} else {
			RIDEBUG2("\t%s:%s %s %s",
				fr_int2str(pair_lists, vpt.vpt_list, "<INVALID>"),
				vp->da->name,
				fr_int2str(fr_tokens, vp->op, "<INVALID>"),
				buffer);
		}

		if (!RDEBUG_ENABLED3) {
			goto next_vp;
		}

		if (vp->da->vendor) {
			dv = dict_vendorbyvalue(vp->da->vendor);
			RDEBUG3("\t\tvendor        : %i (%s)", vp->da->vendor, dv ? dv->name : "unknown");
		}
		RDEBUG3("\t\ttype          : %s", fr_int2str(dict_attr_types, vp->da->type, "<INVALID>"));
		RDEBUG3("\t\tlength        : %zu", vp->length);

		dac = talloc_memdup(request, vp->da, sizeof(DICT_ATTR));
		if (!dac) return -1;
		talloc_set_type(dac, DICT_ATTR);
		dac->flags.vp_free = 0;

	next_vp:
		talloc_free(dac);

		if (vpt.vpt_da) {
			vp = fr_cursor_next_by_da(&cursor, vpt.vpt_da, TAG_ANY);
		} else {
			vp = fr_cursor_next(&cursor);
		}
	}

	*out = '\0';
	return 0;
}

/** Prints the current module processing the request
 *
 */
static ssize_t xlat_module(UNUSED void *instance, REQUEST *request,
			   UNUSED char const *fmt, char *out, size_t outlen)
{
	strlcpy(out, request->module, outlen);

	return strlen(out);
}

#ifdef WITH_UNLANG
/** Implements the Foreach-Variable-X
 *
 * @see modcall()
 */
static ssize_t xlat_foreach(void *instance, REQUEST *request,
			    UNUSED char const *fmt, char *out, size_t outlen)
{
	VALUE_PAIR	**pvp;
	size_t		len;

	/*
	 *	See modcall, "FOREACH" for how this works.
	 */
	pvp = (VALUE_PAIR **) request_data_reference(request, radius_get_vp, *(int*) instance);
	if (!pvp || !*pvp) {
		*out = '\0';
		return 0;
	}

	len = vp_prints_value(out, outlen, *pvp, 0);
	if (is_truncated(len, outlen)) {
		RDEBUG("Insufficient buffer space to write foreach value");
		return -1;
	}

	return len;
}
#endif

/** Print data as string, if possible.
 *
 * If attribute "Foo" is defined as "octets" it will normally
 * be printed as 0x0a0a0a. The xlat "%{string:Foo}" will instead
 * expand to "\n\n\n"
 */
static ssize_t xlat_string(UNUSED void *instance, REQUEST *request,
			   char const *fmt, char *out, size_t outlen)
{
	size_t len;
	ssize_t ret;
	VALUE_PAIR *vp;
	uint8_t const *p;

	while (isspace((int) *fmt)) fmt++;

	if (outlen < 3) {
	nothing:
		*out = '\0';
		return 0;
	}

	if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) goto nothing;

	ret = rad_vp2data(&p, vp);
	if (ret < 0) {
		return ret;
	}

	switch (vp->da->type) {
		case PW_TYPE_OCTETS:
			len = fr_print_string((char const *) p, vp->length, out, outlen);
			break;

		case PW_TYPE_STRING:
			len = strlcpy(out, vp->vp_strvalue, outlen);
			break;

		default:
			len = fr_print_string((char const *) p, ret, out, outlen);
			break;
	}

	return len;
}

/** xlat expand string attribute value
 *
 */
static ssize_t xlat_xlat(UNUSED void *instance, REQUEST *request,
			char const *fmt, char *out, size_t outlen)
{
	VALUE_PAIR *vp;

	while (isspace((int) *fmt)) fmt++;

	if (outlen < 3) {
	nothing:
		*out = '\0';
		return 0;
	}

	if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) goto nothing;

	return radius_xlat(out, outlen, request, vp->vp_strvalue, NULL, NULL);
}

/** Dynamically change the debugging level for the current request
 *
 * Example %{debug:3}
 */
static ssize_t xlat_debug(UNUSED void *instance, REQUEST *request,
			  char const *fmt, char *out, size_t outlen)
{
	int level = 0;

	/*
	 *  Expand to previous (or current) level
	 */
	snprintf(out, outlen, "%d", request->options & RAD_REQUEST_OPTION_DEBUG4);

	/*
	 *  Assume we just want to get the current value and NOT set it to 0
	 */
	if (!*fmt)
		goto done;

	level = atoi(fmt);
	if (level == 0) {
		request->options = RAD_REQUEST_OPTION_NONE;
		request->radlog = NULL;
	} else {
		if (level > 4) level = 4;

		request->options = level;
		request->radlog = vradlog_request;
	}

	done:
	return strlen(out);
}

/*
 *	Compare two xlat_t structs, based ONLY on the module name.
 */
static int xlat_cmp(void const *one, void const *two)
{
	xlat_t const *a = one;
	xlat_t const *b = two;

	if (a->length != b->length) {
		return a->length - b->length;
	}

	return memcmp(a->name, b->name, a->length);
}


/*
 *	find the appropriate registered xlat function.
 */
static xlat_t *xlat_find(char const *name)
{
	xlat_t my_xlat;

	strlcpy(my_xlat.name, name, sizeof(my_xlat.name));
	my_xlat.length = strlen(my_xlat.name);

	return rbtree_finddata(xlat_root, &my_xlat);
}


/** Register an xlat function.
 *
 * @param[in] name xlat name.
 * @param[in] func xlat function to be called.
 * @param[in] escape function to sanitize any sub expansions passed to the xlat function.
 * @param[in] instance of module that's registering the xlat function.
 * @return 0 on success, -1 on failure
 */
int xlat_register(char const *name, RAD_XLAT_FUNC func, RADIUS_ESCAPE_STRING escape, void *instance)
{
	xlat_t	 *c;
	xlat_t	 my_xlat;
	rbnode_t *node;

	if (!name || !*name) {
		DEBUG("xlat_register: Invalid xlat name");
		return -1;
	}

	/*
	 *	First time around, build up the tree...
	 *
	 *	FIXME: This code should be hoisted out of this function,
	 *	and into a global "initialization".  But it isn't critical...
	 */
	if (!xlat_root) {
#ifdef WITH_UNLANG
		int i;
#endif

		xlat_root = rbtree_create(xlat_cmp, free, 0);
		if (!xlat_root) {
			DEBUG("xlat_register: Failed to create tree.");
			return -1;
		}

#ifdef WITH_UNLANG
		for (i = 0; xlat_foreach_names[i] != NULL; i++) {
			xlat_register(xlat_foreach_names[i],
				      xlat_foreach, NULL, &xlat_inst[i]);
			c = xlat_find(xlat_foreach_names[i]);
			rad_assert(c != NULL);
			c->internal = true;
		}
#endif

#define XLAT_REGISTER(_x) xlat_register(STRINGIFY(_x), xlat_ ## _x, NULL, NULL); \
		c = xlat_find(STRINGIFY(_x)); \
		rad_assert(c != NULL); \
		c->internal = true

		XLAT_REGISTER(integer);
		XLAT_REGISTER(strlen);
		XLAT_REGISTER(length);
		XLAT_REGISTER(hex);
		XLAT_REGISTER(string);
		XLAT_REGISTER(xlat);
		XLAT_REGISTER(module);
		XLAT_REGISTER(debug_attr);

		xlat_register("debug", xlat_debug, NULL, &xlat_inst[0]);
		c = xlat_find("debug");
		rad_assert(c != NULL);
		c->internal = true;
	}

	/*
	 *	If it already exists, replace the instance.
	 */
	strlcpy(my_xlat.name, name, sizeof(my_xlat.name));
	my_xlat.length = strlen(my_xlat.name);
	c = rbtree_finddata(xlat_root, &my_xlat);
	if (c) {
		if (c->internal) {
			DEBUG("xlat_register: Cannot re-define internal xlat");
			return -1;
		}

		c->func = func;
		c->escape = escape;
		c->instance = instance;
		return 0;
	}

	/*
	 *	Doesn't exist.  Create it.
	 */
	c = rad_malloc(sizeof(*c));
	memset(c, 0, sizeof(*c));

	c->func = func;
	c->escape = escape;
	strlcpy(c->name, name, sizeof(c->name));
	c->length = strlen(c->name);
	c->instance = instance;

	node = rbtree_insert_node(xlat_root, c);
	if (!node) {
		talloc_free(c);
		return -1;
	}

	return 0;
}

/** Unregister an xlat function
 *
 * We can only have one function to call per name, so the passing of "func"
 * here is extraneous.
 *
 * @param[in] name xlat to unregister.
 * @param[in] func unused.
 * @param[in] instance data.
 */
void xlat_unregister(char const *name, UNUSED RAD_XLAT_FUNC func, void *instance)
{
	xlat_t	*c;
	xlat_t		my_xlat;

	if (!name) return;

	strlcpy(my_xlat.name, name, sizeof(my_xlat.name));
	my_xlat.length = strlen(my_xlat.name);

	c = rbtree_finddata(xlat_root, &my_xlat);
	if (!c) return;

	if (c->instance != instance) return;

	rbtree_deletebydata(xlat_root, c);
}


/** Crappy temporary function to add attribute ref support to xlats
 *
 * This needs to die, and hopefully will die, when xlat functions accept
 * xlat node structures.
 *
 * Provides either a pointer to a buffer which contains the value of the reference VALUE_PAIR
 * in an architecture independent format. Or a pointer to the start of the fmt string.
 *
 * The pointer is only guaranteed to be valid between calls to xlat_fmt_to_ref,
 * and so long as the source VALUE_PAIR is not freed.
 *
 * @param out where to write a pointer to the buffer to the data the xlat function needs to work on.
 * @param request current request.
 * @param fmt string.
 * @returns the length of the data or -1 on error.
 */
ssize_t xlat_fmt_to_ref(uint8_t const **out, REQUEST *request, char const *fmt)
{
	VALUE_PAIR *vp;

	while (isspace((int) *fmt)) fmt++;

	if (fmt[0] == '&') {
		if ((radius_get_vp(&vp, request, fmt) < 0) || !vp) {
			*out = NULL;
			return -1;
		}

		return rad_vp2data(out, vp);
	}

	*out = (uint8_t const *)fmt;
	return strlen(fmt);
}

/** De-register all xlat functions, used mainly for debugging.
 *
 */
void xlat_free(void)
{
	rbtree_free(xlat_root);
}


#ifdef DEBUG_XLAT
#define XLAT_DEBUG DEBUG3
#else
#define XLAT_DEBUG(...)
#endif

static ssize_t xlat_tokenize_expansion(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
				       char const **error);
static ssize_t xlat_tokenize_literal(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
				     int brace, char const **error);
static size_t xlat_process(char **out, REQUEST *request, xlat_exp_t const * const head,
			   RADIUS_ESCAPE_STRING escape, void *escape_ctx);

static ssize_t xlat_tokenize_alternation(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
					 char const **error)
{
	ssize_t slen;
	char *p;
	xlat_exp_t *node;

	rad_assert(fmt[0] == '%');
	rad_assert(fmt[1] == '{');
	rad_assert(fmt[2] == '%');
	rad_assert(fmt[3] == '{');

	XLAT_DEBUG("ALTERNATE <-- %s", fmt);

	node = talloc_zero(ctx, xlat_exp_t);
	node->type = XLAT_ALTERNATE;

	p = fmt + 2;
	slen = xlat_tokenize_expansion(node, p, &node->child, error);
	if (slen <= 0) {
		talloc_free(node);
		return slen - (p - fmt);
	}
	p += slen;

	if (p[0] != ':') {
		talloc_free(node);
		*error = "Expected ':' after first expansion";
		return -(p - fmt);
	}
	p++;

	if (p[0] != '-') {
		talloc_free(node);
		*error = "Expected '-' after ':'";
		return -(p - fmt);
	}
	p++;

	/*
	 *	Allow the RHS to be empty as a special case.
	 */
	if (*p == '}') {
		/*
		 *	Hack up an empty string.
		 */
		node->alternate = talloc_zero(node, xlat_exp_t);
		node->alternate->type = XLAT_LITERAL;
		node->alternate->fmt = talloc_typed_strdup(node->alternate, "");
		*(p++) = '\0';

	} else {
		slen = xlat_tokenize_literal(node, p,  &node->alternate, true, error);
		if (slen <= 0) {
			talloc_free(node);
			return slen - (p - fmt);
		}

		if (!node->alternate) {
			talloc_free(node);
			*error = "Empty expansion is invalid";
			return -(p - fmt);
		}
		p += slen;
	}

	*head = node;
	return p - fmt;
}

static ssize_t xlat_tokenize_expansion(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
				       char const **error)
{
	ssize_t slen;
	char *p, *q, *brace;
	char const *attrname;
	xlat_exp_t *node;

	rad_assert(fmt[0] == '%');
	rad_assert(fmt[1] == '{');

	/*
	 *	%{%{...}:-bar}
	 */
	if ((fmt[2] == '%') && (fmt[3] == '{')) {
		return xlat_tokenize_alternation(ctx, fmt, head, error);
	}

	XLAT_DEBUG("EXPANSION <-- %s", fmt);
	node = talloc_zero(ctx, xlat_exp_t);
	attrname = node->fmt = fmt + 2;
	node->len = 0;

#ifdef HAVE_REGEX_H
	/*
	 *	Handle regex's specially.
	 */
	if (isdigit((int) fmt[2]) && (fmt[3] == '}')) {
		if (fmt[2] == '9') {
			talloc_free(node);
			*error = "Invalid regex reference";
			return -2;
		}

		XLAT_DEBUG("REGEX <-- %s", fmt);
		fmt[3] = '\0';
		node->num = fmt[2] - '0'; /* ASCII */

		node->type = XLAT_REGEX;
		*head = node;
		return 4;
	}
#endif /* HAVE_REGEX_H */

	/*
	 *	%{Attr-Name}
	 *	%{Attr-Name[#]}
	 *	%{Tunnel-Password:1}
	 *	%{Tunnel-Password:1[#]}
	 *	%{request:Attr-Name}
	 *	%{request:Tunnel-Password:1}
	 *	%{request:Tunnel-Password:1[#]}
	 *	%{mod:foo}
	 */
	 brace = NULL;
	for (p = fmt + 2; *p != '\0'; p++) {
		if (*p == ':') break;

		if (isspace((int) *p)) break;

		if (*p == '[') break;

		if (*p == '}') break;
	}

	if (*p != ':') p = NULL;

	/*
	 *	Might be a module name reference.
	 */
	if (p) {
		*p = '\0';

		/*
		 *	%{mod:foo}
		 */
		node->xlat = xlat_find(node->fmt);
		if (node->xlat) {
			node->type = XLAT_MODULE;

			XLAT_DEBUG("MOD <-- %s ... %s", node->fmt, p + 1);

			slen = xlat_tokenize_literal(node, p + 1, &node->child, true, error);
			if (slen <= 0) {
				talloc_free(node);
				return slen - (p - fmt);
			}
			p += slen + 1;

			*head = node;
			rad_assert(node->next == NULL);
			return p - fmt;
		}

		/*
		 *	Modules can have '}' in their RHS, so we
		 *	didn't check for that until now.
		 *
		 *	As of now, node->fmt MUST be a reference to an
		 *	attribute, however complicated.  So it MUST have a closing brace.
		 */
		brace = strchr(p + 1, '}');
		if (!brace) goto no_brace;
		*brace = '\0';

		/*
		 *	%{User-Name}
		 *	%{User-Name[1]}
		 *	%{Tunnel-Password:1}
		 *	%{request:Tunnel-Password:1}
		 *
		 *	<sigh>  The syntax is fairly poor.
		 */
		XLAT_DEBUG("Looking for list in '%s'", attrname);

		/*
		 *	Not a module.  Has to be an attribute
		 *	reference.
		 *
		 *	As of v3, we've removed %{request: ..>} as
		 *	internally registered xlats.
		 */
		*p = ':';
		node->ref = radius_request_name(&attrname, REQUEST_CURRENT);
		rad_assert(node->ref != REQUEST_UNKNOWN);

		node->list = radius_list_name(&attrname, PAIR_LIST_REQUEST);
		if (node->list == PAIR_LIST_UNKNOWN) {
			talloc_free(node);
			*error = "Unknown module";
			return -2;
		}

		/*
		 *	Check for a trailing tag.
		 */
		p = strchr(attrname, ':');
		if (p) *p = '\0';

	} else {
		brace = strchr(attrname, '}');
		if (!brace) {
		no_brace:
			talloc_free(node);
			*error = "No matching closing brace";
			return -1;	/* second character of format string */
		}
		*brace = '\0';

		node->ref = REQUEST_CURRENT;
		node->list = PAIR_LIST_REQUEST;
	}

	*brace = '\0';

	XLAT_DEBUG("Looking for attribute name in %s", attrname);

	/*
	 *	Allow for an array reference.  They come AFTER the
	 *	tag, if the tag exists.  Otherwise, they come after
	 *	the attribute name.
	 */
	if (p) {
		q = strchr(p + 1, '[');
	} else {
		q = strchr(attrname, '[');
	}
	if (q) *(q++) = '\0';

	if (!*attrname) {
		talloc_free(node);
		*error = "Empty expression is invalid";
		return -(attrname - fmt);
	}

	/*
	 *	It's either an attribute name, or a Tunnel-Password:TAG
	 *	with the ':' already set to NULL.
	 */
	node->da = dict_attrbyname(attrname);
	if (!node->da) {
		/*
		 *	Foreach.  Maybe other stuff, too.
		 */
		node->xlat = xlat_find(attrname);
		if (node->xlat) {
			node->type = XLAT_VIRTUAL;
			node->fmt = attrname;

			XLAT_DEBUG("VIRTUAL <-- %s", node->fmt);
			*head = node;
			rad_assert(node->next == NULL);
			brace++;
			return brace - fmt;
		}

		talloc_free(node);
		*error = "Unknown attribute";
		return -(attrname - fmt);
	}

	/*
	 *	Parse the tag.
	 */
	if (p) {
		unsigned long tag;
		char *end;

		if (!node->da->flags.has_tag) {
			talloc_free(node);
			*error = "Attribute cannot have a tag";
			return - (p - fmt);
		}

		tag = strtoul(p + 1, &end, 10);
		p++;

		if (tag == ULONG_MAX) {
			talloc_free(node);
			*error = "Invalid tag value";
			return - (p - fmt);
		}

		node->tag = tag;
		p = end;

		if (*p) {
			talloc_free(node);
			*error = "Unexpected text after tag";
			return - (p - fmt);
		}

	} else {
		node->tag = TAG_ANY;
		/* leave p alone */
	}

	/*
	 *	Check for array reference
	 */
	if (q) {
		unsigned long num;
		char *end;

		p = q;
		if (*p== '#') {
			node->num = XLAT_ATTR_NUMBER;
			p++;

		} else if (*p == '*') {
			node->num = XLAT_ATTR_CONCAT;
			p++;

		} else if (isdigit((int) *p)) {
			num = strtoul(p, &end, 10);
			if ((num == ULONG_MAX) || (num >= XLAT_ATTR_NUMBER)) {
				talloc_free(node);
				*error = "Invalid number";
				return - (p - fmt);
			}
			p = end;
			DEBUG("END %s", p);
			node->num = num;

		} else {
			talloc_free(node);
			*error = "Invalid array reference";
			return - (p - fmt);
		}

		if (*p != ']') {
			talloc_free(node);
			*error = "Expected ']'";
			return - (p - fmt);
		}

		p++;
		if (*p) {
			talloc_free(node);
			*error = "Unexpected text after array reference";
			return - (p - fmt);
		}
	}

	rad_assert(!p || (p == brace));

	node->type = XLAT_ATTRIBUTE;
	p = brace + 1;

	*head = node;
	rad_assert(node->next == NULL);
	return p - fmt;
}


static ssize_t xlat_tokenize_literal(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
				     int brace, char const **error)
{
	char *p, *q;
	xlat_exp_t *node;

	if (!*fmt) return 0;

	XLAT_DEBUG("LITERAL <-- %s", fmt);

	node = talloc_zero(ctx, xlat_exp_t);
	node->fmt = fmt;
	node->len = 0;
	node->type = XLAT_LITERAL;

	p = fmt;
	q = fmt;

	while (*p) {
		/*
		 *	Convert \n to it's literal representation.
		 */
		if (p[0] == '\\') switch (p[1]) {
			case 't':
				*(q++) = '\t';
				p += 2;
				node->len++;
				continue;

			case 'n':
				*(q++) = '\n';
				p += 2;
				node->len++;
				continue;

			case 'x':
				p += 2;
				if (!p[0] || !p[1]) {
					talloc_free(node);
					*error = "Hex expansion requires two hex digits";
					return -(p - fmt);
				}

				if (!fr_hex2bin((uint8_t *) q, p, 2)) {
					talloc_free(node);
					*error = "Invalid hex characters";
					return -(p - fmt);
				}

				/*
				 *	Don't let people shoot themselves in the foot.
				 *	\x00 is forbidden.
				 */
				if (!*q) {
					talloc_free(node);
					*error = "Cannot add zero byte to printable string";
					return -(p - fmt);
				}

				p += 2;
				q++;
				node->len++;
				continue;

			default:
				*(q++) = *p;
				p += 2;
				node->len++;
				continue;
			}

		/*
		 *	Process the expansion.
		 */
		if ((p[0] == '%') && (p[1] == '{')) {
			ssize_t slen;

			XLAT_DEBUG("LITERAL <-- %s", node->fmt);

			slen = xlat_tokenize_expansion(node, p, &node->next, error);
			if (slen <= 0) {
				talloc_free(node);
				return slen - (p - fmt);
			}
			*p = '\0'; /* end the literal */
			p += slen;

			rad_assert(node->next != NULL);

			/*
			 *	Short-circuit the recursive call.
			 *	This saves another function call and
			 *	memory allocation.
			 */
			if (!*p) break;

			/*
			 *	"foo %{User-Name} bar"
			 *	LITERAL		"foo "
			 *	EXPANSION	User-Name
			 *	LITERAL		" bar"
			 */
			slen = xlat_tokenize_literal(node->next, p, &(node->next->next), brace, error);
			rad_assert(slen != 0);
			if (slen < 0) {
				talloc_free(node);
				return slen - (p - fmt);
			}

			p += slen;
			break;	/* stop processing the string */
		}

		/*
		 *	Check for valid single-character expansions.
		 */
		if (p[0] == '%') {
			ssize_t slen;
			xlat_exp_t *next;

			if (!p[1] || !strchr("%dlmtDGHISTYv", p[1])) {
					talloc_free(node);
					*error = "Invalid variable expansion";
					p++;
					return - (p - fmt);
			}

			next = talloc_zero(node, xlat_exp_t);
			next->len = 1;

			if (p[1] == '%') {
				next->fmt = talloc_typed_strdup(next, "%");

				XLAT_DEBUG("LITERAL <-- %s", next->fmt);
				next->type = XLAT_LITERAL;

			} else {
				next->fmt = p + 1;

				XLAT_DEBUG("PERCENT <-- %c", *next->fmt);
				next->type = XLAT_PERCENT;
			}

			node->next = next;
			*p = '\0';
			p += 2;

			if (!*p) break;

			/*
			 *	And recurse.
			 */
			slen = xlat_tokenize_literal(node->next, p, &(node->next->next), brace, error);
			rad_assert(slen != 0);
			if (slen < 0) {
				talloc_free(node);
				return slen - (p - fmt);
			}

			p += slen;
			break;	/* stop processing the string */
		}

		/*
		 *	If required, eat the brace.
		 */
		if (brace && (*p == '}')) {
			*q = '\0';
			p++;
			break;
		}

		*(q++) = *(p++);
		node->len++;
	}

	/*
	 *	Squash zero-width literals
	 */
	if (node->len > 0) {
		*head = node;
	} else {
		*head = talloc_steal(ctx, node->next);
		talloc_free(node);
	}

	return p - fmt;
}


static char const xlat_tabs[] = "																																																																																																																																";

static void xlat_tokenize_debug(xlat_exp_t const *node, int lvl)
{
	rad_assert(node != NULL);

	if (lvl >= (int) sizeof(xlat_tabs)) lvl = sizeof(xlat_tabs);

	while (node) {
		switch (node->type) {
		case XLAT_LITERAL:
			DEBUG("%.*sliteral --> %s", lvl, xlat_tabs, node->fmt);
			break;

		case XLAT_PERCENT:
			DEBUG("%.*spercent --> %c", lvl, xlat_tabs, node->fmt[0]);
			break;

		case XLAT_ATTRIBUTE:
			rad_assert(node->da != NULL);
			DEBUG("%.*sattribute --> %s", lvl, xlat_tabs, node->da->name);
			rad_assert(node->child == NULL);
			if ((node->tag != 0) || (node->num != 0)) {
				DEBUG("%.*s{", lvl, xlat_tabs);

				DEBUG("%.*sref  %d", lvl + 1, xlat_tabs, node->ref);
				DEBUG("%.*slist %d", lvl + 1, xlat_tabs, node->list);

				if (node->tag) DEBUG("%.*stag %d", lvl + 1, xlat_tabs, node->tag);
				if (node->num) {
					if (node->num == XLAT_ATTR_NUMBER) {
						DEBUG("%.*s[#]", lvl + 1, xlat_tabs);
					} else if (node->num == XLAT_ATTR_CONCAT) {
						DEBUG("%.*s[*]", lvl + 1, xlat_tabs);
					} else {
						DEBUG("%.*s[%d]", lvl + 1, xlat_tabs, node->num);
					}
				}

				DEBUG("%.*s}", lvl, xlat_tabs);
			}
			break;

		case XLAT_VIRTUAL:
			rad_assert(node->fmt != NULL);
			DEBUG("%.*svirtual --> %s", lvl, xlat_tabs, node->fmt);
			break;

		case XLAT_MODULE:
			rad_assert(node->xlat != NULL);
			DEBUG("%.*sxlat --> %s", lvl, xlat_tabs, node->xlat->name);
			if (node->child) {
				DEBUG("%.*s{", lvl, xlat_tabs);
				xlat_tokenize_debug(node->child, lvl + 1);
				DEBUG("%.*s}", lvl, xlat_tabs);
			}
			break;

#ifdef HAVE_REGEX_H
		case XLAT_REGEX:
			DEBUG("%.*sregex-var --> %d", lvl, xlat_tabs, node->num);
			break;
#endif

		case XLAT_ALTERNATE:
			DEBUG("%.*sif {", lvl, xlat_tabs);
			xlat_tokenize_debug(node->child, lvl + 1);
			DEBUG("%.*s}", lvl, xlat_tabs);
			DEBUG("%.*selse {", lvl, xlat_tabs);
			xlat_tokenize_debug(node->alternate, lvl + 1);
			DEBUG("%.*s}", lvl, xlat_tabs);
			break;
		}
		node = node->next;
	}
}

size_t xlat_sprint(char *buffer, size_t bufsize, xlat_exp_t const *node)
{
	size_t len;
	char *p, *end;

	if (!node) {
		*buffer = '\0';
		return 0;
	}

	p = buffer;
	end = buffer + bufsize;

	while (node) {
		switch (node->type) {
		case XLAT_LITERAL:
			strlcpy(p, node->fmt, end - p);
			p += strlen(p);
			break;

		case XLAT_PERCENT:
			p[0] = '%';
			p[1] = node->fmt[0];
			p += 2;
			break;

		case XLAT_ATTRIBUTE:
			*(p++) = '%';
			*(p++) = '{';

			if (node->ref != REQUEST_CURRENT) {
				strlcpy(p, fr_int2str(request_refs, node->ref, "??"), end - p);
				p += strlen(p);
				*(p++) = '.';
			}

			if ((node->ref != REQUEST_CURRENT) ||
			    (node->list != PAIR_LIST_REQUEST)) {
				strlcpy(p, fr_int2str(pair_lists, node->list, "??"), end - p);
				p += strlen(p);
				*(p++) = ':';
			}

			strlcpy(p, node->da->name, end - p);
			p += strlen(p);

			if (node->tag != TAG_ANY) {
				*(p++) = ':';
				snprintf(p, end - p, "%u", node->tag);
				p += strlen(p);
			}

			if (node->num != 0) {
				*(p++) = '[';
				switch (node->num) {
				case XLAT_ATTR_NUMBER:
					*(p++) = '#';
					break;

				case XLAT_ATTR_CONCAT:
					*(p++) = '*';
					break;

				default:
					snprintf(p, end - p, "%u", node->num);
					p += strlen(p);
				}
				*(p++) = ']';
			}
			*(p++) = '}';
			break;
#ifdef HAVE_REGEX_H
		case XLAT_REGEX:
			snprintf(p, end - p, "%%{%u}", node->num);
			p += strlen(p);
			break;
#endif
		case XLAT_VIRTUAL:
			*(p++) = '%';
			*(p++) = '{';
			strlcpy(p, node->fmt, end - p);
			p += strlen(p);
			*(p++) = '}';
			break;

		case XLAT_MODULE:
			*(p++) = '%';
			*(p++) = '{';
			strlcpy(p, node->xlat->name, end - p);
			p += strlen(p);
			*(p++) = ':';
			rad_assert(node->child != NULL);
			len = xlat_sprint(p, end - p, node->child);
			p += len;
			*(p++) = '}';
			break;

		case XLAT_ALTERNATE:
			*(p++) = '%';
			*(p++) = '{';

			len = xlat_sprint(p, end - p, node->child);
			p += len;

			*(p++) = ':';
			*(p++) = '-';

			len = xlat_sprint(p, end - p, node->alternate);
			p += len;

			*(p++) = '}';
			break;
		}


		if (p == end) break;

		node = node->next;
	}

	*p = '\0';

	return p - buffer;
}

ssize_t xlat_tokenize(TALLOC_CTX *ctx, char *fmt, xlat_exp_t **head,
		      char const **error)
{
	return xlat_tokenize_literal(ctx, fmt, head, false, error);
}


/** Tokenize an xlat expansion
 *
 * @param[in] request the input request.  Memory will be attached here.
 * @param[in] fmt the format string to expand
 * @param[out] head the head of the xlat list / tree structure.
 */
static ssize_t xlat_tokenize_request(REQUEST *request, char const *fmt, xlat_exp_t **head)
{
	ssize_t slen;
	char *tokens;
	char const *error;

	*head = NULL;

	/*
	 *	Copy the original format string to a buffer so that
	 *	the later functions can mangle it in-place, which is
	 *	much faster.
	 */
	tokens = talloc_typed_strdup(request, fmt);
	if (!tokens) return -1;

	slen = xlat_tokenize_literal(request, tokens, head, false, &error);

	/*
	 *	Zero length expansion, return a zero length node.
	 */
	if (slen == 0) {
		*head = talloc_zero(request, xlat_exp_t);
	}

	/*
	 *	Output something like:
	 *
	 *	"format string"
	 *	"       ^ error was here"
	 */
	if (slen < 0) {
		talloc_free(tokens);
		rad_assert(error != NULL);

		REMARKER(fmt, -slen, error);
		return slen;
	}

	if (*head && (debug_flag > 2)) {
		DEBUG("%s", fmt);
		DEBUG("Parsed xlat tree:");
		xlat_tokenize_debug(*head, 0);
	}

	/*
	 *	All of the nodes point to offsets in the "tokens"
	 *	string.  Let's ensure that free'ing head will free
	 *	"tokens", too.
	 */
	(void) talloc_steal(*head, tokens);

	return slen;
}


static char *xlat_getvp(TALLOC_CTX *ctx, REQUEST *request, pair_lists_t list, DICT_ATTR const *da, int8_t tag,
			int num, bool return_null)
{
	VALUE_PAIR *vp, *vps = NULL, *myvp = NULL;
	RADIUS_PACKET *packet = NULL;
	DICT_VALUE *dv;
	char *ret = NULL;

	/*
	 *	Arg.  Too much abstraction is annoying.
	 */
	switch (list) {
	default:
		if (return_null) return NULL;
		return vp_aprint_type(ctx, da->type);

	case PAIR_LIST_CONTROL:
		vps = request->config_items;
		break;

	case PAIR_LIST_REQUEST:
		packet = request->packet;
		if (packet) vps = packet->vps;
		break;

	case PAIR_LIST_REPLY:
		packet = request->reply;
		if (packet) vps = packet->vps;
		break;

#ifdef WITH_PROXY
	case PAIR_LIST_PROXY_REQUEST:
		packet = request->proxy;
		if (packet) vps = packet->vps;
		break;

	case PAIR_LIST_PROXY_REPLY:
		packet = request->proxy_reply;
		if (packet) vps = packet->vps;
		break;
#endif

#ifdef WITH_COA
	case PAIR_LIST_COA:
	case PAIR_LIST_DM:
		if (request->coa) packet = request->coa->packet;
		if (packet) vps = packet->vps;
		break;

	case PAIR_LIST_COA_REPLY:
	case PAIR_LIST_DM_REPLY:
		if (request->coa) packet = request->coa->reply;
		if (packet) vps = packet->vps;
		break;

#endif
	}

	/*
	 *	Now that we have the list, etc. handled,
	 *	find the VP and print it.
	 */
	if ((da->vendor != 0) || (da->attr < 256) || (list == PAIR_LIST_CONTROL)) {
	print_vp:
		vp = pairfind(vps, da->attr, da->vendor, tag);
		if (!vp) {
			return NULL;
		}
		goto do_print;
	}

	/*
	 *	Some non-packet expansions
	 */
	switch (da->attr) {
	default:
		break;		/* ignore them */

	case PW_CLIENT_SHORTNAME:
		if (request->client && request->client->shortname) {
			return talloc_typed_strdup(ctx, request->client->shortname);
		}
		return talloc_typed_strdup(ctx, "<UNKNOWN-CLIENT>");

	case PW_REQUEST_PROCESSING_STAGE:
		if (request->component) {
			return talloc_typed_strdup(ctx, request->component);
		}
		return talloc_typed_strdup(ctx, "server_core");

	case PW_VIRTUAL_SERVER:
		if (!request->server) return NULL;
		return talloc_typed_strdup(ctx, request->server);

	case PW_MODULE_RETURN_CODE:
		if (!request->rcode) return NULL;
		return talloc_typed_strdup(ctx, fr_int2str(modreturn_table, request->rcode, ""));
	}

	/*
	 *	All of the attributes must now refer to a packet.
	 *	If there's no packet, we can't print any attribute
	 *	referencing it.
	 */
	if (!packet) {
		if (return_null) return NULL;
		return vp_aprint_type(ctx, da->type);
	}

	vp = NULL;
	switch (da->attr) {
	default:
		goto print_vp;

	case PW_PACKET_TYPE:
		dv = dict_valbyattr(PW_PACKET_TYPE, 0, packet->code);
		if (dv) return talloc_typed_strdup(ctx, dv->name);
		return talloc_typed_asprintf(ctx, "%d", packet->code);

	case PW_RESPONSE_PACKET_TYPE:
	{
		int code = 0;

#ifdef WITH_PROXY
		if (request->proxy_reply && (!request->reply || !request->reply->code)) {
			code = request->proxy_reply->code;
		} else
#endif
			if (request->reply) {
				code = request->reply->code;
			}

		return talloc_typed_strdup(ctx, fr_packet_codes[code]);
	}

	/*
	 *	Virtual attributes which require a temporary VALUE_PAIR
	 *	to be allocated. We can't use stack allocated memory
	 *	because of the talloc checks sprinkled throughout the
	 *	various VP functions.
	 */
	case PW_PACKET_AUTHENTICATION_VECTOR:
		myvp = pairalloc(ctx, da);
		pairmemcpy(myvp, packet->vector, sizeof(packet->vector));
		vp = myvp;
		break;

	case PW_CLIENT_IP_ADDRESS:
	case PW_PACKET_SRC_IP_ADDRESS:
		if (packet->src_ipaddr.af == AF_INET) {
			myvp = pairalloc(ctx, da);
			myvp->vp_ipaddr = packet->src_ipaddr.ipaddr.ip4addr.s_addr;
			vp = myvp;
		}
		break;

	case PW_PACKET_DST_IP_ADDRESS:
		if (packet->dst_ipaddr.af == AF_INET) {
			myvp = pairalloc(ctx, da);
			myvp->vp_ipaddr = packet->dst_ipaddr.ipaddr.ip4addr.s_addr;
			vp = myvp;
		}
		break;

	case PW_PACKET_SRC_IPV6_ADDRESS:
		if (packet->src_ipaddr.af == AF_INET6) {
			myvp = pairalloc(ctx, da);
			memcpy(&myvp->vp_ipv6addr,
			       &packet->src_ipaddr.ipaddr.ip6addr,
			       sizeof(packet->src_ipaddr.ipaddr.ip6addr));
			vp = myvp;
		}
		break;

	case PW_PACKET_DST_IPV6_ADDRESS:
		if (packet->dst_ipaddr.af == AF_INET6) {
			myvp = pairalloc(ctx, da);
			memcpy(&myvp->vp_ipv6addr,
			       &packet->dst_ipaddr.ipaddr.ip6addr,
			       sizeof(packet->dst_ipaddr.ipaddr.ip6addr));
			vp = myvp;
		}
		break;

	case PW_PACKET_SRC_PORT:
		myvp = pairalloc(ctx, da);
		myvp->vp_integer = packet->src_port;
		vp = myvp;
		break;

	case PW_PACKET_DST_PORT:
		myvp = pairalloc(ctx, da);
		myvp->vp_integer = packet->dst_port;
		vp = myvp;
		break;
	}

do_print:
	/*
	 *	Fake various operations for virtual attributes.
	 */
	if (num && myvp) {
		char *p;

		/*
		 *	[*] means only one.
		 */
		if (num == XLAT_ATTR_CONCAT) num = 0;

		/*
		 *	[n] means NULL, as there's only one.
		 */
		if ((num > 0) && (num < XLAT_ATTR_NUMBER)) goto finish;

		p = vp_aprint_value(ctx, vp);
		rad_assert(p != NULL);

		/*
		 *	Get the length of it.
		 */
		if (num == XLAT_ATTR_NUMBER) {
			ret = talloc_typed_asprintf(ctx, "%d", (int) strlen(p));
			talloc_free(p);
			goto finish;
		}

		ret = p;
		goto finish;
	}

	/*
	 *	We want the N'th VP.
	 */
	if (num) {
		int count = 0;
		vp_cursor_t cursor;

		switch (num) {
		/*
		 *	Return a count of the VPs.
		 */
		case XLAT_ATTR_NUMBER:
			fr_cursor_init(&cursor, &vp);
			while (fr_cursor_next_by_da(&cursor, da, tag) != NULL) {
				count++;
			}

			return talloc_typed_asprintf(ctx, "%d", count);

		/*
		 *	Ugly, but working.
		 */
		case XLAT_ATTR_CONCAT:
		{
			char *p, *q;

			(void) fr_cursor_init(&cursor, &vp);
			vp = fr_cursor_next_by_da(&cursor, da, tag);
			if (!vp) return NULL;

			p = vp_aprint_value(ctx, vp);
			if (!p) return NULL;
			while ((vp = fr_cursor_next_by_da(&cursor, da, tag)) != NULL) {
				q = vp_aprint_value(ctx, vp);
				if (!q) return NULL;
				p = talloc_strdup_append(p, ",");
				p = talloc_strdup_append(p, q);
			}

			return p;
		}

		default:
			fr_cursor_init(&cursor, &vp);
			while ((vp = fr_cursor_next_by_da(&cursor, da, tag)) != NULL) {
				if (count++ == num) break;
			}
			break;
		}
	}

	if (!vp) {
		if (return_null) return NULL;
		return vp_aprint_type(ctx, da->type);
	}

	ret = vp_aprint_value(ctx, vp);

finish:
	talloc_free(myvp);
	return ret;
}

#ifdef DEBUG_XLAT
static const char *xlat_spaces = "                                                                                                                                                                                                                                                                ";
#endif

static char *xlat_aprint(TALLOC_CTX *ctx, REQUEST *request, xlat_exp_t const * const node,
			 RADIUS_ESCAPE_STRING escape, void *escape_ctx, int lvl)
{
	ssize_t rcode;
	char *str = NULL, *child;
	REQUEST *ref;

	XLAT_DEBUG("%.*sxlat aprint %d", lvl, xlat_spaces, node->type);

	switch (node->type) {
		/*
		 *	Don't escape this.
		 */
	case XLAT_LITERAL:
		XLAT_DEBUG("xlat_aprint LITERAL");
		return talloc_typed_strdup(ctx, node->fmt);

		/*
		 *	Do a one-character expansion.
		 */
	case XLAT_PERCENT:
	{
		char const *p;
		char *nl;
		size_t freespace = 256;
		struct tm ts;
		time_t when;

		XLAT_DEBUG("xlat_aprint PERCENT");

		str = talloc_array(ctx, char, freespace); /* @todo do better allocation */
		p = node->fmt;

		when = request->timestamp;
		if (request->packet) {
			when = request->packet->timestamp.tv_sec;
		}

		switch (*p) {
		case '%':
			str[0] = '%';
			str[1] = '\0';
			break;

		case 'd': /* request day */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%d", &ts);
			break;

		case 'l': /* request timestamp */
			snprintf(str, freespace, "%lu",
				 (unsigned long) when);
			break;

		case 'm': /* request month */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%m", &ts);
			break;

		case 'n': /* Request Number*/
			snprintf(str, freespace, "%i", request->number);
			break;

		case 't': /* request timestamp */
			CTIME_R(&when, str, freespace);
			nl = strchr(str, '\n');
			if (nl) *nl = '\0';
			break;

		case 'D': /* request date */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%Y%m%d", &ts);
			break;

		case 'G': /* request minute */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%M", &ts);
			break;

		case 'H': /* request hour */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%H", &ts);
			break;

		case 'I': /* Request ID */
			if (request->packet) {
				snprintf(str, freespace, "%i", request->packet->id);
			}
			break;

		case 'S': /* request timestamp in SQL format*/
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%Y-%m-%d %H:%M:%S", &ts);
			break;

		case 'T': /* request timestamp */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%Y-%m-%d-%H.%M.%S.000000", &ts);
			break;

		case 'Y': /* request year */
			(void) localtime_r(&when, &ts);
			strftime(str, freespace, "%Y", &ts);
			break;

		case 'v': /* Version of code */
			snprintf(str, freespace, "%s", radiusd_short_version);
			break;

		default:
			rad_assert(0 == 1);
			break;
		}
	}
		break;

	case XLAT_ATTRIBUTE:
		XLAT_DEBUG("xlat_aprint ATTRIBUTE");
		ref = request;
		if (radius_request(&ref, node->ref) < 0) {
			return NULL;
		}

		/*
		 *	Some attributes are virtual <sigh>
		 */
		str = xlat_getvp(ctx, ref, node->list, node->da, node->tag, node->num, true);
		if (str) {
			XLAT_DEBUG("EXPAND attr %s", node->da->name);
			XLAT_DEBUG("       ---> %s", str);
		}
		break;

	case XLAT_VIRTUAL:
		XLAT_DEBUG("xlat_aprint VIRTUAL");
		str = talloc_array(ctx, char, 1024); /* FIXME: have the module call talloc_typed_asprintf */
		rcode = node->xlat->func(node->xlat->instance, request, NULL, str, 1024);
		if (rcode < 0) {
			talloc_free(str);
			return NULL;
		}
		break;

	case XLAT_MODULE:
		XLAT_DEBUG("xlat_aprint MODULE");
		if (xlat_process(&child, request, node->child, node->xlat->escape, node->xlat->instance) == 0) {
			return NULL;
		}

		XLAT_DEBUG("%.*sEXPAND mod %s %s", lvl, xlat_spaces, node->fmt, node->child->fmt);
		XLAT_DEBUG("%.*s      ---> %s", lvl, xlat_spaces, child);

		str = talloc_array(ctx, char, 1024); /* FIXME: have the module call talloc_typed_asprintf */
		*str = '\0';	/* Be sure the string is NULL terminated, we now only free on error */

		rcode = node->xlat->func(node->xlat->instance, request, child, str, 1024);
		talloc_free(child);
		if (rcode < 0) {
			talloc_free(str);
			return NULL;
		}
		break;

#ifdef HAVE_REGEX_H
	case XLAT_REGEX:
		XLAT_DEBUG("xlat_aprint REGEX");
		child = request_data_reference(request, request,
					       REQUEST_DATA_REGEX | node->num);
		if (!child) return NULL;

		str = talloc_typed_strdup(ctx, child);
		break;
#endif

	case XLAT_ALTERNATE:
		XLAT_DEBUG("xlat_aprint ALTERNATE");
		rad_assert(node->child != NULL);
		rad_assert(node->alternate != NULL);

		str = xlat_aprint(ctx, request, node->child, escape, escape_ctx, lvl);
		if (str) break;

		str = xlat_aprint(ctx, request, node->alternate, escape, escape_ctx, lvl);
		break;

	}

	/*
	 *	Escape the non-literals we found above.
	 */
	if (str && escape) {
		char *escaped;

		escaped = talloc_array(ctx, char, 1024); /* FIXME: do something intelligent */
		escape(request, escaped, 1024, str, escape_ctx);
		talloc_free(str);
		str = escaped;
	}

	return str;
}


static size_t xlat_process(char **out, REQUEST *request, xlat_exp_t const * const head,
			   RADIUS_ESCAPE_STRING escape, void *escape_ctx)
{
	int i, list;
	size_t total;
	char **array, *answer;
	xlat_exp_t const *node;

	*out = NULL;

	/*
	 *	There are no nodes to process, so the result is a zero
	 *	length string.
	 */
	if (!head) {
		*out = talloc_zero_array(request, char, 1);
		return 0;
	}

	/*
	 *	Hack for speed.  If it's one expansion, just allocate
	 *	that and return, instead of allocating an intermediary
	 *	array.
	 */
	if (!head->next) {
		/*
		 *	Pass the MAIN escape function.  Recursive
		 *	calls will call node-specific escape
		 *	functions.
		 */
		answer = xlat_aprint(request, request, head, escape, escape_ctx, 0);
		if (!answer) {
			*out = talloc_zero_array(request, char, 1);
			return 0;
		}
		*out = answer;
		return strlen(answer);
	}

	list = 0;		/* FIXME: calculate this once */
	for (node = head; node != NULL; node = node->next) {
		list++;
	}

	array = talloc_array(request, char *, list);
	if (!array) return -1;

	for (node = head, i = 0; node != NULL; node = node->next, i++) {
		array[i] = xlat_aprint(array, request, node, escape, escape_ctx, 0); /* may be NULL */
	}

	total = 0;
	for (i = 0; i < list; i++) {
		if (array[i]) total += strlen(array[i]); /* FIXME: calculate strlen once */
	}

	if (!total) {
		talloc_free(array);
		*out = talloc_zero_array(request, char, 1);
		return 0;
	}

	answer = talloc_array(request, char, total + 1);

	total = 0;
	for (i = 0; i < list; i++) {
		size_t len;

		if (array[i]) {
			len = strlen(array[i]);
			memcpy(answer + total, array[i], len);
			total += len;
		}
	}
	answer[total] = '\0';
	talloc_free(array);	/* and child entries */

	*out = answer;
	return total;
}


/** Replace %whatever in a string.
 *
 * See 'doc/variables.txt' for more information.
 *
 * @param[out] out Where to write pointer to output buffer.
 * @param[in] outlen Size of out.
 * @param[in] request current request.
 * @param[in] node the xlat structure to expand
 * @param[in] escape function to escape final value e.g. SQL quoting.
 * @param[in] escape_ctx pointer to pass to escape function.
 * @return length of string written @bug should really have -1 for failure
 */
static ssize_t xlat_expand_struct(char **out, size_t outlen, REQUEST *request, xlat_exp_t const *node,
				  RADIUS_ESCAPE_STRING escape, void *escape_ctx)
{
	char *buff;
	ssize_t len;

	rad_assert(node != NULL);

	len = xlat_process(&buff, request, node, escape, escape_ctx);

	if ((len < 0) || !buff) {
		rad_assert(buff == NULL);
		if (*out) *out[0] = '\0';
		return len;
	}

	if (!*out) {
		*out = buff;
	} else {
		strlcpy(*out, buff, outlen);
		talloc_free(buff);
	}

	return strlen(*out);
}

static ssize_t xlat_expand(char **out, size_t outlen, REQUEST *request, char const *fmt,
			   RADIUS_ESCAPE_STRING escape, void *escape_ctx) CC_HINT(nonnull (1, 3, 4));

/** Replace %whatever in a string.
 *
 * See 'doc/variables.txt' for more information.
 *
 * @param[out] out Where to write pointer to output buffer.
 * @param[in] outlen Size of out.
 * @param[in] request current request.
 * @param[in] fmt string to expand.
 * @param[in] escape function to escape final value e.g. SQL quoting.
 * @param[in] escape_ctx pointer to pass to escape function.
 * @return length of string written @bug should really have -1 for failure
 */
static ssize_t CC_HINT(nonnull (1, 3, 4)) xlat_expand(char **out, size_t outlen, REQUEST *request, char const *fmt,
						      RADIUS_ESCAPE_STRING escape, void *escape_ctx)
{
	ssize_t len;
	xlat_exp_t *node;

	/*
	 *	Give better errors than the old code.
	 */
	len = xlat_tokenize_request(request, fmt, &node);
	if (len == 0) {
		if (*out) {
			*out[0] = '\0';
		} else {
			*out = talloc_zero_array(request, char, 1);
		}
		return 0;
	}

	if (len < 0) {
		if (*out) *out[0] = '\0';
		return -1;
	}

	len = xlat_expand_struct(out, outlen, request, node, escape, escape_ctx);
	talloc_free(node);

	RDEBUG2("EXPAND %s", fmt);
	RDEBUG2("   --> %s", *out);

	return len;
}

/*
 *	Try to convert an xlat to a tmpl
 */
value_pair_tmpl_t *radius_xlat2tmpl(TALLOC_CTX *ctx, xlat_exp_t *xlat)
{
	value_pair_tmpl_t *vpt;

	if (xlat->next || (xlat->type != XLAT_ATTRIBUTE)) return NULL;

	/*
	 *	Can't convert Nth reference, or tags to templates.
	 *	They have no such fields.
	 */
	if ((xlat->num != 0) || (xlat->tag != TAG_ANY)) return NULL;

	vpt = talloc(ctx, value_pair_tmpl_t);
	if (!vpt) return NULL;

	vpt->type = VPT_TYPE_ATTR;
	vpt->name = talloc_strdup(vpt, xlat->fmt);
	vpt->vpt_request = xlat->ref;
	vpt->vpt_list = xlat->list;
	vpt->vpt_da = xlat->da;

	return vpt;
}

ssize_t radius_xlat(char *out, size_t outlen, REQUEST *request, char const *fmt, RADIUS_ESCAPE_STRING escape, void *ctx)
{
	return xlat_expand(&out, outlen, request, fmt, escape, ctx);
}

ssize_t radius_axlat(char **out, REQUEST *request, char const *fmt, RADIUS_ESCAPE_STRING escape, void *ctx)
{
	return xlat_expand(out, 0, request, fmt, escape, ctx);
}

ssize_t radius_axlat_struct(char **out, REQUEST *request, xlat_exp_t const *xlat, RADIUS_ESCAPE_STRING escape, void *ctx)
{
	return xlat_expand_struct(out, 0, request, xlat, escape, ctx);
}
