src/pattern.c

/*
 * Patterns management functions.
 *
 * Copyright 2009-2010 EXCELIANCE, Emeric Brun <ebrun@exceliance.fr>
 *
 * 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.
 *
 */

#include <string.h>
#include <arpa/inet.h>

#include <proto/pattern.h>
#include <common/standard.h>

/* static structure used on pattern_process if <p> is NULL*/
static struct pattern spattern;

/* trash chunk used for pattern conversions */
static struct chunk trash_chunk;

/* trash buffers used or pattern conversions */
static char pattern_trash_buf1[BUFSIZE];
static char pattern_trash_buf2[BUFSIZE];

/* pattern_trash_buf point on used buffer*/
static char *pattern_trash_buf = pattern_trash_buf1;

/* list head of all known pattern fetch keywords */
static struct pattern_fetch_kw_list pattern_fetches = {
	.list = LIST_HEAD_INIT(pattern_fetches.list)
};

/* list head of all known pattern format conversion keywords */
static struct pattern_conv_kw_list pattern_convs = {
	.list = LIST_HEAD_INIT(pattern_convs.list)
};

/*
 * Registers the pattern fetch keyword list <kwl> as a list of valid keywords for next
 * parsing sessions.
 */
void pattern_register_fetches(struct pattern_fetch_kw_list *pfkl)
{
	LIST_ADDQ(&pattern_fetches.list, &pfkl->list);
}

/*
 * Registers the pattern format coverstion keyword list <pckl> as a list of valid keywords for next
 * parsing sessions.
 */
void pattern_register_convs(struct pattern_conv_kw_list *pckl)
{
	LIST_ADDQ(&pattern_convs.list, &pckl->list);
}

/*
 * Returns the pointer on pattern fetch keyword structure identified by
 * string of <len> in buffer <kw>.
 *
 */
struct pattern_fetch *find_pattern_fetch(const char *kw, int len)
{
	int index;
	struct pattern_fetch_kw_list *kwl;

	list_for_each_entry(kwl, &pattern_fetches.list, list) {
		for (index = 0; kwl->kw[index].kw != NULL; index++) {
			if (strncmp(kwl->kw[index].kw, kw, len) == 0 &&
			    kwl->kw[index].kw[len] == '\0')
				return &kwl->kw[index];
		}
	}
	return NULL;
}

/*
 * Returns the pointer on pattern format conversion keyword structure identified by
 * string of <len> in buffer <kw>.
 *
 */
struct pattern_conv *find_pattern_conv(const char *kw, int len)
{
	int index;
	struct pattern_conv_kw_list *kwl;

	list_for_each_entry(kwl, &pattern_convs.list, list) {
		for (index = 0; kwl->kw[index].kw != NULL; index++) {
			if (strncmp(kwl->kw[index].kw, kw, len) == 0 &&
			    kwl->kw[index].kw[len] == '\0')
				return &kwl->kw[index];
		}
	}
	return NULL;
}


/*
* Returns a static trash struct chunk to use in pattern casts or format conversions
* Swiths the 2 available trash buffers to protect data during convert
*/
static struct chunk *get_trash_chunk(void)
{
	if (pattern_trash_buf == pattern_trash_buf1)
		pattern_trash_buf = pattern_trash_buf2;
	else
		pattern_trash_buf = pattern_trash_buf1;

	trash_chunk.str = pattern_trash_buf;
	trash_chunk.len = 0;
	trash_chunk.size = BUFSIZE;

	return &trash_chunk;
}

/*
* Used to set pattern data from a struct chunk, could be the trash struct chunk
*/
static void pattern_data_setstring(union pattern_data *data, struct chunk *c)
{
	data->str.str = c->str;
	data->str.len = c->len;
	data->str.size = c->size;
}

/******************************************************************/
/*          Pattern casts functions                               */
/******************************************************************/

static int c_ip2int(union pattern_data *data)
{
	data->integer = ntohl(data->ip.s_addr);
	return 1;
}

static int c_ip2str(union pattern_data *data)
{
	struct chunk *trash = get_trash_chunk();

	if (!inet_ntop(AF_INET, (void *)&data->ip, trash->str, trash->size))
		return 0;

	trash->len = strlen(trash->str);
	pattern_data_setstring(data, trash);

	return 1;
}

static int c_int2ip(union pattern_data *data)
{
	data->ip.s_addr = htonl(data->integer);
	return 1;
}

static int c_str2ip(union pattern_data *data)
{
	if (!buf2ip(data->str.str, data->str.len, &data->ip))
		return 0;
	return 1;
}

static int c_int2str(union pattern_data *data)
{
	struct chunk *trash = get_trash_chunk();
	char *pos;

	pos = ultoa_r(data->integer, trash->str, trash->size);

	if (!pos)
		return 0;

	trash->str = pos;
	trash->len = strlen(pos);

	pattern_data_setstring(data, trash);

	return 1;
}

static int c_donothing(union pattern_data *data)
{
	return 1;
}

static int c_str2int(union pattern_data *data)
{
	int i;
	uint32_t ret = 0;

	for (i = 0; i < data->str.len; i++) {
		uint32_t val = data->str.str[i] - '0';

		if (val > 9)
			break;

		ret = ret * 10 + val;
	}

	data->integer = ret;
	return 1;
}

/*****************************************************************/
/*      Pattern casts matrix:                                    */
/*           pattern_casts[from type][to type]                   */
/*           NULL pointer used for impossible pattern casts      */
/*****************************************************************/

typedef int (*pattern_cast_fct)(union pattern_data *data);
static pattern_cast_fct pattern_casts[PATTERN_TYPES][PATTERN_TYPES] = {
	{ c_donothing, c_ip2int,    c_ip2str    },
	{ c_int2ip,    c_donothing, c_int2str   },
	{ c_str2ip,    c_str2int,   c_donothing },
};


/*
 * Parse a pattern expression configuration:
 *        fetch keyword followed by format conversion keywords.
 * Returns a pointer on allocated pattern expression structure.
 */
struct pattern_expr *pattern_parse_expr(char **str, int *idx)
{
	const char *endw;
	const char *end;
	struct pattern_expr *expr;
	struct pattern_fetch *fetch;
	struct pattern_conv *conv;
	unsigned long prev_type;

	if (!str[*idx])
		goto out_error;

	end = str[*idx] + strlen(str[*idx]);
	endw = strchr(str[*idx], '(');

	if (!endw)
		endw = end;
	else if ((end-1)[0] != ')')
		goto out_error;

	fetch = find_pattern_fetch(str[*idx], endw - str[*idx]);
	if (!fetch)
		goto out_error;

	if (fetch->out_type >= PATTERN_TYPES)
		goto out_error;

	prev_type = fetch->out_type;
	expr = calloc(1, sizeof(struct pattern_expr));

	LIST_INIT(&(expr->conv_exprs));
	expr->fetch = fetch;

	if (end != endw) {
		expr->arg_len = end - endw - 2;
		expr->arg = my_strndup(endw + 1, expr->arg_len);
	}

	for (*idx += 1; *(str[*idx]); (*idx)++) {
		struct pattern_conv_expr *conv_expr;

		end = str[*idx] + strlen(str[*idx]);
		endw = strchr(str[*idx], '(');

		if (!endw)
			endw = end;
		else if ((end-1)[0] != ')')
			goto out_error;

		conv = find_pattern_conv(str[*idx], endw - str[*idx]);
		if (!conv)
			break;

		if (conv->in_type >= PATTERN_TYPES ||
		    conv->out_type >= PATTERN_TYPES)
			goto out_error;

		/* If impossible type conversion */
		if (!pattern_casts[prev_type][conv->in_type])
			goto out_error;

		prev_type = conv->out_type;
		conv_expr = calloc(1, sizeof(struct pattern_conv_expr));

		LIST_ADDQ(&(expr->conv_exprs), &(conv_expr->list));
		conv_expr->conv = conv;

		if (end != endw) {
			int i = end - endw - 2;
			char *p = my_strndup(endw + 1, i);

			if (conv->parse_args) {
				i = conv->parse_args(p, &conv_expr->arg_p, &conv_expr->arg_i);
				free(p);
				if (!i)
					goto out_error;
			} else {
				conv_expr->arg_i = i;
				conv_expr->arg_p = p;
			}
		}
	}
	return expr;

out_error:
	/* TODO: prune_pattern_expr(expr); */
	return NULL;
}

/*
 * Process a fetch + format conversion of defined by the pattern expression <expr>
 * on request or response considering the <dir> parameter.
 * Returns a pointer on a typed pattern structure containing the result or NULL if
 * pattern is not found or when format conversion failed.
 *  If <p> is not null, function returns results in structure pointed by <p>.
 *  If <p> is null, functions returns a pointer on a static pattern structure.
 */
struct pattern *pattern_process(struct proxy *px, struct session *l4, void *l7, int dir,
                                struct pattern_expr *expr, struct pattern *p)
{
	struct pattern_conv_expr *conv_expr;

	if (p == NULL)
		p = &spattern;

	if (!expr->fetch->process(px, l4, l7, dir, expr->arg, expr->arg_len, &p->data))
		return NULL;

	p->type = expr->fetch->out_type;

	list_for_each_entry(conv_expr, &expr->conv_exprs, list) {
		if (!pattern_casts[p->type][conv_expr->conv->in_type](&p->data))
			return NULL;

		p->type = conv_expr->conv->in_type;
		if (!conv_expr->conv->process(conv_expr->arg_p, conv_expr->arg_i, &p->data))
			return NULL;

		p->type = conv_expr->conv->out_type;
	}
	return p;
}

/* Converts an argument string to an IPv4 mask stored in network byte order in
 * arg_i. Returns non-zero in case of success, 0 on error.
 */
static int pattern_conv_arg_to_ipmask(const char *arg_str, void **arg_p, int *arg_i)
{
	struct in_addr mask;

	if (!str2mask(arg_str, &mask))
		return 0;

	*arg_i = mask.s_addr;
	return 1;
}

/*****************************************************************/
/*    Pattern format convert functions                           */
/*****************************************************************/

static int pattern_conv_str2lower(const void *arg_p, int arg_i, union pattern_data *data)
{
	int i;

	for (i = 0; i < data->str.len; i++) {
		if ((data->str.str[i] >= 'A') && (data->str.str[i] <= 'Z'))
			data->str.str[i] += 'a' - 'A';
	}
	return 1;
}

static int pattern_conv_str2upper(const void *arg_p, int arg_i, union pattern_data *data)
{
	int i;

	for (i = 0; i < data->str.len; i++) {
		if ((data->str.str[i] >= 'a') && (data->str.str[i] <= 'z'))
			data->str.str[i] += 'A' - 'a';
	}
	return 1;
}

/* takes the netmask in arg_i */
static int pattern_conv_ipmask(const void *arg_p, int arg_i, union pattern_data *data)
{
	data->ip.s_addr &= arg_i;
	return 1;
}

/* Note: must not be declared <const> as its list will be overwritten */
static struct pattern_conv_kw_list pattern_conv_kws = {{ },{
	{ "upper",       pattern_conv_str2upper, PATTERN_TYPE_STRING, PATTERN_TYPE_STRING },
	{ "lower",       pattern_conv_str2lower, PATTERN_TYPE_STRING, PATTERN_TYPE_STRING },
	{ "ipmask",      pattern_conv_ipmask, PATTERN_TYPE_IP, PATTERN_TYPE_IP, pattern_conv_arg_to_ipmask },
	{ NULL, NULL, 0, 0 },
}};

__attribute__((constructor))
static void __pattern_init(void)
{
	/* register pattern format convert keywords */
	pattern_register_convs(&pattern_conv_kws);
}