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 <proto/buffers.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;

	chunk_init(&trash_chunk, pattern_trash_buf, 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)
{
	chunk_initlen(&data->str, c->str, c->size, c->len);
}

/******************************************************************/
/*          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->size = trash->size - (pos - trash->str);
	trash->str = pos;
	trash->len = strlen(pos);

	pattern_data_setstring(data, trash);

	return 1;
}

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

	trash->len = data->str.len < trash->size ? data->str.len : trash->size;
	memcpy(trash->str, data->str.str, trash->len);

	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] = {
/*            to:   IP           INTEGER      STRING       DATA         CONSTSTRING  CONSTDATA */
/* from:    IP */ { c_donothing, c_ip2int,    c_ip2str,    NULL,        c_ip2str,    NULL        },
/*     INTEGER */ { c_int2ip,    c_donothing, c_int2str,   NULL,        c_int2str,   NULL        },
/*      STRING */ { c_str2ip,    c_str2int,   c_donothing, c_donothing, c_donothing, c_donothing },
/*        DATA */ { NULL,        NULL,        NULL,        c_donothing, NULL,        c_donothing },
/* CONSTSTRING */ { c_str2ip,    c_str2int,   c_datadup,   c_datadup,   c_donothing, c_donothing },
/*   CONSTDATA */ { NULL,        NULL,        NULL,        c_datadup,   NULL,	     NULL        },
};


/*
 * 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, char *err, int err_size)
{
	const char *endw;
	const char *end;
	struct pattern_expr *expr;
	struct pattern_fetch *fetch;
	struct pattern_conv *conv;
	unsigned long prev_type;
	char *p;

	snprintf(err, err_size, "memory error.");
	if (!str[*idx]) {

		snprintf(err, err_size, "missing fetch method.");
		goto out_error;
	}

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

	if (!endw)
		endw = end;
	else if ((end-1)[0] != ')') {
		p = my_strndup(str[*idx], endw - str[*idx]);
		if (p) {
			snprintf(err, err_size, "syntax error: missing ')' after keyword '%s'.", p);
			free(p);
		}
		goto out_error;
	}

	fetch = find_pattern_fetch(str[*idx], endw - str[*idx]);
	if (!fetch) {
		p = my_strndup(str[*idx], endw - str[*idx]);
		if (p) {
			snprintf(err, err_size, "unknown fetch method '%s'.", p);
			free(p);
		}
		goto out_error;
	}
	if (fetch->out_type >= PATTERN_TYPES) {

		p = my_strndup(str[*idx], endw - str[*idx]);
		if (p) {
			snprintf(err, err_size, "returns type of fetch method '%s' is unknown.", p);
			free(p);
		}
		goto out_error;
	}

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

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

	if (end != endw) {
		int i = end - endw - 2;

		if (!fetch->parse_args) {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "fetch method '%s' does not support any args.", p);
				free(p);
			}
			goto out_error;
		}
		p = my_strndup(endw + 1, i);
		if (!p)
			goto out_error;
		i = fetch->parse_args(p, &expr->arg_p, &expr->arg_i);
		free(p);
		if (!i) {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "invalid args in fetch method '%s'.", p);
				free(p);
			}
			goto out_error;
		}
	}
	else if (fetch->parse_args) {
		p = my_strndup(str[*idx], endw - str[*idx]);
		if (p) {
			snprintf(err, err_size, "missing args for fetch method '%s'.", p);
			free(p);
		}
		goto out_error;
	}

	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] != ')') {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "syntax error, missing ')' after keyword '%s'.", p);
				free(p);
			}
			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) {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "returns type of conv method '%s' is unknown.", p);
				free(p);
			}
			goto out_error;
		}

		/* If impossible type conversion */
		if (!pattern_casts[prev_type][conv->in_type]) {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "conv method '%s' cannot be applied.", p);
				free(p);
			}
			goto out_error;
		}

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

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

		if (end != endw) {
			int i = end - endw - 2;

			if (!conv->parse_args) {
				p = my_strndup(str[*idx], endw - str[*idx]);

				if (p) {
					snprintf(err, err_size, "conv method '%s' does not support any args.", p);
					free(p);
				}
				goto out_error;
			}

			p = my_strndup(endw + 1, i);
			if (!p)
				goto out_error;
			i = conv->parse_args(p, &conv_expr->arg_p, &conv_expr->arg_i);
			free(p);
			if (!i) {
				p = my_strndup(str[*idx], endw - str[*idx]);
				if (p) {
					snprintf(err, err_size, "invalid args in conv method '%s'.", p);
					free(p);
				}
				goto out_error;
			}
		}
		else if (conv->parse_args) {
			p = my_strndup(str[*idx], endw - str[*idx]);
			if (p) {
				snprintf(err, err_size, "missing args for conv method '%s'.", p);
				free(p);
			}
			goto out_error;
		}

	}

	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_p, expr->arg_i, &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 mask to a pattern_arg type IP.
 * Returns non-zero in case of success, 0 on error.
 */
int pattern_arg_ipmask(const char *arg_str, struct pattern_arg **arg_p, int *arg_i)
{
	*arg_i = 1;
	*arg_p = calloc(1, *arg_i*sizeof(struct pattern_arg));
	(*arg_p)->type = PATTERN_ARG_TYPE_IP;

	if (!str2mask(arg_str, &(*arg_p)->data.ip))
		return 0;

	return 1;
}


/* Converts an argument string to a pattern_arg type STRING.
 * Returns non-zero in case of success, 0 on error.
 */
int pattern_arg_str(const char *arg_str, struct pattern_arg **arg_p, int *arg_i)
{
	*arg_i = 1;
	*arg_p = calloc(1, *arg_i*sizeof(struct pattern_arg));
	(*arg_p)->type = PATTERN_ARG_TYPE_STRING;
	(*arg_p)->data.str.str = strdup(arg_str);
	(*arg_p)->data.str.len = strlen(arg_str);


	return 1;
}


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

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

	if (!data->str.size)
		return 0;

	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 struct pattern_arg *arg_p, int arg_i, union pattern_data *data)
{
	int i;

	if (!data->str.size)
		return 0;

	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 struct pattern_arg *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, NULL,               PATTERN_TYPE_STRING, PATTERN_TYPE_STRING },
	{ "lower",  pattern_conv_str2lower, NULL,               PATTERN_TYPE_STRING, PATTERN_TYPE_STRING },
	{ "ipmask", pattern_conv_ipmask,    pattern_arg_ipmask, PATTERN_TYPE_IP,     PATTERN_TYPE_IP },
	{ NULL, NULL, NULL, 0, 0 },
}};

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