/*
 * uhttpd - Tiny single-threaded httpd
 *
 *   Copyright (C) 2010-2013 Jo-Philipp Wich <xm@subsignal.org>
 *   Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <libubox/avl-cmp.h>
#include <libubox/utils.h>
#include <libubus.h>
#include <fnmatch.h>

#include "ubus-session.h"

static struct avl_tree sessions;
static struct blob_buf buf;

static const struct blobmsg_policy new_policy = {
	.name = "timeout", .type = BLOBMSG_TYPE_INT32
};

static const struct blobmsg_policy sid_policy = {
	.name = "sid", .type = BLOBMSG_TYPE_STRING
};

enum {
	UH_UBUS_SS_SID,
	UH_UBUS_SS_VALUES,
	__UH_UBUS_SS_MAX,
};
static const struct blobmsg_policy set_policy[__UH_UBUS_SS_MAX] = {
	[UH_UBUS_SS_SID] = { .name = "sid", .type = BLOBMSG_TYPE_STRING },
	[UH_UBUS_SS_VALUES] = { .name = "values", .type = BLOBMSG_TYPE_TABLE },
};

enum {
	UH_UBUS_SG_SID,
	UH_UBUS_SG_KEYS,
	__UH_UBUS_SG_MAX,
};
static const struct blobmsg_policy get_policy[__UH_UBUS_SG_MAX] = {
	[UH_UBUS_SG_SID] = { .name = "sid", .type = BLOBMSG_TYPE_STRING },
	[UH_UBUS_SG_KEYS] = { .name = "keys", .type = BLOBMSG_TYPE_ARRAY },
};

enum {
	UH_UBUS_SA_SID,
	UH_UBUS_SA_OBJECTS,
	__UH_UBUS_SA_MAX,
};
static const struct blobmsg_policy acl_policy[__UH_UBUS_SA_MAX] = {
	[UH_UBUS_SA_SID] = { .name = "sid", .type = BLOBMSG_TYPE_STRING },
	[UH_UBUS_SA_OBJECTS] = { .name = "objects", .type = BLOBMSG_TYPE_ARRAY },
};

/*
 * Keys in the AVL tree contain all pattern characters up to the first wildcard.
 * To look up entries, start with the last entry that has a key less than or
 * equal to the method name, then work backwards as long as the AVL key still
 * matches its counterpart in the object name
 */
#define uh_foreach_matching_acl_prefix(_acl, _ses, _obj, _func)			\
	for (_acl = avl_find_le_element(&(_ses)->acls, _obj, _acl, avl);	\
	     _acl;								\
	     _acl = avl_is_first(&(ses)->acls, &(_acl)->avl) ? NULL :		\
		    avl_prev_element((_acl), avl))

#define uh_foreach_matching_acl(_acl, _ses, _obj, _func)			\
	uh_foreach_matching_acl_prefix(_acl, _ses, _obj, _func)			\
		if (!strncmp((_acl)->object, _obj, (_acl)->sort_len) &&		\
		    !fnmatch((_acl)->object, (_obj), FNM_NOESCAPE) &&		\
		    !fnmatch((_acl)->function, (_func), FNM_NOESCAPE))

static void
uh_ubus_random(char *dest)
{
	unsigned char buf[16] = { 0 };
	FILE *f;
	int i;

	f = fopen("/dev/urandom", "r");
	if (!f)
		return;

	fread(buf, 1, sizeof(buf), f);
	fclose(f);

	for (i = 0; i < sizeof(buf); i++)
		sprintf(dest + (i<<1), "%02x", buf[i]);
}

static void
uh_ubus_session_dump_data(struct uh_ubus_session *ses, struct blob_buf *b)
{
	struct uh_ubus_session_data *d;

	avl_for_each_element(&ses->data, d, avl) {
		blobmsg_add_field(b, blobmsg_type(d->attr), blobmsg_name(d->attr),
				  blobmsg_data(d->attr), blobmsg_data_len(d->attr));
	}
}

static void
uh_ubus_session_dump_acls(struct uh_ubus_session *ses, struct blob_buf *b)
{
	struct uh_ubus_session_acl *acl;
	const char *lastobj = NULL;
	void *c = NULL;

	avl_for_each_element(&ses->acls, acl, avl) {
		if (!lastobj || strcmp(acl->object, lastobj))
		{
			if (c) blobmsg_close_array(b, c);
			c = blobmsg_open_array(b, acl->object);
		}

		blobmsg_add_string(b, NULL, acl->function);
		lastobj = acl->object;
	}

	if (c) blobmsg_close_array(b, c);
}

static void
uh_ubus_session_dump(struct uh_ubus_session *ses,
					 struct ubus_context *ctx,
					 struct ubus_request_data *req)
{
	void *c;

	blob_buf_init(&buf, 0);

	blobmsg_add_string(&buf, "sid", ses->id);
	blobmsg_add_u32(&buf, "timeout", ses->timeout);
	blobmsg_add_u32(&buf, "expires", uloop_timeout_remaining(&ses->t) / 1000);

	c = blobmsg_open_table(&buf, "acls");
	uh_ubus_session_dump_acls(ses, &buf);
	blobmsg_close_table(&buf, c);

	c = blobmsg_open_table(&buf, "data");
	uh_ubus_session_dump_data(ses, &buf);
	blobmsg_close_table(&buf, c);

	ubus_send_reply(ctx, req, buf.head);
}

static void
uh_ubus_touch_session(struct uh_ubus_session *ses)
{
	uloop_timeout_set(&ses->t, ses->timeout * 1000);
}

static void
uh_ubus_session_destroy(struct uh_ubus_session *ses)
{
	struct uh_ubus_session_acl *acl, *nacl;
	struct uh_ubus_session_data *data, *ndata;

	uloop_timeout_cancel(&ses->t);
	avl_remove_all_elements(&ses->acls, acl, avl, nacl)
		free(acl);

	avl_remove_all_elements(&ses->data, data, avl, ndata)
		free(data);

	avl_delete(&sessions, &ses->avl);
	free(ses);
}

static void uh_ubus_session_timeout(struct uloop_timeout *t)
{
	struct uh_ubus_session *ses;

	ses = container_of(t, struct uh_ubus_session, t);
	uh_ubus_session_destroy(ses);
}

static struct uh_ubus_session *
uh_ubus_session_create(int timeout)
{
	struct uh_ubus_session *ses;

	ses = calloc(1, sizeof(*ses));
	if (!ses)
		return NULL;

	ses->timeout  = timeout;
	ses->avl.key  = ses->id;
	uh_ubus_random(ses->id);

	avl_insert(&sessions, &ses->avl);
	avl_init(&ses->acls, avl_strcmp, true, NULL);
	avl_init(&ses->data, avl_strcmp, false, NULL);

	ses->t.cb = uh_ubus_session_timeout;
	uh_ubus_touch_session(ses);

	return ses;
}

struct uh_ubus_session *
uh_ubus_session_get(const char *id)
{
	struct uh_ubus_session *ses;

	ses = avl_find_element(&sessions, id, ses, avl);
	if (!ses)
		return NULL;

	uh_ubus_touch_session(ses);
	return ses;
}

static int
uh_ubus_handle_create(struct ubus_context *ctx, struct ubus_object *obj,
					  struct ubus_request_data *req, const char *method,
					  struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct blob_attr *tb;
	int timeout = UBUS_DEFAULT_SESSION_TIMEOUT;

	blobmsg_parse(&new_policy, 1, &tb, blob_data(msg), blob_len(msg));
	if (tb)
		timeout = blobmsg_get_u32(tb);

	ses = uh_ubus_session_create(timeout);
	if (ses)
		uh_ubus_session_dump(ses, ctx, req);

	return 0;
}

static int
uh_ubus_handle_list(struct ubus_context *ctx, struct ubus_object *obj,
					struct ubus_request_data *req, const char *method,
					struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct blob_attr *tb;

	blobmsg_parse(&sid_policy, 1, &tb, blob_data(msg), blob_len(msg));

	if (!tb) {
		avl_for_each_element(&sessions, ses, avl)
			uh_ubus_session_dump(ses, ctx, req);
		return 0;
	}

	ses = uh_ubus_session_get(blobmsg_data(tb));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	uh_ubus_session_dump(ses, ctx, req);

	return 0;
}

static int
uh_id_len(const char *str)
{
	return strcspn(str, "*?[");
}

static int
uh_ubus_session_grant(struct uh_ubus_session *ses, struct ubus_context *ctx,
		      const char *object, const char *function)
{
	struct uh_ubus_session_acl *acl;
	char *new_obj, *new_func, *new_id;
	int id_len;

	if (!object || !function)
		return UBUS_STATUS_INVALID_ARGUMENT;

	uh_foreach_matching_acl_prefix(acl, ses, object, function) {
		if (!strcmp(acl->object, object) &&
		    !strcmp(acl->function, function))
			return 0;
	}

	id_len = uh_id_len(object);
	acl = calloc_a(sizeof(*acl),
		&new_obj, strlen(object) + 1,
		&new_func, strlen(function) + 1,
		&new_id, id_len + 1);

	if (!acl)
		return UBUS_STATUS_UNKNOWN_ERROR;

	acl->object = strcpy(new_obj, object);
	acl->function = strcpy(new_func, function);
	acl->avl.key = strncpy(new_id, object, id_len);
	avl_insert(&ses->acls, &acl->avl);

	return 0;
}

static int
uh_ubus_session_revoke(struct uh_ubus_session *ses, struct ubus_context *ctx,
		       const char *object, const char *function)
{
	struct uh_ubus_session_acl *acl, *next;
	int id_len;
	char *id;

	if (!object && !function) {
		avl_remove_all_elements(&ses->acls, acl, avl, next)
			free(acl);
		return 0;
	}

	id_len = uh_id_len(object);
	id = alloca(id_len + 1);
	strncpy(id, object, id_len);
	id[id_len] = 0;

	acl = avl_find_element(&ses->acls, id, acl, avl);
	while (acl) {
		if (!avl_is_last(&ses->acls, &acl->avl))
			next = avl_next_element(acl, avl);
		else
			next = NULL;

		if (strcmp(id, acl->avl.key) != 0)
			break;

		if (!strcmp(acl->object, object) &&
		    !strcmp(acl->function, function)) {
			avl_delete(&ses->acls, &acl->avl);
			free(acl);
		}
		acl = next;
	}

	return 0;
}


static int
uh_ubus_handle_acl(struct ubus_context *ctx, struct ubus_object *obj,
		   struct ubus_request_data *req, const char *method,
		   struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct blob_attr *tb[__UH_UBUS_SA_MAX];
	struct blob_attr *attr, *sattr;
	const char *object, *function;
	int rem1, rem2;

	int (*cb)(struct uh_ubus_session *ses, struct ubus_context *ctx,
		  const char *object, const char *function);

	blobmsg_parse(acl_policy, __UH_UBUS_SA_MAX, tb, blob_data(msg), blob_len(msg));

	if (!tb[UH_UBUS_SA_SID])
		return UBUS_STATUS_INVALID_ARGUMENT;

	ses = uh_ubus_session_get(blobmsg_data(tb[UH_UBUS_SA_SID]));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	if (!strcmp(method, "grant"))
		cb = uh_ubus_session_grant;
	else
		cb = uh_ubus_session_revoke;

	if (!tb[UH_UBUS_SA_OBJECTS])
		return cb(ses, ctx, NULL, NULL);

	blobmsg_for_each_attr(attr, tb[UH_UBUS_SA_OBJECTS], rem1) {
		if (blob_id(attr) != BLOBMSG_TYPE_ARRAY)
			continue;

		object = NULL;
		function = NULL;

		blobmsg_for_each_attr(sattr, attr, rem2) {
			if (blob_id(sattr) != BLOBMSG_TYPE_STRING)
				continue;

			if (!object)
				object = blobmsg_data(sattr);
			else if (!function)
				function = blobmsg_data(sattr);
			else
				break;
		}

		if (object && function)
			cb(ses, ctx, object, function);
	}

	return 0;
}

static int
uh_ubus_handle_set(struct ubus_context *ctx, struct ubus_object *obj,
				   struct ubus_request_data *req, const char *method,
				   struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct uh_ubus_session_data *data;
	struct blob_attr *tb[__UH_UBUS_SA_MAX];
	struct blob_attr *attr;
	int rem;

	blobmsg_parse(set_policy, __UH_UBUS_SS_MAX, tb, blob_data(msg), blob_len(msg));

	if (!tb[UH_UBUS_SS_SID] || !tb[UH_UBUS_SS_VALUES])
		return UBUS_STATUS_INVALID_ARGUMENT;

	ses = uh_ubus_session_get(blobmsg_data(tb[UH_UBUS_SS_SID]));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	blobmsg_for_each_attr(attr, tb[UH_UBUS_SS_VALUES], rem) {
		if (!blobmsg_name(attr)[0])
			continue;

		data = avl_find_element(&ses->data, blobmsg_name(attr), data, avl);
		if (data) {
			avl_delete(&ses->data, &data->avl);
			free(data);
		}

		data = calloc(1, sizeof(*data) + blob_pad_len(attr));
		if (!data)
			break;

		memcpy(data->attr, attr, blob_pad_len(attr));
		data->avl.key = blobmsg_name(data->attr);
		avl_insert(&ses->data, &data->avl);
	}

	return 0;
}

static int
uh_ubus_handle_get(struct ubus_context *ctx, struct ubus_object *obj,
				   struct ubus_request_data *req, const char *method,
				   struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct uh_ubus_session_data *data;
	struct blob_attr *tb[__UH_UBUS_SA_MAX];
	struct blob_attr *attr;
	void *c;
	int rem;

	blobmsg_parse(get_policy, __UH_UBUS_SG_MAX, tb, blob_data(msg), blob_len(msg));

	if (!tb[UH_UBUS_SG_SID])
		return UBUS_STATUS_INVALID_ARGUMENT;

	ses = uh_ubus_session_get(blobmsg_data(tb[UH_UBUS_SG_SID]));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	blob_buf_init(&buf, 0);
	c = blobmsg_open_table(&buf, "values");

	if (!tb[UH_UBUS_SG_KEYS]) {
		uh_ubus_session_dump_data(ses, &buf);
		return 0;
	}

	blobmsg_for_each_attr(attr, tb[UH_UBUS_SG_KEYS], rem) {
		if (blob_id(attr) != BLOBMSG_TYPE_STRING)
			continue;

		data = avl_find_element(&ses->data, blobmsg_data(attr), data, avl);
		if (!data)
			continue;

		blobmsg_add_field(&buf, blobmsg_type(data->attr),
				  blobmsg_name(data->attr),
				  blobmsg_data(data->attr),
				  blobmsg_data_len(data->attr));
	}

	blobmsg_close_table(&buf, c);
	ubus_send_reply(ctx, req, buf.head);

	return 0;
}

static int
uh_ubus_handle_unset(struct ubus_context *ctx, struct ubus_object *obj,
				     struct ubus_request_data *req, const char *method,
				     struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct uh_ubus_session_data *data, *ndata;
	struct blob_attr *tb[__UH_UBUS_SA_MAX];
	struct blob_attr *attr;
	int rem;

	blobmsg_parse(get_policy, __UH_UBUS_SG_MAX, tb, blob_data(msg), blob_len(msg));

	if (!tb[UH_UBUS_SG_SID])
		return UBUS_STATUS_INVALID_ARGUMENT;

	ses = uh_ubus_session_get(blobmsg_data(tb[UH_UBUS_SG_SID]));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	if (!tb[UH_UBUS_SG_KEYS]) {
		avl_remove_all_elements(&ses->data, data, avl, ndata)
			free(data);
		return 0;
	}

	blobmsg_for_each_attr(attr, tb[UH_UBUS_SG_KEYS], rem) {
		if (blob_id(attr) != BLOBMSG_TYPE_STRING)
			continue;

		data = avl_find_element(&ses->data, blobmsg_data(attr), data, avl);
		if (!data)
			continue;

		avl_delete(&ses->data, &data->avl);
		free(data);
	}

	return 0;
}

static int
uh_ubus_handle_destroy(struct ubus_context *ctx, struct ubus_object *obj,
					   struct ubus_request_data *req, const char *method,
					   struct blob_attr *msg)
{
	struct uh_ubus_session *ses;
	struct blob_attr *tb;

	blobmsg_parse(&sid_policy, 1, &tb, blob_data(msg), blob_len(msg));

	if (!tb)
		return UBUS_STATUS_INVALID_ARGUMENT;

	ses = uh_ubus_session_get(blobmsg_data(tb));
	if (!ses)
		return UBUS_STATUS_NOT_FOUND;

	uh_ubus_session_destroy(ses);

	return 0;
}

bool uh_ubus_session_acl_allowed(struct uh_ubus_session *ses, const char *obj, const char *fun)
{
	struct uh_ubus_session_acl *acl;

	uh_foreach_matching_acl(acl, ses, obj, fun)
		return true;

	return false;
}

int ubus_session_api_init(struct ubus_context *ctx)
{
	static const struct ubus_method session_methods[] = {
		UBUS_METHOD("create",  uh_ubus_handle_create,  &new_policy),
		UBUS_METHOD("list",    uh_ubus_handle_list,    &sid_policy),
		UBUS_METHOD("grant",   uh_ubus_handle_acl,     acl_policy),
		UBUS_METHOD("revoke",  uh_ubus_handle_acl,     acl_policy),
		UBUS_METHOD("set",     uh_ubus_handle_set,     set_policy),
		UBUS_METHOD("get",     uh_ubus_handle_get,     get_policy),
		UBUS_METHOD("unset",   uh_ubus_handle_unset,   get_policy),
		UBUS_METHOD("destroy", uh_ubus_handle_destroy, &sid_policy),
	};

	static struct ubus_object_type session_type =
		UBUS_OBJECT_TYPE("uhttpd", session_methods);

	static struct ubus_object obj = {
		.name = "session",
		.type = &session_type,
		.methods = session_methods,
		.n_methods = ARRAY_SIZE(session_methods),
	};

	avl_init(&sessions, avl_strcmp, false, NULL);

	return ubus_add_object(ctx, &obj);
}