expr: add hash expression

Support for the nft hash expression in libnftnl.

Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 294 insertions, 0 deletions

diff --git a/src/expr/hash.c b/src/expr/hash.c
new file mode 100644
index 0000000..7309907
--- /dev/null
+++ b/src/expr/hash.c
@@ -0,0 +1,294 @@
+/*
+ * (C) 2016 by Laura Garcia <nevola@gmail.com>
+ *
+ * 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 <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <linux/netfilter/nf_tables.h>
+
+#include "internal.h"
+#include <libmnl/libmnl.h>
+#include <libnftnl/expr.h>
+#include <libnftnl/rule.h>
+
+struct nftnl_expr_hash {
+	enum nft_registers	sreg;
+	enum nft_registers	dreg;
+	unsigned int		len;
+	unsigned int		modulus;
+	unsigned int		seed;
+};
+
+static int
+nftnl_expr_hash_set(struct nftnl_expr *e, uint16_t type,
+		    const void *data, uint32_t data_len)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+
+	switch (type) {
+	case NFTNL_EXPR_HASH_SREG:
+		hash->sreg = *((uint32_t *)data);
+		break;
+	case NFTNL_EXPR_HASH_DREG:
+		hash->dreg = *((uint32_t *)data);
+		break;
+	case NFTNL_EXPR_HASH_LEN:
+		hash->len = *((uint32_t *)data);
+		break;
+	case NFTNL_EXPR_HASH_MODULUS:
+		hash->modulus = *((uint32_t *)data);
+		break;
+	case NFTNL_EXPR_HASH_SEED:
+		hash->seed = *((uint32_t *)data);
+		break;
+	default:
+		return -1;
+	}
+	return 0;
+}
+
+static const void *
+nftnl_expr_hash_get(const struct nftnl_expr *e, uint16_t type,
+		    uint32_t *data_len)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+
+	switch (type) {
+	case NFTNL_EXPR_HASH_SREG:
+		*data_len = sizeof(hash->sreg);
+		return &hash->sreg;
+	case NFTNL_EXPR_HASH_DREG:
+		*data_len = sizeof(hash->dreg);
+		return &hash->dreg;
+	case NFTNL_EXPR_HASH_LEN:
+		*data_len = sizeof(hash->len);
+		return &hash->len;
+	case NFTNL_EXPR_HASH_MODULUS:
+		*data_len = sizeof(hash->modulus);
+		return &hash->modulus;
+	case NFTNL_EXPR_HASH_SEED:
+		*data_len = sizeof(hash->seed);
+		return &hash->seed;
+	}
+	return NULL;
+}
+
+static int nftnl_expr_hash_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type = mnl_attr_get_type(attr);
+
+	if (mnl_attr_type_valid(attr, NFTA_HASH_MAX) < 0)
+		return MNL_CB_OK;
+
+	switch (type) {
+	case NFTA_HASH_SREG:
+	case NFTA_HASH_DREG:
+	case NFTA_HASH_LEN:
+	case NFTA_HASH_MODULUS:
+	case NFTA_HASH_SEED:
+		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
+			abi_breakage();
+		break;
+	}
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static void
+nftnl_expr_hash_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+
+	if (e->flags & (1 << NFTNL_EXPR_HASH_SREG))
+		mnl_attr_put_u32(nlh, NFTA_HASH_SREG, htonl(hash->sreg));
+	if (e->flags & (1 << NFTNL_EXPR_HASH_DREG))
+		mnl_attr_put_u32(nlh, NFTA_HASH_DREG, htonl(hash->dreg));
+	if (e->flags & (1 << NFTNL_EXPR_HASH_LEN))
+		mnl_attr_put_u32(nlh, NFTA_HASH_LEN, htonl(hash->len));
+	if (e->flags & (1 << NFTNL_EXPR_HASH_MODULUS))
+		mnl_attr_put_u32(nlh, NFTA_HASH_MODULUS, htonl(hash->modulus));
+	if (e->flags & (1 << NFTNL_EXPR_HASH_SEED))
+		mnl_attr_put_u32(nlh, NFTA_HASH_SEED, htonl(hash->seed));
+
+}
+
+static int
+nftnl_expr_hash_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+	struct nlattr *tb[NFTA_HASH_MAX+1] = {};
+	int ret = 0;
+
+	if (mnl_attr_parse_nested(attr, nftnl_expr_hash_cb, tb) < 0)
+		return -1;
+
+	if (tb[NFTA_HASH_SREG]) {
+		hash->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_SREG]));
+		e->flags |= (1 << NFTNL_EXPR_HASH_SREG);
+	}
+	if (tb[NFTA_HASH_DREG]) {
+		hash->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_DREG]));
+		e->flags |= (1 << NFTNL_EXPR_HASH_DREG);
+	}
+	if (tb[NFTA_HASH_LEN]) {
+		hash->len = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_LEN]));
+		e->flags |= (1 << NFTNL_EXPR_HASH_LEN);
+	}
+	if (tb[NFTA_HASH_MODULUS]) {
+		hash->modulus = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_MODULUS]));
+		e->flags |= (1 << NFTNL_EXPR_HASH_MODULUS);
+	}
+	if (tb[NFTA_HASH_SEED]) {
+		hash->seed = ntohl(mnl_attr_get_u32(tb[NFTA_HASH_SEED]));
+		e->flags |= (1 << NFTNL_EXPR_HASH_SEED);
+	}
+
+	return ret;
+}
+
+static int nftnl_expr_hash_json_parse(struct nftnl_expr *e, json_t *root,
+				      struct nftnl_parse_err *err)
+{
+#ifdef JSON_PARSING
+	uint32_t sreg, dreg, len, modulus, seed;
+
+	if (nftnl_jansson_parse_reg(root, "sreg", NFTNL_TYPE_U32,
+				    &sreg, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_SREG, sreg);
+
+	if (nftnl_jansson_parse_reg(root, "dreg", NFTNL_TYPE_U32,
+				    &dreg, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_DREG, dreg);
+
+	if (nftnl_jansson_parse_val(root, "len", NFTNL_TYPE_U32,
+				    &len, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_LEN, len);
+
+	if (nftnl_jansson_parse_val(root, "modulus", NFTNL_TYPE_U32,
+				    &modulus, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_MODULUS, modulus);
+
+	if (nftnl_jansson_parse_val(root, "seed", NFTNL_TYPE_U32,
+				    &seed, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_SEED, seed);
+
+	return 0;
+#else
+	errno = EOPNOTSUPP;
+	return -1;
+#endif
+}
+
+
+static int nftnl_expr_hash_xml_parse(struct nftnl_expr *e,
+				     mxml_node_t *tree,
+				     struct nftnl_parse_err *err)
+{
+#ifdef XML_PARSING
+	uint32_t sreg, dreg, len, modulus, seed;
+
+	if (nftnl_mxml_reg_parse(tree, "sreg", &sreg, MXML_DESCEND_FIRST,
+				 NFTNL_XML_MAND, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_SREG, sreg);
+
+	if (nftnl_mxml_reg_parse(tree, "dreg", &dreg, MXML_DESCEND_FIRST,
+				 NFTNL_XML_MAND, err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_DREG, dreg);
+
+	if (nftnl_mxml_num_parse(tree, "len", MXML_DESCEND_FIRST, BASE_DEC,
+				 &len, NFTNL_TYPE_U32, NFTNL_XML_MAND,
+				 err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_LEN, len);
+
+	if (nftnl_mxml_num_parse(tree, "modulus", MXML_DESCEND_FIRST, BASE_DEC,
+				 &modulus, NFTNL_TYPE_U32, NFTNL_XML_MAND,
+				 err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_MODULUS, modulus);
+
+	if (nftnl_mxml_num_parse(tree, "seed", MXML_DESCEND_FIRST, BASE_DEC,
+				 &seed, NFTNL_TYPE_U32, NFTNL_XML_MAND,
+				 err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_HASH_SEED, seed);
+
+	return 0;
+#else
+	errno = EOPNOTSUPP;
+	return -1;
+#endif
+}
+
+static int
+nftnl_expr_hash_snprintf_default(char *buf, size_t size,
+				 const struct nftnl_expr *e)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+	int len = size, offset = 0, ret;
+
+	ret = snprintf(buf, len, "reg %u = jhash(reg %u, %u, %u) %% modulus %u",
+		       hash->dreg, hash->sreg, hash->len, hash->seed,
+		       hash->modulus);
+	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+
+	return offset;
+}
+
+static int nftnl_expr_hash_export(char *buf, size_t size,
+				  const struct nftnl_expr *e, int type)
+{
+	struct nftnl_expr_hash *hash = nftnl_expr_data(e);
+
+	NFTNL_BUF_INIT(b, buf, size);
+
+	if (e->flags & (1 << NFTNL_EXPR_HASH_SREG))
+		nftnl_buf_u32(&b, type, hash->sreg, SREG);
+	if (e->flags & (1 << NFTNL_EXPR_HASH_DREG))
+		nftnl_buf_u32(&b, type, hash->dreg, DREG);
+	if (e->flags & (1 << NFTNL_EXPR_HASH_LEN))
+		nftnl_buf_u32(&b, type, hash->len, LEN);
+	if (e->flags & (1 << NFTNL_EXPR_HASH_MODULUS))
+		nftnl_buf_u32(&b, type, hash->modulus, MODULUS);
+	if (e->flags & (1 << NFTNL_EXPR_HASH_SEED))
+		nftnl_buf_u32(&b, type, hash->seed, SEED);
+
+	return nftnl_buf_done(&b);
+}
+
+static int
+nftnl_expr_hash_snprintf(char *buf, size_t len, uint32_t type,
+			 uint32_t flags, const struct nftnl_expr *e)
+{
+	switch (type) {
+	case NFTNL_OUTPUT_DEFAULT:
+		return nftnl_expr_hash_snprintf_default(buf, len, e);
+	case NFTNL_OUTPUT_XML:
+	case NFTNL_OUTPUT_JSON:
+		return nftnl_expr_hash_export(buf, len, e, type);
+	default:
+		break;
+	}
+	return -1;
+}
+
+struct expr_ops expr_ops_hash = {
+	.name		= "hash",
+	.alloc_len	= sizeof(struct nftnl_expr_hash),
+	.max_attr	= NFTA_HASH_MAX,
+	.set		= nftnl_expr_hash_set,
+	.get		= nftnl_expr_hash_get,
+	.parse		= nftnl_expr_hash_parse,
+	.build		= nftnl_expr_hash_build,
+	.snprintf	= nftnl_expr_hash_snprintf,
+	.xml_parse	= nftnl_expr_hash_xml_parse,
+	.json_parse	= nftnl_expr_hash_json_parse,
+};