[libnftables PATCH 4/6] chain: json: add function for parsing chain

[Alvaro Neira <alvaroneay@gmail.com>]

From: Álvaro Neira Ayuso <alvaroneay@gmail.com>

Add function for parsing chains in format JSON

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
---
 include/libnftables/chain.h |    1 
 src/chain.c                 |  138 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 139 insertions(+)

diff --git a/include/libnftables/chain.h b/include/libnftables/chain.h
index 382947f..53fd407 100644
--- a/include/libnftables/chain.h
+++ b/include/libnftables/chain.h
@@ -52,6 +52,7 @@ enum {
 enum nft_chain_parse_type {
 	NFT_CHAIN_PARSE_NONE	= 0,
 	NFT_CHAIN_PARSE_XML,
+	NFT_CHAIN_PARSE_JSON,
 	NFT_CHAIN_PARSE_MAX
 };
 
diff --git a/src/chain.c b/src/chain.c
index 1e07044..d9d41ee 100644
--- a/src/chain.c
+++ b/src/chain.c
@@ -468,6 +468,141 @@ int nft_chain_nlmsg_parse(const struct nlmsghdr *nlh, struct nft_chain *c)
 }
 EXPORT_SYMBOL(nft_chain_nlmsg_parse);
 
+static int str2policy(const char *policy)
+{
+	if (strcmp("accept", policy) == 0) {
+		return NF_ACCEPT;
+	} else if (strcmp("drop", policy) == 0) {
+		return NF_DROP;
+	} else {
+		return -1;
+	}
+}
+
+static int nft_chain_json_parse(struct nft_chain *c, char *json)
+{
+#ifdef JSON_PARSING
+	json_t *root;
+	json_error_t error;
+	uint64_t val64;
+	uint32_t hooknum;
+	int32_t prio;
+	const char *valstr;
+
+	/* Load the tree */
+	root = json_loadb (json, strlen(json), 0, &error);
+	if (!root) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	root = json_object_get(root, "chain");
+	if (root == NULL) {
+		errno = ERANGE;
+		return -1;
+	}
+
+	if (nft_jansson_value_parse_val(root, "version", NFT_TYPE_U64,
+					 &val64) == -1)
+		goto err;
+
+	if (val64 != NFT_CHAIN_JSON_VERSION)
+		goto err;
+
+	valstr = nft_jansson_value_parse_str(root, "name");
+	if (valstr == NULL)
+		goto err;
+
+	nft_chain_attr_set_str(c, NFT_CHAIN_ATTR_NAME, strdup(valstr));
+
+	if (nft_jansson_value_parse_val(root, "handle", NFT_TYPE_U64,
+					 &val64) == -1)
+		goto err;
+
+	nft_chain_attr_set_u64(c,NFT_CHAIN_ATTR_HANDLE, val64);
+
+	if (nft_jansson_value_parse_val(root, "bytes", NFT_TYPE_U64,
+					 &val64) == -1)
+		goto err;
+
+	nft_chain_attr_set_u64(c, NFT_CHAIN_ATTR_BYTES, val64);
+
+	if (nft_jansson_value_parse_val(root, "packets", NFT_TYPE_U64,
+					 &val64) == -1)
+		goto err;
+
+	if (val64 < 0)
+		goto err;
+
+	nft_chain_attr_set_u64(c, NFT_CHAIN_ATTR_PACKETS, val64);
+
+	root = json_object_get(root, "properties");
+
+	valstr = nft_jansson_value_parse_str(root, "family");
+
+	if (valstr == NULL)
+		goto err;
+
+	if (nft_str2family(valstr) == -1)
+		goto err;
+
+	nft_chain_attr_set_u32(c, NFT_CHAIN_ATTR_FAMILY, nft_str2family(valstr));
+
+	valstr = nft_jansson_value_parse_str(root, "table");
+
+	if (valstr == NULL)
+		goto err;
+
+	nft_chain_attr_set_str(c, NFT_CHAIN_ATTR_TABLE, strdup(valstr));
+
+	if (nft_jansson_node_exist(root, "hooknum")) {
+		valstr = nft_jansson_value_parse_str(root, "type");
+
+		if (valstr == NULL)
+			goto err;
+
+		nft_chain_attr_set_str(c, NFT_CHAIN_ATTR_TYPE, strdup(valstr));
+
+		if (nft_jansson_value_parse_val(root, "prio", NFT_TYPE_S32,
+						 &prio) == -1)
+			goto err;
+
+		nft_chain_attr_set_s32(c, NFT_CHAIN_ATTR_PRIO, prio);
+
+		valstr = nft_jansson_value_parse_str(root, "hooknum");
+		for (hooknum = 0; hooknum < NF_INET_NUMHOOKS; hooknum++) {
+			if (strcmp(valstr, hooknum2str_array[hooknum]) == 0) {
+				nft_chain_attr_set_u32(c, NFT_CHAIN_ATTR_HOOKNUM,
+						       hooknum);
+				break;
+			}
+		}
+
+		valstr = nft_jansson_value_parse_str(root, "policy");
+
+		if (valstr == NULL)
+			goto err;
+
+		if (str2policy(valstr) == -1)
+			goto err;
+
+		nft_chain_attr_set_u32(c, NFT_CHAIN_ATTR_POLICY,
+				       str2policy(valstr));
+	}
+
+	free(root);
+	return 0;
+
+err:
+	free(root);
+	errno = ERANGE;
+	return -1;
+#else
+	errno = EOPNOTSUPP;
+	return -1;
+#endif
+}
+
 static int nft_chain_xml_parse(struct nft_chain *c, char *xml)
 {
 #ifdef XML_PARSING
@@ -661,6 +796,9 @@ int nft_chain_parse(struct nft_chain *c, enum nft_chain_parse_type type,
 	case NFT_CHAIN_PARSE_XML:
 		ret = nft_chain_xml_parse(c, data);
 		break;
+	case NFT_CHAIN_PARSE_JSON:
+		ret = nft_chain_json_parse(c, data);
+		break;
 	default:
 		ret = -1;
 		errno = EOPNOTSUPP;

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