From: Anders K. Pedersen <a...@cohaesio.com>

Introduce support for rt expression for routing related data as implemented
in kernel.

Signed-off-by: Anders K. Pedersen <a...@cohaesio.com>
---
 include/libnftnl/expr.h             |  12 ++
 include/linux/netfilter/nf_tables.h |  26 ++++
 src/Makefile.am                     |   1 +
 src/expr/rt.c                       | 268 ++++++++++++++++++++++++++++++++++++
 src/expr_ops.c                      |   2 +
 5 files changed, 309 insertions(+)

diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 4ce2592..e02e5b7 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -64,6 +64,12 @@ enum {
 };
 
 enum {
+       NFTNL_EXPR_RT_KEY       = NFTNL_EXPR_BASE,
+       NFTNL_EXPR_RT_DREG,
+       NFTNL_EXPR_RT_FAMILY,
+};
+
+enum {
        NFTNL_EXPR_CMP_SREG     = NFTNL_EXPR_BASE,
        NFTNL_EXPR_CMP_OP,
        NFTNL_EXPR_CMP_DATA,
@@ -265,6 +271,12 @@ enum {
 };
 
 enum {
+       NFT_EXPR_RT_KEY         = NFT_RULE_EXPR_ATTR_BASE,
+       NFT_EXPR_RT_DREG,
+       NFT_EXPR_RT_FAMILY,
+};
+
+enum {
        NFT_EXPR_CMP_SREG       = NFT_RULE_EXPR_ATTR_BASE,
        NFT_EXPR_CMP_OP,
        NFT_EXPR_CMP_DATA,
diff --git a/include/linux/netfilter/nf_tables.h 
b/include/linux/netfilter/nf_tables.h
index 681082e..81ee4f0 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -724,6 +724,16 @@ enum nft_meta_keys {
 };
 
 /**
+ * enum nft_rt_keys - nf_tables routing expression keys
+ *
+ * @NFT_META_NEXTHOP: routing nexthop
+ */
+enum nft_rt_keys {
+       NFT_RT_CLASSID,
+       NFT_RT_NEXTHOP,
+};
+
+/**
  * enum nft_hash_attributes - nf_tables hash expression netlink attributes
  *
  * @NFTA_HASH_SREG: source register (NLA_U32)
@@ -762,6 +772,22 @@ enum nft_meta_attributes {
 #define NFTA_META_MAX          (__NFTA_META_MAX - 1)
 
 /**
+ * enum nft_rt_attributes - nf_tables routing expression netlink attributes
+ *
+ * @NFTA_RT_DREG: destination register (NLA_U32)
+ * @NFTA_RT_KEY: meta data item to load (NLA_U32: nft_rt_keys)
+ * @NFTA_RT_FAMILY: Address family (NLA_U32)
+ */
+enum nft_rt_attributes {
+       NFTA_RT_UNSPEC,
+       NFTA_RT_DREG,
+       NFTA_RT_KEY,
+       NFTA_RT_FAMILY,
+       __NFTA_RT_MAX
+};
+#define NFTA_RT_MAX            (__NFTA_RT_MAX - 1)
+
+/**
  * enum nft_ct_keys - nf_tables ct expression keys
  *
  * @NFT_CT_STATE: conntrack state (bitmask of enum ip_conntrack_info)
diff --git a/src/Makefile.am b/src/Makefile.am
index 4ab8fca..48ff85a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -43,6 +43,7 @@ libnftnl_la_SOURCES = utils.c         \
                      expr/queue.c      \
                      expr/quota.c      \
                      expr/reject.c     \
+                     expr/rt.c         \
                      expr/target.c     \
                      expr/masq.c       \
                      expr/redir.c      \
diff --git a/src/expr/rt.c b/src/expr/rt.c
new file mode 100644
index 0000000..fa659e7
--- /dev/null
+++ b/src/expr/rt.c
@@ -0,0 +1,268 @@
+/*
+ * Copyright (c) 2016 Anders K. Pedersen <a...@cohaesio.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>
+
+#ifndef NFT_RT_MAX
+#define NFT_RT_MAX (NFT_RT_NEXTHOP + 1)
+#endif
+
+struct nftnl_expr_rt {
+       enum nft_rt_keys        key;
+       enum nft_registers      dreg;
+       int                     family;
+};
+
+static int
+nftnl_expr_rt_set(struct nftnl_expr *e, uint16_t type,
+                      const void *data, uint32_t data_len)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+
+       switch (type) {
+       case NFTNL_EXPR_RT_KEY:
+               rt->key = *((uint32_t *)data);
+               break;
+       case NFTNL_EXPR_RT_DREG:
+               rt->dreg = *((uint32_t *)data);
+               break;
+       case NFTNL_EXPR_RT_FAMILY:
+               rt->family = *((uint32_t *)data);
+               break;
+       default:
+               return -1;
+       }
+       return 0;
+}
+
+static const void *
+nftnl_expr_rt_get(const struct nftnl_expr *e, uint16_t type,
+                      uint32_t *data_len)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+
+       switch (type) {
+       case NFTNL_EXPR_RT_KEY:
+               *data_len = sizeof(rt->key);
+               return &rt->key;
+       case NFTNL_EXPR_RT_DREG:
+               *data_len = sizeof(rt->dreg);
+               return &rt->dreg;
+       case NFTNL_EXPR_RT_FAMILY:
+               *data_len = sizeof(rt->family);
+               return &rt->family;
+       }
+       return NULL;
+}
+
+static int nftnl_expr_rt_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_RT_MAX) < 0)
+               return MNL_CB_OK;
+
+       switch (type) {
+       case NFTA_RT_KEY:
+       case NFTA_RT_DREG:
+       case NFTA_RT_FAMILY:
+               if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
+                       abi_breakage();
+               break;
+       }
+
+       tb[type] = attr;
+       return MNL_CB_OK;
+}
+
+static void
+nftnl_expr_rt_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+
+       if (e->flags & (1 << NFTNL_EXPR_RT_KEY))
+               mnl_attr_put_u32(nlh, NFTA_RT_KEY, htonl(rt->key));
+       if (e->flags & (1 << NFTNL_EXPR_RT_DREG))
+               mnl_attr_put_u32(nlh, NFTA_RT_DREG, htonl(rt->dreg));
+       if (e->flags & (1 << NFTNL_EXPR_RT_FAMILY))
+               mnl_attr_put_u32(nlh, NFTA_RT_FAMILY, htonl(rt->family));
+}
+
+static int
+nftnl_expr_rt_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+       struct nlattr *tb[NFTA_RT_MAX+1] = {};
+
+       if (mnl_attr_parse_nested(attr, nftnl_expr_rt_cb, tb) < 0)
+               return -1;
+
+       if (tb[NFTA_RT_KEY]) {
+               rt->key = ntohl(mnl_attr_get_u32(tb[NFTA_RT_KEY]));
+               e->flags |= (1 << NFTNL_EXPR_RT_KEY);
+       }
+       if (tb[NFTA_RT_DREG]) {
+               rt->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_RT_DREG]));
+               e->flags |= (1 << NFTNL_EXPR_RT_DREG);
+       }
+       if (tb[NFTA_RT_FAMILY]) {
+               rt->family = ntohl(mnl_attr_get_u32(tb[NFTA_RT_FAMILY]));
+               e->flags |= (1 << NFTNL_EXPR_RT_FAMILY);
+       }
+
+       return 0;
+}
+
+static const char *rt_key2str_array[NFT_RT_MAX] = {
+       [NFT_RT_CLASSID]        = "classid",
+       [NFT_RT_NEXTHOP]        = "nexthop",
+};
+
+static const char *rt_key2str(uint8_t key)
+{
+       if (key < NFT_RT_MAX)
+               return rt_key2str_array[key];
+
+       return "unknown";
+}
+
+static inline int str2rt_key(const char *str)
+{
+       int i;
+
+       for (i = 0; i < NFT_RT_MAX; i++) {
+               if (strcmp(str, rt_key2str_array[i]) == 0)
+                       return i;
+       }
+
+       errno = EINVAL;
+       return -1;
+}
+
+static int nftnl_expr_rt_json_parse(struct nftnl_expr *e, json_t *root,
+                                   struct nftnl_parse_err *err)
+{
+#ifdef JSON_PARSING
+       const char *val_str;
+       uint32_t reg;
+       int val32;
+
+       val_str = nftnl_jansson_parse_str(root, "key", err);
+       if (val_str != NULL) {
+               val32 = str2rt_key(val_str);
+               if (val32 >= 0)
+                       nftnl_expr_set_u32(e, NFTNL_EXPR_RT_KEY, val32);
+       }
+
+       if (nftnl_jansson_node_exist(root, "dreg")) {
+               if (nftnl_jansson_parse_reg(root, "dreg", NFTNL_TYPE_U32, &reg,
+                                         err) == 0)
+                       nftnl_expr_set_u32(e, NFTNL_EXPR_RT_DREG, reg);
+       }
+
+       val_str = nftnl_jansson_parse_str(root, "family", err);
+       if (val_str != NULL) {
+               val32 = nftnl_str2family(val_str);
+               if (val32 >= 0)
+                       nftnl_expr_set_u32(e, NFTNL_EXPR_RT_FAMILY, val32);
+       }
+
+       return 0;
+#else
+       errno = EOPNOTSUPP;
+       return -1;
+#endif
+}
+
+static int
+nftnl_expr_rt_snprintf_default(char *buf, size_t len,
+                              const struct nftnl_expr *e)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+
+       if (e->flags & (1 << NFTNL_EXPR_RT_DREG)) {
+               return snprintf(buf, len, "load %s %s => reg %u ",
+                               nftnl_family2str(rt->family),
+                               rt_key2str(rt->key), rt->dreg);
+       }
+       return 0;
+}
+
+static int nftnl_expr_rt_export(char *buf, size_t size,
+                                 const struct nftnl_expr *e, int type)
+{
+       struct nftnl_expr_rt *rt = nftnl_expr_data(e);
+       NFTNL_BUF_INIT(b, buf, size);
+
+       if (e->flags & (1 << NFTNL_EXPR_RT_DREG))
+               nftnl_buf_u32(&b, type, rt->dreg, DREG);
+       if (e->flags & (1 << NFTNL_EXPR_RT_KEY))
+               nftnl_buf_str(&b, type, rt_key2str(rt->key), KEY);
+       if (e->flags & (1 << NFTNL_EXPR_RT_FAMILY))
+               nftnl_buf_str(&b, type, nftnl_family2str(rt->family), FAMILY);
+
+       return nftnl_buf_done(&b);
+}
+
+static int
+nftnl_expr_rt_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_rt_snprintf_default(buf, len, e);
+       case NFTNL_OUTPUT_XML:
+       case NFTNL_OUTPUT_JSON:
+               return nftnl_expr_rt_export(buf, len, e, type);
+       default:
+               break;
+       }
+       return -1;
+}
+
+static bool nftnl_expr_rt_cmp(const struct nftnl_expr *e1,
+                             const struct nftnl_expr *e2)
+{
+       struct nftnl_expr_rt *r1 = nftnl_expr_data(e1);
+       struct nftnl_expr_rt *r2 = nftnl_expr_data(e2);
+       bool eq = true;
+
+       if (e1->flags & (1 << NFTNL_EXPR_RT_KEY))
+               eq &= (r1->key == r2->key);
+       if (e1->flags & (1 << NFTNL_EXPR_RT_DREG))
+               eq &= (r1->dreg == r2->dreg);
+       if (e1->flags & (1 << NFTNL_EXPR_RT_FAMILY))
+               eq &= (r1->family == r2->family);
+
+       return eq;
+}
+
+struct expr_ops expr_ops_rt = {
+       .name           = "rt",
+       .alloc_len      = sizeof(struct nftnl_expr_rt),
+       .max_attr       = NFTA_RT_MAX,
+       .cmp            = nftnl_expr_rt_cmp,
+       .set            = nftnl_expr_rt_set,
+       .get            = nftnl_expr_rt_get,
+       .parse          = nftnl_expr_rt_parse,
+       .build          = nftnl_expr_rt_build,
+       .snprintf       = nftnl_expr_rt_snprintf,
+       .json_parse     = nftnl_expr_rt_json_parse,
+};
diff --git a/src/expr_ops.c b/src/expr_ops.c
index 2a047d2..7c0e891 100644
--- a/src/expr_ops.c
+++ b/src/expr_ops.c
@@ -24,6 +24,7 @@ extern struct expr_ops expr_ops_nat;
 extern struct expr_ops expr_ops_payload;
 extern struct expr_ops expr_ops_redir;
 extern struct expr_ops expr_ops_reject;
+extern struct expr_ops expr_ops_rt;
 extern struct expr_ops expr_ops_queue;
 extern struct expr_ops expr_ops_quota;
 extern struct expr_ops expr_ops_target;
@@ -51,6 +52,7 @@ static struct expr_ops *expr_ops[] = {
        &expr_ops_payload,
        &expr_ops_redir,
        &expr_ops_reject,
+       &expr_ops_rt,
        &expr_ops_queue,
        &expr_ops_quota,
        &expr_ops_target,
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