tools: ynl: create local nlmsg access helpers

Create helpers for accessing payloads of struct nlmsg.
Use them instead of the libmnl ones.
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-5-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/lib/ynl-priv.h

@@ -125,13 +125,50 @@ int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
 void ynl_error_unknown_notification(struct ynl_sock *ys, __u8 cmd);
 int ynl_error_parse(struct ynl_parse_arg *yarg, const char *msg);
 
-/* Attribute helpers */
+/* Netlink message handling helpers */
+
+static inline struct nlmsghdr *ynl_nlmsg_put_header(void *buf)
+{
+	struct nlmsghdr *nlh = buf;
+
+	memset(nlh, 0, sizeof(*nlh));
+	nlh->nlmsg_len = NLMSG_HDRLEN;
+
+	return nlh;
+}
+
+static inline unsigned int ynl_nlmsg_data_len(const struct nlmsghdr *nlh)
+{
+	return nlh->nlmsg_len - NLMSG_HDRLEN;
+}
+
+static inline void *ynl_nlmsg_data(const struct nlmsghdr *nlh)
+{
+	return (unsigned char *)nlh + NLMSG_HDRLEN;
+}
+
+static inline void *
+ynl_nlmsg_data_offset(const struct nlmsghdr *nlh, unsigned int offset)
+{
+	return (unsigned char *)nlh + NLMSG_HDRLEN + offset;
+}
 
 static inline void *ynl_nlmsg_end_addr(const struct nlmsghdr *nlh)
 {
 	return (char *)nlh + nlh->nlmsg_len;
 }
 
+static inline void *
+ynl_nlmsg_put_extra_header(struct nlmsghdr *nlh, unsigned int size)
+{
+	void *tail = ynl_nlmsg_end_addr(nlh);
+
+	nlh->nlmsg_len += NLMSG_ALIGN(size);
+	return tail;
+}
+
+/* Netlink attribute helpers */
+
 static inline unsigned int ynl_attr_type(const struct nlattr *attr)
 {
 	return attr->nla_type & NLA_TYPE_MASK;

tools/net/ynl/lib/ynl.c

@@ -190,9 +190,8 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 		n = snprintf(bad_attr, sizeof(bad_attr), "%sbad attribute: ",
 			     str ? " (" : "");
 
-		start = mnl_nlmsg_get_payload_offset(ys->nlh,
-						     ys->family->hdr_len);
-		end = mnl_nlmsg_get_payload_tail(ys->nlh);
+		start = ynl_nlmsg_data_offset(ys->nlh, ys->family->hdr_len);
+		end = ynl_nlmsg_end_addr(ys->nlh);
 
 		off = ys->err.attr_offs;
 		off -= sizeof(struct nlmsghdr);
@@ -216,9 +215,8 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 		n = snprintf(miss_attr, sizeof(miss_attr), "%smissing attribute: ",
 			     bad_attr[0] ? ", " : (str ? " (" : ""));
 
-		start = mnl_nlmsg_get_payload_offset(ys->nlh,
-						     ys->family->hdr_len);
-		end = mnl_nlmsg_get_payload_tail(ys->nlh);
+		start = ynl_nlmsg_data_offset(ys->nlh, ys->family->hdr_len);
+		end = ynl_nlmsg_end_addr(ys->nlh);
 
 		nest_pol = ys->req_policy;
 		if (tb[NLMSGERR_ATTR_MISS_NEST]) {
@@ -259,7 +257,7 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 
 static int ynl_cb_error(const struct nlmsghdr *nlh, void *data)
 {
-	const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
+	const struct nlmsgerr *err = ynl_nlmsg_data(nlh);
 	struct ynl_parse_arg *yarg = data;
 	unsigned int hlen;
 	int code;
@@ -270,7 +268,7 @@ static int ynl_cb_error(const struct nlmsghdr *nlh, void *data)
 
 	hlen = sizeof(*err);
 	if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
-		hlen += mnl_nlmsg_get_payload_len(&err->msg);
+		hlen += ynl_nlmsg_data_len(&err->msg);
 
 	ynl_ext_ack_check(yarg->ys, nlh, hlen);
 
@@ -413,7 +411,7 @@ struct nlmsghdr *ynl_msg_start(struct ynl_sock *ys, __u32 id, __u16 flags)
 
 	ynl_err_reset(ys);
 
-	nlh = ys->nlh = mnl_nlmsg_put_header(ys->tx_buf);
+	nlh = ys->nlh = ynl_nlmsg_put_header(ys->tx_buf);
 	nlh->nlmsg_type	= id;
 	nlh->nlmsg_flags = flags;
 	nlh->nlmsg_seq = ++ys->seq;
@@ -435,7 +433,7 @@ ynl_gemsg_start(struct ynl_sock *ys, __u32 id, __u16 flags,
 	gehdr.cmd = cmd;
 	gehdr.version = version;
 
-	data = mnl_nlmsg_put_extra_header(nlh, sizeof(gehdr));
+	data = ynl_nlmsg_put_extra_header(nlh, sizeof(gehdr));
 	memcpy(data, &gehdr, sizeof(gehdr));
 
 	return nlh;
@@ -718,7 +716,7 @@ static int ynl_ntf_parse(struct ynl_sock *ys, const struct nlmsghdr *nlh)
 	struct genlmsghdr *gehdr;
 	int ret;
 
-	gehdr = mnl_nlmsg_get_payload(nlh);
+	gehdr = ynl_nlmsg_data(nlh);
 	if (gehdr->cmd >= ys->family->ntf_info_size)
 		return MNL_CB_ERROR;
 	info = &ys->family->ntf_info[gehdr->cmd];
@@ -808,13 +806,13 @@ ynl_check_alien(struct ynl_sock *ys, const struct nlmsghdr *nlh, __u32 rsp_cmd)
 {
 	struct genlmsghdr *gehdr;
 
-	if (mnl_nlmsg_get_payload_len(nlh) < sizeof(*gehdr)) {
+	if (ynl_nlmsg_data_len(nlh) < sizeof(*gehdr)) {
 		yerr(ys, YNL_ERROR_INV_RESP,
 		     "Kernel responded with truncated message");
 		return -1;
 	}
 
-	gehdr = mnl_nlmsg_get_payload(nlh);
+	gehdr = ynl_nlmsg_data(nlh);
 	if (gehdr->cmd != rsp_cmd)
 		return ynl_ntf_parse(ys, nlh);
 

tools/net/ynl/ynl-gen-c.py

@@ -1650,7 +1650,7 @@ def _multi_parse(ri, struct, init_lines, local_vars):
         ri.cw.p(f'dst->{arg} = {arg};')
 
     if ri.fixed_hdr:
-        ri.cw.p('hdr = mnl_nlmsg_get_payload_offset(nlh, sizeof(struct genlmsghdr));')
+        ri.cw.p('hdr = ynl_nlmsg_data_offset(nlh, sizeof(struct genlmsghdr));')
         ri.cw.p(f"memcpy(&dst->_hdr, hdr, sizeof({ri.fixed_hdr}));")
     for anest in sorted(all_multi):
         aspec = struct[anest]
@@ -1794,7 +1794,7 @@ def print_req(ri):
 
     if ri.fixed_hdr:
         ri.cw.p("hdr_len = sizeof(req->_hdr);")
-        ri.cw.p("hdr = mnl_nlmsg_put_extra_header(nlh, hdr_len);")
+        ri.cw.p("hdr = ynl_nlmsg_put_extra_header(nlh, hdr_len);")
         ri.cw.p("memcpy(hdr, &req->_hdr, hdr_len);")
         ri.cw.nl()
 
@@ -1857,7 +1857,7 @@ def print_dump(ri):
 
     if ri.fixed_hdr:
         ri.cw.p("hdr_len = sizeof(req->_hdr);")
-        ri.cw.p("hdr = mnl_nlmsg_put_extra_header(nlh, hdr_len);")
+        ri.cw.p("hdr = ynl_nlmsg_put_extra_header(nlh, hdr_len);")
         ri.cw.p("memcpy(hdr, &req->_hdr, hdr_len);")
         ri.cw.nl()