Merge branch 'tools-ynl-generate-code-for-the-handshake-family'

Jakub Kicinski says:

====================
tools: ynl: generate code for the handshake family

Add necessary features and generate user space C code for serializing
/ deserializing messages of the handshake family.

In addition to basics already present in netdev and fou, handshake
has nested attrs and multi-attr u32.
====================

Link: https://lore.kernel.org/r/20230606194302.919343-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 593 insertions, 11 deletions

diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
index bbf5d83755c9..916723193b60 100644
--- a/tools/net/ynl/generated/Makefile
+++ b/tools/net/ynl/generated/Makefile
@@ -9,7 +9,7 @@ endif
 
 TOOL:=../ynl-gen-c.py
 
-GENS:=fou netdev
+GENS:=handshake fou netdev
 SRCS=$(patsubst %,%-user.c,${GENS})
 HDRS=$(patsubst %,%-user.h,${GENS})
 OBJS=$(patsubst %,%-user.o,${GENS})
diff --git a/tools/net/ynl/generated/handshake-user.c b/tools/net/ynl/generated/handshake-user.c
new file mode 100644
index 000000000000..fe99c4ef7373
--- /dev/null
+++ b/tools/net/ynl/generated/handshake-user.c
@@ -0,0 +1,385 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/handshake.yaml */
+/* YNL-GEN user source */
+
+#include <stdlib.h>
+#include "handshake-user.h"
+#include "ynl.h"
+#include <linux/handshake.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <libmnl/libmnl.h>
+#include <linux/genetlink.h>
+
+/* Enums */
+static const char * const handshake_op_strmap[] = {
+	[HANDSHAKE_CMD_READY] = "ready",
+	[HANDSHAKE_CMD_ACCEPT] = "accept",
+	[HANDSHAKE_CMD_DONE] = "done",
+};
+
+const char *handshake_op_str(int op)
+{
+	if (op < 0 || op >= (int)MNL_ARRAY_SIZE(handshake_op_strmap))
+		return NULL;
+	return handshake_op_strmap[op];
+}
+
+static const char * const handshake_handler_class_strmap[] = {
+	[0] = "none",
+	[1] = "tlshd",
+	[2] = "max",
+};
+
+const char *handshake_handler_class_str(enum handshake_handler_class value)
+{
+	if (value < 0 || value >= (int)MNL_ARRAY_SIZE(handshake_handler_class_strmap))
+		return NULL;
+	return handshake_handler_class_strmap[value];
+}
+
+static const char * const handshake_msg_type_strmap[] = {
+	[0] = "unspec",
+	[1] = "clienthello",
+	[2] = "serverhello",
+};
+
+const char *handshake_msg_type_str(enum handshake_msg_type value)
+{
+	if (value < 0 || value >= (int)MNL_ARRAY_SIZE(handshake_msg_type_strmap))
+		return NULL;
+	return handshake_msg_type_strmap[value];
+}
+
+static const char * const handshake_auth_strmap[] = {
+	[0] = "unspec",
+	[1] = "unauth",
+	[2] = "psk",
+	[3] = "x509",
+};
+
+const char *handshake_auth_str(enum handshake_auth value)
+{
+	if (value < 0 || value >= (int)MNL_ARRAY_SIZE(handshake_auth_strmap))
+		return NULL;
+	return handshake_auth_strmap[value];
+}
+
+/* Policies */
+extern struct ynl_policy_nest handshake_x509_nest;
+extern struct ynl_policy_nest handshake_accept_nest;
+extern struct ynl_policy_nest handshake_done_nest;
+
+struct ynl_policy_attr handshake_x509_policy[HANDSHAKE_A_X509_MAX + 1] = {
+	[HANDSHAKE_A_X509_CERT] = { .name = "cert", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_X509_PRIVKEY] = { .name = "privkey", .type = YNL_PT_U32, },
+};
+
+struct ynl_policy_nest handshake_x509_nest = {
+	.max_attr = HANDSHAKE_A_X509_MAX,
+	.table = handshake_x509_policy,
+};
+
+struct ynl_policy_attr handshake_accept_policy[HANDSHAKE_A_ACCEPT_MAX + 1] = {
+	[HANDSHAKE_A_ACCEPT_SOCKFD] = { .name = "sockfd", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_HANDLER_CLASS] = { .name = "handler-class", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_MESSAGE_TYPE] = { .name = "message-type", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_TIMEOUT] = { .name = "timeout", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_AUTH_MODE] = { .name = "auth-mode", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_PEER_IDENTITY] = { .name = "peer-identity", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_ACCEPT_CERTIFICATE] = { .name = "certificate", .type = YNL_PT_NEST, .nest = &handshake_x509_nest, },
+	[HANDSHAKE_A_ACCEPT_PEERNAME] = { .name = "peername", .type = YNL_PT_NUL_STR, },
+};
+
+struct ynl_policy_nest handshake_accept_nest = {
+	.max_attr = HANDSHAKE_A_ACCEPT_MAX,
+	.table = handshake_accept_policy,
+};
+
+struct ynl_policy_attr handshake_done_policy[HANDSHAKE_A_DONE_MAX + 1] = {
+	[HANDSHAKE_A_DONE_STATUS] = { .name = "status", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_DONE_SOCKFD] = { .name = "sockfd", .type = YNL_PT_U32, },
+	[HANDSHAKE_A_DONE_REMOTE_AUTH] = { .name = "remote-auth", .type = YNL_PT_U32, },
+};
+
+struct ynl_policy_nest handshake_done_nest = {
+	.max_attr = HANDSHAKE_A_DONE_MAX,
+	.table = handshake_done_policy,
+};
+
+/* Common nested types */
+void handshake_x509_free(struct handshake_x509 *obj)
+{
+}
+
+int handshake_x509_parse(struct ynl_parse_arg *yarg,
+			 const struct nlattr *nested)
+{
+	struct handshake_x509 *dst = yarg->data;
+	const struct nlattr *attr;
+
+	mnl_attr_for_each_nested(attr, nested) {
+		if (mnl_attr_get_type(attr) == HANDSHAKE_A_X509_CERT) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.cert = 1;
+			dst->cert = mnl_attr_get_u32(attr);
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_X509_PRIVKEY) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.privkey = 1;
+			dst->privkey = mnl_attr_get_u32(attr);
+		}
+	}
+
+	return 0;
+}
+
+/* ============== HANDSHAKE_CMD_ACCEPT ============== */
+/* HANDSHAKE_CMD_ACCEPT - do */
+void handshake_accept_req_free(struct handshake_accept_req *req)
+{
+	free(req);
+}
+
+void handshake_accept_rsp_free(struct handshake_accept_rsp *rsp)
+{
+	unsigned int i;
+
+	free(rsp->peer_identity);
+	for (i = 0; i < rsp->n_certificate; i++)
+		handshake_x509_free(&rsp->certificate[i]);
+	free(rsp->certificate);
+	free(rsp->peername);
+	free(rsp);
+}
+
+int handshake_accept_rsp_parse(const struct nlmsghdr *nlh, void *data)
+{
+	struct ynl_parse_arg *yarg = data;
+	struct handshake_accept_rsp *dst;
+	unsigned int n_peer_identity = 0;
+	unsigned int n_certificate = 0;
+	const struct nlattr *attr;
+	struct ynl_parse_arg parg;
+	int i;
+
+	dst = yarg->data;
+	parg.ys = yarg->ys;
+
+	if (dst->certificate)
+		return ynl_error_parse(yarg, "attribute already present (accept.certificate)");
+	if (dst->peer_identity)
+		return ynl_error_parse(yarg, "attribute already present (accept.peer-identity)");
+
+	mnl_attr_for_each(attr, nlh, sizeof(struct genlmsghdr)) {
+		if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_SOCKFD) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.sockfd = 1;
+			dst->sockfd = mnl_attr_get_u32(attr);
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_MESSAGE_TYPE) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.message_type = 1;
+			dst->message_type = mnl_attr_get_u32(attr);
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_TIMEOUT) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.timeout = 1;
+			dst->timeout = mnl_attr_get_u32(attr);
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_AUTH_MODE) {
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+			dst->_present.auth_mode = 1;
+			dst->auth_mode = mnl_attr_get_u32(attr);
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_PEER_IDENTITY) {
+			n_peer_identity++;
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_CERTIFICATE) {
+			n_certificate++;
+		}
+		else if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_PEERNAME) {
+			unsigned int len;
+
+			if (ynl_attr_validate(yarg, attr))
+				return MNL_CB_ERROR;
+
+			len = strnlen(mnl_attr_get_str(attr), mnl_attr_get_payload_len(attr));
+			dst->_present.peername_len = len;
+			dst->peername = malloc(len + 1);
+			memcpy(dst->peername, mnl_attr_get_str(attr), len);
+			dst->peername[len] = 0;
+		}
+	}
+
+	if (n_certificate) {
+		dst->certificate = calloc(n_certificate, sizeof(*dst->certificate));
+		dst->n_certificate = n_certificate;
+		i = 0;
+		parg.rsp_policy = &handshake_x509_nest;
+		mnl_attr_for_each(attr, nlh, sizeof(struct genlmsghdr)) {
+			if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_CERTIFICATE) {
+				parg.data = &dst->certificate[i];
+				if (handshake_x509_parse(&parg, attr))
+					return MNL_CB_ERROR;
+				i++;
+			}
+		}
+	}
+	if (n_peer_identity) {
+		dst->peer_identity = calloc(n_peer_identity, sizeof(*dst->peer_identity));
+		dst->n_peer_identity = n_peer_identity;
+		i = 0;
+		mnl_attr_for_each(attr, nlh, sizeof(struct genlmsghdr)) {
+			if (mnl_attr_get_type(attr) == HANDSHAKE_A_ACCEPT_PEER_IDENTITY) {
+				dst->peer_identity[i] = mnl_attr_get_u32(attr);
+				i++;
+			}
+		}
+	}
+
+	return MNL_CB_OK;
+}
+
+struct handshake_accept_rsp *
+handshake_accept(struct ynl_sock *ys, struct handshake_accept_req *req)
+{
+	struct ynl_req_state yrs = { .yarg = { .ys = ys, }, };
+	struct handshake_accept_rsp *rsp;
+	struct nlmsghdr *nlh;
+	int err;
+
+	nlh = ynl_gemsg_start_req(ys, ys->family_id, HANDSHAKE_CMD_ACCEPT, 1);
+	ys->req_policy = &handshake_accept_nest;
+	yrs.yarg.rsp_policy = &handshake_accept_nest;
+
+	if (req->_present.handler_class)
+		mnl_attr_put_u32(nlh, HANDSHAKE_A_ACCEPT_HANDLER_CLASS, req->handler_class);
+
+	rsp = calloc(1, sizeof(*rsp));
+	yrs.yarg.data = rsp;
+	yrs.cb = handshake_accept_rsp_parse;
+	yrs.rsp_cmd = HANDSHAKE_CMD_ACCEPT;
+
+	err = ynl_exec(ys, nlh, &yrs);
+	if (err < 0)
+		goto err_free;
+
+	return rsp;
+
+err_free:
+	handshake_accept_rsp_free(rsp);
+	return NULL;
+}
+
+/* HANDSHAKE_CMD_ACCEPT - notify */
+void handshake_accept_ntf_free(struct handshake_accept_ntf *rsp)
+{
+	unsigned int i;
+
+	free(rsp->obj.peer_identity);
+	for (i = 0; i < rsp->obj.n_certificate; i++)
+		handshake_x509_free(&rsp->obj.certificate[i]);
+	free(rsp->obj.certificate);
+	free(rsp->obj.peername);
+	free(rsp);
+}
+
+/* ============== HANDSHAKE_CMD_DONE ============== */
+/* HANDSHAKE_CMD_DONE - do */
+void handshake_done_req_free(struct handshake_done_req *req)
+{
+	free(req->remote_auth);
+	free(req);
+}
+
+int handshake_done(struct ynl_sock *ys, struct handshake_done_req *req)
+{
+	struct nlmsghdr *nlh;
+	int err;
+
+	nlh = ynl_gemsg_start_req(ys, ys->family_id, HANDSHAKE_CMD_DONE, 1);
+	ys->req_policy = &handshake_done_nest;
+
+	if (req->_present.status)
+		mnl_attr_put_u32(nlh, HANDSHAKE_A_DONE_STATUS, req->status);
+	if (req->_present.sockfd)
+		mnl_attr_put_u32(nlh, HANDSHAKE_A_DONE_SOCKFD, req->sockfd);
+	for (unsigned int i = 0; i < req->n_remote_auth; i++)
+		mnl_attr_put_u32(nlh, HANDSHAKE_A_DONE_REMOTE_AUTH, req->remote_auth[i]);
+
+	err = ynl_exec(ys, nlh, NULL);
+	if (err < 0)
+		return -1;
+
+	return 0;
+}
+
+/* --------------- Common notification parsing --------------- */
+struct ynl_ntf_base_type *handshake_ntf_parse(struct ynl_sock *ys)
+{
+	struct ynl_parse_arg yarg = { .ys = ys, };
+	struct ynl_ntf_base_type *rsp;
+	struct genlmsghdr *genlh;
+	struct nlmsghdr *nlh;
+	mnl_cb_t parse;
+	int len, err;
+
+	len = mnl_socket_recvfrom(ys->sock, ys->rx_buf, MNL_SOCKET_BUFFER_SIZE);
+	if (len < (ssize_t)(sizeof(*nlh) + sizeof(*genlh)))
+		return NULL;
+
+	nlh = (struct nlmsghdr *)ys->rx_buf;
+	genlh = mnl_nlmsg_get_payload(nlh);
+
+	switch (genlh->cmd) {
+	case HANDSHAKE_CMD_READY:
+		rsp = calloc(1, sizeof(struct handshake_accept_ntf));
+		parse = handshake_accept_rsp_parse;
+		yarg.rsp_policy = &handshake_accept_nest;
+		rsp->free = (void *)handshake_accept_ntf_free;
+		break;
+	default:
+		ynl_error_unknown_notification(ys, genlh->cmd);
+		return NULL;
+	}
+
+	yarg.data = rsp->data;
+
+	err = mnl_cb_run2(ys->rx_buf, len, 0, 0, parse, &yarg,
+			 ynl_cb_array, NLMSG_MIN_TYPE);
+	if (err < 0)
+		goto err_free;
+
+	rsp->family = nlh->nlmsg_type;
+	rsp->cmd = genlh->cmd;
+	return rsp;
+
+err_free:
+	free(rsp);
+	return NULL;
+}
+
+static const struct ynl_ntf_info handshake_ntf_info[] =  {
+	[HANDSHAKE_CMD_READY] =  {
+		.alloc_sz	= sizeof(struct handshake_accept_ntf),
+		.cb		= handshake_accept_rsp_parse,
+		.policy		= &handshake_accept_nest,
+		.free		= (void *)handshake_accept_ntf_free,
+	},
+};
+
+const struct ynl_family ynl_handshake_family =  {
+	.name		= "handshake",
+	.ntf_info	= handshake_ntf_info,
+	.ntf_info_size	= MNL_ARRAY_SIZE(handshake_ntf_info),
+};
diff --git a/tools/net/ynl/generated/handshake-user.h b/tools/net/ynl/generated/handshake-user.h
new file mode 100644
index 000000000000..38e0844f2efd
--- /dev/null
+++ b/tools/net/ynl/generated/handshake-user.h
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/handshake.yaml */
+/* YNL-GEN user header */
+
+#ifndef _LINUX_HANDSHAKE_GEN_H
+#define _LINUX_HANDSHAKE_GEN_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <linux/types.h>
+#include <linux/handshake.h>
+
+struct ynl_sock;
+
+extern const struct ynl_family ynl_handshake_family;
+
+/* Enums */
+const char *handshake_op_str(int op);
+const char *handshake_handler_class_str(enum handshake_handler_class value);
+const char *handshake_msg_type_str(enum handshake_msg_type value);
+const char *handshake_auth_str(enum handshake_auth value);
+
+/* Common nested types */
+struct handshake_x509 {
+	struct {
+		__u32 cert:1;
+		__u32 privkey:1;
+	} _present;
+
+	__u32 cert;
+	__u32 privkey;
+};
+
+/* ============== HANDSHAKE_CMD_ACCEPT ============== */
+/* HANDSHAKE_CMD_ACCEPT - do */
+struct handshake_accept_req {
+	struct {
+		__u32 handler_class:1;
+	} _present;
+
+	enum handshake_handler_class handler_class;
+};
+
+static inline struct handshake_accept_req *handshake_accept_req_alloc(void)
+{
+	return calloc(1, sizeof(struct handshake_accept_req));
+}
+void handshake_accept_req_free(struct handshake_accept_req *req);
+
+static inline void
+handshake_accept_req_set_handler_class(struct handshake_accept_req *req,
+				       enum handshake_handler_class handler_class)
+{
+	req->_present.handler_class = 1;
+	req->handler_class = handler_class;
+}
+
+struct handshake_accept_rsp {
+	struct {
+		__u32 sockfd:1;
+		__u32 message_type:1;
+		__u32 timeout:1;
+		__u32 auth_mode:1;
+		__u32 peername_len;
+	} _present;
+
+	__u32 sockfd;
+	enum handshake_msg_type message_type;
+	__u32 timeout;
+	enum handshake_auth auth_mode;
+	unsigned int n_peer_identity;
+	__u32 *peer_identity;
+	unsigned int n_certificate;
+	struct handshake_x509 *certificate;
+	char *peername;
+};
+
+void handshake_accept_rsp_free(struct handshake_accept_rsp *rsp);
+
+/*
+ * Handler retrieves next queued handshake request
+ */
+struct handshake_accept_rsp *
+handshake_accept(struct ynl_sock *ys, struct handshake_accept_req *req);
+
+/* HANDSHAKE_CMD_ACCEPT - notify */
+struct handshake_accept_ntf {
+	__u16 family;
+	__u8 cmd;
+	struct ynl_ntf_base_type *next;
+	void (*free)(struct handshake_accept_ntf *ntf);
+	struct handshake_accept_rsp obj __attribute__ ((aligned (8)));
+};
+
+void handshake_accept_ntf_free(struct handshake_accept_ntf *rsp);
+
+/* ============== HANDSHAKE_CMD_DONE ============== */
+/* HANDSHAKE_CMD_DONE - do */
+struct handshake_done_req {
+	struct {
+		__u32 status:1;
+		__u32 sockfd:1;
+	} _present;
+
+	__u32 status;
+	__u32 sockfd;
+	unsigned int n_remote_auth;
+	__u32 *remote_auth;
+};
+
+static inline struct handshake_done_req *handshake_done_req_alloc(void)
+{
+	return calloc(1, sizeof(struct handshake_done_req));
+}
+void handshake_done_req_free(struct handshake_done_req *req);
+
+static inline void
+handshake_done_req_set_status(struct handshake_done_req *req, __u32 status)
+{
+	req->_present.status = 1;
+	req->status = status;
+}
+static inline void
+handshake_done_req_set_sockfd(struct handshake_done_req *req, __u32 sockfd)
+{
+	req->_present.sockfd = 1;
+	req->sockfd = sockfd;
+}
+static inline void
+__handshake_done_req_set_remote_auth(struct handshake_done_req *req,
+				     __u32 *remote_auth,
+				     unsigned int n_remote_auth)
+{
+	free(req->remote_auth);
+	req->remote_auth = remote_auth;
+	req->n_remote_auth = n_remote_auth;
+}
+
+/*
+ * Handler reports handshake completion
+ */
+int handshake_done(struct ynl_sock *ys, struct handshake_done_req *req);
+
+/* --------------- Common notification parsing --------------- */
+struct ynl_ntf_base_type *handshake_ntf_parse(struct ynl_sock *ys);
+
+#endif /* _LINUX_HANDSHAKE_GEN_H */
diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py
index 1e64c5c2a087..c07340715601 100755
--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -94,7 +94,10 @@ class Type(SpecAttr):
     def arg_member(self, ri):
         member = self._complex_member_type(ri)
         if member:
-            return [member + ' *' + self.c_name]
+            arg = [member + ' *' + self.c_name]
+            if self.presence_type() == 'count':
+                arg += ['unsigned int n_' + self.c_name]
+            return arg
         raise Exception(f"Struct member not implemented for class type {self.type}")
 
     def struct_member(self, ri):
@@ -188,9 +191,12 @@ class Type(SpecAttr):
                 code.append(presence + ' = 1;')
         code += self._setter_lines(ri, member, presence)
 
-        ri.cw.write_func('static inline void',
-                         f"{op_prefix(ri, direction, deref=deref)}_set_{'_'.join(ref)}",
-                         body=code,
+        func_name = f"{op_prefix(ri, direction, deref=deref)}_set_{'_'.join(ref)}"
+        free = bool([x for x in code if 'free(' in x])
+        alloc = bool([x for x in code if 'alloc(' in x])
+        if free and not alloc:
+            func_name = '__' + func_name
+        ri.cw.write_func('static inline void', func_name, body=code,
                          args=[f'{type_name(ri, direction, deref=deref)} *{var}'] + self.arg_member(ri))
 
 
@@ -444,6 +450,13 @@ class TypeMultiAttr(Type):
     def presence_type(self):
         return 'count'
 
+    def _mnl_type(self):
+        t = self.type
+        # mnl does not have a helper for signed types
+        if t[0] == 's':
+            t = 'u' + t[1:]
+        return t
+
     def _complex_member_type(self, ri):
         if 'type' not in self.attr or self.attr['type'] == 'nest':
             return f"struct {self.nested_render_name}"
@@ -457,9 +470,14 @@ class TypeMultiAttr(Type):
         return 'type' not in self.attr or self.attr['type'] == 'nest'
 
     def free(self, ri, var, ref):
-        if 'type' not in self.attr or self.attr['type'] == 'nest':
+        if self.attr['type'] in scalars:
+            ri.cw.p(f"free({var}->{ref}{self.c_name});")
+        elif 'type' not in self.attr or self.attr['type'] == 'nest':
             ri.cw.p(f"for (i = 0; i < {var}->{ref}n_{self.c_name}; i++)")
             ri.cw.p(f'{self.nested_render_name}_free(&{var}->{ref}{self.c_name}[i]);')
+            ri.cw.p(f"free({var}->{ref}{self.c_name});")
+        else:
+            raise Exception(f"Free of MultiAttr sub-type {self.attr['type']} not supported yet")
 
     def _attr_typol(self):
         if 'type' not in self.attr or self.attr['type'] == 'nest':
@@ -470,7 +488,26 @@ class TypeMultiAttr(Type):
             raise Exception(f"Sub-type {self.attr['type']} not supported yet")
 
     def _attr_get(self, ri, var):
-        return f'{var}->n_{self.c_name}++;', None, None
+        return f'n_{self.c_name}++;', None, None
+
+    def attr_put(self, ri, var):
+        if self.attr['type'] in scalars:
+            put_type = self._mnl_type()
+            ri.cw.p(f"for (unsigned int i = 0; i < {var}->n_{self.c_name}; i++)")
+            ri.cw.p(f"mnl_attr_put_{put_type}(nlh, {self.enum_name}, {var}->{self.c_name}[i]);")
+        elif 'type' not in self.attr or self.attr['type'] == 'nest':
+            ri.cw.p(f"for (unsigned int i = 0; i < {var}->n_{self.c_name}; i++)")
+            self._attr_put_line(ri, var, f"{self.nested_render_name}_put(nlh, " +
+                                f"{self.enum_name}, &{var}->{self.c_name}[i])")
+        else:
+            raise Exception(f"Put of MultiAttr sub-type {self.attr['type']} not supported yet")
+
+    def _setter_lines(self, ri, member, presence):
+        # For multi-attr we have a count, not presence, hack up the presence
+        presence = presence[:-(len('_present.') + len(self.c_name))] + "n_" + self.c_name
+        return [f"free({member});",
+                f"{member} = {self.c_name};",
+                f"{presence} = n_{self.c_name};"]
 
 
 class TypeArrayNest(Type):
@@ -1269,6 +1306,11 @@ def _multi_parse(ri, struct, init_lines, local_vars):
         local_vars.append('struct ynl_parse_arg parg;')
         init_lines.append('parg.ys = yarg->ys;')
 
+    all_multi = array_nests | multi_attrs
+
+    for anest in sorted(all_multi):
+        local_vars.append(f"unsigned int n_{struct[anest].c_name} = 0;")
+
     ri.cw.block_start()
     ri.cw.write_func_lvar(local_vars)
 
@@ -1279,6 +1321,11 @@ def _multi_parse(ri, struct, init_lines, local_vars):
     for arg in struct.inherited:
         ri.cw.p(f'dst->{arg} = {arg};')
 
+    for anest in sorted(all_multi):
+        aspec = struct[anest]
+        ri.cw.p(f"if (dst->{aspec.c_name})")
+        ri.cw.p(f'return ynl_error_parse(yarg, "attribute already present ({struct.attr_set.name}.{aspec.name})");')
+
     ri.cw.nl()
     ri.cw.block_start(line=iter_line)
 
@@ -1294,8 +1341,9 @@ def _multi_parse(ri, struct, init_lines, local_vars):
     for anest in sorted(array_nests):
         aspec = struct[anest]
 
-        ri.cw.block_start(line=f"if (dst->n_{aspec.c_name})")
-        ri.cw.p(f"dst->{aspec.c_name} = calloc(dst->n_{aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
+        ri.cw.block_start(line=f"if (n_{aspec.c_name})")
+        ri.cw.p(f"dst->{aspec.c_name} = calloc({aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
+        ri.cw.p(f"dst->n_{aspec.c_name} = n_{aspec.c_name};")
         ri.cw.p('i = 0;')
         ri.cw.p(f"parg.rsp_policy = &{aspec.nested_render_name}_nest;")
         ri.cw.block_start(line=f"mnl_attr_for_each_nested(attr, attr_{aspec.c_name})")
@@ -1309,8 +1357,9 @@ def _multi_parse(ri, struct, init_lines, local_vars):
 
     for anest in sorted(multi_attrs):
         aspec = struct[anest]
-        ri.cw.block_start(line=f"if (dst->n_{aspec.c_name})")
-        ri.cw.p(f"dst->{aspec.c_name} = calloc(dst->n_{aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
+        ri.cw.block_start(line=f"if (n_{aspec.c_name})")
+        ri.cw.p(f"dst->{aspec.c_name} = calloc(n_{aspec.c_name}, sizeof(*dst->{aspec.c_name}));")
+        ri.cw.p(f"dst->n_{aspec.c_name} = n_{aspec.c_name};")
         ri.cw.p('i = 0;')
         if 'nested-attributes' in aspec:
             ri.cw.p(f"parg.rsp_policy = &{aspec.nested_render_name}_nest;")