tools: ynl: stop using mnl socket helpers

Most libmnl socket helpers can be replaced by direct calls to
the underlying libc API. We need portid, the netlink manpage
suggests we bind() address of zero.

Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-14-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -35,6 +35,8 @@ enum ynl_parse_result {
 	YNL_PARSE_CB_OK = 1,
 };
 
+#define YNL_SOCKET_BUFFER_SIZE		(1 << 17)
+
 #define YNL_ARRAY_SIZE(array)	(sizeof(array) ?			\
 				 sizeof(array) / sizeof(array[0]) : 0)
 

tools/net/ynl/lib/ynl.c

@@ -3,10 +3,12 @@
 #include <poll.h>
 #include <string.h>
 #include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
 #include <linux/types.h>
-
 #include <libmnl/libmnl.h>
 #include <linux/genetlink.h>
+#include <sys/socket.h>
 
 #include "ynl.h"
 
@@ -464,7 +466,7 @@ static int ynl_sock_read_msgs(struct ynl_parse_arg *yarg, ynl_parse_cb_t cb)
 	ssize_t len, rem;
 	int ret;
 
-	len = mnl_socket_recvfrom(ys->sock, ys->rx_buf, MNL_SOCKET_BUFFER_SIZE);
+	len = recv(ys->socket, ys->rx_buf, YNL_SOCKET_BUFFER_SIZE, 0);
 	if (len < 0)
 		return len;
 
@@ -596,7 +598,7 @@ static int ynl_sock_read_family(struct ynl_sock *ys, const char *family_name)
 	nlh = ynl_gemsg_start_req(ys, GENL_ID_CTRL, CTRL_CMD_GETFAMILY, 1);
 	ynl_attr_put_str(nlh, CTRL_ATTR_FAMILY_NAME, family_name);
 
-	err = mnl_socket_sendto(ys->sock, nlh, nlh->nlmsg_len);
+	err = send(ys->socket, nlh, nlh->nlmsg_len, 0);
 	if (err < 0) {
 		perr(ys, "failed to request socket family info");
 		return err;
@@ -621,38 +623,54 @@ static int ynl_sock_read_family(struct ynl_sock *ys, const char *family_name)
 struct ynl_sock *
 ynl_sock_create(const struct ynl_family *yf, struct ynl_error *yse)
 {
+	struct sockaddr_nl addr;
 	struct ynl_sock *ys;
+	socklen_t addrlen;
 	int one = 1;
 
-	ys = malloc(sizeof(*ys) + 2 * MNL_SOCKET_BUFFER_SIZE);
+	ys = malloc(sizeof(*ys) + 2 * YNL_SOCKET_BUFFER_SIZE);
 	if (!ys)
 		return NULL;
 	memset(ys, 0, sizeof(*ys));
 
 	ys->family = yf;
 	ys->tx_buf = &ys->raw_buf[0];
-	ys->rx_buf = &ys->raw_buf[MNL_SOCKET_BUFFER_SIZE];
+	ys->rx_buf = &ys->raw_buf[YNL_SOCKET_BUFFER_SIZE];
 	ys->ntf_last_next = &ys->ntf_first;
 
-	ys->sock = mnl_socket_open(NETLINK_GENERIC);
-	if (!ys->sock) {
+	ys->socket = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+	if (ys->socket < 0) {
 		__perr(yse, "failed to create a netlink socket");
 		goto err_free_sock;
 	}
 
-	if (mnl_socket_setsockopt(ys->sock, NETLINK_CAP_ACK,
-				  &one, sizeof(one))) {
+	if (setsockopt(ys->socket, SOL_NETLINK, NETLINK_CAP_ACK,
+		       &one, sizeof(one))) {
 		__perr(yse, "failed to enable netlink ACK");
 		goto err_close_sock;
 	}
-	if (mnl_socket_setsockopt(ys->sock, NETLINK_EXT_ACK,
-				  &one, sizeof(one))) {
+	if (setsockopt(ys->socket, SOL_NETLINK, NETLINK_EXT_ACK,
+		       &one, sizeof(one))) {
 		__perr(yse, "failed to enable netlink ext ACK");
 		goto err_close_sock;
 	}
 
+	memset(&addr, 0, sizeof(addr));
+	addr.nl_family = AF_NETLINK;
+	if (bind(ys->socket, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		__perr(yse, "unable to bind to a socket address");
+		goto err_close_sock;;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addrlen = sizeof(addr);
+	if (getsockname(ys->socket, (struct sockaddr *)&addr, &addrlen) < 0) {
+		__perr(yse, "unable to read socket address");
+		goto err_close_sock;;
+	}
+	ys->portid = addr.nl_pid;
 	ys->seq = random();
-	ys->portid = mnl_socket_get_portid(ys->sock);
+
 
 	if (ynl_sock_read_family(ys, yf->name)) {
 		if (yse)
@@ -663,7 +681,7 @@ ynl_sock_create(const struct ynl_family *yf, struct ynl_error *yse)
 	return ys;
 
 err_close_sock:
-	mnl_socket_close(ys->sock);
+	close(ys->socket);
 err_free_sock:
 	free(ys);
 	return NULL;
@@ -673,7 +691,7 @@ void ynl_sock_destroy(struct ynl_sock *ys)
 {
 	struct ynl_ntf_base_type *ntf;
 
-	mnl_socket_close(ys->sock);
+	close(ys->socket);
 	while ((ntf = ynl_ntf_dequeue(ys)))
 		ynl_ntf_free(ntf);
 	free(ys->mcast_groups);
@@ -700,9 +718,9 @@ int ynl_subscribe(struct ynl_sock *ys, const char *grp_name)
 		return -1;
 	}
 
-	err = mnl_socket_setsockopt(ys->sock, NETLINK_ADD_MEMBERSHIP,
-				    &ys->mcast_groups[i].id,
-				    sizeof(ys->mcast_groups[i].id));
+	err = setsockopt(ys->socket, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
+			 &ys->mcast_groups[i].id,
+			 sizeof(ys->mcast_groups[i].id));
 	if (err < 0) {
 		perr(ys, "Subscribing to multicast group failed");
 		return -1;
@@ -713,7 +731,7 @@ int ynl_subscribe(struct ynl_sock *ys, const char *grp_name)
 
 int ynl_socket_get_fd(struct ynl_sock *ys)
 {
-	return mnl_socket_get_fd(ys->sock);
+	return ys->socket;
 }
 
 struct ynl_ntf_base_type *ynl_ntf_dequeue(struct ynl_sock *ys)
@@ -785,7 +803,7 @@ int ynl_ntf_check(struct ynl_sock *ys)
 		 */
 		struct pollfd pfd = { };
 
-		pfd.fd = mnl_socket_get_fd(ys->sock);
+		pfd.fd = ys->socket;
 		pfd.events = POLLIN;
 		err = poll(&pfd, 1, 1);
 		if (err < 1)
@@ -851,7 +869,7 @@ int ynl_exec(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
 {
 	int err;
 
-	err = mnl_socket_sendto(ys->sock, req_nlh, req_nlh->nlmsg_len);
+	err = send(ys->socket, req_nlh, req_nlh->nlmsg_len, 0);
 	if (err < 0)
 		return err;
 
@@ -904,7 +922,7 @@ int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
 {
 	int err;
 
-	err = mnl_socket_sendto(ys->sock, req_nlh, req_nlh->nlmsg_len);
+	err = send(ys->socket, req_nlh, req_nlh->nlmsg_len, 0);
 	if (err < 0)
 		return err;
 

tools/net/ynl/lib/ynl.h

@@ -59,7 +59,7 @@ struct ynl_sock {
 
 /* private: */
 	const struct ynl_family *family;
-	struct mnl_socket *sock;
+	int socket;
 	__u32 seq;
 	__u32 portid;
 	__u16 family_id;