[iproute2-next,v5,3/5] utils: Add generic socket helpers

diff --git a/include/mnl_utils.h b/include/mnl_utils.h
index fa826ef1..9e7d6879 100644
--- a/include/mnl_utils.h
+++ b/include/mnl_utils.h
@@ -2,6 +2,22 @@ 
 #ifndef __MNL_UTILS_H__
 #define __MNL_UTILS_H__ 1
 
+struct mnlu_gen_socket {
+	struct mnl_socket *nl;
+	char *buf;
+	uint32_t family;
+	unsigned int seq;
+	uint8_t version;
+};
+
+int mnlu_gen_socket_open(struct mnlu_gen_socket *nlg, const char *family_name,
+			 uint8_t version);
+void mnlu_gen_socket_close(struct mnlu_gen_socket *nlg);
+struct nlmsghdr *mnlu_gen_socket_cmd_prepare(struct mnlu_gen_socket *nlg,
+					     uint8_t cmd, uint16_t flags);
+int mnlu_gen_socket_sndrcv(struct mnlu_gen_socket *nlg, const struct nlmsghdr *nlh,
+			   mnl_cb_t data_cb, void *data);
+
 struct mnl_socket *mnlu_socket_open(int bus);
 struct nlmsghdr *mnlu_msg_prepare(void *buf, uint32_t nlmsg_type, uint16_t flags,
 				  void *extra_header, size_t extra_header_size);
diff --git a/lib/mnl_utils.c b/lib/mnl_utils.c
index 46384ff8..4f699455 100644
--- a/lib/mnl_utils.c
+++ b/lib/mnl_utils.c
@@ -7,6 +7,7 @@ 
 #include <string.h>
 #include <time.h>
 #include <libmnl/libmnl.h>
+#include <linux/genetlink.h>
 
 #include "libnetlink.h"
 #include "mnl_utils.h"
@@ -108,3 +109,123 @@  int mnlu_socket_recv_run(struct mnl_socket *nl, unsigned int seq, void *buf, siz
 
 	return err;
 }
+
+static int get_family_id_attr_cb(const struct nlattr *attr, void *data)
+{
+	int type = mnl_attr_get_type(attr);
+	const struct nlattr **tb = data;
+
+	if (mnl_attr_type_valid(attr, CTRL_ATTR_MAX) < 0)
+		return MNL_CB_ERROR;
+
+	if (type == CTRL_ATTR_FAMILY_ID &&
+	    mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
+		return MNL_CB_ERROR;
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static int get_family_id_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);
+	struct nlattr *tb[CTRL_ATTR_MAX + 1] = {};
+	uint32_t *p_id = data;
+
+	mnl_attr_parse(nlh, sizeof(*genl), get_family_id_attr_cb, tb);
+	if (!tb[CTRL_ATTR_FAMILY_ID])
+		return MNL_CB_ERROR;
+	*p_id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
+	return MNL_CB_OK;
+}
+
+static int family_get(struct mnlu_gen_socket *nlg, const char *family_name)
+{
+	struct genlmsghdr hdr = {};
+	struct nlmsghdr *nlh;
+	int err;
+
+	hdr.cmd = CTRL_CMD_GETFAMILY;
+	hdr.version = 0x1;
+
+	nlh = mnlu_msg_prepare(nlg->buf, GENL_ID_CTRL,
+			       NLM_F_REQUEST | NLM_F_ACK,
+			       &hdr, sizeof(hdr));
+
+	mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, family_name);
+
+	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
+	if (err < 0)
+		return err;
+
+	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf,
+				   MNL_SOCKET_BUFFER_SIZE,
+				   get_family_id_cb, &nlg->family);
+	return err;
+}
+
+int mnlu_gen_socket_open(struct mnlu_gen_socket *nlg, const char *family_name,
+			 uint8_t version)
+{
+	int err;
+
+	nlg->buf = malloc(MNL_SOCKET_BUFFER_SIZE);
+	if (!nlg->buf)
+		goto err_buf_alloc;
+
+	nlg->nl = mnlu_socket_open(NETLINK_GENERIC);
+	if (!nlg->nl)
+		goto err_socket_open;
+
+	err = family_get(nlg, family_name);
+	if (err)
+		goto err_socket;
+
+	return 0;
+
+err_socket:
+	mnl_socket_close(nlg->nl);
+err_socket_open:
+	free(nlg->buf);
+err_buf_alloc:
+	return -1;
+}
+
+void mnlu_gen_socket_close(struct mnlu_gen_socket *nlg)
+{
+	mnl_socket_close(nlg->nl);
+	free(nlg->buf);
+}
+
+struct nlmsghdr *mnlu_gen_socket_cmd_prepare(struct mnlu_gen_socket *nlg,
+					     uint8_t cmd, uint16_t flags)
+{
+	struct genlmsghdr hdr = {};
+	struct nlmsghdr *nlh;
+
+	hdr.cmd = cmd;
+	hdr.version = nlg->version;
+	nlh = mnlu_msg_prepare(nlg->buf, nlg->family, flags, &hdr, sizeof(hdr));
+	nlg->seq = nlh->nlmsg_seq;
+	return nlh;
+}
+
+int mnlu_gen_socket_sndrcv(struct mnlu_gen_socket *nlg, const struct nlmsghdr *nlh,
+			   mnl_cb_t data_cb, void *data)
+{
+	int err;
+
+	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
+	if (err < 0) {
+		perror("Failed to send data");
+		return -errno;
+	}
+
+	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf,
+				   MNL_SOCKET_BUFFER_SIZE,
+				   data_cb, data);
+	if (err < 0) {
+		fprintf(stderr, "kernel answers: %s\n", strerror(errno));
+		return -errno;
+	}
+	return 0;
+}