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/* SPDX-License-Identifier: GPL-2.0 */
/*
* libgenl.c GENL library
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/genetlink.h>
#include "libgenl.h"
static int genl_parse_getfamily(struct nlmsghdr *nlh)
{
struct rtattr *tb[CTRL_ATTR_MAX + 1];
struct genlmsghdr *ghdr = NLMSG_DATA(nlh);
int len = nlh->nlmsg_len;
struct rtattr *attrs;
if (nlh->nlmsg_type != GENL_ID_CTRL) {
fprintf(stderr, "Not a controller message, nlmsg_len=%d "
"nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type);
return -1;
}
len -= NLMSG_LENGTH(GENL_HDRLEN);
if (len < 0) {
fprintf(stderr, "wrong controller message len %d\n", len);
return -1;
}
if (ghdr->cmd != CTRL_CMD_NEWFAMILY) {
fprintf(stderr, "Unknown controller command %d\n", ghdr->cmd);
return -1;
}
attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
if (tb[CTRL_ATTR_FAMILY_ID] == NULL) {
fprintf(stderr, "Missing family id TLV\n");
return -1;
}
return rta_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);
}
int genl_resolve_family(struct rtnl_handle *grth, const char *family)
{
GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
NLM_F_REQUEST);
struct nlmsghdr *answer;
int fnum;
addattr_l(&req.n, sizeof(req), CTRL_ATTR_FAMILY_NAME,
family, strlen(family) + 1);
if (rtnl_talk(grth, &req.n, &answer) < 0) {
fprintf(stderr, "Error talking to the kernel\n");
return -2;
}
fnum = genl_parse_getfamily(answer);
free(answer);
return fnum;
}
static int genl_parse_grps(struct rtattr *attr, const char *name, unsigned int *id)
{
const struct rtattr *pos;
rtattr_for_each_nested(pos, attr) {
struct rtattr *tb[CTRL_ATTR_MCAST_GRP_MAX + 1];
parse_rtattr_nested(tb, CTRL_ATTR_MCAST_GRP_MAX, pos);
if (tb[CTRL_ATTR_MCAST_GRP_NAME] && tb[CTRL_ATTR_MCAST_GRP_ID]) {
if (strcmp(name, rta_getattr_str(tb[CTRL_ATTR_MCAST_GRP_NAME])) == 0) {
*id = rta_getattr_u32(tb[CTRL_ATTR_MCAST_GRP_ID]);
return 0;
}
}
}
errno = ENOENT;
return -1;
}
int genl_add_mcast_grp(struct rtnl_handle *grth, __u16 fnum, const char *group)
{
GENL_REQUEST(req, 1024, GENL_ID_CTRL, 0, 0, CTRL_CMD_GETFAMILY,
NLM_F_REQUEST);
struct rtattr *tb[CTRL_ATTR_MAX + 1];
struct nlmsghdr *answer = NULL;
struct genlmsghdr *ghdr;
struct rtattr *attrs;
int len, ret = -1;
unsigned int id;
addattr16(&req.n, sizeof(req), CTRL_ATTR_FAMILY_ID, fnum);
if (rtnl_talk(grth, &req.n, &answer) < 0) {
fprintf(stderr, "Error talking to the kernel\n");
return -2;
}
ghdr = NLMSG_DATA(answer);
len = answer->nlmsg_len;
if (answer->nlmsg_type != GENL_ID_CTRL) {
errno = EINVAL;
goto err_free;
}
len -= NLMSG_LENGTH(GENL_HDRLEN);
if (len < 0) {
errno = EINVAL;
goto err_free;
}
attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);
if (tb[CTRL_ATTR_MCAST_GROUPS] == NULL) {
errno = ENOENT;
fprintf(stderr, "Missing mcast groups TLV\n");
goto err_free;
}
if (genl_parse_grps(tb[CTRL_ATTR_MCAST_GROUPS], group, &id) < 0)
goto err_free;
ret = rtnl_add_nl_group(grth, id);
err_free:
free(answer);
return ret;
}
int genl_init_handle(struct rtnl_handle *grth, const char *family,
int *genl_family)
{
if (*genl_family >= 0)
return 0;
if (rtnl_open_byproto(grth, 0, NETLINK_GENERIC) < 0) {
fprintf(stderr, "Cannot open generic netlink socket\n");
return -1;
}
*genl_family = genl_resolve_family(grth, family);
if (*genl_family < 0)
return -1;
return 0;
}
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