genl-family-get.c

/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

#include <libmnl/libmnl.h>
#include <linux/genetlink.h>

static int parse_mc_grps_cb(const struct nlattr *attr, void *data)
{
        const struct nlattr **tb = data;
        int type = mnl_attr_get_type(attr);

        /* skip unsupported attribute in user-space */
        if (mnl_attr_type_valid(attr, CTRL_ATTR_MCAST_GRP_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case CTRL_ATTR_MCAST_GRP_ID:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        case CTRL_ATTR_MCAST_GRP_NAME:
                if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        }
        tb[type] = attr;
        return MNL_CB_OK;
}

static void parse_genl_mc_grps(struct nlattr *nested)
{
        struct nlattr *pos;

        mnl_attr_for_each_nested(pos, nested) {
                struct nlattr *tb[CTRL_ATTR_MCAST_GRP_MAX+1] = {};

                mnl_attr_parse_nested(pos, parse_mc_grps_cb, tb);
                if (tb[CTRL_ATTR_MCAST_GRP_ID]) {
                        printf("id-0x%x ",
                                mnl_attr_get_u32(tb[CTRL_ATTR_MCAST_GRP_ID]));
                }
                if (tb[CTRL_ATTR_MCAST_GRP_NAME]) {
                        printf("name: %s ",
                                mnl_attr_get_str(tb[CTRL_ATTR_MCAST_GRP_NAME]));
                }
                printf("\n");
        }
}

static int parse_family_ops_cb(const struct nlattr *attr, void *data)
{
        const struct nlattr **tb = data;
        int type = mnl_attr_get_type(attr);

        if (mnl_attr_type_valid(attr, CTRL_ATTR_OP_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case CTRL_ATTR_OP_ID:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        case CTRL_ATTR_OP_MAX:
                break;
        default:
                return MNL_CB_OK;
        }
        tb[type] = attr;
        return MNL_CB_OK;
}

static void parse_genl_family_ops(struct nlattr *nested)
{
        struct nlattr *pos;

        mnl_attr_for_each_nested(pos, nested) {
                struct nlattr *tb[CTRL_ATTR_OP_MAX+1] = {};

                mnl_attr_parse_nested(pos, parse_family_ops_cb, tb);
                if (tb[CTRL_ATTR_OP_ID]) {
                        printf("id-0x%x ",
                                mnl_attr_get_u32(tb[CTRL_ATTR_OP_ID]));
                }
                if (tb[CTRL_ATTR_OP_MAX]) {
                        printf("flags ");
                }
                printf("\n");
        }
}

static int data_attr_cb(const struct nlattr *attr, void *data)
{
        const struct nlattr **tb = data;
        int type = mnl_attr_get_type(attr);

        if (mnl_attr_type_valid(attr, CTRL_ATTR_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case CTRL_ATTR_FAMILY_NAME:
                if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        case CTRL_ATTR_FAMILY_ID:
                if (mnl_attr_validate(attr, MNL_TYPE_U16) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        case CTRL_ATTR_VERSION:
        case CTRL_ATTR_HDRSIZE:
        case CTRL_ATTR_MAXATTR:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        case CTRL_ATTR_OPS:
        case CTRL_ATTR_MCAST_GROUPS:
                if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 0) {
                        perror("mnl_attr_validate");
                        return MNL_CB_ERROR;
                }
                break;
        }
        tb[type] = attr;
        return MNL_CB_OK;
}

static int data_cb(const struct nlmsghdr *nlh, void *data)
{
        struct nlattr *tb[CTRL_ATTR_MAX+1] = {};
        struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);

        mnl_attr_parse(nlh, sizeof(*genl), data_attr_cb, tb);
        if (tb[CTRL_ATTR_FAMILY_NAME]) {
                printf("name=%s\t",
                        mnl_attr_get_str(tb[CTRL_ATTR_FAMILY_NAME]));
        }
        if (tb[CTRL_ATTR_FAMILY_ID]) {
                printf("id=%u\t",
                        mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]));
        }
        if (tb[CTRL_ATTR_VERSION]) {
                printf("version=%u\t",
                        mnl_attr_get_u32(tb[CTRL_ATTR_VERSION]));
        }
        if (tb[CTRL_ATTR_HDRSIZE]) {
                printf("hdrsize=%u\t",
                        mnl_attr_get_u32(tb[CTRL_ATTR_HDRSIZE]));
        }
        if (tb[CTRL_ATTR_MAXATTR]) {
                printf("maxattr=%u\t",
                        mnl_attr_get_u32(tb[CTRL_ATTR_MAXATTR]));
        }
        printf("\n");
        if (tb[CTRL_ATTR_OPS]) {
                printf("ops:\n");
                parse_genl_family_ops(tb[CTRL_ATTR_OPS]);
        }
        if (tb[CTRL_ATTR_MCAST_GROUPS]) {
                printf("grps:\n");
                parse_genl_mc_grps(tb[CTRL_ATTR_MCAST_GROUPS]);
        }
        printf("\n");
        return MNL_CB_OK;
}

int main(int argc, char *argv[])
{
        struct mnl_socket *nl;
        char buf[MNL_SOCKET_BUFFER_SIZE];
        struct nlmsghdr *nlh;
        struct genlmsghdr *genl;
        int ret;
        unsigned int seq, portid;

        if (argc > 2) {
                printf("%s [family name]\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        nlh = mnl_nlmsg_put_header(buf);
        nlh->nlmsg_type = GENL_ID_CTRL;
        nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
        nlh->nlmsg_seq = seq = time(NULL);

        genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
        genl->cmd = CTRL_CMD_GETFAMILY;
        genl->version = 1;

        mnl_attr_put_u32(nlh, CTRL_ATTR_FAMILY_ID, GENL_ID_CTRL);
        if (argc >= 2)
                mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, argv[1]);
        else
                nlh->nlmsg_flags |= NLM_F_DUMP;

        nl = mnl_socket_open(NETLINK_GENERIC);
        if (nl == NULL) {
                perror("mnl_socket_open");
                exit(EXIT_FAILURE);
        }

        if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
                perror("mnl_socket_bind");
                exit(EXIT_FAILURE);
        }
        portid = mnl_socket_get_portid(nl);

        if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
                perror("mnl_socket_sendto");
                exit(EXIT_FAILURE);
        }

        ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
        while (ret > 0) {
                ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
                if (ret <= 0)
                        break;
                ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
        }
        if (ret == -1) {
                perror("error");
                exit(EXIT_FAILURE);
        }

        mnl_socket_close(nl);

        return 0;
}