nlmsg.c

/*
 * (C) 2015 by Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <arpa/inet.h>
#include <libmnl/libmnl.h>
#include <libnetfilter_log/libnetfilter_log.h>
#include <errno.h>
#include "internal.h"

struct nlmsghdr *
nflog_nlmsg_put_header(char *buf, uint8_t type, uint8_t family, uint16_t qnum)
{
        struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
        struct nfgenmsg *nfg;

        nlh->nlmsg_type = (NFNL_SUBSYS_ULOG << 8) | type;
        nlh->nlmsg_flags = NLM_F_REQUEST;

        nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
        nfg->nfgen_family = family;
        nfg->version = NFNETLINK_V0;
        nfg->res_id = htons(qnum);

        return nlh;
}

int nflog_attr_put_cfg_mode(struct nlmsghdr *nlh, uint8_t mode, uint32_t range)
{
        struct nfulnl_msg_config_mode nfmode = {
                .copy_mode = mode,
                .copy_range = htonl(range)
        };

        mnl_attr_put(nlh, NFULA_CFG_MODE, sizeof(nfmode), &nfmode);

        /* it may returns -1 in future */
        return 0;
}

int nflog_attr_put_cfg_cmd(struct nlmsghdr *nlh, uint8_t cmd)
{
        struct nfulnl_msg_config_cmd nfcmd = {
                .command = cmd
        };

        mnl_attr_put(nlh, NFULA_CFG_CMD, sizeof(nfcmd), &nfcmd);

        /* it may returns -1 in future */
        return 0;
}

static int nflog_parse_attr_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, NFULA_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case NFULA_HWTYPE:              /* hardware type */
        case NFULA_HWLEN:               /* hardware header length */
                if (mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
                        return MNL_CB_ERROR;
                break;
        case NFULA_MARK:                /* __u32 nfmark */
        case NFULA_IFINDEX_INDEV:       /* __u32 ifindex */
        case NFULA_IFINDEX_OUTDEV:      /* __u32 ifindex */
        case NFULA_IFINDEX_PHYSINDEV:   /* __u32 ifindex */
        case NFULA_IFINDEX_PHYSOUTDEV:  /* __u32 ifindex */
        case NFULA_UID:                 /* user id of socket */
        case NFULA_SEQ:                 /* instance-local sequence number */
        case NFULA_SEQ_GLOBAL:          /* global sequence number */
        case NFULA_GID:                 /* group id of socket */
        case NFULA_CT_INFO:             /* enum ip_conntrack_info */
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        return MNL_CB_ERROR;
                break;
        case NFULA_PACKET_HDR:
                if (mnl_attr_validate2(attr, MNL_TYPE_UNSPEC,
                    sizeof(struct nfulnl_msg_packet_hdr)) < 0) {
                        return MNL_CB_ERROR;
                }
                break;
        case NFULA_TIMESTAMP:           /* nfulnl_msg_packet_timestamp */
                if (mnl_attr_validate2(attr, MNL_TYPE_UNSPEC,
                    sizeof(struct nfulnl_msg_packet_timestamp)) < 0) {
                        return MNL_CB_ERROR;
                }
                break;
        case NFULA_HWADDR:              /* nfulnl_msg_packet_hw */
                if (mnl_attr_validate2(attr, MNL_TYPE_UNSPEC,
                    sizeof(struct nfulnl_msg_packet_hw)) < 0) {
                        return MNL_CB_ERROR;
                }
                break;
        case NFULA_PREFIX:              /* string prefix */
                if (mnl_attr_validate(attr, MNL_TYPE_NUL_STRING) < 0)
                        return MNL_CB_ERROR;
                break;
        case NFULA_HWHEADER:            /* hardware header */
        case NFULA_PAYLOAD:             /* opaque data payload */
        case NFULA_CT:                  /* nf_conntrack_netlink.h */
                break;
        }
        tb[type] = attr;
        return MNL_CB_OK;
}

int nflog_nlmsg_parse(const struct nlmsghdr *nlh, struct nlattr **attr)
{
        return mnl_attr_parse(nlh, sizeof(struct nfgenmsg),
                              nflog_parse_attr_cb, attr);
}

int nflog_nlmsg_snprintf(char *buf, size_t bufsiz, const struct nlmsghdr *nlh,
                         struct nlattr **attr, enum nflog_output_type type,
                         uint32_t flags)
{
        /* This is a hack to re-use the existing old API code. */
        struct nflog_data nfad = {
                .nfa    = (struct nfattr **)&attr[1],
        };
        int ret;

        switch (type) {
        case NFLOG_OUTPUT_XML:
                ret = nflog_snprintf_xml(buf, bufsiz, &nfad, flags);
                break;
        default:
                ret = -1;
                errno = EOPNOTSUPP;
                break;
        }
        return ret;
}