tipc/msg.c

   1 /*
   2  * msg.c        Messaging (netlink) helper functions.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Richard Alpe <richard.alpe@ericsson.com>
  10  */
  11
  12 #include <stdio.h>
  13 #include <time.h>
  14 #include <errno.h>
  15
  16 #include <linux/tipc_netlink.h>
  17 #include <linux/tipc.h>
  18 #include <linux/genetlink.h>
  19 #include <libmnl/libmnl.h>
  20
  21 #include "msg.h"
  22
  23 int parse_attrs(const struct nlattr *attr, void *data)
  24 {
  25         const struct nlattr **tb = data;
  26         int type = mnl_attr_get_type(attr);
  27
  28         tb[type] = attr;
  29
  30         return MNL_CB_OK;
  31 }
  32
  33 static int family_id_cb(const struct nlmsghdr *nlh, void *data)
  34 {
  35         struct nlattr *tb[CTRL_ATTR_MAX + 1] = {};
  36         struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);
  37         int *id = data;
  38
  39         mnl_attr_parse(nlh, sizeof(*genl), parse_attrs, tb);
  40         if (!tb[CTRL_ATTR_FAMILY_ID])
  41                 return MNL_CB_ERROR;
  42
  43         *id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
  44
  45         return MNL_CB_OK;
  46 }
  47
  48 static struct mnl_socket *msg_send(struct nlmsghdr *nlh)
  49 {
  50         int ret;
  51         struct mnl_socket *nl;
  52
  53         nl = mnl_socket_open(NETLINK_GENERIC);
  54         if (nl == NULL) {
  55                 perror("mnl_socket_open");
  56                 return NULL;
  57         }
  58
  59         ret = mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID);
  60         if (ret < 0) {
  61                 perror("mnl_socket_bind");
  62                 return NULL;
  63         }
  64
  65         ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
  66         if (ret < 0) {
  67                 perror("mnl_socket_send");
  68                 return NULL;
  69         }
  70
  71         return nl;
  72 }
  73
  74 static int msg_recv(struct mnl_socket *nl, mnl_cb_t callback, void *data, int seq)
  75 {
  76         int ret;
  77         unsigned int portid;
  78         char buf[MNL_SOCKET_BUFFER_SIZE];
  79
  80         portid = mnl_socket_get_portid(nl);
  81
  82         ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
  83         while (ret > 0) {
  84                 ret = mnl_cb_run(buf, ret, seq, portid, callback, data);
  85                 if (ret <= 0)
  86                         break;
  87                 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
  88         }
  89         if (ret == -1)
  90                 perror("error");
  91
  92         mnl_socket_close(nl);
  93
  94         return ret;
  95 }
  96
  97 static int msg_query(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
  98 {
  99         unsigned int seq;
 100         struct mnl_socket *nl;
 101
 102         seq = time(NULL);
 103         nlh->nlmsg_seq = seq;
 104
 105         nl = msg_send(nlh);
 106         if (!nl)
 107                 return -ENOTSUP;
 108
 109         return msg_recv(nl, callback, data, seq);
 110 }
 111
 112 static int get_family(void)
 113 {
 114         int err;
 115         int nl_family;
 116         struct nlmsghdr *nlh;
 117         struct genlmsghdr *genl;
 118         char buf[MNL_SOCKET_BUFFER_SIZE];
 119
 120         nlh = mnl_nlmsg_put_header(buf);
 121         nlh->nlmsg_type = GENL_ID_CTRL;
 122         nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
 123
 124         genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
 125         genl->cmd = CTRL_CMD_GETFAMILY;
 126         genl->version = 1;
 127
 128         mnl_attr_put_u16(nlh, CTRL_ATTR_FAMILY_ID, GENL_ID_CTRL);
 129         mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, TIPC_GENL_V2_NAME);
 130
 131         if ((err = msg_query(nlh, family_id_cb, &nl_family)))
 132                 return err;
 133
 134         return nl_family;
 135 }
 136
 137 int msg_doit(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
 138 {
 139         nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
 140         return msg_query(nlh, callback, data);
 141 }
 142
 143 int msg_dumpit(struct nlmsghdr *nlh, mnl_cb_t callback, void *data)
 144 {
 145         nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
 146         return msg_query(nlh, callback, data);
 147 }
 148
 149 struct nlmsghdr *msg_init(char *buf, int cmd)
 150 {
 151         int family;
 152         struct nlmsghdr *nlh;
 153         struct genlmsghdr *genl;
 154
 155         family = get_family();
 156         if (family <= 0) {
 157                 fprintf(stderr,
 158                         "Unable to get TIPC nl family id (module loaded?)\n");
 159                 return NULL;
 160         }
 161
 162         nlh = mnl_nlmsg_put_header(buf);
 163         nlh->nlmsg_type = family;
 164
 165         genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
 166         genl->cmd = cmd;
 167         genl->version = 1;
 168
 169         return nlh;
 170 }