/*
 * libnetlink.c        RTnetlink service routines.
 *
 *             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.
 *
 * Authors:    Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <fcntl.h>
#include <net/if_arp.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/uio.h>

#include "libnetlink.h"

void rtnl_close(struct rtnl_handle *rth)
{
       close(rth->fd);
}

int rtnl_open_byproto(struct rtnl_handle *rth, unsigned subscriptions,
                     int protocol)
{
       socklen_t addr_len;
       int sndbuf = 32768;
       int rcvbuf = 32768;

       memset(rth, 0, sizeof(*rth));

       rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
       if (rth->fd < 0) {
               perror("Cannot open netlink socket");
               return -1;
       }

       if (setsockopt(rth->fd,SOL_SOCKET,SO_SNDBUF,&sndbuf,sizeof(sndbuf)) < 0) {
               perror("SO_SNDBUF");
               return -1;
       }

       if (setsockopt(rth->fd,SOL_SOCKET,SO_RCVBUF,&rcvbuf,sizeof(rcvbuf)) < 0) {
               perror("SO_RCVBUF");
               return -1;
       }

       memset(&rth->local, 0, sizeof(rth->local));
       rth->local.nl_family = AF_NETLINK;
       rth->local.nl_groups = subscriptions;

       if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) {
               perror("Cannot bind netlink socket");
               return -1;
       }
       addr_len = sizeof(rth->local);
       if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) {
               perror("Cannot getsockname");
               return -1;
       }
       if (addr_len != sizeof(rth->local)) {
               fprintf(stderr, "Wrong address length %d\n", addr_len);
               return -1;
       }
       if (rth->local.nl_family != AF_NETLINK) {
               fprintf(stderr, "Wrong address family %d\n", rth->local.nl_family);
               return -1;
       }
       rth->seq = time(NULL);
       return 0;
}

int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
{
       return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
}

int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
{
       struct {
               struct nlmsghdr nlh;
               struct rtgenmsg g;
       } req;
       struct sockaddr_nl nladdr;

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;

       memset(&req, 0, sizeof(req));
       req.nlh.nlmsg_len = sizeof(req);
       req.nlh.nlmsg_type = type;
       req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
       req.nlh.nlmsg_pid = 0;
       req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
       req.g.rtgen_family = family;

       return sendto(rth->fd, (void*)&req, sizeof(req), 0,
                     (struct sockaddr*)&nladdr, sizeof(nladdr));
}

int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
{
       struct sockaddr_nl nladdr;

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;

       return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
}

int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
{
       struct nlmsghdr nlh;
       struct sockaddr_nl nladdr;
       struct iovec iov[2] = {
               { .iov_base = &nlh, .iov_len = sizeof(nlh) },
               { .iov_base = req, .iov_len = len }
       };
       struct msghdr msg = {
               .msg_name = &nladdr,
               .msg_namelen =  sizeof(nladdr),
               .msg_iov = iov,
               .msg_iovlen = 2,
       };

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;

       nlh.nlmsg_len = NLMSG_LENGTH(len);
       nlh.nlmsg_type = type;
       nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
       nlh.nlmsg_pid = 0;
       nlh.nlmsg_seq = rth->dump = ++rth->seq;

       return sendmsg(rth->fd, &msg, 0);
}

int rtnl_dump_filter(struct rtnl_handle *rth,
                    rtnl_filter_t filter,
                    void *arg1,
                    rtnl_filter_t junk,
                    void *arg2)
{
       struct sockaddr_nl nladdr;
       struct iovec iov;
       struct msghdr msg = {
               .msg_name = &nladdr,
               .msg_namelen = sizeof(nladdr),
               .msg_iov = &iov,
               .msg_iovlen = 1,
       };
       char buf[16384];

       iov.iov_base = buf;
       while (1) {
               int status;
               struct nlmsghdr *h;

               iov.iov_len = sizeof(buf);
               status = recvmsg(rth->fd, &msg, 0);

               if (status < 0) {
                       if (errno == EINTR)
                               continue;
                       perror("OVERRUN");
                       continue;
               }

               if (status == 0) {
                       fprintf(stderr, "EOF on netlink\n");
                       return -1;
               }

               h = (struct nlmsghdr*)buf;
               while (NLMSG_OK(h, status)) {
                       int err;

                       if (nladdr.nl_pid != 0 ||
                           h->nlmsg_pid != rth->local.nl_pid ||
                           h->nlmsg_seq != rth->dump) {
                               if (junk) {
                                       err = junk(&nladdr, h, arg2);
                                       if (err < 0)
                                               return err;
                               }
                               goto skip_it;
                       }

                       if (h->nlmsg_type == NLMSG_DONE)
                               return 0;
                       if (h->nlmsg_type == NLMSG_ERROR) {
                               struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
                               if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
                                       fprintf(stderr, "ERROR truncated\n");
                               } else {
                                       errno = -err->error;
                                       perror("RTNETLINK answers");
                               }
                               return -1;
                       }
                       err = filter(&nladdr, h, arg1);
                       if (err < 0)
                               return err;

skip_it:
                       h = NLMSG_NEXT(h, status);
               }
               if (msg.msg_flags & MSG_TRUNC) {
                       fprintf(stderr, "Message truncated\n");
                       continue;
               }
               if (status) {
                       fprintf(stderr, "!!!Remnant of size %d\n", status);
                       exit(1);
               }
       }
}

int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
             unsigned groups, struct nlmsghdr *answer,
             rtnl_filter_t junk,
             void *jarg)
{
       int status;
       unsigned seq;
       struct nlmsghdr *h;
       struct sockaddr_nl nladdr;
       struct iovec iov = {
               .iov_base = (void*) n,
               .iov_len = n->nlmsg_len
       };
       struct msghdr msg = {
               .msg_name = &nladdr,
               .msg_namelen = sizeof(nladdr),
               .msg_iov = &iov,
               .msg_iovlen = 1,
       };
       char   buf[16384];

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;
       nladdr.nl_pid = peer;
       nladdr.nl_groups = groups;

       n->nlmsg_seq = seq = ++rtnl->seq;

       if (answer == NULL)
               n->nlmsg_flags |= NLM_F_ACK;

       status = sendmsg(rtnl->fd, &msg, 0);

       if (status < 0) {
               perror("Cannot talk to rtnetlink");
               return -1;
       }

       memset(buf,0,sizeof(buf));

       iov.iov_base = buf;

       while (1) {
               iov.iov_len = sizeof(buf);
               status = recvmsg(rtnl->fd, &msg, 0);

               if (status < 0) {
                       if (errno == EINTR)
                               continue;
                       perror("OVERRUN");
                       continue;
               }
               if (status == 0) {
                       fprintf(stderr, "EOF on netlink\n");
                       return -1;
               }
               if (msg.msg_namelen != sizeof(nladdr)) {
                       fprintf(stderr, "sender address length == %d\n", msg.msg_namelen);
                       exit(1);
               }
               for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
                       int err;
                       int len = h->nlmsg_len;
                       int l = len - sizeof(*h);

                       if (l<0 || len>status) {
                               if (msg.msg_flags & MSG_TRUNC) {
                                       fprintf(stderr, "Truncated message\n");
                                       return -1;
                               }
                               fprintf(stderr, "!!!malformed message: len=%d\n", len);
                               exit(1);
                       }

                       if (nladdr.nl_pid != peer ||
                           h->nlmsg_pid != rtnl->local.nl_pid ||
                           h->nlmsg_seq != seq) {
                               if (junk) {
                                       err = junk(&nladdr, h, jarg);
                                       if (err < 0)
                                               return err;
                               }
                               continue;
                       }

                       if (h->nlmsg_type == NLMSG_ERROR) {
                               struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
                               if (l < sizeof(struct nlmsgerr)) {
                                       fprintf(stderr, "ERROR truncated\n");
                               } else {
                                       errno = -err->error;
                                       if (errno == 0) {
                                               if (answer)
                                                       memcpy(answer, h, h->nlmsg_len);
                                               return 0;
                                       }
                                       perror("RTNETLINK answers");
                               }
                               return -1;
                       }
                       if (answer) {
                               memcpy(answer, h, h->nlmsg_len);
                               return 0;
                       }

                       fprintf(stderr, "Unexpected reply!!!\n");

                       status -= NLMSG_ALIGN(len);
                       h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
               }
               if (msg.msg_flags & MSG_TRUNC) {
                       fprintf(stderr, "Message truncated\n");
                       continue;
               }
               if (status) {
                       fprintf(stderr, "!!!Remnant of size %d\n", status);
                       exit(1);
               }
       }
}

int rtnl_listen(struct rtnl_handle *rtnl,
               rtnl_filter_t handler,
               void *jarg)
{
       int status;
       struct nlmsghdr *h;
       struct sockaddr_nl nladdr;
       struct iovec iov;
       struct msghdr msg = {
               .msg_name = &nladdr,
               .msg_namelen = sizeof(nladdr),
               .msg_iov = &iov,
               .msg_iovlen = 1,
       };
       char   buf[8192];

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;
       nladdr.nl_pid = 0;
       nladdr.nl_groups = 0;

       iov.iov_base = buf;
       while (1) {
               iov.iov_len = sizeof(buf);
               status = recvmsg(rtnl->fd, &msg, 0);

               if (status < 0) {
                       if (errno == EINTR)
                               continue;
                       perror("OVERRUN");
                       continue;
               }
               if (status == 0) {
                       fprintf(stderr, "EOF on netlink\n");
                       return -1;
               }
               if (msg.msg_namelen != sizeof(nladdr)) {
                       fprintf(stderr, "Sender address length == %d\n", msg.msg_namelen);
                       exit(1);
               }
               for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
                       int err;
                       int len = h->nlmsg_len;
                       int l = len - sizeof(*h);

                       if (l<0 || len>status) {
                               if (msg.msg_flags & MSG_TRUNC) {
                                       fprintf(stderr, "Truncated message\n");
                                       return -1;
                               }
                               fprintf(stderr, "!!!malformed message: len=%d\n", len);
                               exit(1);
                       }

                       err = handler(&nladdr, h, jarg);
                       if (err < 0)
                               return err;

                       status -= NLMSG_ALIGN(len);
                       h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
               }
               if (msg.msg_flags & MSG_TRUNC) {
                       fprintf(stderr, "Message truncated\n");
                       continue;
               }
               if (status) {
                       fprintf(stderr, "!!!Remnant of size %d\n", status);
                       exit(1);
               }
       }
}

int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
                  void *jarg)
{
       int status;
       struct sockaddr_nl nladdr;
       char   buf[8192];
       struct nlmsghdr *h = (void*)buf;

       memset(&nladdr, 0, sizeof(nladdr));
       nladdr.nl_family = AF_NETLINK;
       nladdr.nl_pid = 0;
       nladdr.nl_groups = 0;

       while (1) {
               int err, len, type;
               int l;

               status = fread(&buf, 1, sizeof(*h), rtnl);

               if (status < 0) {
                       if (errno == EINTR)
                               continue;
                       perror("rtnl_from_file: fread");
                       return -1;
               }
               if (status == 0)
                       return 0;

               len = h->nlmsg_len;
               type= h->nlmsg_type;
               l = len - sizeof(*h);

               if (l<0 || len>sizeof(buf)) {
                       fprintf(stderr, "!!!malformed message: len=%d @%lu\n",
                               len, ftell(rtnl));
                       return -1;
               }

               status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);

               if (status < 0) {
                       perror("rtnl_from_file: fread");
                       return -1;
               }
               if (status < l) {
                       fprintf(stderr, "rtnl-from_file: truncated message\n");
                       return -1;
               }

               err = handler(&nladdr, h, jarg);
               if (err < 0)
                       return err;
       }
}

int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
{
       int len = RTA_LENGTH(4);
       struct rtattr *rta;
       if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
               fprintf(stderr,"addattr32: Error! max allowed bound %d exceeded\n",maxlen);
               return -1;
       }
       rta = NLMSG_TAIL(n);
       rta->rta_type = type;
       rta->rta_len = len;
       memcpy(RTA_DATA(rta), &data, 4);
       n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
       return 0;
}

int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
             int alen)
{
       int len = RTA_LENGTH(alen);
       struct rtattr *rta;

       if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
               fprintf(stderr, "addattr_l ERROR: message exceeded bound of %d\n",maxlen);
               return -1;
       }
       rta = NLMSG_TAIL(n);
       rta->rta_type = type;
       rta->rta_len = len;
       memcpy(RTA_DATA(rta), data, alen);
       n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
       return 0;
}

int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
{
       if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
               fprintf(stderr, "addraw_l ERROR: message exceeded bound of %d\n",maxlen);
               return -1;
       }

       memcpy(NLMSG_TAIL(n), data, len);
       memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
       n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
       return 0;
}

int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
{
       int len = RTA_LENGTH(4);
       struct rtattr *subrta;

       if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
               fprintf(stderr,"rta_addattr32: Error! max allowed bound %d exceeded\n",maxlen);
               return -1;
       }
       subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
       subrta->rta_type = type;
       subrta->rta_len = len;
       memcpy(RTA_DATA(subrta), &data, 4);
       rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
       return 0;
}

int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
                 const void *data, int alen)
{
       struct rtattr *subrta;
       int len = RTA_LENGTH(alen);

       if (RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len) > maxlen) {
               fprintf(stderr,"rta_addattr_l: Error! max allowed bound %d exceeded\n",maxlen);
               return -1;
       }
       subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
       subrta->rta_type = type;
       subrta->rta_len = len;
       memcpy(RTA_DATA(subrta), data, alen);
       rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
       return 0;
}

int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
{
       memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
       while (RTA_OK(rta, len)) {
               if (rta->rta_type <= max)
                       tb[rta->rta_type] = rta;
               rta = RTA_NEXT(rta,len);
       }
       if (len)
               fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
       return 0;
}

int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int len)
{
       int i = 0;

       memset(tb, 0, sizeof(struct rtattr *) * max);
       while (RTA_OK(rta, len)) {
               if (rta->rta_type <= max && i < max)
                       tb[i++] = rta;
               rta = RTA_NEXT(rta,len);
       }
       if (len)
               fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
       return i;
}
