1 | /*
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2 | * libnetlink.c RTnetlink service routines.
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3 | *
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4 | * This program is free software; you can redistribute it and/or
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5 | * modify it under the terms of the GNU General Public License
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6 | * as published by the Free Software Foundation; either version
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7 | * 2 of the License, or (at your option) any later version.
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8 | *
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9 | * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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10 | *
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11 | */
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12 |
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13 | #include "libbb.h"
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14 | #include <sys/socket.h>
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15 |
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16 | #include <errno.h>
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17 | #include <string.h>
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18 | #include <time.h>
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19 | #include <unistd.h>
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20 |
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21 | #include <sys/uio.h>
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22 |
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23 | #include "libnetlink.h"
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24 |
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25 | void rtnl_close(struct rtnl_handle *rth)
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26 | {
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27 | close(rth->fd);
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28 | }
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29 |
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30 | int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
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31 | {
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32 | socklen_t addr_len;
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33 |
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34 | memset(rth, 0, sizeof(rth));
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35 |
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36 | rth->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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37 | if (rth->fd < 0) {
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38 | bb_perror_msg("Cannot open netlink socket");
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39 | return -1;
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40 | }
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41 |
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42 | memset(&rth->local, 0, sizeof(rth->local));
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43 | rth->local.nl_family = AF_NETLINK;
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44 | rth->local.nl_groups = subscriptions;
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45 |
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46 | if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) {
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47 | bb_perror_msg("Cannot bind netlink socket");
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48 | return -1;
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49 | }
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50 | addr_len = sizeof(rth->local);
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51 | if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) {
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52 | bb_perror_msg("Cannot getsockname");
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53 | return -1;
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54 | }
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55 | if (addr_len != sizeof(rth->local)) {
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56 | bb_error_msg("Wrong address length %d", addr_len);
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57 | return -1;
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58 | }
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59 | if (rth->local.nl_family != AF_NETLINK) {
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60 | bb_error_msg("Wrong address family %d", rth->local.nl_family);
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61 | return -1;
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62 | }
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63 | rth->seq = time(NULL);
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64 | return 0;
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65 | }
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66 |
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67 | int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
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68 | {
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69 | struct {
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70 | struct nlmsghdr nlh;
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71 | struct rtgenmsg g;
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72 | } req;
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73 | struct sockaddr_nl nladdr;
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74 |
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75 | memset(&nladdr, 0, sizeof(nladdr));
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76 | nladdr.nl_family = AF_NETLINK;
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77 |
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78 | req.nlh.nlmsg_len = sizeof(req);
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79 | req.nlh.nlmsg_type = type;
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80 | req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
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81 | req.nlh.nlmsg_pid = 0;
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82 | req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
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83 | req.g.rtgen_family = family;
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84 |
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85 | return sendto(rth->fd, (void*)&req, sizeof(req), 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
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86 | }
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87 |
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88 | int rtnl_send(struct rtnl_handle *rth, char *buf, int len)
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89 | {
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90 | struct sockaddr_nl nladdr;
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91 |
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92 | memset(&nladdr, 0, sizeof(nladdr));
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93 | nladdr.nl_family = AF_NETLINK;
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94 |
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95 | return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
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96 | }
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97 |
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98 | int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
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99 | {
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100 | struct nlmsghdr nlh;
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101 | struct sockaddr_nl nladdr;
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102 | struct iovec iov[2] = { { &nlh, sizeof(nlh) }, { req, len } };
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103 | struct msghdr msg = {
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104 | (void*)&nladdr, sizeof(nladdr),
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105 | iov, 2,
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106 | NULL, 0,
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107 | 0
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108 | };
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109 |
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110 | memset(&nladdr, 0, sizeof(nladdr));
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111 | nladdr.nl_family = AF_NETLINK;
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112 |
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113 | nlh.nlmsg_len = NLMSG_LENGTH(len);
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114 | nlh.nlmsg_type = type;
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115 | nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
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116 | nlh.nlmsg_pid = 0;
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117 | nlh.nlmsg_seq = rth->dump = ++rth->seq;
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118 |
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119 | return sendmsg(rth->fd, &msg, 0);
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120 | }
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121 |
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122 | int rtnl_dump_filter(struct rtnl_handle *rth,
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123 | int (*filter)(struct sockaddr_nl *, struct nlmsghdr *n, void *),
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124 | void *arg1,
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125 | int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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126 | void *arg2)
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127 | {
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128 | char buf[8192];
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129 | struct sockaddr_nl nladdr;
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130 | struct iovec iov = { buf, sizeof(buf) };
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131 |
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132 | while (1) {
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133 | int status;
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134 | struct nlmsghdr *h;
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135 |
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136 | struct msghdr msg = {
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137 | (void*)&nladdr, sizeof(nladdr),
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138 | &iov, 1,
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139 | NULL, 0,
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140 | 0
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141 | };
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142 |
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143 | status = recvmsg(rth->fd, &msg, 0);
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144 |
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145 | if (status < 0) {
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146 | if (errno == EINTR)
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147 | continue;
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148 | bb_perror_msg("OVERRUN");
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149 | continue;
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150 | }
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151 | if (status == 0) {
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152 | bb_error_msg("EOF on netlink");
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153 | return -1;
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154 | }
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155 | if (msg.msg_namelen != sizeof(nladdr)) {
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156 | bb_error_msg_and_die("sender address length == %d", msg.msg_namelen);
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157 | }
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158 |
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159 | h = (struct nlmsghdr*)buf;
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160 | while (NLMSG_OK(h, status)) {
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161 | int err;
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162 |
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163 | if (nladdr.nl_pid != 0 ||
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164 | h->nlmsg_pid != rth->local.nl_pid ||
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165 | h->nlmsg_seq != rth->dump) {
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166 | if (junk) {
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167 | err = junk(&nladdr, h, arg2);
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168 | if (err < 0) {
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169 | return err;
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170 | }
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171 | }
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172 | goto skip_it;
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173 | }
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174 |
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175 | if (h->nlmsg_type == NLMSG_DONE) {
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176 | return 0;
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177 | }
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178 | if (h->nlmsg_type == NLMSG_ERROR) {
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179 | struct nlmsgerr *l_err = (struct nlmsgerr*)NLMSG_DATA(h);
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180 | if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
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181 | bb_error_msg("ERROR truncated");
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182 | } else {
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183 | errno = -l_err->error;
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184 | bb_perror_msg("RTNETLINK answers");
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185 | }
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186 | return -1;
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187 | }
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188 | err = filter(&nladdr, h, arg1);
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189 | if (err < 0) {
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190 | return err;
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191 | }
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192 |
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193 | skip_it:
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194 | h = NLMSG_NEXT(h, status);
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195 | }
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196 | if (msg.msg_flags & MSG_TRUNC) {
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197 | bb_error_msg("Message truncated");
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198 | continue;
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199 | }
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200 | if (status) {
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201 | bb_error_msg_and_die("!!!Remnant of size %d", status);
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202 | }
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203 | }
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204 | }
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205 |
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206 | int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
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207 | unsigned groups, struct nlmsghdr *answer,
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208 | int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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209 | void *jarg)
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210 | {
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211 | int status;
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212 | unsigned seq;
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213 | struct nlmsghdr *h;
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214 | struct sockaddr_nl nladdr;
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215 | struct iovec iov = { (void*)n, n->nlmsg_len };
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216 | char buf[8192];
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217 | struct msghdr msg = {
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218 | (void*)&nladdr, sizeof(nladdr),
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219 | &iov, 1,
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220 | NULL, 0,
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221 | 0
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222 | };
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223 |
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224 | memset(&nladdr, 0, sizeof(nladdr));
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225 | nladdr.nl_family = AF_NETLINK;
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226 | nladdr.nl_pid = peer;
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227 | nladdr.nl_groups = groups;
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228 |
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229 | n->nlmsg_seq = seq = ++rtnl->seq;
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230 | if (answer == NULL) {
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231 | n->nlmsg_flags |= NLM_F_ACK;
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232 | }
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233 | status = sendmsg(rtnl->fd, &msg, 0);
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234 |
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235 | if (status < 0) {
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236 | bb_perror_msg("Cannot talk to rtnetlink");
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237 | return -1;
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238 | }
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239 |
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240 | iov.iov_base = buf;
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241 |
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242 | while (1) {
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243 | iov.iov_len = sizeof(buf);
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244 | status = recvmsg(rtnl->fd, &msg, 0);
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245 |
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246 | if (status < 0) {
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247 | if (errno == EINTR) {
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248 | continue;
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249 | }
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250 | bb_perror_msg("OVERRUN");
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251 | continue;
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252 | }
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253 | if (status == 0) {
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254 | bb_error_msg("EOF on netlink");
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255 | return -1;
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256 | }
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257 | if (msg.msg_namelen != sizeof(nladdr)) {
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258 | bb_error_msg_and_die("sender address length == %d", msg.msg_namelen);
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259 | }
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260 | for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
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261 | int l_err;
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262 | int len = h->nlmsg_len;
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263 | int l = len - sizeof(*h);
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264 |
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265 | if (l<0 || len>status) {
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266 | if (msg.msg_flags & MSG_TRUNC) {
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267 | bb_error_msg("Truncated message");
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268 | return -1;
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269 | }
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270 | bb_error_msg_and_die("!!!malformed message: len=%d", len);
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271 | }
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272 |
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273 | if (nladdr.nl_pid != peer ||
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274 | h->nlmsg_pid != rtnl->local.nl_pid ||
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275 | h->nlmsg_seq != seq) {
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276 | if (junk) {
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277 | l_err = junk(&nladdr, h, jarg);
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278 | if (l_err < 0) {
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279 | return l_err;
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280 | }
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281 | }
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282 | continue;
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283 | }
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284 |
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285 | if (h->nlmsg_type == NLMSG_ERROR) {
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286 | struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
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287 | if (l < sizeof(struct nlmsgerr)) {
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288 | bb_error_msg("ERROR truncated");
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289 | } else {
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290 | errno = -err->error;
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291 | if (errno == 0) {
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292 | if (answer) {
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293 | memcpy(answer, h, h->nlmsg_len);
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294 | }
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295 | return 0;
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296 | }
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297 | bb_perror_msg("RTNETLINK answers");
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298 | }
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299 | return -1;
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300 | }
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301 | if (answer) {
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302 | memcpy(answer, h, h->nlmsg_len);
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303 | return 0;
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304 | }
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305 |
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306 | bb_error_msg("Unexpected reply!!!");
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307 |
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308 | status -= NLMSG_ALIGN(len);
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309 | h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
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310 | }
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311 | if (msg.msg_flags & MSG_TRUNC) {
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312 | bb_error_msg("Message truncated");
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313 | continue;
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314 | }
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315 | if (status) {
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316 | bb_error_msg_and_die("!!!Remnant of size %d", status);
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317 | }
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318 | }
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319 | }
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320 |
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321 | int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
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322 | {
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323 | int len = RTA_LENGTH(4);
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324 | struct rtattr *rta;
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325 | if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen)
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326 | return -1;
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327 | rta = (struct rtattr*)(((char*)n) + NLMSG_ALIGN(n->nlmsg_len));
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328 | rta->rta_type = type;
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329 | rta->rta_len = len;
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330 | memcpy(RTA_DATA(rta), &data, 4);
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331 | n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
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332 | return 0;
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333 | }
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334 |
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335 | int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen)
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336 | {
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337 | int len = RTA_LENGTH(alen);
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338 | struct rtattr *rta;
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339 |
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340 | if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen)
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341 | return -1;
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342 | rta = (struct rtattr*)(((char*)n) + NLMSG_ALIGN(n->nlmsg_len));
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343 | rta->rta_type = type;
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344 | rta->rta_len = len;
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345 | memcpy(RTA_DATA(rta), data, alen);
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346 | n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
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347 | return 0;
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348 | }
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349 |
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350 | int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
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351 | {
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352 | int len = RTA_LENGTH(4);
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353 | struct rtattr *subrta;
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354 |
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355 | if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
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356 | return -1;
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357 | }
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358 | subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
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359 | subrta->rta_type = type;
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360 | subrta->rta_len = len;
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361 | memcpy(RTA_DATA(subrta), &data, 4);
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362 | rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
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363 | return 0;
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364 | }
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365 |
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366 | int rta_addattr_l(struct rtattr *rta, int maxlen, int type, void *data, int alen)
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367 | {
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368 | struct rtattr *subrta;
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369 | int len = RTA_LENGTH(alen);
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370 |
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371 | if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
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372 | return -1;
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373 | }
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374 | subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
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375 | subrta->rta_type = type;
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376 | subrta->rta_len = len;
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377 | memcpy(RTA_DATA(subrta), data, alen);
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378 | rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
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379 | return 0;
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380 | }
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381 |
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382 |
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383 | int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
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384 | {
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385 | while (RTA_OK(rta, len)) {
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386 | if (rta->rta_type <= max) {
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387 | tb[rta->rta_type] = rta;
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388 | }
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389 | rta = RTA_NEXT(rta,len);
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390 | }
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391 | if (len) {
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392 | bb_error_msg("!!!Deficit %d, rta_len=%d", len, rta->rta_len);
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393 | }
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394 | return 0;
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395 | }
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