Do more boundary and sanity checking when adding dhcp options.
Simplify parameter list for ifchd_cmd().
This commit is contained in:
Nicholas J. Kain
parent
0e62d46f8b
commit
ddf9daf8e4
@ -79,7 +79,8 @@ static void init_header(struct dhcpMessage *packet, char type)
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packet->hlen = 6; // ETH_10MB_LEN
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packet->cookie = htonl(DHCP_MAGIC);
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packet->options[0] = DHCP_END;
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add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
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add_u32_option(packet->options, DHCP_OPTIONS_BUFSIZE, DHCP_MESSAGE_TYPE,
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type);
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}
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/* initialize a packet with the proper defaults */
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@ -93,10 +94,13 @@ static void init_packet(struct dhcpMessage *packet, char type)
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init_header(packet, type);
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memcpy(packet->chaddr, client_config.arp, 6);
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add_option_string(packet->options, client_config.clientid);
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add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE,
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client_config.clientid);
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if (client_config.hostname)
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add_option_string(packet->options, client_config.hostname);
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add_option_string(packet->options, (unsigned char *)&vendor_id);
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add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE,
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client_config.hostname);
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add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE,
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(unsigned char *)&vendor_id);
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}
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#define MAC_BCAST_ADDR (unsigned char *) "\xff\xff\xff\xff\xff\xff"
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@ -117,11 +121,13 @@ int send_discover(uint32_t xid, uint32_t requested)
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init_packet(&packet, DHCPDISCOVER);
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packet.xid = xid;
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if (requested)
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add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP,
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requested);
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/* Request a RFC-specified max size to work around buggy servers. */
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add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
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add_requests(&packet);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE,
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DHCP_MAX_SIZE, htons(576));
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add_option_request_list(&packet);
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log_line("Sending discover...");
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return bcast_raw_packet(&packet);
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}
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@ -135,10 +141,11 @@ int send_selecting(uint32_t xid, uint32_t server, uint32_t requested)
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init_packet(&packet, DHCPREQUEST);
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packet.xid = xid;
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add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
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add_simple_option(packet.options, DHCP_SERVER_ID, server);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP,
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requested);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server);
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add_requests(&packet);
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add_option_request_list(&packet);
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addr.s_addr = requested;
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log_line("Sending select for %s...", inet_ntoa(addr));
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return bcast_raw_packet(&packet);
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@ -153,7 +160,7 @@ int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
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packet.xid = xid;
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packet.ciaddr = ciaddr;
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add_requests(&packet);
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add_option_request_list(&packet);
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log_line("Sending renew...");
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if (server)
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return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server,
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@ -179,8 +186,9 @@ int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
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*/
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packet.xid = xid;
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/* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
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add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
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add_simple_option(packet.options, DHCP_SERVER_ID, server);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP,
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requested);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server);
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log_line("Sending decline...");
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return bcast_raw_packet(&packet);
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@ -195,8 +203,9 @@ int send_release(uint32_t server, uint32_t ciaddr)
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packet.xid = random_xid();
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packet.ciaddr = ciaddr;
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add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
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add_simple_option(packet.options, DHCP_SERVER_ID, server);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP,
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ciaddr);
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add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server);
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log_line("Sending release...");
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return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server,
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@ -1,5 +1,5 @@
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/* ifchange.c - functions to call the interface change daemon
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* Time-stamp: <2011-03-30 12:02:55 nk>
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* Time-stamp: <2011-03-30 13:14:37 nk>
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*
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* (c) 2004-2011 Nicholas J. Kain <njkain at gmail dot com>
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*
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@ -40,13 +40,14 @@
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/* Fill buf with the ifchd command text of option 'option'. */
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/* Returns 0 if successful, -1 if nothing was filled in. */
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static int ifchd_cmd(char *buf, size_t buflen,
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unsigned char *option, ssize_t optlen,
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uint8_t code, enum option_type type, const char *optname)
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static int ifchd_cmd(char *buf, size_t buflen, uint8_t *option, ssize_t optlen,
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uint8_t code)
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{
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char *obuf = buf;
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uint8_t *ooption = option;
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ssize_t typelen = option_length(type);
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const char *optname = option_name(code);
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enum option_type type = option_type(code);
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ssize_t typelen = option_length(code);
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if (!option || type == OPTION_NONE)
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return -1;
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@ -181,8 +182,7 @@ static void send_cmd(int sockfd, struct dhcpMessage *packet,
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memset(buf, '\0', sizeof buf);
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optdata = get_option_data(packet, code, &optlen);
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if (ifchd_cmd(buf, sizeof buf, optdata, optlen, code, option_type(code),
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option_name(code)) == -1)
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if (ifchd_cmd(buf, sizeof buf, optdata, optlen, code) == -1)
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return;
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sockwrite(sockfd, buf, strlen(buf));
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}
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131
ndhc/options.c
131
ndhc/options.c
@ -1,7 +1,21 @@
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/*
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* options.c -- DHCP server option packet tools
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* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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* Fixes and hardening: Nicholas J. Kain <njkain at gmail dot com>
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/* options.c - DHCP options handling
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* Time-stamp: <2011-03-30 15:52:12 nk>
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*
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* (c) 2004-2011 Nicholas J. Kain <njkain at gmail dot com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <stdio.h>
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@ -13,12 +27,6 @@
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#include "log.h"
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#include "malloc.h"
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enum {
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OPT_CODE = 0,
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OPT_LEN = 1,
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OPT_DATA = 2
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};
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struct dhcp_option {
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char name[10];
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enum option_type type;
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@ -55,7 +63,7 @@ static struct dhcp_option options[] = {
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{"maxsize" , OPTION_U16, 0x39},
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{"tftp" , OPTION_STRING, 0x42},
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{"bootfile" , OPTION_STRING, 0x43},
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{"" , OPTION_NONE, 0x00}
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{"NONE" , OPTION_NONE, 0x00}
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};
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// List of options that will be sent on the parameter request list to the
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@ -102,7 +110,7 @@ const char *option_name(uint8_t code)
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return bad_option_name;
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}
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uint8_t option_length(enum option_type type)
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static uint8_t option_type_length(enum option_type type)
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{
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switch (type) {
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case OPTION_IP: return 4;
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@ -115,6 +123,16 @@ uint8_t option_length(enum option_type type)
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}
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}
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uint8_t option_length(uint8_t code)
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{
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int i;
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for (i = 0; options[i].code; i++)
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if (options[i].code == code)
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return option_type_length(options[i].type);
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log_warning("option_length: unknown length for code 0x%02x", code);
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return 0;
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}
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int option_valid_list(uint8_t code)
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{
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int i;
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@ -254,61 +272,60 @@ uint8_t *get_option_data(struct dhcpMessage *packet, int code, ssize_t *optlen)
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}
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/* return the position of the 'end' option */
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int get_end_option_idx(uint8_t *optbuf, size_t bufsize)
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ssize_t get_end_option_idx(uint8_t *optbuf, size_t bufsize)
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{
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int i = 0;
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while (i < bufsize && optbuf[i] != DHCP_END) {
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if (optbuf[i] != DHCP_PADDING)
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i += optbuf[i+1] + 2;
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else
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i++;
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}
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if (i < bufsize - 1)
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int i;
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for (i = 0; i < bufsize; ++i) {
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if (optbuf[i] == DHCP_END)
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return i;
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else {
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log_warning("get_end_option_idx(): did not find DHCP_END marker");
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return bufsize - 1;
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if (optbuf[i] == DHCP_PADDING)
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continue;
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if (optbuf[i] != DHCP_PADDING)
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i += optbuf[i+1] + 1;
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}
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log_warning("get_end_option_idx(): did not find DHCP_END marker");
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return -1;
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}
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/* add an option string to the options (an option string contains an option
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* code, length, then data) */
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int add_option_string(unsigned char *optionptr, unsigned char *string)
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size_t add_option_string(uint8_t *optbuf, size_t buflen, uint8_t *optstr)
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{
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// XXX: not real length
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int end = get_end_option_idx(optionptr, DHCP_OPTIONS_BUFSIZE);
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size_t end = get_end_option_idx(optbuf, buflen);
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size_t datalen = optstr[1];
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/* end position + string length + option code/length + end option */
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if (end + string[OPT_LEN] + 2 + 1 >= DHCP_OPTIONS_BUFSIZE) {
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log_error("Option 0x%02x did not fit into the packet!",
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string[OPT_CODE]);
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if (end == -1) {
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log_warning("add_option_string: Buffer has no DHCP_END marker");
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return 0;
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}
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memcpy(optionptr + end, string, string[OPT_LEN] + 2);
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optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
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return string[OPT_LEN] + 2;
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/* end position + optstr length + option code/length + end option */
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if (end + datalen + 2 + 1 >= buflen) {
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log_warning("Option 0x%02x did not fit into the packet!", optstr[0]);
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return 0;
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}
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memcpy(optbuf + end, optstr, datalen + 2);
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optbuf[end + datalen + 2] = DHCP_END;
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return datalen + 2;
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}
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int add_simple_option(unsigned char *optionptr, unsigned char code,
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size_t add_u32_option(uint8_t *optbuf, size_t buflen, uint8_t code,
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uint32_t data)
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{
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int i, length = 0;
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unsigned char option[2 + 4];
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int length = 0;
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uint8_t option[6];
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for (i = 0; options[i].code; i++)
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if (options[i].code == code) {
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length = option_length(options[i].type);
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}
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length = option_length(code);
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log_line("aso(): code=0x%02x length=0x%02x", code, length);
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option[OPT_CODE] = code;
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option[OPT_LEN] = (unsigned char)length;
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log_line("add_u32_option: code=0x%02x length=0x%02x", code, length);
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option[0] = code;
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option[1] = length;
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if (!length) {
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log_error("Could not add option 0x%02x", code);
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log_warning("add_u32_option: option code 0x%02x has 0 length", code);
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return 0;
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} else if (length == 1) {
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}
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if (length == 1) {
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uint8_t t = (uint8_t)data;
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memcpy(option + 2, &t, 1);
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} else if (length == 2) {
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@ -318,20 +335,18 @@ int add_simple_option(unsigned char *optionptr, unsigned char code,
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uint32_t t = (uint32_t)data;
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memcpy(option + 2, &t, 4);
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}
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return add_option_string(optionptr, option);
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return add_option_string(optbuf, buflen, option);
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}
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/* Add a paramater request list for stubborn DHCP servers. Don't do bounds */
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/* checking here because it goes towards the head of the packet. */
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void add_requests(struct dhcpMessage *packet)
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/* Add a paramater request list for stubborn DHCP servers */
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void add_option_request_list(struct dhcpMessage *packet)
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{
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// XXX: not real length
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int end = get_end_option_idx(packet->options, DHCP_OPTIONS_BUFSIZE);
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int i, len = 0;
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int i;
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uint8_t reqdata[sizeof req_opts + 1];
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packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
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reqdata[0] = DHCP_PARAM_REQ;
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reqdata[1] = sizeof reqdata - 2;
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for (i = 0; req_opts[i]; i++)
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packet->options[end + OPT_DATA + len++] = req_opts[i];
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packet->options[end + OPT_LEN] = len;
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packet->options[end + OPT_DATA + len] = DHCP_END;
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reqdata[i + 2] = req_opts[i];
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add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, reqdata);
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}
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@ -1,4 +1,22 @@
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/* options.h */
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/* options.h - DHCP options handling
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* Time-stamp: <2011-03-30 15:50:30 nk>
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*
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* (c) 2004-2011 Nicholas J. Kain <njkain at gmail dot com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
|
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* the Free Software Foundation; either version 2 of the License, or
|
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef OPTIONS_H_
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#define OPTIONS_H_
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@ -64,7 +82,7 @@ enum option_type {
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const char *option_name(uint8_t code);
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enum option_type option_type(uint8_t code);
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uint8_t option_length(enum option_type type);
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uint8_t option_length(uint8_t code);
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int option_valid_list(uint8_t code);
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size_t sizeof_option(unsigned char code, size_t datalen);
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size_t set_option(unsigned char *buf, size_t buflen, unsigned char code,
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@ -76,10 +94,10 @@ unsigned char *alloc_dhcp_client_id_option(unsigned char type,
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unsigned char *idstr, size_t idstrlen);
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uint8_t *get_option_data(struct dhcpMessage *packet, int code, ssize_t *optlen);
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int get_end_option_idx(uint8_t *optbuf, size_t bufsize);
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int add_option_string(unsigned char *optionptr, unsigned char *string);
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int add_simple_option(unsigned char *optionptr, unsigned char code, uint32_t data);
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void add_requests(struct dhcpMessage *packet);
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ssize_t get_end_option_idx(uint8_t *optbuf, size_t bufsize);
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size_t add_option_string(uint8_t *optbuf, size_t buflen, uint8_t *optstr);
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size_t add_u32_option(uint8_t *optbuf, size_t buflen, uint8_t code,
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uint32_t data);
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void add_option_request_list(struct dhcpMessage *packet);
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#endif
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@ -105,8 +105,13 @@ int raw_packet(struct dhcpMessage *payload, uint32_t source_ip,
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* In order to work with those buggy servers,
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* we truncate packets after end option byte.
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*/
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padding = DHCP_OPTIONS_BUFSIZE - 1 - get_end_option_idx(packet.data.options,
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ssize_t endloc = get_end_option_idx(packet.data.options,
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DHCP_OPTIONS_BUFSIZE);
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if (endloc == -1) {
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log_error("raw_packet: attempt to send packet with no DHCP_END");
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goto out_fd;
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}
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padding = DHCP_OPTIONS_BUFSIZE - 1 - endloc;
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packet.ip.protocol = IPPROTO_UDP;
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packet.ip.saddr = source_ip;
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@ -165,8 +170,13 @@ int kernel_packet(struct dhcpMessage *payload, uint32_t source_ip,
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if (connect(fd, (struct sockaddr *)&client, sizeof(struct sockaddr)) == -1)
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goto out_fd;
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padding = DHCP_OPTIONS_BUFSIZE - 1 - get_end_option_idx(payload->options,
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ssize_t endloc = get_end_option_idx(payload->options,
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DHCP_OPTIONS_BUFSIZE);
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if (endloc == -1) {
|
||||
log_error("kernel_packet: attempt to send packet with no DHCP_END");
|
||||
goto out_fd;
|
||||
}
|
||||
padding = DHCP_OPTIONS_BUFSIZE - 1 - endloc;
|
||||
result = safe_write(fd, (const char *)payload, DHCP_SIZE - padding);
|
||||
if (result == -1)
|
||||
log_error("kernel_packet: write failed: %s", strerror(errno));
|
||||
|
||||
Loading…
Reference in New Issue
Block a user