dnsmasq.c File Reference

File containing the implementation of dnsmasq service configuration utilities. More...

#include <stdbool.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "dhcp_config.h"
#include "../utils/allocs.h"
#include "../utils/log.h"
#include "../utils/os.h"
#include "../utils/squeue.h"

Include dependency graph for dnsmasq.c:

Macros
#define	PROCESS_RESTART_TIME   5
#define	MAX_DHCP_CHECK_COUNT   100
#define	DNSMASQ_BIND_INTERFACE_OPTION   "--bind-interfaces"
#define	DNSMASQ_BIND_DYNAMIC_OPTION   "--bind-dynamic"
#define	DNSMASQ_NO_DAEMON_OPTION   "--no-daemon"
#define	DNSMASQ_LOG_QUERIES_OPTION   "--log-queries"
#define	DNSMASQ_CONF_FILE_OPTION   "-C"
#define	DNSMASQ_SCRIPT_STR

Functions
int	define_dhcp_interface_name (const struct dhcp_conf *dconf, uint16_t vlanid, char *ifname)
	Creates the DHCP interface name for the given vlan id. More...
int	generate_dnsmasq_conf (struct dhcp_conf *dconf, UT_array *dns_server_array)
	Generates the dnsmasq configuration file. More...
int	generate_dnsmasq_script (char *dhcp_script_path, char *supervisor_control_path)
	Generates the dnsmasq executable script for DHCP requests. More...
void	get_dnsmasq_args (const char *dnsmasq_bin_path, const char *dnsmasq_conf_path, const char *argv[static 6])
	Builds the argv for calling dnsmasq. More...
int	check_dhcp_running (char *name, int wait_time)
char *	run_dhcp_process (const char *dhcp_bin_path, const char *dhcp_conf_path)
	Execute the DHCP server. More...
bool	kill_dhcp_process (void)
	Terminate the DHCP server. More...
int	signal_dhcp_process (const char *dhcp_bin_path)
	Signal the DHCP process to reload the config. More...
int	clear_dhcp_lease_entry (char *mac_addr, char *dhcp_leasefile_path)
	Clear the DHCP lease entry for a MAC addrress. More...

Detailed Description

File containing the implementation of dnsmasq service configuration utilities.

Author

Alexandru Mereacre

Date

2021

Copyright

SPDX-FileCopyrightText: © 2021 NQMCyber Ltd and edgesec contributors SPDX-License-Identifier: LGPL-3.0-or-later

Macro Definition Documentation

DNSMASQ_BIND_DYNAMIC_OPTION

#define DNSMASQ_BIND_DYNAMIC_OPTION   "--bind-dynamic"

DNSMASQ_BIND_INTERFACE_OPTION

#define DNSMASQ_BIND_INTERFACE_OPTION   "--bind-interfaces"

DNSMASQ_CONF_FILE_OPTION

#define DNSMASQ_CONF_FILE_OPTION   "-C"

DNSMASQ_LOG_QUERIES_OPTION

#define DNSMASQ_LOG_QUERIES_OPTION   "--log-queries"

DNSMASQ_NO_DAEMON_OPTION

#define DNSMASQ_NO_DAEMON_OPTION   "--no-daemon"

DNSMASQ_SCRIPT_STR

#define DNSMASQ_SCRIPT_STR

Value:

  "#!/bin/sh\n"                                                                \
  "sockpath=\"%s\"\n"                                                          \
  "str=\"SET_IP $1 $2 $3\"\n"                                                  \
  "\n"                                                                         \
  "nccheck=`nc -help 2>&1 >/dev/null | grep 'OpenBSD netcat'`\n"               \
  "if [ -z \"$nccheck\" ]\n"                                                   \
  "then\n"                                                                     \
  "\techo \"Using socat\"\n"                                                   \
  "\tcommand=\"socat - UNIX-CLIENT:$sockpath\"\n"                              \
  "else\n"                                                                     \
  "\techo \"Using netcat\"\n"                                                  \
  "\tcommand=\"nc -uU $sockpath -w2 -W1\"\n"                                   \
  "fi\n"                                                                       \
  "\n"                                                                         \
  "echo \"Sending $str ...\"\n"                                                \
  "echo $str | $command\n"

MAX_DHCP_CHECK_COUNT

#define MAX_DHCP_CHECK_COUNT   100

PROCESS_RESTART_TIME

#define PROCESS_RESTART_TIME   5

Function Documentation

check_dhcp_running()

int check_dhcp_running	(	char *	name,
		int	wait_time
	)

clear_dhcp_lease_entry()

int clear_dhcp_lease_entry	(	char *	mac_addr,
		char *	dhcp_leasefile_path
	)

Clear the DHCP lease entry for a MAC addrress.

Parameters

mac_addr	The MAC address string
dhcp_leasefile_path	The DHCP file path

Returns

int 0 on success, -1 on failure

define_dhcp_interface_name()

int define_dhcp_interface_name	(	const struct dhcp_conf *	dconf,
		uint16_t	vlanid,
		char *	ifname
	)

Creates the DHCP interface name for the given vlan id.

Parameters

	dconf	The dhcp configuration structure.
	vlanid	The vlan id.
[out]	ifname	The DHCP interface name.

Precondition

vlanid must be less than 4095 chars

ifname must point to at least #IF_NAMESIZE bytes.

Return values

0	Success
-1	Error (invalid args)

generate_dnsmasq_conf()

int generate_dnsmasq_conf	(	struct dhcp_conf *	dconf,
		UT_array *	dns_server_array
	)

Generates the dnsmasq configuration file.

Parameters

dconf	The dhcp configuration structure.
dns_server_array	The array including the DNS servers IP addresses.

Returns

0 on success, -1 otherwise

generate_dnsmasq_script()

int generate_dnsmasq_script	(	char *	dhcp_script_path,
		char *	supervisor_control_path
	)

Generates the dnsmasq executable script for DHCP requests.

Parameters

dhcp_script_path	The dhcp executable script path string.
supervisor_control_path	The UNIX domains supervisor control path.

Returns

0 on success, -1 otherwise

get_dnsmasq_args()

void get_dnsmasq_args	(	const char *	dnsmasq_bin_path,
		const char *	dnsmasq_conf_path,
		const char *	argv[static 6]
	)

Builds the argv for calling dnsmasq.

Parameters

	dnsmasq_bin_path	The path to the dnsmasq binary.
	dnsmasq_conf_path	The path to the dnsmasq config file.
[in,out]	argv	The array to store the args warning.

Precondition

argv must have space for at least 6 pointers.

kill_dhcp_process()

bool kill_dhcp_process

(

void

)

Terminate the DHCP server.

Returns

bool true on success, false otherwise

run_dhcp_process()

char* run_dhcp_process	(	const char *	dhcp_bin_path,
		const char *	dhcp_conf_path
	)

Execute the DHCP server.

This function returns a pointer to statically allocated memory, which may be overwritten by subsequent calls.

Parameters

dhcp_bin_path	The DHCP server binary path
dhcp_conf_path	The DHCP server config path

Returns

The pointer to the statically allocated process name, NULL on failure. Do not pass this pointer to free()

signal_dhcp_process()

int signal_dhcp_process

(

const char *

dhcp_bin_path

)

Signal the DHCP process to reload the config.

Parameters

dhcp_bin_path

The DHCP server binary path

Returns

int 0 on success, -1 on failure