1# Generate /etc/resolv.conf
2# Support resolvconf(8) if available
3# We can merge other dhcpcd resolv.conf files into one like resolvconf,
4# but resolvconf is preferred as other applications like VPN clients
5# can readily hook into it.
6# Also, resolvconf can configure local nameservers such as bind
7# or dnsmasq. This is important as the libc resolver isn't that powerful.
8
9resolv_conf_dir="$state_dir/resolv.conf"
10NL="
11"
12
13build_resolv_conf()
14{
15	local cf="$state_dir/resolv.conf.$ifname"
16	local interfaces= header= search= srvs= servers= x=
17
18	# Build a list of interfaces
19	interfaces=$(list_interfaces "$resolv_conf_dir")
20
21	# Build the resolv.conf
22	if [ -n "$interfaces" ]; then
23		# Build the header
24		for x in ${interfaces}; do
25			header="$header${header:+, }$x"
26		done
27
28		# Build the search list
29		domain=$(cd "$resolv_conf_dir"; \
30			key_get_value "domain " ${interfaces})
31		search=$(cd "$resolv_conf_dir"; \
32			key_get_value "search " ${interfaces})
33		set -- ${domain}
34		domain="$1"
35		[ -n "$2" ] && search="$search $*"
36		[ -n "$search" ] && search="$(uniqify $search)"
37		[ "$domain" = "$search" ] && search=
38		[ -n "$domain" ] && domain="domain $domain$NL"
39		[ -n "$search" ] && search="search $search$NL"
40
41		# Build the nameserver list
42		srvs=$(cd "$resolv_conf_dir"; \
43			key_get_value "nameserver " ${interfaces})
44		for x in $(uniqify ${srvs}); do
45			servers="${servers}nameserver $x$NL"
46		done
47	fi
48	header="$signature_base${header:+ $from }$header"
49
50	# Assemble resolv.conf using our head and tail files
51	[ -f "$cf" ] && rm -f "$cf"
52	[ -d "$resolv_conf_dir" ] || mkdir -p "$resolv_conf_dir"
53	echo "$header" > "$cf"
54	if [ -f /etc/resolv.conf.head ]; then
55		cat /etc/resolv.conf.head >> "$cf"
56	else
57		echo "# /etc/resolv.conf.head can replace this line" >> "$cf"
58	fi
59	printf %s "$domain$search$servers" >> "$cf"
60	if [ -f /etc/resolv.conf.tail ]; then
61		cat /etc/resolv.conf.tail >> "$cf"
62	else
63		echo "# /etc/resolv.conf.tail can replace this line" >> "$cf"
64	fi
65	if change_file /etc/resolv.conf "$cf"; then
66		chmod 644 /etc/resolv.conf
67	fi
68	rm -f "$cf"
69}
70
71add_resolv_conf()
72{
73	local x= conf="$signature$NL" i=${ra_count:-0} ra= warn=true
74
75	while [ $i -ne 0 ]; do
76		eval ra=\$ra${i}_rdnss
77		new_domain_name_servers="$new_domain_name_servers${new_domain_name_servers:+ }$ra"
78		eval ra=\$ra${i}_dnssl
79		new_domain_search="$new_domain_search${new_domain_search:+ }$ra"
80		i=$(($i - 1))
81	done
82
83	# If we don't have any configuration, remove it
84	if [ -z "$new_domain_name_servers" -a \
85		-z "$new_domain_name" -a \
86		-z "$new_domain_search" ]; then
87		remove_resolv_conf
88		return $?
89	fi
90
91	# Derive a new domain from our various hostname options
92	if [ -z "$new_domain_name" ]; then
93		if [ "$new_dhcp6_fqdn" != "${new_dhcp6_fqdn#*.}" ]; then
94			new_domain_name="${new_dhcp6_fqdn#*.}"
95		elif [ "$new_fqdn" != "${new_fqdn#*.}" ]; then
96			new_domain_name="${new_fqdn#*.}"
97		elif [ "$new_host_name" != "${new_host_name#*.}" ]; then
98			new_domain_name="${new_host_name#*.}"
99		fi
100	fi
101
102	if [ -n "$new_domain_name" ]; then
103		set -- $new_domain_name
104		if valid_domainname "$1"; then
105			conf="${conf}domain $1$NL"
106		else
107			syslog err "Invalid domain name: $1"
108		fi
109		# If there is no search this, make this one
110		if [ -z "$new_domain_search" ]; then
111			new_domain_search="$new_domain_name"
112			[ "$new_domain_name" = "$1" ] && warn=true
113		fi
114	fi
115	if [ -n "$new_domain_search" ]; then
116		if valid_domainname_list $new_domain_search; then
117			conf="${conf}search $new_domain_search$NL"
118		elif ! $warn; then
119			syslog err "Invalid domain name in list:" \
120			    "$new_domain_search"
121		fi
122	fi
123	for x in ${new_domain_name_servers}; do
124		conf="${conf}nameserver $x$NL"
125	done
126	if type resolvconf >/dev/null 2>&1; then
127		[ -n "$ifmetric" ] && export IF_METRIC="$ifmetric"
128		printf %s "$conf" | resolvconf -a "$ifname"
129		return $?
130	fi
131
132	if [ -e "$resolv_conf_dir/$ifname" ]; then
133		rm -f "$resolv_conf_dir/$ifname"
134	fi
135	[ -d "$resolv_conf_dir" ] || mkdir -p "$resolv_conf_dir"
136	printf %s "$conf" > "$resolv_conf_dir/$ifname"
137	build_resolv_conf
138}
139
140remove_resolv_conf()
141{
142	if type resolvconf >/dev/null 2>&1; then
143		resolvconf -d "$ifname" -f
144	else
145		if [ -e "$resolv_conf_dir/$ifname" ]; then
146			rm -f "$resolv_conf_dir/$ifname"
147		fi
148		build_resolv_conf
149	fi
150}
151
152# For ease of use, map DHCP6 names onto our DHCP4 names
153case "$reason" in
154BOUND6|RENEW6|REBIND6|REBOOT6|INFORM6)
155	new_domain_name_servers="$new_dhcp6_name_servers"
156	new_domain_search="$new_dhcp6_domain_search"
157	;;
158esac
159
160if $if_up || [ "$reason" = ROUTERADVERT ]; then
161	add_resolv_conf
162elif $if_down; then
163	remove_resolv_conf
164fi
165