[type/__dtnrch_getssl_script_henet] Add CNAME resolver using nslookup

1 files changed, 43 insertions, 39 deletions

diff --git a/type/__dtnrch_getssl_script_henet/files/dns/nslookup.sh b/type/__dtnrch_getssl_script_henet/files/dns/nslookup.sh
index c475e9a..53dbbdf 100644
--- a/type/__dtnrch_getssl_script_henet/files/dns/nslookup.sh
+++ b/type/__dtnrch_getssl_script_henet/files/dns/nslookup.sh
@@ -1,46 +1,50 @@
-find_auth_dns() (
-	domain=${1:?}
+if expr "$(ls -l "$(command -v nslookup)")" : '.*-> .*busybox' >/dev/null
+then
+	echo 'busybox nslookup is not supported.' >&2
+	exit 1
+fi
+
+LF='
+'
+
+find_zone_and_ns() {
+	zone=${1:?}
+	zone=${zone%.}
 
-	until test -n "${ns-}" || test "${domain}" = "${domain##*.}"
+	while test -n "${zone}"
 	do
-		ns=$(
-			nslookup -debug -type=NS "${domain}" \
-			| awk '\
-			  /^Authoritative answer/ { block = "non-auth" }
-			  /^Non-authoritative answer:$/ { block = "non-auth" }
-
-			  debug && /^[ ]{4}([A-Z][A-Z ]*):$/ {
-				  debug_block = substr($0, 5, length - 6)
-			  }
-			  debug_block == "ANSWERS" && /nameserver = / {
-				  key = "nameserver = "
-				  origin = substr($0, index($0, key) + length(key))
-			  }
-			  END { print origin }')
-
-		domain=${domain#*.}
+		if ! nslookup -nosearch -class=IN -type=CNAME "${zone}" \
+			| grep -q -F 'canonical name = '
+		then
+			# Only if not a CNAME
+			name_servers=$(
+				nslookup -nosearch -class=IN -type=NS "${zone}" \
+				| sed -n -e 's/^.*[[:space:]]nameserver = \(.*\)$/\1/p')
+			if test -n "${name_servers}"
+			then
+				break
+			fi
+		fi
+
+		zone=$(expr "${zone}" : '[^.]\{1,\}\.\(.*\)$')
 	done
-	test -n "${ns}" || return 2
-
-	# Check authority
-	echo $ns
-	origin=$(
-		nslookup -debug -type=SOA "$1" "${ns}" \
-		| awk '\
-		  /^-+$/ { debug = !debug; debug_block = "" }
-		  debug && /^[ ]{4}([A-Z][A-Z ]*):$/ {
-			  debug_block = substr($0, 5, length - 6)
-		  }
-		  debug { print debug_block }
-		  debug_block ~ /AUTHORITY RECORDS?/ && /origin = / {
-			  key = "origin = "
-			  print substr($0, index($0, key) + length(key))
-		  }')
-
-	test -n "${origin}" && echo "${origin}" || return 1
-)
+
+	test -n "${zone}" || return 1
+	ns=${name_servers%%${LF}*}
+	ns=${ns%.}
+	printf '%s@%s\n' "${zone}" "${ns}"
+}
 
 resolve_cnames() (
 	domain=${1:?}
-	auth_dns
+	domain=${domain%.}
+
+	zone_and_ns=$(find_zone_and_ns "${domain}")
+	ns=${zone_and_ns#*@}
+
+	cname=$(
+		nslookup -nosearch -norecurse -class=IN -type=CNAME "${domain}" "${ns}" \
+		| sed -n -e 's/^.*[[:space:]]canonical name = \(.*\)$/\1/p')
+
+	test -n "${cname}" && resolve_cnames "${cname}" || echo "${domain}"
 )