busybox: nslookup_lede: mimic output format of old Busybox applet

When invoking "nslookup_lede" with a domain argument and without explicit
query type, issue both A and AAAA queries and display the resulting IP
addresses in a numbered list style, similar to how the old BusyBox nslookup
used to output the records.

This is required for compatibility with certain scripts.

Ref: https://forum.lede-project.org/t/nslookup-ipv6-in-lede-17-01-1

Signed-off-by: Jo-Philipp Wich <[email protected]>

package/utils/busybox/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=busybox
 PKG_VERSION:=1.26.2
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 PKG_FLAGS:=essential
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2

package/utils/busybox/patches/230-add_nslookup_lede.patch

@@ -1,4 +1,4 @@
-From 1188f159e0b0a9c07bed835c7313bedf5322a9e3 Mon Sep 17 00:00:00 2001
+From ab0f8bb80527928f513297ab93e3ec8c8b48dd50 Mon Sep 17 00:00:00 2001
 From: Jo-Philipp Wich <[email protected]>
 Date: Tue, 14 Mar 2017 22:21:34 +0100
 Subject: [PATCH] networking: add LEDE nslookup applet
@@ -12,16 +12,34 @@ and the libresolv primitives to parse received DNS responses.
 
 Signed-off-by: Jo-Philipp Wich <[email protected]>
 ---
- networking/nslookup_lede.c | 894 +++++++++++++++++++++++++++++++++++++++++++++
- 1 file changed, 894 insertions(+)
+ Makefile.flags             |   6 +
+ networking/nslookup_lede.c | 915 +++++++++++++++++++++++++++++++++++++++++++++
+ 2 files changed, 921 insertions(+)
  create mode 100644 networking/nslookup_lede.c
 
+diff --git a/Makefile.flags b/Makefile.flags
+index 65021de25..096ab7756 100644
+--- a/Makefile.flags
++++ b/Makefile.flags
+@@ -134,6 +134,12 @@ else
+ LDLIBS += m
+ endif
+ 
++# nslookup_lede might need the resolv library
++RESOLV_AVAILABLE := $(shell echo 'int main(void){res_init();return 0;}' >resolvtest.c; $(CC) $(CFLAGS) -include resolv.h -lresolv -o /dev/null resolvtest.c >/dev/null 2>&1 && echo "y"; rm resolvtest.c)
++ifeq ($(RESOLV_AVAILABLE),y)
++LDLIBS += resolv
++endif
++
+ # libpam may use libpthread, libdl and/or libaudit.
+ # On some platforms that requires an explicit -lpthread, -ldl, -laudit.
+ # However, on *other platforms* it fails when some of those flags
 diff --git a/networking/nslookup_lede.c b/networking/nslookup_lede.c
 new file mode 100644
-index 000000000..f3e42d3bb
+index 000000000..c6c90ddf3
 --- /dev/null
 +++ b/networking/nslookup_lede.c
-@@ -0,0 +1,894 @@
+@@ -0,0 +1,915 @@
 +/*
 + * nslookup_lede - musl compatible replacement for busybox nslookup
 + *
@@ -145,7 +163,7 @@ index 000000000..f3e42d3bb
 +static unsigned int default_timeout = 5;
 +
 +
-+static int parse_reply(const unsigned char *msg, size_t len)
++static int parse_reply(const unsigned char *msg, size_t len, int *bb_style_counter)
 +{
 +	ns_msg handle;
 +	ns_rr rr;
@@ -165,6 +183,9 @@ index 000000000..f3e42d3bb
 +			return -1;
 +		}
 +
++		if (bb_style_counter && *bb_style_counter == 1)
++			printf("Name:      %s\n", ns_rr_name(rr));
++
 +		rdlen = ns_rr_rdlen(rr);
 +
 +		switch (ns_rr_type(rr))
@@ -175,7 +196,10 @@ index 000000000..f3e42d3bb
 +				return -1;
 +			}
 +			inet_ntop(AF_INET, ns_rr_rdata(rr), astr, sizeof(astr));
-+			printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
++			if (bb_style_counter)
++				printf("Address %d: %s\n", (*bb_style_counter)++, astr);
++			else
++				printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
 +			break;
 +
 +#if ENABLE_FEATURE_IPV6
@@ -185,7 +209,10 @@ index 000000000..f3e42d3bb
 +				return -1;
 +			}
 +			inet_ntop(AF_INET6, ns_rr_rdata(rr), astr, sizeof(astr));
-+			printf("%s\thas AAAA address %s\n", ns_rr_name(rr), astr);
++			if (bb_style_counter)
++				printf("Address %d: %s\n", (*bb_style_counter)++, astr);
++			else
++				printf("%s\thas AAAA address %s\n", ns_rr_name(rr), astr);
 +			break;
 +#endif
 +
@@ -752,7 +779,7 @@ index 000000000..f3e42d3bb
 +	llist_t *type_strings = NULL;
 +	int n_ns = 0, n_queries = 0;
 +	int c, opts, option_index = 0;
-+	int stats = 0;
++	int stats = 0, bb_style_counter = 0;
 +	unsigned int types = 0;
 +	HEADER *header;
 +
@@ -769,10 +796,8 @@ index 000000000..f3e42d3bb
 +		ptr = llist_pop(&type_strings);
 +
 +		/* skip leading text, e.g. when invoked with -querytype=AAAA */
-+		if ((chr = strchr(ptr, '=')) != NULL) {
-+			ptr = chr;
-+			*ptr++ = 0;
-+		}
++		if ((chr = strchr(ptr, '=')) != NULL)
++			ptr = chr + 1;
 +
 +		for (c = 0; qtypes[c].name; c++)
 +			if (!strcmp(qtypes[c].name, ptr))
@@ -813,14 +838,21 @@ index 000000000..f3e42d3bb
 +		/* No explicit type given, guess query type.
 +		 * If we can convert the domain argument into a ptr (means that
 +		 * inet_pton() could read it) we assume a PTR request, else
-+		 * we issue A queries. */
++		 * we issue A+AAAA queries and switch to an output format
++		 * mimicking the one of the traditional nslookup applet. */
 +		if (types == 0) {
 +			ptr = make_ptr(argv[option_index]);
 +
-+			if (ptr)
++			if (ptr) {
 +				add_query(&queries, &n_queries, T_PTR, ptr);
-+			else
++			}
++			else {
++				bb_style_counter = 1;
 +				add_query(&queries, &n_queries, T_A, argv[option_index]);
++#if ENABLE_FEATURE_IPV6
++				add_query(&queries, &n_queries, T_AAAA, argv[option_index]);
++#endif
++			}
 +		}
 +		else {
 +			for (c = 0; qtypes[c].name; c++)
@@ -889,12 +921,18 @@ index 000000000..f3e42d3bb
 +		c = 0;
 +
 +		if (queries[rc].rlen) {
-+			header = (HEADER *)queries[rc].reply;
++			if (!bb_style_counter) {
++				header = (HEADER *)queries[rc].reply;
 +
-+			if (!header->aa)
-+				printf("Non-authoritative answer:\n");
++				if (!header->aa)
++					printf("Non-authoritative answer:\n");
 +
-+			c = parse_reply(queries[rc].reply, queries[rc].rlen);
++				c = parse_reply(queries[rc].reply, queries[rc].rlen, NULL);
++			}
++			else {
++				c = parse_reply(queries[rc].reply, queries[rc].rlen,
++				                &bb_style_counter);
++			}
 +		}
 +
 +		if (c == 0)
@@ -902,7 +940,8 @@ index 000000000..f3e42d3bb
 +		else if (c < 0)
 +			printf("*** Can't find %s: Parse error\n", queries[rc].name);
 +
-+		printf("\n");
++		if (!bb_style_counter)
++			printf("\n");
 +	}
 +
 +	rc = 0;