From 8604fcb3686a74d8f2a0632027525486febd45a4 Mon Sep 17 00:00:00 2001
From: Tom Marshall <tdm.code@gmail.com>
Date: Thu, 16 Jan 2020 13:07:04 -0800
Subject: [PATCH] bionic: Support wildcards in cached hosts file

If an exact name is not found in the hosts file and the host name
contains at least one dot, search for entries of the form "*.domain",
where domain is the portion of the host name after the first dot.  If
that is not found, repeat using the domain.

Example: a.b.c.example.com would search for the following in turn:
	a.b.c.example.com
	*.b.c.example.com
	*.c.example.com
	*.example.com
	*.com

Change-Id: I4b0bb81699151d5b371850daebf785e35ec9b180
---
 libc/dns/net/hosts_cache.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/libc/dns/net/hosts_cache.c b/libc/dns/net/hosts_cache.c
index deafb78b73..5038986be6 100644
--- a/libc/dns/net/hosts_cache.c
+++ b/libc/dns/net/hosts_cache.c
@@ -121,7 +121,7 @@ static int cmp_hcent_name(const void *a, const void *b)
 	return hstrcmp(na, nb);
 }
 
-static struct hcent *_hcfindname(const char *name)
+static struct hcent *_hcfindname_exact(const char *name)
 {
 	size_t first, last, mid;
 	struct hcent *cur = NULL;
@@ -162,6 +162,33 @@ static struct hcent *_hcfindname(const char *name)
 	return cur;
 }
 
+static struct hcent *_hcfindname(const char *name)
+{
+	struct hcent *ent;
+	char namebuf[MAX_HOSTLEN];
+	char *p;
+	char *dot;
+
+	ent = _hcfindname_exact(name);
+	if (!ent && strlen(name) < sizeof(namebuf)) {
+		strcpy(namebuf, name);
+		p = namebuf;
+		do {
+			dot = strchr(p, '.');
+			if (!dot)
+				break;
+			if (dot > p) {
+				*(dot - 1) = '*';
+				ent = _hcfindname_exact(dot - 1);
+			}
+			p = dot + 1;
+		}
+		while (!ent);
+	}
+
+	return ent;
+}
+
 /*
  * Find next name on line, if any.
  *
