[U-Boot] [PATCH] lib: net_utils: make string_to_ip stricter

[Chris Packham <judge.packham@gmail.com>]

Previously values greater than 255 were implicitly truncated. Add some
stricter checking to reject addresses with components >255.

With the input "1234192.168.1.1" the old behaviour would truncate the
address to 192.168.1.1. New behaviour rejects the string outright and
returns 0.0.0.0, which for the purposes of IP addresses can be
considered an error.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
---
This was part of my long running IPv6 patchset (which I promise I'll get
back to someday). But I feel this stands on it's own merits.

 lib/net_utils.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/net_utils.c b/lib/net_utils.c
index cfae84275241..f148b8a70a7d 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -24,11 +24,16 @@ struct in_addr string_to_ip(const char *s)
 
 	for (addr.s_addr = 0, i = 0; i < 4; ++i) {
 		ulong val = s ? simple_strtoul(s, &e, 10) : 0;
+		if (val > 255) {
+			addr.s_addr = 0;
+			return addr;
+		}
 		addr.s_addr <<= 8;
 		addr.s_addr |= (val & 0xFF);
-		if (s) {
-			s = (*e) ? e+1 : e;
-		}
+		if (*e == '.')
+			s = e + 1;
+		else
+			break;
 	}
 
 	addr.s_addr = htonl(addr.s_addr);
-- 
2.11.0.24.ge6920cf