[openwrt/openwrt] map: fix psidlen becoming negative (FS#1430)

[LEDE Commits]

dedeckeh pushed a commit to openwrt/openwrt.git, branch master:
https://git.lede-project.org/479aaf6375e1823c484e2251f11eee5b911c48e7

commit 479aaf6375e1823c484e2251f11eee5b911c48e7
Author: Hans Dedecker <dedeckeh at gmail.com>
AuthorDate: Thu Mar 29 16:25:14 2018 +0200

    map: fix psidlen becoming negative (FS#1430)
    
    Fix psidlen becomes negative in case embedded address bit lenght is smaller than
    IPv4 suffix length.
    While at it improve parameter checking making the code more logical and
    easier to read.
    
    Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
---
 package/network/ipv6/map/Makefile      |  2 +-
 package/network/ipv6/map/src/mapcalc.c | 26 ++++++++++++++++----------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/package/network/ipv6/map/Makefile b/package/network/ipv6/map/Makefile
index ce04235..7796704 100644
--- a/package/network/ipv6/map/Makefile
+++ b/package/network/ipv6/map/Makefile
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=map
 PKG_VERSION:=4
-PKG_RELEASE:=9
+PKG_RELEASE:=10
 PKG_LICENSE:=GPL-2.0
 
 include $(INCLUDE_DIR)/package.mk
diff --git a/package/network/ipv6/map/src/mapcalc.c b/package/network/ipv6/map/src/mapcalc.c
index 6233bce..66610c4 100644
--- a/package/network/ipv6/map/src/mapcalc.c
+++ b/package/network/ipv6/map/src/mapcalc.c
@@ -4,6 +4,7 @@
  * Author: Steven Barth <cyrus at openwrt.org>
  * Copyright (c) 2014-2015 cisco Systems, Inc.
  * Copyright (c) 2015 Steven Barth <cyrus at openwrt.org>
+ * Copyright (c) 2018 Hans Dedecker <dedeckeh at gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2
@@ -311,25 +312,30 @@ int main(int argc, char *argv[])
 
 		if (psidlen <= 0) {
 			psidlen = ealen - (32 - prefix4len);
+			if (psidlen < 0)
+				psidlen = 0;
+
 			psid = -1;
 		}
 
-		if (psid < 0 && psidlen <= 16 && psidlen >= 0 && pdlen >= 0 && ealen >= psidlen) {
+		if (prefix4len < 0 || prefix6len < 0 || ealen < 0 || psidlen > 16 || ealen < psidlen) {
+			fprintf(stderr, "Skipping invalid or incomplete rule: %s\n", argv[i]);
+			status = 1;
+			continue;
+		}
+
+		if (psid < 0 && psidlen >= 0 && pdlen >= 0) {
 			bmemcpys64(&psid16, &pd, prefix6len + ealen - psidlen, psidlen);
 			psid = be16_to_cpu(psid16);
 		}
 
-		psid = psid >> (16 - psidlen);
-		psid16 = cpu_to_be16(psid);
-		psid = psid << (16 - psidlen);
-
-		if (prefix4len < 0 || prefix6len < 0 || ealen < 0 || ealen < psidlen) {
-			fprintf(stderr, "Skipping invalid or incomplete rule: %s\n", argv[i]);
-			status = 1;
-			continue;
+		if (psidlen > 0) {
+			psid = psid >> (16 - psidlen);
+			psid16 = cpu_to_be16(psid);
+			psid = psid << (16 - psidlen);
 		}
 
-		if ((pdlen >= 0 || ealen == psidlen) && ealen >= psidlen) {
+		if (pdlen >= 0 || ealen == psidlen) {
 			bmemcpys64(&ipv4addr, &pd, prefix6len, ealen - psidlen);
 			ipv4addr.s_addr = htonl(ntohl(ipv4addr.s_addr) >> prefix4len);
 			bmemcpy(&ipv4addr, &ipv4prefix, prefix4len);