From: Michael Altizer (mialtize) <mialtize@cisco.com>
Date: Tue, 8 Oct 2019 15:23:53 +0000 (-0400)
Subject: Merge pull request #1785 in SNORT/snort3 from ~MIALTIZE/snort3:cksum_alignment to... 
X-Git-Tag: 3.0.0-262~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=900c723709891c928005357841dccda75954889c;p=thirdparty%2Fsnort3.git

Merge pull request #1785 in SNORT/snort3 from ~MIALTIZE/snort3:cksum_alignment to master

Squashed commit of the following:

commit e4482a20e1e3c5720bd83d999baba9e6baffe5da
Author: Michael Altizer <mialtize@cisco.com>
Date:   Mon Oct 7 15:13:32 2019 -0400

    codecs: Fix checksumming a single byte of unaligned data
---

diff --git a/src/codecs/ip/checksum.h b/src/codecs/ip/checksum.h
index d8a62d142..53e303d5c 100644
--- a/src/codecs/ip/checksum.h
+++ b/src/codecs/ip/checksum.h
@@ -100,9 +100,6 @@ inline uint16_t cksum_add(const uint16_t* buf, std::size_t len, uint32_t cksum)
             cksum += *sp++;
             len -= 2;
         }
-        // if len was odd, sum in the last byte...
-        if ( len )
-            cksum += (uint16_t) *(const uint8_t *)sp;
     }
     else if ( len > 1 )
     {
@@ -168,11 +165,12 @@ inline uint16_t cksum_add(const uint16_t* buf, std::size_t len, uint32_t cksum)
             cksum += sp[15];
             sp += 16;
         }
-        // if len is odd, sum in the last byte...
-        if ( len & 0x01)
-            cksum += (uint16_t) *(const uint8_t *)sp;
     }
 
+    // if len is odd, sum in the last byte...
+    if ( len & 0x01 )
+        cksum += *((const uint8_t*) sp);
+
     cksum  = (cksum >> 16) + (cksum & 0x0000ffff);
     cksum += (cksum >> 16);