From 72e038b9bf2dfbc97b4ba2b21a7a214137b53da6 Mon Sep 17 00:00:00 2001
From: Matias Fontanini <matias.fontanini@gmail.com>
Date: Thu, 4 Feb 2016 20:20:14 -0800
Subject: [PATCH] Fix invalid endian on IP fragment offset on OSX

---
 src/ip.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/ip.cpp b/src/ip.cpp
index d822098..4d0b79d 100644
--- a/src/ip.cpp
+++ b/src/ip.cpp
@@ -429,10 +429,13 @@ void IP::write_serialization(uint8_t* buffer, uint32_t total_sz, const PDU* pare
             protocol(new_flag);
         }
     }
+
+    uint16_t original_frag_off = ip_.frag_off;
     
     #if __FreeBSD__ || defined(__FreeBSD_kernel__) || __APPLE__
         if (!parent) {
             total_sz = Endian::host_to_be<uint16_t>(total_sz);
+            ip_.frag_off = Endian::be_to_host(ip_.frag_off);
         }
     #endif
     tot_len(total_sz);
@@ -440,6 +443,9 @@ void IP::write_serialization(uint8_t* buffer, uint32_t total_sz, const PDU* pare
 
     stream.write(ip_);
 
+    // Restore the fragment offset field in case we flipped it
+    ip_.frag_off = original_frag_off;
+
     for (options_type::const_iterator it = ip_options_.begin(); it != ip_options_.end(); ++it) {
         write_option(*it, stream);
     }