/*
 * Mausezahn - A fast versatile traffic generator
 * Copyright (C) 2008-2010 Herbert Haas
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the 
 * Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT 
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with 
 * this program; if not, see http://www.gnu.org/licenses/gpl-2.0.html
 * 
*/

#include "mz.h"
#include "mops.h"




// -- TOC: --
//
// u_int16_t      mops_sum16                  (u_int16_t len, u_int8_t buff[])
// int            mops_get_transport_sum      (struct mops *mp)


//////////////////////////////////////////////////////////////////////////////////
//
//  See also:
//  
//  RFC1071 - Computing the Internet checksum
//  
//////////////////////////////////////////////////////////////////////////////////



// Generic 16-bit checksum code as required for IP and other headers.
// The checksum is calculated over buff[] which is of length len. 
//
// RETURN VALUE: The checksum! (Validated - correct!!!)
// 
// Example:  t16 = mops_sum16 (20, &mp->frame[fp]);
// 
u_int16_t mops_sum16 (u_int16_t len, u_int8_t buff[])
{
   
   u_int16_t word16;
   u_int32_t sum=0;
   u_int16_t i;
       
   // make 16 bit words out of every two adjacent 8 bit words in the packet and add them up
   for (i=0; i<len; i=i+2)
     {
	word16 =((buff[i]<<8)&0xFF00)+buff[i+1];
	sum = sum + (u_int32_t) word16;
     }
   
   // take only 16 bits out of the 32 bit sum and add up the carries
   while (sum>>16)
     sum = (sum & 0xFFFF)+(sum >> 16);
   
   // one's complement the result
   sum = ~sum;
   
   return ((u_int16_t) sum);
}





// sets UDP or TCP checksum within mp[]->frame
//   TODO: copying the whole segment is ugly and slow;
//         make it more efficient and realize it in-place.
//         
int mops_get_transport_sum(struct mops *mp)
{
   u_int8_t buf[MAX_PAYLOAD_SIZE];
   u_int16_t len;
   int udp_used;
   
   u_int16_t sum;
   
   udp_used = mp->use_UDP; // 0 or 1, 0 means TCP
   
   // IP Pseudoheader (12 Bytes)
   mops_hton4(&mp->ip_src, &buf[0]);
   mops_hton4(&mp->ip_dst, &buf[4]);
   buf[9]=0x00;

   
   // Copy segment
   if (udp_used) 
     {
	buf[10]=0x11; // proto UDP (17 dec)
	len = mp->udp_len;
	mops_hton2(&len, &buf[11]);
	memcpy(&buf[13], &mp->frame[mp->begin_UDP], len);
	// reset checksum to zero
	buf[19] = 0x00;
	buf[20] = 0x00;
	sum = mops_sum16(len+12, buf); 
	// insert checksum in UDP header (in frame)
	mops_hton2 (&sum, &mp->frame[(mp->begin_UDP)+7]);

     }
   else
     {
	buf[10]=0x06; // proto TCP
	len = mp->ip_len - mp->ip_IHL;
	mops_hton2((u_int16_t*)&len, &buf[11]);
	memcpy(&buf[13], &mp->frame[mp->begin_TCP], len);
	// reset checksum to zero
	buf[29] = 0x00;
	buf[30] = 0x00;
	sum = mops_sum16(len+12, buf);
	// insert checksum in TCP header (in frame)
	mops_hton2 (&sum, &mp->frame[(mp->begin_TCP)+17]);
     }
   
   
   return 0;
}

);'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2016-12-12 21:58:13 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2016-12-12 21:58:13 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/ecryptfs?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba</a> (<a href='/cgit.cgi/linux/net-next.git/patch/fs/ecryptfs?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/'>f63906f41699c8e38af9d12b063e2ceab0286ef2</a> /<a href='/cgit.cgi/linux/net-next.git/tree/fs/ecryptfs'>fs/ecryptfs</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/ecryptfs?id=e34bac726d27056081d0250c0e173e4b155aa340'>e34bac726d27056081d0250c0e173e4b155aa340</a> (<a href='/cgit.cgi/linux/net-next.git/diff/fs/ecryptfs?id2=e34bac726d27056081d0250c0e173e4b155aa340'>diff</a>)</td></tr><tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/ecryptfs?id=868c97a846a73e937d835b09b8c885a69df50ec8'>868c97a846a73e937d835b09b8c885a69df50ec8</a> (<a href='/cgit.cgi/linux/net-next.git/diff/fs/ecryptfs?id2=868c97a846a73e937d835b09b8c885a69df50ec8'>diff</a>)</td></tr></table>
<div class='commit-subject'>Merge tag 'docs-4.10' of git://git.lwn.net/linux<span class='decoration'><a class='deco' href='/cgit.cgi/linux/net-next.git/commit/fs/ecryptfs?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>HEAD</a><a class='branch-deco' href='/cgit.cgi/linux/net-next.git/log/fs/ecryptfs'>master</a></span></div><div class='commit-msg'>Pull documentation update from Jonathan Corbet:
 "These are the documentation changes for 4.10.

  It's another busy cycle for the docs tree, as the sphinx conversion
  continues. Highlights include:

   - Further work on PDF output, which remains a bit of a pain but
     should be more solid now.

   - Five more DocBook template files converted to Sphinx. Only 27 to
     go... Lots of plain-text files have also been converted and
     integrated.

   - Images in binary formats have been replaced with more
     source-friendly versions.

   - Various bits of organizational work, including the renaming of
     various files discussed at the kernel summit.

   - New documentation for the device_link mechanism.

  ... and, of course, lots of typo fixes and small updates"

* tag 'docs-4.10' of git://git.lwn.net/linux: (193 commits)
  dma-buf: Extract dma-buf.rst
  Update Documentation/00-INDEX
  docs: 00-INDEX: document directories/files with no docs
  docs: 00-INDEX: remove non-existing entries
  docs: 00-INDEX: add missing entries for documentation files/dirs
  docs: 00-INDEX: consolidate process/ and admin-guide/ description
  scripts: add a script to check if Documentation/00-INDEX is sane
  Docs: change sh -&gt; awk in REPORTING-BUGS
  Documentation/core-api/device_link: Add initial documentation
  core-api: remove an unexpected unident
  ppc/idle: Add documentation for powersave=off
  Doc: Correct typo, "Introdution" =&gt; "Introduction"
  Documentation/atomic_ops.txt: convert to ReST markup
  Documentation/local_ops.txt: convert to ReST markup
  Documentation/assoc_array.txt: convert to ReST markup
  docs-rst: parse-headers.pl: cleanup the documentation
  docs-rst: fix media cleandocs target
  docs-rst: media/Makefile: reorganize the rules
  docs-rst: media: build SVG from graphviz files
  docs-rst: replace bayer.png by a SVG image
  ...
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/'>Diffstat</a> (limited to 'fs/ecryptfs')</div><table summary='diffstat' class='diffstat'>