src/mops_mpls.c

   1 /*
   2  * Mausezahn - A fast versatile traffic generator
   3  * Copyright (C) 2008-2010 Herbert Haas
   4  *
   5  * This program is free software; you can redistribute it and/or modify it under
   6  * the terms of the GNU General Public License version 2 as published by the
   7  * Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  11  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
  12  * details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, see http://www.gnu.org/licenses/gpl-2.0.html
  16  *
  17 */
  18
  19
  20 #include "mz.h"
  21 #include "mops.h"
  22
  23 // Assigns MPLS tag at position i (starting at zero!) with values:
  24 //
  25 //  m        ... total number of tags (important to set BoS in last tag)
  26 //  Label    ... label value
  27 //  Exp      ... EXP field (typically CoS)
  28 //  TTL      ... Time To Live
  29 //
  30 // NOTE: Two usage possibilities!
  31 //
  32 //   1.) When called from for-loop to add all tags the total size mpls_s
  33 //       is updated continuously and the BoS is set in the last tag.
  34 //       Therefore set m = total number of tags!
  35 //
  36 //   2.) But when changing a particular tag within an existing MPLS stack
  37 //       the total number of tags does not change, therefore use m=0.
  38 //
  39 // RETURN VALUE: 0 upon success, 1 upon failure
  40 //
  41 int mops_mpls(struct mops *mp, int i, int m, u_int32_t Label, u_int8_t Exp, u_int8_t TTL)
  42 {
  43    u_int8_t *ptr;
  44
  45    if ((m) && (i>=m)) return 1; // label index greater than number of labels!
  46    if (Label > 1048575) return 1;
  47    if (Exp > 7) return 1;
  48
  49    // Create binary tag: Label(20) EXP(3) BoS(1) TTL(8)
  50    Label <<= 4;
  51    ptr = (u_int8_t *) &Label;
  52    mp->mpls[4*i+0] = *(ptr+2);
  53    mp->mpls[4*i+1] = *(ptr+1);
  54    mp->mpls[4*i+2] = *(ptr+0);
  55    Exp <<= 1;
  56    mp->mpls[4*i+2] |= Exp;
  57    mp->mpls[4*i+3] = TTL;
  58
  59    if ((m) && (i==(m-1)))  // reached last tag!
  60        {
  61           mp->mpls[4*i+2] |= 0x01; // set BoS in last tag
  62           mp->mpls_s =4*m;
  63           mp->use_MPLS = 1;
  64           if ( (mp->eth_type != 0x8847) && (mp->eth_type != 0x8848) )
  65             {
  66                mp->eth_type_backup = mp->eth_type;
  67             }
  68           mp->eth_type = 0x8847;
  69        }
  70    return 0;
  71 }
  72
  73
  74 // Remove MPLS tags from packet mp
  75 //
  76 // j indicates which tag to be removed (1..n)
  77 // j=0 means: remove all tags!
  78 //
  79 // RETURN VALUE: 1 upon failure, 0 upon success
  80 int mops_mpls_remove (struct mops *mp, int j)
  81 {
  82    int a, b, k;
  83
  84
  85    if (j==0)  // remove all tags
  86      {
  87         if (mp->use_MPLS)
  88           {
  89              mp->mpls_s=0;
  90              mp->use_MPLS=0;
  91              mp->eth_type = mp->eth_type_backup; // restore original ethertype
  92              return 0;
  93           }
  94         else
  95           return 1;
  96      }
  97
  98    k = mp->mpls_s/4;
  99    if (j>k) return 1;   // The packet only consists of k tag(s)
 100
 101    if (k==1) // only delete the single tag
 102      {
 103         mp->mpls_s=0;
 104         mp->use_MPLS=0;
 105         mp->eth_type = mp->eth_type_backup; // restore original ethertype
 106         return 0;
 107      }
 108
 109    // if we got here we have more than one tag:
 110
 111    if (j==k) // remove last tag (of several)
 112      {
 113         mp->mpls_s -=4;
 114         return 0;
 115      }
 116
 117    // remove some non-ending tag: 0, 1, 2, 3
 118    a = (j-1)*4; // target
 119    b = j*4;     // source (what should be copied)
 120    memcpy(&mp->mpls[a], &mp->mpls[b], (k-j)*4);
 121    mp->mpls_s -=4;
 122    return 0;
 123 }
 124
 125
 126 // Set BOS in tag k where k=1..n
 127 int mops_mpls_bos (struct mops *mp, int k)
 128 {
 129    int n;
 130
 131    n = mp->mpls_s/4; // n = total number of tags
 132    if (k>n) return 1;
 133
 134    mp->mpls[(k-1)*4+2] |= 0x01;
 135    return 0;
 136 }
 137
 138
 139 // Unset BOS in tag k where k=1..n
 140 int mops_mpls_nobos (struct mops *mp, int k)
 141 {
 142    int n;
 143
 144    n = mp->mpls_s/4; // n = total number of tags
 145    if (k>n) return 1;
 146
 147    mp->mpls[(k-1)*4+2] &= 0xfe;
 148    return 0;
 149 }