tc/em_cmp.c

   1 /*
   2  * em_cmp.c             Simple comparison Ematch
   3  *
   4  *              This program is free software; you can distribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15 #include <syslog.h>
  16 #include <fcntl.h>
  17 #include <sys/socket.h>
  18 #include <netinet/in.h>
  19 #include <arpa/inet.h>
  20 #include <string.h>
  21 #include <errno.h>
  22
  23 #include "m_ematch.h"
  24 #include <linux/tc_ematch/tc_em_cmp.h>
  25
  26 extern struct ematch_util cmp_ematch_util;
  27
  28 static void cmp_print_usage(FILE *fd)
  29 {
  30         fprintf(fd,
  31             "Usage: cmp(ALIGN at OFFSET [ ATTRS ] { eq | lt | gt } VALUE)\n" \
  32             "where: ALIGN  := { u8 | u16 | u32 }\n" \
  33             "       ATTRS  := [ layer LAYER ] [ mask MASK ] [ trans ]\n" \
  34             "       LAYER  := { link | network | transport | 0..%d }\n" \
  35             "\n" \
  36             "Example: cmp(u16 at 3 layer 2 mask 0xff00 gt 20)\n",
  37             TCF_LAYER_MAX);
  38 }
  39
  40 static int cmp_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
  41                           struct bstr *args)
  42 {
  43         struct bstr *a;
  44         int align, opnd = 0;
  45         unsigned long offset = 0, layer = TCF_LAYER_NETWORK, mask = 0, value = 0;
  46         int offset_present = 0, value_present = 0;
  47         struct tcf_em_cmp cmp;
  48
  49         memset(&cmp, 0, sizeof(cmp));
  50
  51 #define PARSE_ERR(CARG, FMT, ARGS...) \
  52         em_parse_error(EINVAL, args, CARG, &cmp_ematch_util, FMT ,##ARGS)
  53
  54         if (args == NULL)
  55                 return PARSE_ERR(args, "cmp: missing arguments");
  56
  57         if (!bstrcmp(args, "u8"))
  58                 align = TCF_EM_ALIGN_U8;
  59         else if (!bstrcmp(args, "u16"))
  60                 align = TCF_EM_ALIGN_U16;
  61         else if (!bstrcmp(args, "u32"))
  62                 align = TCF_EM_ALIGN_U32;
  63         else
  64                 return PARSE_ERR(args, "cmp: invalid alignment");
  65
  66         for (a = bstr_next(args); a; a = bstr_next(a)) {
  67                 if (!bstrcmp(a, "at")) {
  68                         if (a->next == NULL)
  69                                 return PARSE_ERR(a, "cmp: missing argument");
  70                         a = bstr_next(a);
  71
  72                         offset = bstrtoul(a);
  73                         if (offset == ULONG_MAX)
  74                                 return PARSE_ERR(a, "cmp: invalid offset, " \
  75                                     "must be numeric");
  76
  77                         offset_present = 1;
  78                 } else if (!bstrcmp(a, "layer")) {
  79                         if (a->next == NULL)
  80                                 return PARSE_ERR(a, "cmp: missing argument");
  81                         a = bstr_next(a);
  82
  83                         layer = parse_layer(a);
  84                         if (layer == INT_MAX) {
  85                                 layer = bstrtoul(a);
  86                                 if (layer == ULONG_MAX)
  87                                         return PARSE_ERR(a, "cmp: invalid " \
  88                                             "layer");
  89                         }
  90
  91                         if (layer > TCF_LAYER_MAX)
  92                                 return PARSE_ERR(a, "cmp: illegal layer, " \
  93                                     "must be in 0..%d", TCF_LAYER_MAX);
  94                 } else if (!bstrcmp(a, "mask")) {
  95                         if (a->next == NULL)
  96                                 return PARSE_ERR(a, "cmp: missing argument");
  97                         a = bstr_next(a);
  98
  99                         mask = bstrtoul(a);
 100                         if (mask == ULONG_MAX)
 101                                 return PARSE_ERR(a, "cmp: invalid mask");
 102                 } else if (!bstrcmp(a, "trans")) {
 103                         cmp.flags |= TCF_EM_CMP_TRANS;
 104                 } else if (!bstrcmp(a, "eq") || !bstrcmp(a, "gt") ||
 105                     !bstrcmp(a, "lt")) {
 106
 107                         if (!bstrcmp(a, "eq"))
 108                                 opnd = TCF_EM_OPND_EQ;
 109                         else if (!bstrcmp(a, "gt"))
 110                                 opnd = TCF_EM_OPND_GT;
 111                         else if (!bstrcmp(a, "lt"))
 112                                 opnd = TCF_EM_OPND_LT;
 113
 114                         if (a->next == NULL)
 115                                 return PARSE_ERR(a, "cmp: missing argument");
 116                         a = bstr_next(a);
 117
 118                         value = bstrtoul(a);
 119                         if (value == ULONG_MAX)
 120                                 return PARSE_ERR(a, "cmp: invalid value");
 121
 122                         value_present = 1;
 123                 } else
 124                         return PARSE_ERR(a, "nbyte: unknown parameter");
 125         }
 126
 127         if (offset_present == 0 || value_present == 0)
 128                 return PARSE_ERR(a, "cmp: offset and value required");
 129
 130         cmp.val = (__u32) value;
 131         cmp.mask = (__u32) mask;
 132         cmp.off = (__u16) offset;
 133         cmp.align = (__u8) align;
 134         cmp.layer = (__u8) layer;
 135         cmp.opnd = (__u8) opnd;
 136
 137         addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
 138         addraw_l(n, MAX_MSG, &cmp, sizeof(cmp));
 139
 140 #undef PARSE_ERR
 141         return 0;
 142 }
 143
 144 static int cmp_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
 145                           int data_len)
 146 {
 147         struct tcf_em_cmp *cmp = data;
 148
 149         if (data_len < sizeof(*cmp)) {
 150                 fprintf(stderr, "CMP header size mismatch\n");
 151                 return -1;
 152         }
 153
 154         if (cmp->align == TCF_EM_ALIGN_U8)
 155                 fprintf(fd, "u8 ");
 156         else if (cmp->align == TCF_EM_ALIGN_U16)
 157                 fprintf(fd, "u16 ");
 158         else if (cmp->align == TCF_EM_ALIGN_U32)
 159                 fprintf(fd, "u32 ");
 160
 161         fprintf(fd, "at %d layer %d ", cmp->off, cmp->layer);
 162
 163         if (cmp->mask)
 164                 fprintf(fd, "mask 0x%x ", cmp->mask);
 165
 166         if (cmp->flags & TCF_EM_CMP_TRANS)
 167                 fprintf(fd, "trans ");
 168
 169         if (cmp->opnd == TCF_EM_OPND_EQ)
 170                 fprintf(fd, "eq ");
 171         else if (cmp->opnd == TCF_EM_OPND_LT)
 172                 fprintf(fd, "lt ");
 173         else if (cmp->opnd == TCF_EM_OPND_GT)
 174                 fprintf(fd, "gt ");
 175
 176         fprintf(fd, "%d", cmp->val);
 177
 178         return 0;
 179 }
 180
 181 struct ematch_util cmp_ematch_util = {
 182         .kind = "cmp",
 183         .kind_num = TCF_EM_CMP,
 184         .parse_eopt = cmp_parse_eopt,
 185         .print_eopt = cmp_print_eopt,
 186         .print_usage = cmp_print_usage
 187 };