tc/em_u32.c

   1 /*
   2  * em_u32.c             U32 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 <fcntl.h>
  16 #include <sys/socket.h>
  17 #include <netinet/in.h>
  18 #include <arpa/inet.h>
  19 #include <string.h>
  20 #include <errno.h>
  21
  22 #include "m_ematch.h"
  23
  24 extern struct ematch_util u32_ematch_util;
  25
  26 static void u32_print_usage(FILE *fd)
  27 {
  28         fprintf(fd,
  29             "Usage: u32(ALIGN VALUE MASK at [ nexthdr+ ] OFFSET)\n" \
  30             "where: ALIGN  := { u8 | u16 | u32 }\n" \
  31             "\n" \
  32             "Example: u32(u16 0x1122 0xffff at nexthdr+4)\n");
  33 }
  34
  35 static int u32_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
  36                           struct bstr *args)
  37 {
  38         struct bstr *a;
  39         int align, nh_len;
  40         unsigned long key, mask, offmask = 0, offset;
  41         struct tc_u32_key u_key = {};
  42
  43 #define PARSE_ERR(CARG, FMT, ARGS...) \
  44         em_parse_error(EINVAL, args, CARG, &u32_ematch_util, FMT, ##ARGS)
  45
  46         if (args == NULL)
  47                 return PARSE_ERR(args, "u32: missing arguments");
  48
  49         if (!bstrcmp(args, "u8"))
  50                 align = 1;
  51         else if (!bstrcmp(args, "u16"))
  52                 align = 2;
  53         else if (!bstrcmp(args, "u32"))
  54                 align = 4;
  55         else
  56                 return PARSE_ERR(args, "u32: invalid alignment");
  57
  58         a = bstr_next(args);
  59         if (a == NULL)
  60                 return PARSE_ERR(a, "u32: missing key");
  61
  62         key = bstrtoul(a);
  63         if (key == ULONG_MAX)
  64                 return PARSE_ERR(a, "u32: invalid key, must be numeric");
  65
  66         a = bstr_next(a);
  67         if (a == NULL)
  68                 return PARSE_ERR(a, "u32: missing mask");
  69
  70         mask = bstrtoul(a);
  71         if (mask == ULONG_MAX)
  72                 return PARSE_ERR(a, "u32: invalid mask, must be numeric");
  73
  74         a = bstr_next(a);
  75         if (a == NULL || bstrcmp(a, "at") != 0)
  76                 return PARSE_ERR(a, "u32: missing \"at\"");
  77
  78         a = bstr_next(a);
  79         if (a == NULL)
  80                 return PARSE_ERR(a, "u32: missing offset");
  81
  82         nh_len = strlen("nexthdr+");
  83         if (a->len > nh_len && !memcmp(a->data, "nexthdr+", nh_len)) {
  84                 char buf[a->len - nh_len + 1];
  85
  86                 offmask = -1;
  87                 memcpy(buf, a->data + nh_len, a->len - nh_len);
  88                 offset = strtoul(buf, NULL, 0);
  89         } else if (!bstrcmp(a, "nexthdr+")) {
  90                 a = bstr_next(a);
  91                 if (a == NULL)
  92                         return PARSE_ERR(a, "u32: missing offset");
  93                 offset = bstrtoul(a);
  94         } else
  95                 offset = bstrtoul(a);
  96
  97         if (offset == ULONG_MAX)
  98                 return PARSE_ERR(a, "u32: invalid offset");
  99
 100         if (a->next)
 101                 return PARSE_ERR(a->next, "u32: unexpected trailer");
 102
 103         switch (align) {
 104                 case 1:
 105                         if (key > 0xFF)
 106                                 return PARSE_ERR(a, "Illegal key (>0xFF)");
 107                         if (mask > 0xFF)
 108                                 return PARSE_ERR(a, "Illegal mask (>0xFF)");
 109
 110                         key <<= 24 - ((offset & 3) * 8);
 111                         mask <<= 24 - ((offset & 3) * 8);
 112                         offset &= ~3;
 113                         break;
 114
 115                 case 2:
 116                         if (key > 0xFFFF)
 117                                 return PARSE_ERR(a, "Illegal key (>0xFFFF)");
 118                         if (mask > 0xFFFF)
 119                                 return PARSE_ERR(a, "Illegal mask (>0xFFFF)");
 120
 121                         if ((offset & 3) == 0) {
 122                                 key <<= 16;
 123                                 mask <<= 16;
 124                         }
 125                         offset &= ~3;
 126                         break;
 127         }
 128
 129         key = htonl(key);
 130         mask = htonl(mask);
 131
 132         if (offset % 4)
 133                 return PARSE_ERR(a, "u32: invalid offset alignment, " \
 134                     "must be aligned to 4.");
 135
 136         key &= mask;
 137
 138         u_key.mask = mask;
 139         u_key.val = key;
 140         u_key.off = offset;
 141         u_key.offmask = offmask;
 142
 143         addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
 144         addraw_l(n, MAX_MSG, &u_key, sizeof(u_key));
 145
 146 #undef PARSE_ERR
 147         return 0;
 148 }
 149
 150 static int u32_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
 151                           int data_len)
 152 {
 153         struct tc_u32_key *u_key = data;
 154
 155         if (data_len < sizeof(*u_key)) {
 156                 fprintf(stderr, "U32 header size mismatch\n");
 157                 return -1;
 158         }
 159
 160         fprintf(fd, "%08x/%08x at %s%d",
 161             (unsigned int) ntohl(u_key->val),
 162             (unsigned int) ntohl(u_key->mask),
 163             u_key->offmask ? "nexthdr+" : "",
 164             u_key->off);
 165
 166         return 0;
 167 }
 168
 169 struct ematch_util u32_ematch_util = {
 170         .kind = "u32",
 171         .kind_num = TCF_EM_U32,
 172         .parse_eopt = u32_parse_eopt,
 173         .print_eopt = u32_print_eopt,
 174         .print_usage = u32_print_usage
 175 };