1*a71a9546SAutomerger Merge Worker #include <stdio.h>
2*a71a9546SAutomerger Merge Worker #include <xtables.h>
3*a71a9546SAutomerger Merge Worker #include <linux/netfilter/xt_tcpmss.h>
4*a71a9546SAutomerger Merge Worker
5*a71a9546SAutomerger Merge Worker enum {
6*a71a9546SAutomerger Merge Worker O_TCPMSS = 0,
7*a71a9546SAutomerger Merge Worker };
8*a71a9546SAutomerger Merge Worker
tcpmss_help(void)9*a71a9546SAutomerger Merge Worker static void tcpmss_help(void)
10*a71a9546SAutomerger Merge Worker {
11*a71a9546SAutomerger Merge Worker printf(
12*a71a9546SAutomerger Merge Worker "tcpmss match options:\n"
13*a71a9546SAutomerger Merge Worker "[!] --mss value[:value] Match TCP MSS range.\n"
14*a71a9546SAutomerger Merge Worker " (only valid for TCP SYN or SYN/ACK packets)\n");
15*a71a9546SAutomerger Merge Worker }
16*a71a9546SAutomerger Merge Worker
17*a71a9546SAutomerger Merge Worker static const struct xt_option_entry tcpmss_opts[] = {
18*a71a9546SAutomerger Merge Worker {.name = "mss", .id = O_TCPMSS, .type = XTTYPE_UINT16RC,
19*a71a9546SAutomerger Merge Worker .flags = XTOPT_MAND | XTOPT_INVERT},
20*a71a9546SAutomerger Merge Worker XTOPT_TABLEEND,
21*a71a9546SAutomerger Merge Worker };
22*a71a9546SAutomerger Merge Worker
tcpmss_parse(struct xt_option_call * cb)23*a71a9546SAutomerger Merge Worker static void tcpmss_parse(struct xt_option_call *cb)
24*a71a9546SAutomerger Merge Worker {
25*a71a9546SAutomerger Merge Worker struct xt_tcpmss_match_info *mssinfo = cb->data;
26*a71a9546SAutomerger Merge Worker
27*a71a9546SAutomerger Merge Worker xtables_option_parse(cb);
28*a71a9546SAutomerger Merge Worker mssinfo->mss_min = cb->val.u16_range[0];
29*a71a9546SAutomerger Merge Worker mssinfo->mss_max = mssinfo->mss_min;
30*a71a9546SAutomerger Merge Worker if (cb->nvals == 2) {
31*a71a9546SAutomerger Merge Worker mssinfo->mss_max = cb->val.u16_range[1];
32*a71a9546SAutomerger Merge Worker if (mssinfo->mss_max < mssinfo->mss_min)
33*a71a9546SAutomerger Merge Worker xtables_error(PARAMETER_PROBLEM,
34*a71a9546SAutomerger Merge Worker "tcpmss: invalid range given");
35*a71a9546SAutomerger Merge Worker }
36*a71a9546SAutomerger Merge Worker if (cb->invert)
37*a71a9546SAutomerger Merge Worker mssinfo->invert = 1;
38*a71a9546SAutomerger Merge Worker }
39*a71a9546SAutomerger Merge Worker
40*a71a9546SAutomerger Merge Worker static void
tcpmss_print(const void * ip,const struct xt_entry_match * match,int numeric)41*a71a9546SAutomerger Merge Worker tcpmss_print(const void *ip, const struct xt_entry_match *match, int numeric)
42*a71a9546SAutomerger Merge Worker {
43*a71a9546SAutomerger Merge Worker const struct xt_tcpmss_match_info *info = (void *)match->data;
44*a71a9546SAutomerger Merge Worker
45*a71a9546SAutomerger Merge Worker printf(" tcpmss match %s", info->invert ? "!" : "");
46*a71a9546SAutomerger Merge Worker if (info->mss_min == info->mss_max)
47*a71a9546SAutomerger Merge Worker printf("%u", info->mss_min);
48*a71a9546SAutomerger Merge Worker else
49*a71a9546SAutomerger Merge Worker printf("%u:%u", info->mss_min, info->mss_max);
50*a71a9546SAutomerger Merge Worker }
51*a71a9546SAutomerger Merge Worker
tcpmss_save(const void * ip,const struct xt_entry_match * match)52*a71a9546SAutomerger Merge Worker static void tcpmss_save(const void *ip, const struct xt_entry_match *match)
53*a71a9546SAutomerger Merge Worker {
54*a71a9546SAutomerger Merge Worker const struct xt_tcpmss_match_info *info = (void *)match->data;
55*a71a9546SAutomerger Merge Worker
56*a71a9546SAutomerger Merge Worker printf("%s --mss ", info->invert ? " !" : "");
57*a71a9546SAutomerger Merge Worker if (info->mss_min == info->mss_max)
58*a71a9546SAutomerger Merge Worker printf("%u", info->mss_min);
59*a71a9546SAutomerger Merge Worker else
60*a71a9546SAutomerger Merge Worker printf("%u:%u", info->mss_min, info->mss_max);
61*a71a9546SAutomerger Merge Worker }
62*a71a9546SAutomerger Merge Worker
tcpmss_xlate(struct xt_xlate * xl,const struct xt_xlate_mt_params * params)63*a71a9546SAutomerger Merge Worker static int tcpmss_xlate(struct xt_xlate *xl,
64*a71a9546SAutomerger Merge Worker const struct xt_xlate_mt_params *params)
65*a71a9546SAutomerger Merge Worker {
66*a71a9546SAutomerger Merge Worker const struct xt_tcpmss_match_info *info = (void *)params->match->data;
67*a71a9546SAutomerger Merge Worker
68*a71a9546SAutomerger Merge Worker xt_xlate_add(xl, "tcp option maxseg size %s", info->invert ? "!= " : "");
69*a71a9546SAutomerger Merge Worker
70*a71a9546SAutomerger Merge Worker if (info->mss_min == info->mss_max)
71*a71a9546SAutomerger Merge Worker xt_xlate_add(xl, "%u", info->mss_min);
72*a71a9546SAutomerger Merge Worker else
73*a71a9546SAutomerger Merge Worker xt_xlate_add(xl, "%u-%u", info->mss_min, info->mss_max);
74*a71a9546SAutomerger Merge Worker
75*a71a9546SAutomerger Merge Worker return 1;
76*a71a9546SAutomerger Merge Worker }
77*a71a9546SAutomerger Merge Worker
78*a71a9546SAutomerger Merge Worker static struct xtables_match tcpmss_match = {
79*a71a9546SAutomerger Merge Worker .family = NFPROTO_UNSPEC,
80*a71a9546SAutomerger Merge Worker .name = "tcpmss",
81*a71a9546SAutomerger Merge Worker .version = XTABLES_VERSION,
82*a71a9546SAutomerger Merge Worker .size = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
83*a71a9546SAutomerger Merge Worker .userspacesize = XT_ALIGN(sizeof(struct xt_tcpmss_match_info)),
84*a71a9546SAutomerger Merge Worker .help = tcpmss_help,
85*a71a9546SAutomerger Merge Worker .print = tcpmss_print,
86*a71a9546SAutomerger Merge Worker .save = tcpmss_save,
87*a71a9546SAutomerger Merge Worker .x6_parse = tcpmss_parse,
88*a71a9546SAutomerger Merge Worker .x6_options = tcpmss_opts,
89*a71a9546SAutomerger Merge Worker .xlate = tcpmss_xlate,
90*a71a9546SAutomerger Merge Worker };
91*a71a9546SAutomerger Merge Worker
_init(void)92*a71a9546SAutomerger Merge Worker void _init(void)
93*a71a9546SAutomerger Merge Worker {
94*a71a9546SAutomerger Merge Worker xtables_register_match(&tcpmss_match);
95*a71a9546SAutomerger Merge Worker }
96