aboutsummaryrefslogtreecommitdiff
path: root/src/cmd/ip/snoopy/udp.c
blob: da9510f6002939d5266cdf084ca7cf6ac4629e63 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
#include <u.h>
#include <libc.h>
#include <ip.h>
#include "dat.h"
#include "protos.h"

typedef struct Hdr	Hdr;
struct Hdr
{
	uchar	sport[2];	/* Source port */
	uchar	dport[2];	/* Destination port */
	uchar	len[2];		/* data length */
	uchar	cksum[2];	/* Checksum */
};

enum
{
	UDPLEN=	8
};

enum
{
	Os,
	Od,
	Osd,
	Osetport
};

static Field p_fields[] =
{
	{"s",		Fnum,	Os,	"source port",	} ,
	{"d",		Fnum,	Od,	"dest port",	} ,
	{"a",		Fnum,	Osd,	"source/dest port",	} ,
	{"sd",		Fnum,	Osd,	"source/dest port",	} ,
	{0}
};

#define ANYPORT ~0UL

static Mux p_mux[] =
{
	{"bootp",	67, },
	{"ninep",	6346, },	/* tvs */
	{"dns", 53 },
	{"rtp",		ANYPORT, },
	{"rtcp",	ANYPORT, },
	{0}
};

/* default next protocol, can be changed by p_filter, reset by p_compile */
static Proto	*defproto = &dump;

static void
p_compile(Filter *f)
{
	Mux *m;

	if(f->op == '='){
		compile_cmp(udp.name, f, p_fields);
		return;
	}
	for(m = p_mux; m->name != nil; m++)
		if(strcmp(f->s, m->name) == 0){
			f->pr = m->pr;
			f->ulv = m->val;
			f->subop = Osd;
			return;
		}

	sysfatal("unknown udp field or protocol: %s", f->s);
}

static int
p_filter(Filter *f, Msg *m)
{
	Hdr *h;

	if(m->pe - m->ps < UDPLEN)
		return 0;

	h = (Hdr*)m->ps;
	m->ps += UDPLEN;

	switch(f->subop){
	case Os:
		return NetS(h->sport) == f->ulv;
	case Od:
		return NetS(h->dport) == f->ulv;
	case Osd:
		if(f->ulv == ANYPORT){
			defproto = f->pr;
			return 1;
		}
		return NetS(h->sport) == f->ulv || NetS(h->dport) == f->ulv;
	}
	return 0;
}

static int
p_seprint(Msg *m)
{
	Hdr *h;
	int dport, sport;


	if(m->pe - m->ps < UDPLEN)
		return -1;
	h = (Hdr*)m->ps;
	m->ps += UDPLEN;

	/* next protocol */
	sport = NetS(h->sport);
	dport = NetS(h->dport);
	demux(p_mux, sport, dport, m, defproto);
	defproto = &dump;

	m->p = seprint(m->p, m->e, "s=%d d=%d ck=%4.4ux ln=%4d",
			NetS(h->sport), dport,
			NetS(h->cksum), NetS(h->len));
	return 0;
}

Proto udp =
{
	"udp",
	p_compile,
	p_filter,
	p_seprint,
	p_mux,
	"%lud",
	p_fields,
	defaultframer
};