1 files changed, 117 insertions, 0 deletions
diff --git a/src/cmd/ip/snoopy/radiotap.c b/src/cmd/ip/snoopy/radiotap.c
new file mode 100644
index 00000000..889dc8ab
--- /dev/null
+++ b/src/cmd/ip/snoopy/radiotap.c
@@ -0,0 +1,117 @@
+/*
+ * Radio tap as exported by BSD and Linux.
+ * The wireless ethernet devices return this format on Linux
+ * when running in monitor mode.
+ *
+ * TODO: Automatically determine whether the ethernet
+ * device is radio or ether, so that -h is not needed.
+ */
+
+#include <u.h>
+#include <libc.h>
+#include <ip.h>
+#include "dat.h"
+#include "protos.h"
+
+static Mux p_mux[] =
+{
+	{ "802.11", 0 },
+	{ 0 }
+};
+
+typedef struct Hdr Hdr;
+struct Hdr
+{
+	uchar vers;
+	uchar pad;
+	ushort	len;
+	ulong	present;
+};
+
+static int
+unpackhdr(uchar *p, uchar *ep, Hdr *h)
+{
+	if(p+sizeof(Hdr) > ep)
+		return -1;
+	h->vers = p[0];
+	h->pad = p[1];
+	h->len = LittleS(p+2);
+	h->present = LittleL(p+4);
+	// can be more present fields if 0x80000000 is set in each along the chain.
+	if(p+h->len > ep)
+		return -1;
+	return 0;
+}
+
+enum
+{
+	Ot,
+};
+
+static Field p_fields[] =
+{
+	{ 0 }
+};
+
+static void
+p_compile(Filter *f)
+{
+	Mux *m;
+
+	if(f->op == '='){
+		compile_cmp(radiotap.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 = Ot;
+			return;
+		}
+	}
+	sysfatal("unknown radiotap field or protocol: %s", f->s);
+}
+
+static int
+p_filter(Filter *f, Msg *m)
+{
+	Hdr h;
+
+	memset(&h, 0, sizeof h);
+	if(unpackhdr(m->ps, m->pe, &h) < 0)
+		return 0;
+	m->ps += h.len;
+	switch(f->subop){
+	case Ot:
+		return 1;
+	}
+	return 0;
+}
+
+static int
+p_seprint(Msg *m)
+{
+	Hdr h;
+	
+	memset(&h, 0, sizeof h);
+	if(unpackhdr(m->ps, m->pe, &h) < 0)
+		return -1;
+
+	m->p = seprint(m->p, m->e, "%.*H", h.len, m->ps);
+	m->ps += h.len;
+	m->pr = &p80211;
+	return 0;
+}
+
+Proto radiotap =
+{
+	"radiotap",
+	p_compile,
+	p_filter,
+	p_seprint,
+	p_mux,
+	nil,
+	nil,
+	defaultframer
+};