On Fri, Jul 17, 2015 at 03:59:12AM +0300, Vadim Zhukov wrote:
> 2015-07-17 2:53 GMT+03:00 Stefan Sperling <s...@stsp.name>:
> > I don't think we should bother with invalid data. If it's not valid,
> > we should silently skip it. Else tcpdump would have to print all sorts
> > of warnings.
>
> I don't insist on explicit warning ("invalid nchan" or something like
> that), no. But, IMHO, we should display data we gathered without
> mangling; otherwise, we'll fool the user that nchan is 1 when it's 0
> actually.
Fair enough. I figure we can roll this into the code path for operating
element IDs (which were also skipped because because I don't find them
very interesting) and print the data in raw form.
Like this?
Index: print-802_11.c
===================================================================
RCS file: /cvs/src/usr.sbin/tcpdump/print-802_11.c,v
retrieving revision 1.19
diff -u -p -r1.19 print-802_11.c
--- print-802_11.c 16 Jul 2015 20:57:13 -0000 1.19
+++ print-802_11.c 17 Jul 2015 17:00:02 -0000
@@ -78,6 +78,7 @@ int ieee80211_hdr(struct ieee80211_fram
int ieee80211_data(struct ieee80211_frame *, u_int);
void ieee80211_print_element(u_int8_t *, u_int);
void ieee80211_print_essid(u_int8_t *, u_int);
+void ieee80211_print_country(u_int8_t *, u_int);
void ieee80211_print_htcaps(u_int8_t *, u_int);
int ieee80211_elements(struct ieee80211_frame *, u_int);
int ieee80211_frame(struct ieee80211_frame *, u_int);
@@ -233,6 +234,48 @@ ieee80211_print_essid(u_int8_t *essid, u
/* Caller checks len */
void
+ieee80211_print_country(u_int8_t *data, u_int len)
+{
+ u_int8_t first_chan, nchan, maxpower;
+
+ if (len < 6)
+ return;
+
+ /* country string */
+ printf(" '%c%c%c'", data[0], data[1], data[2]);
+
+ len -= 3;
+ data += 3;
+
+ /* channels and corresponding TX power limits */
+ while (len > 0) {
+ if (len < 3)
+ break;
+
+ /* no pretty-printing for nonsensical zero values,
+ * nor for operating extension IDs (values >= 201) */
+ if (data[0] == 0 || data[1] == 0 ||
+ data[0] >= 201 || data[1] >= 201) {
+ printf(", %d %d %d", data[0], data[1], data[2]);
+ continue;
+ }
+
+ first_chan = data[0];
+ nchan = data[1];
+ maxpower = data[2];
+
+ printf(", channel%s %d", nchan == 1 ? "" : "s", first_chan);
+ if (nchan > 1)
+ printf("-%d", first_chan + nchan - 1);
+ printf(" limit %ddB", maxpower);
+
+ len -= 3;
+ data += 3;
+ }
+}
+
+/* Caller checks len */
+void
ieee80211_print_htcaps(u_int8_t *data, u_int len)
{
u_int16_t htcaps;
@@ -392,8 +435,7 @@ ieee80211_elements(struct ieee80211_fram
break;
case IEEE80211_ELEMID_COUNTRY:
printf(", country");
- for (i = len; i > 0; i--, data++)
- printf(" %u", data[0]);
+ ieee80211_print_country(data, len);
break;
case IEEE80211_ELEMID_CHALLENGE:
printf(", challenge");
@@ -436,6 +478,10 @@ ieee80211_elements(struct ieee80211_fram
printf(", htcaps");
if (vflag)
ieee80211_print_htcaps(data, len);
+ break;
+ case IEEE80211_ELEMID_POWER_CONSTRAINT:
+ ELEM_CHECK(1);
+ printf(", power constraint %udB", data[0]);
break;
case IEEE80211_ELEMID_VENDOR:
printf(", vendor");
