| Message ID | CAAYDh_gQU8h_31p6PMSu_qC=cEzLr9S6ah=kc9Gu4W8ctwhj8g@mail.gmail.com |
|---|---|
| State | Changes Requested |
| Headers | show |
On Fri, Feb 17, 2017 at 03:54:56PM +0900, Siwon Kang wrote: > The function ieee80211_chan_to_freq() is supposed to return -1 if the > specified channel is unknown. However, current if-conditional statements > do not catch a few wrong combination. For example, {"US", 81, 13} for > country code, operating class, channel, respectively should > return -1 because op_class 81 is not in the list and channel 13 is not > allowed but currently returns 2472 as if it is global. > > This patch removes 'if (freq > 0)' to prevent from stepping over when an > input op_class is out of the list of a country then finally going to > ieee80211_chan_to_freq_global(). Instead, it returns result of > sub-function directly which is correct. Does this fix something externally observable? It looks like the current design of the function uses the global table as a backup path on purpose. As such, I would rather not modify this unless there is a clearly identifiable misbehavior and/or no chances of breaking some existing use cases. > - int freq; > + if (country_match(us_op_class_cc, country)) In addition, this is whitespace damaged (tabs converted to a single space), so I cannot apply it.
>> - int freq; >> + if (country_match(us_op_class_cc, country)) > > In addition, this is whitespace damaged (tabs converted to a single > space), so I cannot apply it. At first, I am very sorry about the whitespace. I should have rather attached the patch file than copy-and-paste the contents. I used to upload through git send-email but it is blocked by gmail now. Please kindly use attached file for the patch work. > Does this fix something externally observable? It looks like the current > design of the function uses the global table as a backup path on > purpose. As such, I would rather not modify this unless there is a > clearly identifiable misbehavior and/or no chances of breaking some > existing use cases. The externally observable malfunction is the set provided in the patch as an example. As you know well, the US regulatory does not allow ch 12 and 13 so this function shall return -1 if the country code is explicitly given as 'US' just like that -1 is returned for channel 14 when CC is in the set of 'us' or 'eu'. However, it currently returns 2467 or 2472 for the input 12 or 13 + US so that it looks those channels are allowed. The header comments says the return must be -1 if the specified channel is unknown. Since the channel 12, 13 are unknown in US, it shall return -1. As well as it shouldn't use global table as a backup path because, as stated in a doxygen format description, the function uses global op_class only if the country code is unknown. In above case it specifies the known country code - US so it should not use global op_class. /** * ieee80211_chan_to_freq - Convert channel info to frequency * @country: Country code, if known; otherwise, global operating class is used * @op_class: Operating class * @chan: Channel number * Returns: Frequency in MHz or -1 if the specified channel is unknown */ FYI, I am making an API utiliizing this function. If this function returns positive values for the channels not allowed in the region, I have to add check routine for channels' validity which is major advantage of using this function. I'd very appreciate if you could kindly take your precious time for a careful review.
diff --git a/src/common/ieee802_11_common.c b/src/common/ieee802_11_common.c index a8d68e5..5ba5071 100644 --- a/src/common/ieee802_11_common.c +++ b/src/common/ieee802_11_common.c @@ -1133,31 +1133,17 @@ static int ieee80211_chan_to_freq_global(u8 op_class, u8 chan) */ int ieee80211_chan_to_freq(const char *country, u8 op_class, u8 chan) { - int freq; + if (country_match(us_op_class_cc, country)) + return ieee80211_chan_to_freq_us(op_class, chan); - if (country_match(us_op_class_cc, country)) { - freq = ieee80211_chan_to_freq_us(op_class, chan); - if (freq > 0) - return freq; - } - - if (country_match(eu_op_class_cc, country)) { - freq = ieee80211_chan_to_freq_eu(op_class, chan); - if (freq > 0) - return freq; - } + if (country_match(eu_op_class_cc, country)) + return ieee80211_chan_to_freq_eu(op_class, chan); - if (country_match(jp_op_class_cc, country)) { - freq = ieee80211_chan_to_freq_jp(op_class, chan); - if (freq > 0) - return freq; - } + if (country_match(jp_op_class_cc, country)) + return ieee80211_chan_to_freq_jp(op_class, chan); - if (country_match(cn_op_class_cc, country)) { - freq = ieee80211_chan_to_freq_cn(op_class, chan); - if (freq > 0) - return freq; - } + if (country_match(cn_op_class_cc, country)) + return ieee80211_chan_to_freq_cn(op_class, chan); return ieee80211_chan_to_freq_global(op_class, chan);
The function ieee80211_chan_to_freq() is supposed to return -1 if the specified channel is unknown. However, current if-conditional statements do not catch a few wrong combination. For example, {"US", 81, 13} for country code, operating class, channel, respectively should return -1 because op_class 81 is not in the list and channel 13 is not allowed but currently returns 2472 as if it is global. This patch removes 'if (freq > 0)' to prevent from stepping over when an input op_class is out of the list of a country then finally going to ieee80211_chan_to_freq_global(). Instead, it returns result of sub-function directly which is correct. Signed-off-by: Siwon Kang <kkangshawn@gmail.com> --- src/common/ieee802_11_common.c | 30 ++++++++---------------------- 1 file changed, 8 insertions(+), 22 deletions(-) }