From: Johannes Berg <johannes.berg@xxxxxxxxx>
Parsing the P2P attributes can be tricky as their
contents can be split across multiple (vendor) IEs.
Thus, it's not possible to parse them like IEs (by
returning a pointer to the data.) Instead, provide
a function that copies the attribute data into a
caller-provided buffer and returns the size needed
(useful in case the buffer was too small.)
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/net/cfg80211.h | 19 ++++++++++
net/wireless/util.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 118 insertions(+)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 83a2c82..ae6d5e5 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -3623,6 +3623,25 @@ u32 cfg80211_calculate_bitrate(struct rate_info *rate);
*/
void cfg80211_unregister_wdev(struct wireless_dev *wdev);
+/**
+ * cfg80211_get_p2p_attr - find and copy a P2P attribute from IE buffer
+ * @ies: the input IE buffer
+ * @len: the input length
+ * @attr: the attribute ID to find
+ * @buf: output buffer, can be %NULL if the data isn't needed, e.g.
+ * if the function is only called to get the needed buffer size
+ * @bufsize: size of the output buffer
+ *
+ * The function finds a given P2P attribute in the (vendor) IEs and
+ * copies its contents to the given buffer.
+ *
+ * The return value is a negative error code (-%EILSEQ or -%ENOENT) if
+ * the data is malformed or the attribute can't be found (respectively),
+ * or the length of the found attribute (which can be zero).
+ */
+unsigned int cfg80211_get_p2p_attr(const u8 *ies, unsigned int len,
+ u8 attr, u8 *buf, unsigned int bufsize);
+
/* Logging, debugging and troubleshooting/diagnostic helpers. */
/* wiphy_printk helpers, similar to dev_printk */
diff --git a/net/wireless/util.c b/net/wireless/util.c
index cf11239..2964223 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -980,6 +980,105 @@ u32 cfg80211_calculate_bitrate(struct rate_info *rate)
}
EXPORT_SYMBOL(cfg80211_calculate_bitrate);
+unsigned int cfg80211_get_p2p_attr(const u8 *ies, unsigned int len,
+ u8 attr, u8 *buf, unsigned int bufsize)
+{
+ u8 *out = buf;
+ u16 attr_remaining = 0;
+ bool desired_attr = false;
+ u16 desired_len = 0;
+
+ while (len > 0) {
+ unsigned int iedatalen;
+ unsigned int copy;
+ const u8 *iedata;
+
+ if (len < 2)
+ return -EILSEQ;
+ iedatalen = ies[1];
+ if (iedatalen + 2 > len)
+ return -EILSEQ;
+
+ if (ies[0] != WLAN_EID_VENDOR_SPECIFIC)
+ goto cont;
+
+ if (iedatalen < 4)
+ goto cont;
+
+ iedata = ies + 2;
+
+ /* check WFA OUI, P2P subtype */
+ if (iedata[0] != 0x50 || iedata[1] != 0x6f ||
+ iedata[2] != 0x9a || iedata[3] != 0x09)
+ goto cont;
+
+ iedatalen -= 4;
+ iedata += 4;
+
+ /* check attribute continuation into this IE */
+ copy = min_t(unsigned int, attr_remaining, iedatalen);
+ if (copy && desired_attr) {
+ desired_len += copy;
+ if (out) {
+ memcpy(out, iedata, min(bufsize, copy));
+ out += min(bufsize, copy);
+ bufsize -= min(bufsize, copy);
+ }
+
+
+ if (copy == attr_remaining)
+ return desired_len;
+ }
+
+ attr_remaining -= copy;
+ if (attr_remaining)
+ goto cont;
+
+ iedatalen -= copy;
+ iedata += copy;
+
+ while (iedatalen > 0) {
+ u16 attr_len;
+
+ /* P2P attribute ID & size must fit */
+ if (iedatalen < 3)
+ return -EILSEQ;
+ desired_attr = iedata[0] == attr;
+ attr_len = get_unaligned_le16(iedata + 1);
+ iedatalen -= 3;
+ iedata += 3;
+
+ copy = min_t(unsigned int, attr_len, iedatalen);
+
+ if (desired_attr) {
+ desired_len += copy;
+ if (out) {
+ memcpy(out, iedata, min(bufsize, copy));
+ out += min(bufsize, copy);
+ bufsize -= min(bufsize, copy);
+ }
+
+ if (copy == attr_len)
+ return desired_len;
+ }
+
+ iedata += copy;
+ iedatalen -= copy;
+ attr_remaining = attr_len - copy;
+ }
+
+ cont:
+ len -= ies[1] + 2;
+ ies += ies[1] + 2;
+ }
+
+ if (attr_remaining && desired_attr)
+ return -EILSEQ;
+
+ return -ENOENT;
+}
+EXPORT_SYMBOL(cfg80211_get_p2p_attr);
+
bool ieee80211_operating_class_to_band(u8 operating_class,
enum ieee80211_band *band)
{
--
1.8.0
--
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