common: Add support for element defragmentation

Add support for element defragmentation as defined in IEEE
P802.11-REVmd/D3.0, 10.28.12 (Element defragmentation).

Signed-off-by: Ilan Peer <ilan.peer@intel.com>

diff --git a/src/common/ieee802_11_common.c b/src/common/ieee802_11_common.c
index 679170d492c6c3dc551d48af722b2256229e7507..71876c084718ab85e939b55b6328b4831665b851 100644 (file)
--- a/src/common/ieee802_11_common.c
+++ b/src/common/ieee802_11_common.c
@@ -206,6 +206,8 @@ static int ieee802_11_parse_extension(const u8 *pos, size_t elen,
        ext_id = *pos++;
        elen--;
 
+       elems->frag_ies.last_eid_ext = 0;
+
        switch (ext_id) {
        case WLAN_EID_EXT_ASSOC_DELAY_INFO:
                if (elen != 1)
@@ -295,10 +297,39 @@ static int ieee802_11_parse_extension(const u8 *pos, size_t elen,
                return -1;
        }
 
+       if (elen == 254)
+               elems->frag_ies.last_eid_ext = ext_id;
+
        return 0;
 }
 
 
+static void ieee802_11_parse_fragment(struct frag_ies_info *frag_ies,
+                                     const u8 *pos, u8 elen)
+{
+       if (frag_ies->n_frags >= MAX_NUM_FRAG_IES_SUPPORTED) {
+               wpa_printf(MSG_MSGDUMP, "Too many element fragments - skip");
+               return;
+       }
+
+       /*
+        * Note: while EID == 0 is a valid ID (SSID IE), it should not be
+        * fragmented.
+        */
+       if (!frag_ies->last_eid) {
+               wpa_printf(MSG_MSGDUMP,
+                          "Fragment without a valid last element - skip");
+               return;
+       }
+
+       frag_ies->frags[frag_ies->n_frags].ie = pos;
+       frag_ies->frags[frag_ies->n_frags].ie_len = elen;
+       frag_ies->frags[frag_ies->n_frags].eid = frag_ies->last_eid;
+       frag_ies->frags[frag_ies->n_frags].eid_ext = frag_ies->last_eid_ext;
+       frag_ies->n_frags++;
+}
+
+
 /**
  * ieee802_11_parse_elems - Parse information elements in management frames
  * @start: Pointer to the start of IEs
@@ -516,7 +547,7 @@ ParseRes ieee802_11_parse_elems(const u8 *start, size_t len,
                        elems->dils_len = elen;
                        break;
                case WLAN_EID_FRAGMENT:
-                       /* TODO */
+                       ieee802_11_parse_fragment(&elems->frag_ies, pos, elen);
                        break;
                case WLAN_EID_EXTENSION:
                        if (ieee802_11_parse_extension(pos, elen, elems,
@@ -532,6 +563,12 @@ ParseRes ieee802_11_parse_elems(const u8 *start, size_t len,
                                   id, elen);
                        break;
                }
+
+               if (id != WLAN_EID_FRAGMENT && elen == 255)
+                       elems->frag_ies.last_eid = id;
+
+               if (id == WLAN_EID_EXTENSION && !elems->frag_ies.last_eid_ext)
+                       elems->frag_ies.last_eid = 0;
        }
 
        if (!for_each_element_completed(elem, start, len)) {
@@ -2391,3 +2428,78 @@ int op_class_to_ch_width(u8 op_class)
        }
        return CHANWIDTH_USE_HT;
 }
+
+
+struct wpabuf * ieee802_11_defrag_data(struct ieee802_11_elems *elems,
+                                      u8 eid, u8 eid_ext,
+                                      const u8 *data, u8 len)
+{
+       struct frag_ies_info *frag_ies = &elems->frag_ies;
+       struct wpabuf *buf;
+       unsigned int i;
+
+       if (!elems || !data || !len)
+               return NULL;
+
+       buf = wpabuf_alloc_copy(data, len);
+       if (!buf)
+               return NULL;
+
+       for (i = 0; i < frag_ies->n_frags; i++) {
+               int ret;
+
+               if (frag_ies->frags[i].eid != eid ||
+                   frag_ies->frags[i].eid_ext != eid_ext)
+                       continue;
+
+               ret = wpabuf_resize(&buf, frag_ies->frags[i].ie_len);
+               if (ret < 0) {
+                       wpabuf_free(buf);
+                       return NULL;
+               }
+
+               /* Copy only the fragment data (without the EID and length) */
+               wpabuf_put_data(buf, frag_ies->frags[i].ie,
+                               frag_ies->frags[i].ie_len);
+       }
+
+       return buf;
+}
+
+
+struct wpabuf * ieee802_11_defrag(struct ieee802_11_elems *elems,
+                                 u8 eid, u8 eid_ext)
+{
+       const u8 *data;
+       u8 len;
+
+       /*
+        * TODO: Defragmentation mechanism can be supported for all IEs. For now
+        * handle only those that are used (or use ieee802_11_defrag_data()).
+        */
+       switch (eid) {
+       case WLAN_EID_EXTENSION:
+               switch (eid_ext) {
+               case WLAN_EID_EXT_FILS_HLP_CONTAINER:
+                       data = elems->fils_hlp;
+                       len = elems->fils_hlp_len;
+                       break;
+               case WLAN_EID_EXT_WRAPPED_DATA:
+                       data = elems->wrapped_data;
+                       len = elems->wrapped_data_len;
+                       break;
+               default:
+                       wpa_printf(MSG_DEBUG,
+                                  "Defragmentation not supported. eid_ext=%u",
+                                  eid_ext);
+                       return NULL;
+               }
+               break;
+       default:
+               wpa_printf(MSG_DEBUG,
+                          "Defragmentation not supported. eid=%u", eid);
+               return NULL;
+       }
+
+       return ieee802_11_defrag_data(elems, eid, eid_ext, data, len);
+}

diff --git a/src/common/ieee802_11_common.h b/src/common/ieee802_11_common.h
index bb2793d0847c45f340d927d3b58137cd03eb627d..7994cd7d64cdc2d30a8a176e4ebd3e57bfa6c349 100644 (file)
--- a/src/common/ieee802_11_common.h
+++ b/src/common/ieee802_11_common.h
@@ -21,6 +21,7 @@ struct element {
 struct hostapd_hw_modes;
 
 #define MAX_NOF_MB_IES_SUPPORTED 5
+#define MAX_NUM_FRAG_IES_SUPPORTED 3
 
 struct mb_ies_info {
        struct {
@@ -30,6 +31,21 @@ struct mb_ies_info {
        u8 nof_ies;
 };
 
+struct frag_ies_info {
+       struct {
+               u8 eid;
+               u8 eid_ext;
+               const u8 *ie;
+               u8 ie_len;
+       } frags[MAX_NUM_FRAG_IES_SUPPORTED];
+
+       u8 n_frags;
+
+       /* the last parsed element ID and element extension ID */
+       u8 last_eid;
+       u8 last_eid_ext;
+};
+
 /* Parsed Information Elements */
 struct ieee802_11_elems {
        const u8 *ssid;
@@ -151,6 +167,7 @@ struct ieee802_11_elems {
        u8 short_ssid_list_len;
 
        struct mb_ies_info mb_ies;
+       struct frag_ies_info frag_ies;
 };
 
 typedef enum { ParseOK = 0, ParseUnknown = 1, ParseFailed = -1 } ParseRes;
@@ -293,4 +310,10 @@ void hostapd_encode_edmg_chan(int edmg_enable, u8 edmg_channel,
 int ieee802_edmg_is_allowed(struct ieee80211_edmg_config allowed,
                            struct ieee80211_edmg_config requested);
 
+struct wpabuf * ieee802_11_defrag_data(struct ieee802_11_elems *elems,
+                                      u8 eid, u8 eid_ext,
+                                      const u8 *data, u8 len);
+struct wpabuf * ieee802_11_defrag(struct ieee802_11_elems *elems,
+                                 u8 eid, u8 eid_ext);
+
 #endif /* IEEE802_11_COMMON_H */