diff options
Diffstat (limited to 'sys/net80211/ieee80211_input.h')
| -rw-r--r-- | sys/net80211/ieee80211_input.h | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/sys/net80211/ieee80211_input.h b/sys/net80211/ieee80211_input.h index 5b38ddd..b90f46a 100644 --- a/sys/net80211/ieee80211_input.h +++ b/sys/net80211/ieee80211_input.h @@ -142,6 +142,104 @@ ishtinfooui(const uint8_t *frm) return frm[1] > 3 && LE_READ_4(frm+2) == ((BCM_OUI_HTINFO<<24)|BCM_OUI); } +#include <sys/endian.h> /* For le16toh() */ + +/* + * Check the current frame sequence number against the current TID + * state and return whether it's in sequence or should be dropped. + * + * Since out of order packet and duplicate packet eliminations should + * be done by the AMPDU RX code, this routine blindly accepts all + * frames from a HT station w/ a TID that is currently doing AMPDU-RX. + * HT stations without WME or where the TID is not doing AMPDU-RX + * are checked like non-HT stations. + * + * The routine only eliminates packets whose sequence/fragment + * match or are less than the last seen sequence/fragment number + * AND are retransmits It doesn't try to eliminate out of order packets. + * + * Since all frames after sequence number 4095 will be less than 4095 + * (as the seqnum wraps), handle that special case so packets aren't + * incorrectly dropped - ie, if the next packet is sequence number 0 + * but a retransmit since the initial packet didn't make it. + */ +static __inline int +ieee80211_check_rxseq(struct ieee80211_node *ni, struct ieee80211_frame *wh) +{ +#define SEQ_LEQ(a,b) ((int)((a)-(b)) <= 0) +#define SEQ_EQ(a,b) ((int)((a)-(b)) == 0) +#define HAS_SEQ(type) ((type & 0x4) == 0) +#define SEQNO(a) ((a) >> IEEE80211_SEQ_SEQ_SHIFT) +#define FRAGNO(a) ((a) & IEEE80211_SEQ_FRAG_MASK) + uint16_t rxseq; + uint8_t type; + uint8_t tid; + struct ieee80211_rx_ampdu *rap; + + rxseq = le16toh(*(uint16_t *)wh->i_seq); + type = wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK; + + /* Types with no sequence number are always treated valid */ + if (! HAS_SEQ(type)) + return 1; + + tid = ieee80211_gettid(wh); + + /* + * Only do the HT AMPDU check for WME stations; non-WME HT stations + * shouldn't exist outside of debugging. We should at least + * handle that. + */ + if (tid < WME_NUM_TID) { + rap = &ni->ni_rx_ampdu[tid]; + /* HT nodes currently doing RX AMPDU are always valid */ + if ((ni->ni_flags & IEEE80211_NODE_HT) && + (rap->rxa_flags & IEEE80211_AGGR_RUNNING)) + return 1; + } + + /* + * Otherwise, retries for packets below or equal to the last + * seen sequence number should be dropped. + */ + + /* + * Treat frame seqnum 4095 as special due to boundary + * wrapping conditions. + */ + if (SEQNO(ni->ni_rxseqs[tid]) == 4095) { + /* + * Drop retransmits on seqnum 4095/current fragment for itself. + */ + if (SEQ_EQ(rxseq, ni->ni_rxseqs[tid]) && + (wh->i_fc[1] & IEEE80211_FC1_RETRY)) + return 0; + /* + * Treat any subsequent frame as fine if the last seen frame + * is 4095 and it's not a retransmit for the same sequence + * number. However, this doesn't capture incorrectly ordered + * fragments w/ sequence number 4095. It shouldn't be seen + * in practice, but see the comment above for further info. + */ + return 1; + } + + /* + * At this point we assume that retransmitted seq/frag numbers below + * the current can simply be eliminated. + */ + if ((wh->i_fc[1] & IEEE80211_FC1_RETRY) && + SEQ_LEQ(rxseq, ni->ni_rxseqs[tid])) + return 0; + + return 1; +#undef SEQ_LEQ +#undef SEQ_EQ +#undef HAS_SEQ +#undef SEQNO +#undef FRAGNO +} + void ieee80211_deliver_data(struct ieee80211vap *, struct ieee80211_node *, struct mbuf *); struct mbuf *ieee80211_defrag(struct ieee80211_node *, |
