diff options
| -rw-r--r-- | node/AntiRecursion.hpp | 66 | ||||
| -rw-r--r-- | node/Constants.hpp | 5 |
2 files changed, 42 insertions, 29 deletions
diff --git a/node/AntiRecursion.hpp b/node/AntiRecursion.hpp index 4bb24bf3..8629d19a 100644 --- a/node/AntiRecursion.hpp +++ b/node/AntiRecursion.hpp @@ -35,28 +35,28 @@ namespace ZeroTier { -#define ZT_ANTIRECURSION_TAIL_LEN 128 +/** + * Size of anti-recursion history + */ +#define ZT_ANTIRECURSION_HISTORY_SIZE 16 /** * Filter to prevent recursion (ZeroTier-over-ZeroTier) * * This works by logging ZeroTier packets that we send. It's then invoked - * again against packets read from local Ethernet taps. If the last N + * again against packets read from local Ethernet taps. If the last 32 * bytes representing the ZeroTier packet match in the tap frame, then * the frame is a re-injection of a frame that we sent and is rejected. * * This means that ZeroTier packets simply will not traverse ZeroTier * networks, which would cause all sorts of weird problems. * - * NOTE: this is applied to low-level packets before they are sent to - * SocketManager and/or sockets, not to fully assembled packets before - * (possible) fragmentation. + * This is highly optimized code since it's checked for every packet. */ class AntiRecursion { public: AntiRecursion() - throw() { memset(_history,0,sizeof(_history)); _ptr = 0; @@ -68,13 +68,20 @@ public: * @param data ZT packet data * @param len Length of packet */ - inline void logOutgoingZT(const void *data,unsigned int len) - throw() + inline void logOutgoingZT(const void *const data,const unsigned int len) { - ArItem *i = &(_history[_ptr++ % ZT_ANTIRECURSION_HISTORY_SIZE]); - const unsigned int tl = (len > ZT_ANTIRECURSION_TAIL_LEN) ? ZT_ANTIRECURSION_TAIL_LEN : len; - memcpy(i->tail,((const unsigned char *)data) + (len - tl),tl); - i->len = tl; + if (len < 32) + return; +#ifdef ZT_NO_TYPE_PUNNING + memcpy(_history[++_ptr % ZT_ANTIRECURSION_HISTORY_SIZE].tail,reinterpret_cast<const uint8_t *>(data) + (len - 32),32); +#else + uint64_t *t = _history[++_ptr % ZT_ANTIRECURSION_HISTORY_SIZE].tail; + const uint64_t *p = reinterpret_cast<const uint64_t *>(reinterpret_cast<const uint8_t *>(data) + (len - 32)); + *(t++) = *(p++); + *(t++) = *(p++); + *(t++) = *(p++); + *t = *p; +#endif } /** @@ -84,25 +91,36 @@ public: * @param len Length of frame * @return True if frame is OK to be passed, false if it's a ZT frame that we sent */ - inline bool checkEthernetFrame(const void *data,unsigned int len) - throw() + inline bool checkEthernetFrame(const void *const data,const unsigned int len) const { - for(unsigned int h=0;h<ZT_ANTIRECURSION_HISTORY_SIZE;++h) { - ArItem *i = &(_history[h]); - if ((i->len > 0)&&(len >= i->len)&&(!memcmp(((const unsigned char *)data) + (len - i->len),i->tail,i->len))) + if (len < 32) + return true; + const uint8_t *const pp = reinterpret_cast<const uint8_t *>(data) + (len - 32); + const _ArItem *i = _history; + const _ArItem *const end = i + ZT_ANTIRECURSION_HISTORY_SIZE; + while (i != end) { +#ifdef ZT_NO_TYPE_PUNNING + if (!memcmp(pp,i->tail,32)) return false; +#else + const uint64_t *t = i->tail; + const uint64_t *p = reinterpret_cast<const uint64_t *>(pp); + uint64_t bits = *(t++) ^ *(p++); + bits |= *(t++) ^ *(p++); + bits |= *(t++) ^ *(p++); + bits |= *t ^ *p; + if (!bits) + return false; +#endif + ++i; } return true; } private: - struct ArItem - { - unsigned char tail[ZT_ANTIRECURSION_TAIL_LEN]; - unsigned int len; - }; - ArItem _history[ZT_ANTIRECURSION_HISTORY_SIZE]; - volatile unsigned int _ptr; + struct _ArItem { uint64_t tail[4]; }; + _ArItem _history[ZT_ANTIRECURSION_HISTORY_SIZE]; + volatile unsigned long _ptr; }; } // namespace ZeroTier diff --git a/node/Constants.hpp b/node/Constants.hpp index 5a4d4a4d..1d5fa6f4 100644 --- a/node/Constants.hpp +++ b/node/Constants.hpp @@ -310,11 +310,6 @@ #define ZT_NAT_T_TACTICAL_ESCALATION_DELAY 1000 /** - * Size of anti-recursion history (see AntiRecursion.hpp) - */ -#define ZT_ANTIRECURSION_HISTORY_SIZE 16 - -/** * Minimum delay between attempts to confirm new paths to peers (to avoid HELLO flooding) */ #define ZT_MIN_PATH_CONFIRMATION_INTERVAL 1000 |