зеркало из https://github.com/microsoft/ivy.git
103 строки
2.3 KiB
XML
103 строки
2.3 KiB
XML
#lang ivy1.7
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include pcap
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include order
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type type_bits
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interpret type_bits -> bv[7]
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object quic_long_type = {
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type this = {initial,retry,handshake,zero_rtt_protected}
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}
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type cid
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interpret cid -> bv[64]
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type version
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interpret version -> bv[32]
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type pkt_num
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interpret pkt_num -> bv[32]
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# a fake type for packets
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type quic_packet = struct {
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hdr_long : bool,
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hdr_type : type_bits,
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hdr_cid : cid,
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hdr_version : version,
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hdr_pkt_num : pkt_num
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}
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include quic_deser
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instance pc : pcap(quic_packet,quic_deser)
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action show_packet(src:ip.endpoint,dst:ip.endpoint,pkt:quic_packet)
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import show_packet
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# Monitor packets on the wire
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# For each endpoint, the set of connectino ids that have been sent
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relation conn_seen(E:ip.endpoint,C:cid)
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# For each endpoint and connection id, track the last packet number sent
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function last_pkt_num(E:ip.endpoint,C:cid) : pkt_num
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after init {
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conn_seen(E,C) := false;
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}
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implement pc.handle(src:ip.endpoint,dst:ip.endpoint,pkt:quic_packet) {
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call show_packet(src,dst,pkt);
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var cid := pkt.hdr_cid;
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var pnum := pkt.hdr_pkt_num;
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# If the connection is new, the packet number is exact. Just
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# record we have seen this cid.
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if ~conn_seen(src,cid) {
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conn_seen(src,cid) := true;
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}
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# Else, we have to figure the current packet number based on the last.
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# It should be the least packet number greater than the last whose
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# low order bits match the number given in the packet. To compute
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# this, we have to take into account the actual number of bits.
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else {
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var last := last_pkt_num(src,cid);
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# If long format or type is 0x1d, we match 32 bits
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if pkt.hdr_long | pkt.hdr_type = 0x1d {
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if some(n:pkt_num) n > last & bfe[0][31](n) = pnum minimizing n {
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pnum := n
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}
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}
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# else if long format or type is 0x1e, we match 16 bits
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else if pkt.hdr_type = 0x1e {
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if some(n:pkt_num) n > last & bfe[0][15](n) = pnum minimizing n {
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pnum := n
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}
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}
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# else (type is 0x1f) we match 8 bits
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else {
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if some(n:pkt_num) n > last & bfe[0][7](n) = pnum minimizing n {
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pnum := n
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}
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}
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};
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last_pkt_num(src,cid) := pnum
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}
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attribute radix=16
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