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QUIC: small connection tracking optimization 

Track valid CID lengths, this makes it possible to detect whether any
valid QUIC long packet is present in the capture and allows for skipping
some hash-table lookups.

Change-Id: I20db2ca1d40af2a9b34fffe24b4b636f358d5795
Ping-Bug: 13881
Reviewed-on: https://code.wireshark.org/review/29727
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
This commit is contained in:
Peter Wu 2018-09-19 00:40:12 +02:00 committed by Alexis La Goutte
parent cff328d5bc
commit fc9e404ab2
1 changed files with 13 additions and 2 deletions
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15
epan/dissectors/packet-quic.c
View File

@ -255,6 +255,7 @@ typedef struct quic_datagram {
static wmem_map_t *quic_client_connections, *quic_server_connections;
static wmem_map_t *quic_initial_connections; /* Initial.DCID -> connection */
static wmem_list_t *quic_connections; /* All unique connections. */
static guint32 quic_cid_lengths; /* Bitmap of CID lengths. */
static guint quic_connections_count;
/* Returns the QUIC draft version or 0 if not applicable. */
@ -649,6 +650,13 @@ quic_cids_insert(quic_cid_t *cid, quic_info_data_t *conn, gboolean from_server)
// Replace any previous CID key with the new one.
wmem_map_remove(connections, cid);
wmem_map_insert(connections, cid, conn);
quic_cid_lengths |= (1 << cid->len);
}
static inline gboolean
quic_cids_is_known_length(const quic_cid_t *cid)
{
return (quic_cid_lengths & (1 << cid->len)) != 0;
}
/**
@ -669,7 +677,7 @@ quic_connection_find_dcid(packet_info *pinfo, const quic_cid_t *dcid, gboolean *
quic_info_data_t *conn = NULL;
gboolean check_ports = FALSE;
if (dcid && dcid->len > 0) {
if (dcid && dcid->len > 0 && quic_cids_is_known_length(dcid)) {
conn = (quic_info_data_t *) wmem_map_lookup(quic_client_connections, dcid);
if (conn) {
// DCID recognized by client, so it was from server.
@ -738,7 +746,9 @@ quic_connection_find(packet_info *pinfo, guint8 long_packet_type,
// actual DCID is unknown, so just keep decrementing until found.
while (!conn && dcid->len > 4) {
dcid->len--;
conn = quic_connection_find_dcid(pinfo, dcid, from_server);
if (quic_cids_is_known_length(dcid)) {
conn = quic_connection_find_dcid(pinfo, dcid, from_server);
}
}
if (!conn) {
// No match found, truncate DCID (not really needed, but this
@ -2291,6 +2301,7 @@ quic_init(void)
quic_initial_connections = wmem_map_new(wmem_file_scope(), quic_connection_hash, quic_connection_equal);
quic_client_connections = wmem_map_new(wmem_file_scope(), quic_connection_hash, quic_connection_equal);
quic_server_connections = wmem_map_new(wmem_file_scope(), quic_connection_hash, quic_connection_equal);
quic_cid_lengths = 0;
}
/** Release QUIC dissection state on closing a capture file. */