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Fix time skew values from untrusted sources

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Now when we receive a large time skew from a source which isn't a trusted dir, we go contact a trusted dir to trigger a NETINFO cell.
This commit is contained in:
AltF4 2011-02-09 22:03:53 -07:00 committed by Nick Mathewson
parent aa178aae03
commit b8bef61a8f
1 changed files with 28 additions and 4 deletions
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32
src/or/command.c
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@ -44,6 +44,8 @@ uint64_t stats_n_destroy_cells_processed = 0;
uint64_t stats_n_versions_cells_processed = 0;
/** How many CELL_NETINFO cells have we received, ever? */
uint64_t stats_n_netinfo_cells_processed = 0;
/** Have we received skew info from a NETINFO cell from a trusted dir, ever? */
static int received_skew_from_trusted_dir = 0;
/* These are the main functions for processing cells */
static void command_process_create_cell(cell_t *cell, or_connection_t *conn);
@ -617,15 +619,19 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
}
/* Act on apparent skew. */
/** Warn when we get a netinfo skew with at least this value. */
/** Warn when we get a netinfo skew with at least this value.
Ignore if we've already recieved skew info from a trusted dir */
#define NETINFO_NOTICE_SKEW 3600
if (labs(apparent_skew) > NETINFO_NOTICE_SKEW &&
router_get_by_digest(conn->identity_digest)) {
router_get_by_digest(conn->identity_digest) &&
!received_skew_from_trusted_dir) {
char dbuf[64];
int severity;
/*XXXX be smarter about when everybody says we are skewed. */
if (router_digest_is_trusted_dir(conn->identity_digest))
if (router_digest_is_trusted_dir(conn->identity_digest)) {
severity = LOG_WARN;
received_skew_from_trusted_dir = 1;
}
else
severity = LOG_INFO;
format_time_interval(dbuf, sizeof(dbuf), apparent_skew);
@ -636,11 +642,29 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
conn->_base.address, (int)conn->_base.port,
apparent_skew>0 ? "ahead" : "behind", dbuf,
apparent_skew>0 ? "behind" : "ahead");
if (severity == LOG_WARN) /* only tell the controller if an authority */
if (severity == LOG_WARN) { /* only tell the controller if an authority */
control_event_general_status(LOG_WARN,
"CLOCK_SKEW SKEW=%ld SOURCE=OR:%s:%d",
apparent_skew,
conn->_base.address, conn->_base.port);
}
else { /* Connect to a trusted dir to trigger a NETINFO cell*/
routerstatus_t *any_trusted_dir =
router_pick_trusteddirserver(NO_AUTHORITY, 0);
const tor_addr_t trusted_dir_addr;
tor_addr_from_ipv4n(&trusted_dir_addr, any_trusted_dir->addr);
connection_or_connect(&trusted_dir_addr,
any_trusted_dir->or_port,
any_trusted_dir->descriptor_digest);
}
}
/* Mark a flag if we get a good skew from a trusted dir */
if (labs(apparent_skew) < NETINFO_NOTICE_SKEW &&
router_digest_is_trusted_dir(conn->identity_digest) &&
!received_skew_from_trusted_dir) {
received_skew_from_trusted_dir = 1;
}
/* XXX maybe act on my_apparent_addr, if the source is sufficiently