commit 905287415b834db1a92205e8436f66a3b2d6846c
Author: Nick Mathewson <ni...@torproject.org>
Date: Thu Jan 8 11:00:21 2015 -0500
Avoid attempts to double-remove edge connections from the DNS resolver.
Also, avoid crashing when we attempt to double-remove an edge
connection from the DNS resolver: just log a bug warning instead.
Fixes bug 14129. Bugfix on 0d20fee2fbd48978, which was in 0.0.7rc1.
jowr found the bug. cypherpunks wrote the fix. I added the log
message and removed the assert.
---
changes/bug14129 | 7 +++++++
src/or/dns.c | 6 +++++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/changes/bug14129 b/changes/bug14129
new file mode 100644
index 0000000..6153cd8
--- /dev/null
+++ b/changes/bug14129
@@ -0,0 +1,7 @@
+ o Major bugfixes (exit node stability):
+
+ - Fix an assertion failure that could occur under high DNS load. Fixes
+ bug 14129; bugfix on Tor 0.0.7rc1. Found by "jowr"; diagnosed and fixed
+ by "cypherpunks".
+
+
diff --git a/src/or/dns.c b/src/or/dns.c
index fb1b10d..8b6e3b0 100644
--- a/src/or/dns.c
+++ b/src/or/dns.c
@@ -557,6 +557,8 @@ purge_expired_resolves(time_t now)
/* Connections should only be pending if they have no socket. */
tor_assert(!SOCKET_OK(pend->conn->base_.s));
pendconn = pend->conn;
+ /* Prevent double-remove */
+ pendconn->base_.state = EXIT_CONN_STATE_RESOLVEFAILED;
if (!pendconn->base_.marked_for_close) {
connection_edge_end(pendconn, END_STREAM_REASON_TIMEOUT);
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
@@ -1132,7 +1134,9 @@ connection_dns_remove(edge_connection_t *conn)
return; /* more are pending */
}
}
- tor_assert(0); /* not reachable unless onlyconn not in pending list */
+ log_warn(LD_BUG, "Connection (fd "TOR_SOCKET_T_FORMAT") was not waiting "
+ "for a resolve of %s, but we tried to remove it.",
+ conn->base_.s, escaped_safe_str(conn->base_.address));
}
}
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