Documentation examples, description and code were disagreeing on what
this option actually does. Now they will all agree that it will
*prepend* a random-byte string to the hostname name before resolving
to work around DNS caching (needs a "*" wildcard record in the zone).
Fix trac #143
Signed-off-by: Gert Doering <g...@greenie.muc.de>
---
doc/openvpn.8 | 2 +-
src/openvpn/misc.c | 27 +++++++++------------------
2 files changed, 10 insertions(+), 19 deletions(-)
diff --git a/doc/openvpn.8 b/doc/openvpn.8
index b53d383..3e2e1a4 100644
--- a/doc/openvpn.8
+++ b/doc/openvpn.8
@@ -271,7 +271,7 @@ failover capability.
.\"*********************************************************
.TP
.B \-\-remote-random-hostname
-Add a random string (6 characters) to first DNS label of hostname to prevent
+Prepend a random string (6 bytes, 12 hex characters) to hostname to prevent
DNS caching. For example, "foo.bar.gov" would be modified to
"<random-chars>.foo.bar.gov".
.\"*********************************************************
diff --git a/src/openvpn/misc.c b/src/openvpn/misc.c
index 4688444..7483184 100644
--- a/src/openvpn/misc.c
+++ b/src/openvpn/misc.c
@@ -926,32 +926,23 @@ create_temp_file (const char *directory, const char
*prefix, struct gc_arena *gc
}
/*
- * Add a random string to first DNS label of hostname to prevent DNS caching.
+ * Prepend a random string to hostname to prevent DNS caching.
* For example, foo.bar.gov would be modified to <random-chars>.foo.bar.gov.
- * Of course, this requires explicit support in the DNS server.
+ * Of course, this requires explicit support in the DNS server (wildcard).
*/
const char *
hostname_randomize(const char *hostname, struct gc_arena *gc)
{
# define n_rnd_bytes 6
- char *hst = string_alloc(hostname, gc);
- char *dot = strchr(hst, '.');
+ uint8_t rnd_bytes[n_rnd_bytes];
+ const char *rnd_str;
+ struct buffer hname = alloc_buf_gc (strlen(hostname)+sizeof(rnd_bytes)*2+4,
gc);
- if (dot)
- {
- uint8_t rnd_bytes[n_rnd_bytes];
- const char *rnd_str;
- struct buffer hname = alloc_buf_gc
(strlen(hostname)+sizeof(rnd_bytes)*2+4, gc);
-
- *dot++ = '\0';
- prng_bytes (rnd_bytes, sizeof (rnd_bytes));
- rnd_str = format_hex_ex (rnd_bytes, sizeof (rnd_bytes), 40, 0, NULL, gc);
- buf_printf(&hname, "%s-0x%s.%s", hst, rnd_str, dot);
- return BSTR(&hname);
- }
- else
- return hostname;
+ prng_bytes (rnd_bytes, sizeof (rnd_bytes));
+ rnd_str = format_hex_ex (rnd_bytes, sizeof (rnd_bytes), 40, 0, NULL, gc);
+ buf_printf(&hname, "%s.%s", rnd_str, hostname);
+ return BSTR(&hname);
# undef n_rnd_bytes
}
--
1.8.1.5
