From 066e2b91ffe594dbfd0eabe55c3ec7f0f587309a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@des.no>
Date: Thu, 15 Aug 2013 15:21:31 +0000
Subject: [PATCH] Record the last successful use of a TOTP key.  Also add
 commented-out logic to prevent reuse of the same code or an earlier code
 within the window, and make some minor type adjustments.

git-svn-id: svn+ssh://svn.openpam.org/svn/openpam/trunk@693 185d5e19-27fe-0310-9dcf-9bff6b9f3609
---
 include/security/oath.h       |  4 ++--
 include/security/oath_types.h |  1 +
 lib/liboath/oath_hotp.c       |  4 ++--
 lib/liboath/oath_totp.c       | 16 ++++++++++++++--
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/security/oath.h b/include/security/oath.h
index 7dfed25..ae9ea98 100644
--- a/include/security/oath.h
+++ b/include/security/oath.h
@@ -45,11 +45,11 @@ char *oath_key_to_uri(const struct oath_key *);
 struct oath_key *oath_dummy_key(enum oath_mode, enum oath_hash, unsigned int);
 
 unsigned int oath_hotp(const uint8_t *, size_t, uint64_t, unsigned int);
-int oath_hotp_current(struct oath_key *);
+unsigned int oath_hotp_current(struct oath_key *);
 int oath_hotp_match(struct oath_key *, unsigned int, int);
 
 unsigned int oath_totp(const uint8_t *, size_t, unsigned int);
-int oath_totp_match(const struct oath_key *, unsigned int, int);
 unsigned int oath_totp_current(const struct oath_key *);
+int oath_totp_match(struct oath_key *, unsigned int, int);
 
 #endif
diff --git a/include/security/oath_types.h b/include/security/oath_types.h
index 84324db..8877f41 100644
--- a/include/security/oath_types.h
+++ b/include/security/oath_types.h
@@ -41,6 +41,7 @@ struct oath_key {
 	unsigned int	 digits;
 	uint64_t	 counter;
 	unsigned int	 timestep; /* in seconds */
+	uint64_t	 lastuse;
 
 	/* housekeeping */
 	unsigned int	 mapped:1;
diff --git a/lib/liboath/oath_hotp.c b/lib/liboath/oath_hotp.c
index 28d0d63..e3df98e 100644
--- a/lib/liboath/oath_hotp.c
+++ b/lib/liboath/oath_hotp.c
@@ -92,7 +92,7 @@ oath_hotp(const uint8_t *K, size_t Klen, uint64_t seq, unsigned int Digit)
 /*
  * Computes the current code for the given key and advances the counter.
  */
-int
+unsigned int
 oath_hotp_current(struct oath_key *k)
 {
 	unsigned int code;
@@ -111,7 +111,7 @@ oath_hotp_current(struct oath_key *k)
 /*
  * Compares the code provided by the user with expected values within a
  * given window.  Returns 1 if there was a match, 0 if not, and -1 if an
- * error occurred.
+ * error occurred.  Also advances the counter if there was a match.
  */
 int
 oath_hotp_match(struct oath_key *k, unsigned int response, int window)
diff --git a/lib/liboath/oath_totp.c b/lib/liboath/oath_totp.c
index 4c3e2c4..195e8d5 100644
--- a/lib/liboath/oath_totp.c
+++ b/lib/liboath/oath_totp.c
@@ -67,8 +67,13 @@ oath_totp_current(const struct oath_key *k)
 	return (code);
 }
 
+/*
+ * Compares the code provided by the user with expected values within a
+ * given window.  Returns 1 if there was a match, 0 if not, and -1 if an
+ * error occurred.
+ */
 int
-oath_totp_match(const struct oath_key *k, unsigned int response, int window)
+oath_totp_match(struct oath_key *k, unsigned int response, int window)
 {
 	unsigned int code;
 	uint64_t seq;
@@ -85,9 +90,16 @@ oath_totp_match(const struct oath_key *k, unsigned int response, int window)
 	seq = time(NULL) / k->timestep;
 	dummy = (strcmp(k->label, OATH_DUMMY_LABEL) == 0);
 	for (int i = -window; i <= window; ++i) {
+#if OATH_TOTP_PREVENT_REUSE
+		/* XXX disabled for now, should be a key parameter? */
+		if (seq + i <= k->lastuse)
+			continue;
+#endif
 		code = oath_hotp(k->key, k->keylen, seq + i, k->digits);
-		if (code == response && !dummy)
+		if (code == response && !dummy) {
+			k->lastuse = seq;
 			return (1);
+		}
 	}
 	return (0);
 }