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authorMatthias Schiffer <mschiffer@universe-factory.net>2014-05-28 04:52:58 +0200
committerMatthias Schiffer <mschiffer@universe-factory.net>2014-05-28 04:52:58 +0200
commitd5da100c55d80391d2e941a41c0e0dccf2a6e33e (patch)
tree1aca67556ed8ea1e2f9fa2a73ebf1a84e8cd34a7 /src/methods/common.h
parentd859894f7a88e07e7beae8dc355278cfd6c185e2 (diff)
downloadfastd-d5da100c55d80391d2e941a41c0e0dccf2a6e33e.tar
fastd-d5da100c55d80391d2e941a41c0e0dccf2a6e33e.zip
Still more documentation
Diffstat (limited to 'src/methods/common.h')
-rw-r--r--src/methods/common.h53
1 files changed, 47 insertions, 6 deletions
diff --git a/src/methods/common.h b/src/methods/common.h
index 7b0a4ff..7a06f92 100644
--- a/src/methods/common.h
+++ b/src/methods/common.h
@@ -23,26 +23,37 @@
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+/**
+ \file
+
+ Definitions for the common packet format used by most methods
+*/
+
#pragma once
#include "../fastd.h"
+/** The length of the nonce in the common method packet header */
#define COMMON_NONCEBYTES 6
+/** The length of the flags in the common method packet header */
#define COMMON_FLAGBYTES 1
+/** The length of the common method packet header */
#define COMMON_HEADBYTES (COMMON_NONCEBYTES+COMMON_FLAGBYTES)
+
+/** Common method session state */
typedef struct fastd_method_common {
- struct timespec valid_till;
- struct timespec refresh_after;
+ struct timespec valid_till; /**< How long the session is valid */
+ struct timespec refresh_after; /**< When to try refreshing the session */
- uint8_t send_nonce[COMMON_NONCEBYTES];
- uint8_t receive_nonce[COMMON_NONCEBYTES];
+ uint8_t send_nonce[COMMON_NONCEBYTES]; /**< The next nonce to use */
+ uint8_t receive_nonce[COMMON_NONCEBYTES]; /**< The hightest nonce received to far for this session */
- struct timespec reorder_timeout;
- uint64_t receive_reorder_seen;
+ struct timespec reorder_timeout; /**< How long to packets with a lower sequence number (nonce) than the newest received */
+ uint64_t receive_reorder_seen; /**< Bitmap specifying which of the 64 sequence numbers (nonces) before \a receive_nonce have bit seen */
} fastd_method_common_t;
@@ -51,6 +62,11 @@ bool fastd_method_is_nonce_valid(const fastd_method_common_t *session, const uin
bool fastd_method_reorder_check(fastd_peer_t *peer, fastd_method_common_t *session, const uint8_t nonce[COMMON_NONCEBYTES], int64_t age);
+/**
+ The common \a session_is_valid implementation
+
+ A session is valid when session->valid_till has not timeouted, unless almost all nonces have been used up (which \b should be impossible)
+*/
static inline bool fastd_method_session_common_is_valid(const fastd_method_common_t *session) {
if (session->send_nonce[0] == 0xff && session->send_nonce[1] == 0xff)
return false;
@@ -58,10 +74,20 @@ static inline bool fastd_method_session_common_is_valid(const fastd_method_commo
return (!fastd_timed_out(&session->valid_till));
}
+/**
+ The common \a session_is_initiator implementation
+
+ The initiator of a session uses the odd nonces, the responder the even ones.
+*/
static inline bool fastd_method_session_common_is_initiator(const fastd_method_common_t *session) {
return (session->send_nonce[COMMON_NONCEBYTES-1] & 1);
}
+/**
+ The common \a session_want_refresh implementation
+
+ A session wants to be refreshed when session->refresh_after has timeouted, or if lots of nonces have been used up
+*/
static inline bool fastd_method_session_common_want_refresh(const fastd_method_common_t *session) {
if (session->send_nonce[0] == 0xff)
return true;
@@ -72,6 +98,7 @@ static inline bool fastd_method_session_common_want_refresh(const fastd_method_c
return false;
}
+/** The common \a session_superseded implementation */
static inline void fastd_method_session_common_superseded(fastd_method_common_t *session) {
struct timespec valid_max = fastd_in_seconds(KEY_VALID_OLD);
@@ -79,6 +106,12 @@ static inline void fastd_method_session_common_superseded(fastd_method_common_t
session->valid_till = valid_max;
}
+/**
+ Increments the send nonce
+
+ As one side of a connection uses the even nonces and the other side the odd ones,
+ the nonce is always incremented by 2.
+*/
static inline void fastd_method_increment_nonce(fastd_method_common_t *session) {
session->send_nonce[COMMON_NONCEBYTES-1] += 2;
@@ -91,22 +124,30 @@ static inline void fastd_method_increment_nonce(fastd_method_common_t *session)
}
}
+/** Adds the common header to a packet buffer */
static inline void fastd_method_put_common_header(fastd_buffer_t *buffer, const uint8_t nonce[COMMON_NONCEBYTES], uint8_t flags) {
fastd_buffer_pull_head_from(buffer, nonce, COMMON_NONCEBYTES);
fastd_buffer_pull_head_from(buffer, &flags, 1);
}
+/** Removes the common header from a packet buffer */
static inline void fastd_method_take_common_header(fastd_buffer_t *buffer, uint8_t nonce[COMMON_NONCEBYTES], uint8_t *flags) {
fastd_buffer_push_head_to(buffer, flags, 1);
fastd_buffer_push_head_to(buffer, nonce, COMMON_NONCEBYTES);
}
+/** Handles the common header of a packet */
static inline bool fastd_method_handle_common_header(const fastd_method_common_t *session, fastd_buffer_t *buffer, uint8_t nonce[COMMON_NONCEBYTES], uint8_t *flags, int64_t *age) {
fastd_method_take_common_header(buffer, nonce, flags);
return fastd_method_is_nonce_valid(session, nonce, age);
}
+/**
+ Expands a nonce from COMMON_NONCEBYTES to a buffer of arbitrary length
+
+ The last byte of the buffer is set to 1 as many cryptographic algorithms are specified to have a counter starting with 1 concatenated to the nonce
+*/
static inline void fastd_method_expand_nonce(uint8_t *buf, const uint8_t nonce[COMMON_NONCEBYTES], size_t len) {
if (!len)
return;