A bit more documentation

3 files changed, 70 insertions, 11 deletions

diff --git a/src/method.h b/src/method.h
index d7f3304..32b5b5c 100644
--- a/src/method.h
+++ b/src/method.h
@@ -23,39 +23,60 @@
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+/**
+   \file method.h
+
+   Management of encryption methods
+*/
+
 
 #pragma once
 
 #include "fastd.h"
 
 
+/** Information about a single encryption method */
 struct fastd_method_info {
-	const char *name;
-	const fastd_method_provider_t *provider;
-	fastd_method_t *method;
+	const char *name;				/**< The method name */
+	const fastd_method_provider_t *provider;	/**< The provider of the method */
+	fastd_method_t *method;				/**< Provider-specific method data */
 };
 
+/** Describes a method provider (an implementation of a class of encryption methods) */
 struct fastd_method_provider {
-	size_t max_overhead;
-	size_t min_encrypt_head_space;
-	size_t min_decrypt_head_space;
-	size_t min_encrypt_tail_space;
-	size_t min_decrypt_tail_space;
+	size_t max_overhead;				/**< The maximum number of bytes of overhead the methods may add */
+	size_t min_encrypt_head_space;			/**< The minimum head space needed for encrytion */
+	size_t min_decrypt_head_space;			/**< The minimum head space needed for decryption */
+	size_t min_encrypt_tail_space;			/**< The minimum tail space needed for encryption */
+	size_t min_decrypt_tail_space;			/**< The minimum tail space needed for decryption */
 
+	/** Tries to create a method with the given name */
 	bool (*create_by_name)(const char *name, fastd_method_t **method);
+	/** Frees the resources allocated for a method */
 	void (*destroy)(fastd_method_t *method);
 
+	/** Returns the key length used by a method */
 	size_t (*key_length)(const fastd_method_t *method);
 
+	/** Initiates a session */
 	fastd_method_session_state_t* (*session_init)(const fastd_method_t *method, const uint8_t *secret, bool initiator);
+	/** Initiates a session in pre-v11 compatiblity mode */
 	fastd_method_session_state_t* (*session_init_compat)(const fastd_method_t *method, const uint8_t *secret, size_t length, bool initiator);
+	/** Closes a session */
+	void (*session_free)(fastd_method_session_state_t *session);
+
+	/** Determines if a session is currently valid */
 	bool (*session_is_valid)(fastd_method_session_state_t *session);
+	/** Determines if this fastd instance is the intiator of a given session */
 	bool (*session_is_initiator)(fastd_method_session_state_t *session);
+	/** Checks if this side wants to refresh the session, negotiating a new session key */
 	bool (*session_want_refresh)(fastd_method_session_state_t *session);
+	/** Marks a session as superseded after a refresh */
 	void (*session_superseded)(fastd_method_session_state_t *session);
-	void (*session_free)(fastd_method_session_state_t *session);
 
+	/** Encrypts a packet for a given session, adding method-specific headers */
 	bool (*encrypt)(fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
+	/** Decrypts a packet for a given session, stripping method-specific headers */
 	bool (*decrypt)(fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
 };
 
@@ -63,6 +84,7 @@ struct fastd_method_provider {
 bool fastd_method_create_by_name(const char *name, const fastd_method_provider_t **provider, fastd_method_t **method);
 
 
+/** Finds the fastd_method_info_t for a configured method */
 static inline const fastd_method_info_t* fastd_method_get_by_name(const char *name) {
 	size_t i;
 	for (i = 0; conf.methods[i].name; i++) {
diff --git a/src/sha256.c b/src/sha256.c
index 38bc43d..c05adbc 100644
--- a/src/sha256.c
+++ b/src/sha256.c
@@ -23,6 +23,12 @@
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+/**
+   \file sha256.c
+
+   Small SHA256 and HMAC-SHA256 implementation
+*/
+
 
 #include "sha256.h"
 
@@ -32,10 +38,16 @@
 #include <arpa/inet.h>
 
 
+/** right-rotation of a 32bit value */
 static inline uint32_t rotr(uint32_t x, int r) {
 	return (x >> r) | (x << (32-r));
 }
 
+/**
+   Copies a (potentially incomplete) input block, while switching from big endian to CPU byte order
+
+   After the last byte, a one-bit is added, as SHA256 defines.
+*/
 static inline void copy_words(uint32_t w[8], const uint32_t *in, ssize_t *left) {
 	size_t i;
 	for (i = 0; i < 8; i++) {
@@ -58,6 +70,7 @@ static inline void copy_words(uint32_t w[8], const uint32_t *in, ssize_t *left)
 	}
 }
 
+/** Hashes a list of input blocks */
 static void sha256_list(uint32_t out[FASTD_SHA256_HASH_WORDS], const uint32_t *const *in, size_t len) {
 	static const uint32_t k[64] = {
 		0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
@@ -126,6 +139,7 @@ static void sha256_list(uint32_t out[FASTD_SHA256_HASH_WORDS], const uint32_t *c
 		out[i] = htonl(h[i]);
 }
 
+/** Hashes a NULL-terminated va_list of complete input blocks */
 static void sha256_blocks_va(uint32_t out[FASTD_SHA256_HASH_WORDS], va_list ap) {
 	size_t count = 0;
 	va_list ap2;
@@ -145,6 +159,7 @@ static void sha256_blocks_va(uint32_t out[FASTD_SHA256_HASH_WORDS], va_list ap)
 	sha256_list(out, blocks, count*FASTD_SHA256_BLOCK_BYTES);
 }
 
+/** Hashes complete input blocks (argument list must by NULL-terminated) */
 void fastd_sha256_blocks(fastd_sha256_t *out, ...) {
 	va_list ap;
 
@@ -153,6 +168,7 @@ void fastd_sha256_blocks(fastd_sha256_t *out, ...) {
 	va_end(ap);
 }
 
+/** Hashes a buffer of arbitraty length (must by 32bit-aligned) */
 void fastd_sha256(fastd_sha256_t *out, const uint32_t *in, size_t len) {
 	size_t i, count = (len+FASTD_SHA256_BLOCK_BYTES-1) / FASTD_SHA256_BLOCK_BYTES;
 	const uint32_t *blocks[count];
@@ -163,6 +179,7 @@ void fastd_sha256(fastd_sha256_t *out, const uint32_t *in, size_t len) {
 	sha256_list(out->w, blocks, len);
 }
 
+/** Computes the HMAC-SHA256 of a list of (potentially incomplete) input blocks */
 static void hmacsha256_list(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], const uint32_t *const *in, size_t len) {
 	static const uint32_t ipad2[8] = {
 		0x36363636,
@@ -205,6 +222,7 @@ static void hmacsha256_list(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSH
 	fastd_sha256_blocks(out, opad, opad2, temp, NULL);
 }
 
+/** Computes the HMAC-SHA256 of a list of NULL-terminated va_list of input blocks */
 static void hmacsha256_blocks_va(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], va_list ap) {
 	size_t count = 0;
 	va_list ap2;
@@ -224,6 +242,8 @@ static void hmacsha256_blocks_va(fastd_sha256_t *out, const uint32_t key[FASTD_H
 	hmacsha256_list(out, key, blocks, count*FASTD_SHA256_BLOCK_BYTES);
 }
 
+
+/** Computes the HMAC-SHA256 of the complete blocks given as arguments (the argument list must be NULL-terminated) */
 void fastd_hmacsha256_blocks(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], ...) {
 	va_list ap;
 
@@ -232,6 +252,7 @@ void fastd_hmacsha256_blocks(fastd_sha256_t *out, const uint32_t key[FASTD_HMACS
 	va_end(ap);
 }
 
+/** Verifies the HMAC-SHA256 of the complete blocks given as arguments (the argument list must be NULL-terminated) */
 bool fastd_hmacsha256_blocks_verify(const uint8_t mac[FASTD_SHA256_HASH_BYTES], const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], ...) {
 	va_list ap;
 	fastd_sha256_t out;
@@ -243,6 +264,7 @@ bool fastd_hmacsha256_blocks_verify(const uint8_t mac[FASTD_SHA256_HASH_BYTES],
 	return !memcmp(out.b, mac, FASTD_SHA256_HASH_BYTES);
 }
 
+/** Computes the HMAC-SHA256 of an arbitraty input buffer */
 void fastd_hmacsha256(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], const uint32_t *in, size_t len) {
 	size_t i, count = (len+FASTD_SHA256_BLOCK_BYTES-1) / FASTD_SHA256_BLOCK_BYTES;
 	const uint32_t *blocks[count];
@@ -253,6 +275,7 @@ void fastd_hmacsha256(fastd_sha256_t *out, const uint32_t key[FASTD_HMACSHA256_K
 	hmacsha256_list(out, key, blocks, len);
 }
 
+/** Verifies the HMAC-SHA256 of an arbitraty input buffer */
 bool fastd_hmacsha256_verify(const uint8_t mac[FASTD_SHA256_HASH_BYTES], const uint32_t key[FASTD_HMACSHA256_KEY_WORDS], const uint32_t *in, size_t len) {
 	fastd_sha256_t out;
 
diff --git a/src/sha256.h b/src/sha256.h
index 30a8d35..a0b8805 100644
--- a/src/sha256.h
+++ b/src/sha256.h
@@ -23,6 +23,13 @@
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
+/**
+   \file sha256.h
+
+   Small SHA256 and HMAC-SHA256 implementation
+*/
+
+
 
 #pragma once
 
@@ -31,20 +38,27 @@
 #include <stdint.h>
 
 
+/** 32bit words per SHA256 hash */
 #define FASTD_SHA256_HASH_WORDS 8
+/** 32bit words per input block */
 #define FASTD_SHA256_BLOCK_WORDS 8
 
+/** 32bit words per HMAC-SHA256 key */
 #define FASTD_HMACSHA256_KEY_WORDS 8
 
+/** bytes per SHA256 hash */
 #define FASTD_SHA256_HASH_BYTES (4*FASTD_SHA256_HASH_WORDS)
+/** bytes per input block */
 #define FASTD_SHA256_BLOCK_BYTES (4*FASTD_SHA256_BLOCK_WORDS)
 
+/** bytes per HMAC-SHA256 key */
 #define FASTD_HMACSHA256_KEY_BYTES (4*FASTD_HMACSHA256_KEY_WORDS)
 
 
+/** A SHA256 hash output */
 typedef union fastd_sha256 {
-	uint32_t w[FASTD_SHA256_HASH_WORDS];
-	uint8_t b[FASTD_SHA256_HASH_BYTES];
+	uint32_t w[FASTD_SHA256_HASH_WORDS];		/**< 32bit-word-wise access */
+	uint8_t b[FASTD_SHA256_HASH_BYTES];		/**< bytewise access */
 } fastd_sha256_t;