tls: merge sha1 and sha256 hmac functions

function                                             old     new   delta
hmac_begin                                             -     196    +196
hmac_sha256                                           61      68      +7
hmac                                                 250      87    -163
hmac_sha256_begin                                    190       -    -190
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/1 up/down: 203/-353)         Total: -150 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 12 insertions, 44 deletions

diff --git a/networking/tls.c b/networking/tls.c
index cb6b09476..bbf2b158f 100644
--- a/networking/tls.c
+++ b/networking/tls.c
@@ -367,11 +367,12 @@ static unsigned hmac_sha_precomputed_v(
         return sha_end(&pre->hashed_key_xor_opad, out);
 }
 
-static void hmac_sha256_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size)
+typedef void md5sha_begin_func(md5sha_ctx_t *ctx) FAST_FUNC;
+static void hmac_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
 {
         uint8_t key_xor_ipad[SHA_INSIZE];
         uint8_t key_xor_opad[SHA_INSIZE];
-        uint8_t tempkey[SHA256_OUTSIZE];
+        uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
         unsigned i;
 
         // "The authentication key can be of any length up to INSIZE, the
@@ -380,7 +381,7 @@ static void hmac_sha256_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned ke
         // resultant OUTSIZE byte string as the actual key to HMAC."
         if (key_size > SHA_INSIZE) {
                 md5sha_ctx_t ctx;
-                sha256_begin(&ctx);
+                begin(&ctx);
                 md5sha_hash(&ctx, key, key_size);
                 key_size = sha_end(&ctx, tempkey);
         }
@@ -394,41 +395,8 @@ static void hmac_sha256_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned ke
                 key_xor_opad[i] = 0x5c;
         }
 
-        sha256_begin(&pre->hashed_key_xor_ipad);
-        sha256_begin(&pre->hashed_key_xor_opad);
-        md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
-        md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
-}
-// TODO: ^^^ vvv merge?
-static void hmac_sha1_begin(hmac_precomputed_t *pre, uint8_t *key, unsigned key_size)
-{
-        uint8_t key_xor_ipad[SHA_INSIZE];
-        uint8_t key_xor_opad[SHA_INSIZE];
-        uint8_t tempkey[SHA1_OUTSIZE];
-        unsigned i;
-
-        // "The authentication key can be of any length up to INSIZE, the
-        // block length of the hash function.  Applications that use keys longer
-        // than INSIZE bytes will first hash the key using H and then use the
-        // resultant OUTSIZE byte string as the actual key to HMAC."
-        if (key_size > SHA_INSIZE) {
-                md5sha_ctx_t ctx;
-                sha1_begin(&ctx);
-                md5sha_hash(&ctx, key, key_size);
-                key_size = sha_end(&ctx, tempkey);
-        }
-
-        for (i = 0; i < key_size; i++) {
-                key_xor_ipad[i] = key[i] ^ 0x36;
-                key_xor_opad[i] = key[i] ^ 0x5c;
-        }
-        for (; i < SHA_INSIZE; i++) {
-                key_xor_ipad[i] = 0x36;
-                key_xor_opad[i] = 0x5c;
-        }
-
-        sha1_begin(&pre->hashed_key_xor_ipad);
-        sha1_begin(&pre->hashed_key_xor_opad);
+        begin(&pre->hashed_key_xor_ipad);
+        begin(&pre->hashed_key_xor_opad);
         md5sha_hash(&pre->hashed_key_xor_ipad, key_xor_ipad, SHA_INSIZE);
         md5sha_hash(&pre->hashed_key_xor_opad, key_xor_opad, SHA_INSIZE);
 }
@@ -441,11 +409,11 @@ static unsigned hmac(tls_state_t *tls, uint8_t *out, uint8_t *key, unsigned key_
 
         va_start(va, key_size);
 
-        if (tls->MAC_size == SHA256_OUTSIZE)
-                hmac_sha256_begin(&pre, key, key_size);
-        else
-                hmac_sha1_begin(&pre, key, key_size);
-
+        hmac_begin(&pre, key, key_size,
+                        (tls->MAC_size == SHA256_OUTSIZE)
+                                ? sha256_begin
+                                : sha1_begin
+        );
         len = hmac_sha_precomputed_v(&pre, out, va);
 
         va_end(va);
@@ -460,7 +428,7 @@ static unsigned hmac_sha256(/*tls_state_t *tls,*/ uint8_t *out, uint8_t *key, un
 
         va_start(va, key_size);
 
-        hmac_sha256_begin(&pre, key, key_size);
+        hmac_begin(&pre, key, key_size, sha256_begin);
         len = hmac_sha_precomputed_v(&pre, out, va);
 
         va_end(va);