tls: if !ENABLE_FEATURE_TLS_SHA1, tls->MAC_size is always SHA256_OUTSIZE for AES-CBC

function                                             old     new   delta
tls_xread_record                                     634     636      +2
xwrite_encrypted                                     579     580      +1
tls_handshake                                       2095    2085     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 3/-10)              Total: -7 bytes

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

1 files changed, 12 insertions, 6 deletions

diff --git a/networking/tls.c b/networking/tls.c
index 3efb0519d..be13c6d5e 100644
--- a/networking/tls.c
+++ b/networking/tls.c
@@ -407,6 +407,12 @@ static void hash_handshake(tls_state_t *tls, const char *fmt, const void *buffer
 #endif
 }
 
+#if !ENABLE_FEATURE_TLS_SHA1
+# define TLS_MAC_SIZE(tls) SHA256_OUTSIZE
+#else
+# define TLS_MAC_SIZE(tls) (tls)->MAC_size
+#endif
+
 // RFC 2104:
 // HMAC(key, text) based on a hash H (say, sha256) is:
 // ipad = [0x36 x INSIZE]
@@ -691,7 +697,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
 
         /* Calculate MAC signature */
         hmac(tls, buf + size, /* result */
-                tls->client_write_MAC_key, tls->MAC_size,
+                tls->client_write_MAC_key, TLS_MAC_SIZE(tls),
                 &tls->write_seq64_be, sizeof(tls->write_seq64_be),
                 xhdr, RECHDR_LEN,
                 buf, size,
@@ -699,7 +705,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
         );
         tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
 
-        size += tls->MAC_size;
+        size += TLS_MAC_SIZE(tls);
 
         // RFC 5246:
         // 6.2.3.1.  Null or Standard Stream Cipher
@@ -784,7 +790,7 @@ static void xwrite_encrypted_and_hmac_signed(tls_state_t *tls, unsigned size, un
 
         tls_get_random(buf - AES_BLOCK_SIZE, AES_BLOCK_SIZE); /* IV */
         dbg("before crypt: 5 hdr + %u data + %u hash bytes\n",
-                        size - tls->MAC_size, tls->MAC_size);
+                        size - TLS_MAC_SIZE(tls), TLS_MAC_SIZE(tls));
 
         /* Fill IV and padding in outbuf */
         // RFC is talking nonsense:
@@ -1099,7 +1105,7 @@ static int tls_xread_record(tls_state_t *tls, const char *expected)
                         tls_aesgcm_decrypt(tls, p, sz);
                         dbg("encrypted size:%u\n", sz);
                 } else
-                if (tls->min_encrypted_len_on_read > tls->MAC_size) {
+                if (tls->min_encrypted_len_on_read > TLS_MAC_SIZE(tls)) {
                         /* AES+SHA */
                         uint8_t *p = tls->inbuf + RECHDR_LEN;
                         int padding_len;
@@ -1118,7 +1124,7 @@ static int tls_xread_record(tls_state_t *tls, const char *expected)
                         padding_len = p[sz - 1];
                         dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[0], padding_len);
                         padding_len++;
-                        sz -= tls->MAC_size + padding_len; /* drop MAC and padding */
+                        sz -= TLS_MAC_SIZE(tls) + padding_len; /* drop MAC and padding */
                 } else {
                         /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
                         /* else: no encryption yet on input, subtract zero = NOP */
@@ -2245,7 +2251,7 @@ void FAST_FUNC tls_handshake(tls_state_t *tls, const char *sni)
                 tls->min_encrypted_len_on_read = tls->MAC_size;
         } else
         if (!(tls->flags & ENCRYPTION_AESGCM)) {
-                unsigned mac_blocks = (unsigned)(tls->MAC_size + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
+                unsigned mac_blocks = (unsigned)(TLS_MAC_SIZE(tls) + AES_BLOCK_SIZE-1) / AES_BLOCK_SIZE;
                 /* all incoming packets now should be encrypted and have
                  * at least IV + (MAC padded to blocksize):
                  */