SSH2 MACs now use dynamically allocated contexts.

[u/mdw/putty] / sshmd5.c

diff --git a/sshmd5.c b/sshmd5.c
index 0625f76..22c3e65 100644 (file)
--- a/sshmd5.c
+++ b/sshmd5.c
@@ -208,44 +208,46 @@ void MD5Final(unsigned char output[16], struct MD5Context *s)
  * HMAC wrapper on it.
  */
 
-static struct MD5Context md5_cs_mac_s1, md5_cs_mac_s2;
-static struct MD5Context md5_sc_mac_s1, md5_sc_mac_s2;
+static void *md5_make_context(void)
+{
+    return smalloc(2*sizeof(struct MD5Context));
+}
+
+static void md5_free_context(void *handle)
+{
+    sfree(handle);
+}
 
-static void md5_key(struct MD5Context *s1, struct MD5Context *s2,
-                   unsigned char *key, int len)
+static void md5_key_internal(void *handle, unsigned char *key, int len)
 {
+    struct MD5Context *keys = (struct MD5Context *)handle;
     unsigned char foo[64];
     int i;
 
     memset(foo, 0x36, 64);
     for (i = 0; i < len && i < 64; i++)
        foo[i] ^= key[i];
-    MD5Init(s1);
-    MD5Update(s1, foo, 64);
+    MD5Init(&keys[0]);
+    MD5Update(&keys[0], foo, 64);
 
     memset(foo, 0x5C, 64);
     for (i = 0; i < len && i < 64; i++)
        foo[i] ^= key[i];
-    MD5Init(s2);
-    MD5Update(s2, foo, 64);
+    MD5Init(&keys[0]);
+    MD5Update(&keys[0], foo, 64);
 
     memset(foo, 0, 64);                       /* burn the evidence */
 }
 
-static void md5_cskey(unsigned char *key)
-{
-    md5_key(&md5_cs_mac_s1, &md5_cs_mac_s2, key, 16);
-}
-
-static void md5_sckey(unsigned char *key)
+static void md5_key(void *handle, unsigned char *key)
 {
-    md5_key(&md5_sc_mac_s1, &md5_sc_mac_s2, key, 16);
+    md5_key_internal(handle, key, 16);
 }
 
-static void md5_do_hmac(struct MD5Context *s1, struct MD5Context *s2,
-                       unsigned char *blk, int len, unsigned long seq,
-                       unsigned char *hmac)
+static void md5_do_hmac(void *handle, unsigned char *blk, int len,
+                       unsigned long seq, unsigned char *hmac)
 {
+    struct MD5Context *keys = (struct MD5Context *)handle;
     struct MD5Context s;
     unsigned char intermediate[16];
 
@@ -254,31 +256,32 @@ static void md5_do_hmac(struct MD5Context *s1, struct MD5Context *s2,
     intermediate[2] = (unsigned char) ((seq >> 8) & 0xFF);
     intermediate[3] = (unsigned char) ((seq) & 0xFF);
 
-    s = *s1;                          /* structure copy */
+    s = keys[0];                      /* structure copy */
     MD5Update(&s, intermediate, 4);
     MD5Update(&s, blk, len);
     MD5Final(intermediate, &s);
-    s = *s2;                          /* structure copy */
+    s = keys[1];                      /* structure copy */
     MD5Update(&s, intermediate, 16);
     MD5Final(hmac, &s);
 }
 
-static void md5_generate(unsigned char *blk, int len, unsigned long seq)
+static void md5_generate(void *handle, unsigned char *blk, int len,
+                        unsigned long seq)
 {
-    md5_do_hmac(&md5_cs_mac_s1, &md5_cs_mac_s2, blk, len, seq, blk + len);
+    md5_do_hmac(handle, blk, len, seq, blk + len);
 }
 
-static int md5_verify(unsigned char *blk, int len, unsigned long seq)
+static int md5_verify(void *handle, unsigned char *blk, int len,
+                     unsigned long seq)
 {
     unsigned char correct[16];
-    md5_do_hmac(&md5_sc_mac_s1, &md5_sc_mac_s2, blk, len, seq, correct);
+    md5_do_hmac(handle, blk, len, seq, correct);
     return !memcmp(correct, blk + len, 16);
 }
 
 const struct ssh_mac ssh_md5 = {
-    md5_cskey, md5_sckey,
-    md5_generate,
-    md5_verify,
+    md5_make_context, md5_free_context, md5_key,
+    md5_generate, md5_verify,
     "hmac-md5",
     16
 };