[tac_plus] [PATCH tac_plus] Avoid unnecessary marshalling when computing MD5 bitstream cipher

[Philip Prindeville]

From: Philip Prindeville <philipp at redfish-solutions.com>

MD5Update() can be called iteratively, so there's no need for the
data passed to it to be marshalled into contiguous storage.

---
 encrypt.c | 33 ++++++---------------------------
 1 file changed, 6 insertions(+), 27 deletions(-)

diff --git a/encrypt.c b/encrypt.c
index 90d4506..487f304 100644
--- a/encrypt.c
+++ b/encrypt.c
@@ -39,37 +39,16 @@ void
 create_md5_hash(int session_id, char *key, u_char version, u_char seq_no,
 		u_char *prev_hash, u_char *hash)
 {
-    u_char *md_stream, *mdp;
-    int md_len;
     MD5_CTX mdcontext;
 
-    md_len = sizeof(session_id) + strlen(key) + sizeof(version) +
-	sizeof(seq_no);
-
-    if (prev_hash) {
-	md_len += TAC_MD5_DIGEST_LEN;
-    }
-    mdp = md_stream = (u_char *) tac_malloc(md_len);
-    memcpy(mdp, &session_id, sizeof(session_id));
-    mdp += sizeof(session_id);
-
-    memcpy(mdp, key, strlen(key));
-    mdp += strlen(key);
-
-    memcpy(mdp, &version, sizeof(version));
-    mdp += sizeof(version);
-
-    memcpy(mdp, &seq_no, sizeof(seq_no));
-    mdp += sizeof(seq_no);
-
-    if (prev_hash) {
-	memcpy(mdp, prev_hash, TAC_MD5_DIGEST_LEN);
-	mdp += TAC_MD5_DIGEST_LEN;
-    }
     MD5Init(&mdcontext);
-    MD5Update(&mdcontext, md_stream, md_len);
+    MD5Update(&mdcontext, (u_char *)&session_id, sizeof(session_id));
+    MD5Update(&mdcontext, key, strlen(key));
+    MD5Update(&mdcontext, &version, sizeof(version));
+    MD5Update(&mdcontext, &seq_no, sizeof(seq_no));
+    if (prev_hash)
+	MD5Update(&mdcontext, prev_hash, TAC_MD5_DIGEST_LEN);
     MD5Final(hash, &mdcontext);
-    free(md_stream);
     return;
 }