Fix MAC Algo Match

1. Rearrange the matching of the MAC Algos when decoding the KEX Init
   message. It should only dereference the handshake info to check if it
   is using an AEAD cipher if ret is WS_SUCCESS. (If the handshake info
   isn't present, there will be an error present.) This prevents a
   possible NULL dereference.

Author: ejohnstown

src/internal.c

@@ -3978,15 +3978,14 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
         listSz = (word32)sizeof(list);
         ret = GetNameList(list, &listSz, buf, len, &begin);
     }
-    if (!ssh->handshake->aeadMode) {
-        if (ret == WS_SUCCESS) {
-            cannedAlgoNamesSz = AlgoListSz(ssh->algoListMac);
-            cannedListSz = (word32)sizeof(cannedList);
-            ret = GetNameListRaw(cannedList, &cannedListSz,
-                    (const byte*)ssh->algoListMac, cannedAlgoNamesSz);
-        }
+    if (ret == WS_SUCCESS && !ssh->handshake->aeadMode) {
+        cannedAlgoNamesSz = AlgoListSz(ssh->algoListMac);
+        cannedListSz = (word32)sizeof(cannedList);
+        ret = GetNameListRaw(cannedList, &cannedListSz,
+                (const byte*)ssh->algoListMac, cannedAlgoNamesSz);
         if (ret == WS_SUCCESS) {
-            algoId = MatchIdLists(side, list, listSz, cannedList, cannedListSz);
+            algoId = MatchIdLists(side, list, listSz,
+                    cannedList, cannedListSz);
             if (algoId == ID_UNKNOWN) {
                 WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo C2S");
                 ret = WS_MATCH_MAC_ALGO_E;
@@ -4000,15 +3999,13 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
         listSz = (word32)sizeof(list);
         ret = GetNameList(list, &listSz, buf, len, &begin);
     }
-    if (!ssh->handshake->aeadMode) {
-        if (ret == WS_SUCCESS) {
-            algoId = MatchIdLists(side, list, listSz, &algoId, 1);
-            if (algoId == ID_UNKNOWN) {
-                WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo S2C");
-                ret = WS_MATCH_MAC_ALGO_E;
-            }
+    if (ret == WS_SUCCESS && !ssh->handshake->aeadMode) {
+        algoId = MatchIdLists(side, list, listSz, &algoId, 1);
+        if (algoId == ID_UNKNOWN) {
+            WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo S2C");
+            ret = WS_MATCH_MAC_ALGO_E;
         }
-        if (ret == WS_SUCCESS) {
+        else {
             ssh->handshake->macId = algoId;
             ssh->handshake->macSz = MacSzForId(algoId);
             ssh->handshake->keys.macKeySz =