Fix String References

1. When looking up a name in the name-ID map, don't bother checking if
   the name is NULL.
2. The GetString functions should fail if the destination string
   parameter is NULL.
3. The GetString functions should not bother to copy an empty string
   found in the data stream.
4. When checking the public key type provided by the callback, do not
   check it when it is NULL.

src/internal.c

@@ -2827,6 +2827,9 @@ byte NameToId(const char* name, word32 nameSz)
     byte id = ID_UNKNOWN;
     word32 i;
 
+    if (name == NULL)
+        return id;
+
     for (i = 0; i < (sizeof(NameIdMap)/sizeof(NameIdPair)); i++) {
         if (nameSz == (word32)WSTRLEN(NameIdMap[i].name) &&
             XMEMCMP(name, NameIdMap[i].name, nameSz) == 0) {
@@ -3582,14 +3585,20 @@ int GetMpint(word32* mpintSz, const byte** mpint,
  * the provided buffer, and terminates it with a NULL. */
 int GetString(char* s, word32* sSz, const byte* buf, word32 len, word32 *idx)
 {
-    int result;
+    int result = WS_SUCCESS;
     word32 strSz;
     const byte* str;
 
-    result = GetStringRef(&strSz, &str, buf, len, idx);
+    if (s == NULL || sSz == NULL)
+        result = WS_BAD_ARGUMENT;
+
+    if (result == WS_SUCCESS)
+        result = GetStringRef(&strSz, &str, buf, len, idx);
+
     if (result == WS_SUCCESS) {
         *sSz = (strSz >= *sSz) ? *sSz - 1 : strSz; /* -1 for null char */
-        WMEMCPY(s, str, *sSz);
+        if (strSz && str)
+            WMEMCPY(s, str, *sSz);
         s[*sSz] = 0;
     }
 
@@ -3602,22 +3611,24 @@ int GetString(char* s, word32* sSz, const byte* buf, word32 len, word32 *idx)
 int GetStringAlloc(void* heap, char** s, word32* sSz,
         const byte* buf, word32 len, word32 *idx)
 {
-    int result;
+    int result = WS_SUCCESS;
     const byte *str;
+    char* newStr;
     word32 strSz;
 
-    if (s == NULL) {
-        return WS_BAD_ARGUMENT;
-    }
+    if (s == NULL)
+        result = WS_BAD_ARGUMENT;
+
+    if (result == WS_SUCCESS)
+        result = GetStringRef(&strSz, &str, buf, len, idx);
 
-    result = GetStringRef(&strSz, &str, buf, len, idx);
     if (result == WS_SUCCESS) {
-        char* newStr;
-
         newStr = (char*)WMALLOC(strSz + 1, heap, DYNTYPE_STRING);
         if (newStr == NULL)
-            return WS_MEMORY_E;
+            result = WS_MEMORY_E;
+    }
 
+    if (result == WS_SUCCESS) {
         if (strSz > 0 && str)
             WMEMCPY(newStr, str, strSz);
         newStr[strSz] = 0;
@@ -3638,9 +3649,14 @@ int GetStringAlloc(void* heap, char** s, word32* sSz,
 int GetStringRef(word32* strSz, const byte** str,
         const byte* buf, word32 len, word32* idx)
 {
-    int result;
+    int result = WS_SUCCESS;
+
+    if (str == NULL || strSz == NULL)
+        result = WS_BAD_ARGUMENT;
+
+    if (result == WS_SUCCESS)
+        result = GetUint32(strSz, buf, len, idx);
 
-    result = GetUint32(strSz, buf, len, idx);
     if (result == WS_SUCCESS) {
         if (*idx <= len && *strSz <= len - *idx) {
             if (*strSz) {
@@ -6907,8 +6923,8 @@ static int DoUserAuthRequestRsa(WOLFSSH* ssh, WS_UserAuthData_PublicKey* pk,
     }
 
     if (ret == WS_SUCCESS) {
-        if (publicKeyTypeSz != 7 &&
-            WMEMCMP(publicKeyType, "ssh-rsa", 7) != 0) {
+        if (publicKeyTypeSz != 7 || publicKeyType == NULL
+            || WMEMCMP(publicKeyType, "ssh-rsa", 7) != 0) {
 
             WLOG(WS_LOG_DEBUG,
                 "Public Key's type does not match public key type");
@@ -6946,8 +6962,10 @@ static int DoUserAuthRequestRsa(WOLFSSH* ssh, WS_UserAuthData_PublicKey* pk,
     }
 
     if (ret == WS_SUCCESS) {
-        if (publicKeyTypeSz != pk->publicKeyTypeSz &&
-            WMEMCMP(publicKeyType, pk->publicKeyType, publicKeyTypeSz) != 0) {
+        if (publicKeyTypeSz != pk->publicKeyTypeSz
+            || publicKeyType == NULL
+            || WMEMCMP(publicKeyType, pk->publicKeyType,
+                    publicKeyTypeSz) != 0) {
 
             WLOG(WS_LOG_DEBUG,
                  "Signature's type does not match public key type");