Rename conflicting Avro fields

When a user defined field conflicts with an internal MaxScale field, the
field is suffixed with an underscore.

server/modules/include/avrorouter.h

@@ -71,6 +71,23 @@ static const char *avro_event_type   = "event_type";
 static const char *avro_timestamp    = "timestamp";
 static char *avro_client_ouput[]     = { "Undefined", "JSON", "Avro" };
 
+static inline bool is_reserved_word(const char* word)
+{
+    return strcasecmp(word, avro_domain) == 0 ||
+        strcasecmp(word, avro_server_id) == 0 ||
+        strcasecmp(word, avro_sequence) == 0 ||
+        strcasecmp(word, avro_event_number) == 0 ||
+        strcasecmp(word, avro_event_type) == 0 ||
+        strcasecmp(word, avro_timestamp) == 0;
+}
+
+static inline void fix_reserved_word(char *tok)
+{
+    if (is_reserved_word(tok))
+    {
+        strcat(tok, "_");
+    }
+}
 
 /** How a binlog file is closed */
 typedef enum avro_binlog_end

server/modules/routing/avro/avro_schema.c

@@ -584,6 +584,7 @@ static int process_column_definition(const char *nameptr, char*** dest, char***
         char type[100] = "";
         int len = extract_type_length(nameptr, type);
         nameptr = next_field_definition(nameptr);
+        fix_reserved_word(colname);
 
         lengths[i] = len;
         types[i] = strdup(type);
@@ -834,11 +835,15 @@ void make_avro_token(char* dest, const char* src, int length)
 
     memcpy(dest, src, length);
     dest[length] = '\0';
+    fix_reserved_word(dest);
 }
 
 int get_column_index(TABLE_CREATE *create, const char *tok)
 {
     int idx = -1;
+    char safe_tok[strlen(tok) + 2];
+    strcpy(safe_tok, tok);
+    fix_reserved_word(safe_tok);
 
     for (int x = 0; x < create->columns; x++)
     {