blaze822: add blaze822_headerlen

blaze822.c

@@ -555,6 +555,12 @@ error:
 	return 0;
 }
 
+size_t
+blaze822_headerlen(struct message *mesg)
+{
+	return mesg->end - mesg->msg;
+}
+
 char *
 blaze822_body(struct message *mesg)
 {

blaze822.h

@@ -22,6 +22,7 @@ time_t blaze822_date(char *);
 char *blaze822_addr(char *, char **, char **);
 char *blaze822_body(struct message *mesg);
 size_t blaze822_bodylen(struct message *mesg);
+size_t blaze822_headerlen(struct message *mesg);
 
 int blaze822_loop(int, char **, void (*)(char *));