initial hashmap code

src/hashmap.c

@@ -0,0 +1,9 @@
+#include "hashmap.h"
+
+int hash(int sockfd) { return sockfd % HASHMAP_MAX_ITEMS; }
+
+void hm_insert(struct hashmap *map, int sockfd, struct sockaddr_storage *sas) {
+	int index = hash(sockfd);
+	map[index].sockfd = sockfd;
+	map[index].sas = *sas;
+}