add docs and some hashmap code

include/hashmap.h

@@ -1,19 +1,32 @@
 #ifndef __HASHMAP_C__
 #define __HASHMAP_C__
 
+#include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
 
-#define HASHMAP_MAX_CLIENTS 10000
+/* Each process on Linux can have a maximum of 1024 open file descriptors */
+#define HASHMAP_MAX_CLIENTS 1024
 
 struct hashmap {
 	int sockfd;
 	struct sockaddr_storage sas;
+	struct hashmap *next;
 };
 
+/* Calculate the hash code of a file descriptor */
 int hash(int sockfd);
+
+/* Initialize the hash map */
 void hm_init(struct hashmap *map);
+
+/* Insert a new key in the hash map */
 void hm_insert(struct hashmap *map, int sockfd, struct sockaddr_storage *sas);
+
+/* Search for a key in the hash map */
 struct hashmap *hm_lookup(struct hashmap *map, int sockfd);
 
+/* Clean up the hash map */
+void hm_free(struct hashmap *map);
+
 #endif