Added code.

server/src/include/session.h

@@ -0,0 +1,96 @@
+#ifndef SESSION_H
+#define SESSION_H
+
+#include <libwebsockets.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+// Includes terminating null.
+#define SESSION_USERNAME_MAX_LEN 32
+#define SESSION_CHAT_BUF_SIZE 1024
+
+/**
+ * session_t
+ * Represents a single WebSocket client session in the chat server.
+ */
+typedef struct SESSION {
+    struct lws* wsi;                     // Libwebsockets connection handle.
+    uint64_t id;                         // Unique session ID.
+    struct SESSION* next;                // Next session in the internal list.
+    char name[SESSION_USERNAME_MAX_LEN]; // Stored username.
+    bool named;                          // True once username is set.
+    unsigned char buf[LWS_PRE + SESSION_CHAT_BUF_SIZE]; // Outgoing buffer per session
+    size_t buf_len;                      // Length of data in buf
+} Session;
+
+/**
+ * session_create
+ * Allocate and initialize a new session, adding it to the internal list.
+ *
+ * @param wsi   The libwebsockets connection handle.
+ * @return      Pointer to the new session, or NULL on failure.
+ */
+Session* session_create(struct lws* wsi);
+
+/**
+ * session_destroy
+ * Remove the given session from the internal list and free its memory.
+ *
+ * @param sess  The session to destroy.
+ */
+void session_destroy(Session* sess);
+
+/**
+ * session_get_head
+ * Retrieve the head of the internal session linked list.
+ *
+ * @return The first session in the list, or NULL if none.
+ */
+Session* session_get_head(void);
+
+/**
+ * session_broadcast
+ * Iterate every session in the internal list and invoke the callback.
+ *
+ * @param cb   Function to call for each session.
+ * @param user Arbitrary user data passed through to each callback.
+ */
+void session_broadcast(void (*cb)(Session* sess, void* user), void* user);
+
+/**
+ * session_set_username
+ * Store a username in the given session.
+ *
+ * @param sess      The session to update.
+ * @param username  Null-terminated string to copy into the session.
+ */
+void session_set_username(Session* sess, const char* username);
+
+/**
+ * session_get_username
+ * Fetch the username stored in the session.
+ *
+ * @param sess  The session to query.
+ * @return      Pointer to the stored username (readonly).
+ */
+const char* session_get_username(const Session* sess);
+
+/**
+ * session_has_username
+ * Check whether a session has already set a username.
+ *
+ * @param sess  The session to query.
+ * @return      True if a username is set, false otherwise.
+ */
+bool session_has_username(const Session* sess);
+
+/**
+ * session_get_id
+ * Fetch the session ID.
+ *
+ * @param sess  The session to query.
+ * @return      The session's unique ID.
+ */
+uint64_t session_get_id(const Session* sess);
+
+#endif // SESSION_H