init

lib/data/session.cpp

@@ -0,0 +1,108 @@
+#include "session.hpp"
+#include <pgmspace.h> // Required for PROGMEM
+
+// Definition of the global instance
+SessionManager sessionManager;
+
+// The character set is now stored in flash memory to save RAM.
+const char charset[] PROGMEM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+SessionManager::SessionManager() {
+    session_mutex_ = xSemaphoreCreateMutex();
+    for (size_t i = 0; i < MAX_SESSIONS; ++i) {
+        sessions_[i].username[0] = '\0';
+    }
+}
+
+SessionManager::~SessionManager() {
+    vSemaphoreDelete(session_mutex_);
+}
+
+const char* SessionManager::createSession(const char* username) {
+    const char* result_token = nullptr;
+    // Lock the mutex to ensure exclusive access to the sessions array.
+    if (xSemaphoreTake(session_mutex_, portMAX_DELAY) == pdTRUE) {
+        for (size_t i = 0; i < MAX_SESSIONS; ++i) {
+            if (sessions_[i].username[0] == '\0') {
+                strncpy(sessions_[i].username, username, sizeof(sessions_[i].username) - 1);
+                sessions_[i].username[sizeof(sessions_[i].username) - 1] = '\0';
+
+                generateToken(sessions_[i].token, sizeof(sessions_[i].token));
+
+                sessions_[i].expiry_time = millis() + (15 * 60 * 1000);
+
+                result_token = sessions_[i].token;
+                break; // Exit loop once a slot is found
+            }
+        }
+        xSemaphoreGive(session_mutex_); // Release the mutex
+    }
+    return result_token;
+}
+
+const char* SessionManager::validateSession(const char* token) {
+    if (token == nullptr) {
+        return nullptr;
+    }
+
+    // We must copy the username to a static buffer, because the session array
+    // could be modified by another task after we release the mutex.
+    static char valid_username[33];
+    valid_username[0] = '\0';
+
+    if (xSemaphoreTake(session_mutex_, portMAX_DELAY) == pdTRUE) {
+        for (size_t i = 0; i < MAX_SESSIONS; ++i) {
+            if (sessions_[i].username[0] != '\0' && strcmp(sessions_[i].token, token) == 0) {
+                if (millis() < sessions_[i].expiry_time) {
+                    strcpy(valid_username, sessions_[i].username);
+                } else {
+                    sessions_[i].username[0] = '\0'; // Expired, clear it
+                }
+                break;
+            }
+        }
+        xSemaphoreGive(session_mutex_);
+    }
+
+    return (valid_username[0] != '\0') ? valid_username : nullptr;
+}
+
+bool SessionManager::endSession(const char* token) {
+    if (token == nullptr) return false;
+
+    bool found = false;
+    if (xSemaphoreTake(session_mutex_, portMAX_DELAY) == pdTRUE) {
+        for (size_t i = 0; i < MAX_SESSIONS; ++i) {
+            if (sessions_[i].username[0] != '\0' && strcmp(sessions_[i].token, token) == 0) {
+                sessions_[i].username[0] = '\0';
+                found = true;
+                break;
+            }
+        }
+        xSemaphoreGive(session_mutex_);
+    }
+    return found;
+}
+
+void SessionManager::cleanupExpiredSessions() {
+    unsigned long current_time = millis();
+    if (xSemaphoreTake(session_mutex_, portMAX_DELAY) == pdTRUE) {
+        for (size_t i = 0; i < MAX_SESSIONS; ++i) {
+            if (sessions_[i].username[0] != '\0') {
+                if (current_time >= sessions_[i].expiry_time) {
+                    sessions_[i].username[0] = '\0';
+                }
+            }
+        }
+        xSemaphoreGive(session_mutex_);
+    }
+}
+
+void SessionManager::generateToken(char* buffer, size_t buffer_size) {
+    const size_t charset_size = sizeof(charset) - 1;
+    for (size_t i = 0; i < buffer_size - 1; ++i) {
+        // Read the character directly from flash memory (PROGMEM).
+        buffer[i] = pgm_read_byte(&charset[esp_random() % charset_size]);
+    }
+    buffer[buffer_size - 1] = '\0';
+}