🚧 Write notes for client

src/client/main.cc

@@ -13,8 +13,28 @@ using std::cout, std::cin, std::endl, std::string;
  * Remember to build with the flags "-L/usr/lib -lssl -lcrypto"
  */
 
+/**
+ * Gets the latest error from OpenSSL and returns it as an string.
+ * This makes it easier to log any errors that OpenSSL throws.
+ */
+string getCtxError() {
+
+    // Get the latest error code
+    unsigned long errCode = ERR_get_error();
+
+    // Define a buffer of 128 bytes to hold the error message
+    char errBuffer[128];
+
+    // Get a human readable description of the error from OpenSSL and write it
+    // to the buffer
+    ERR_error_string_n(errCode, errBuffer, sizeof(errBuffer));
+    return errBuffer;
+}
+
 int main() {
 
+    // Define a structure to contains the content of a message and the user who
+    // sent it
     struct Message {
         string content;
         string username;
@@ -24,20 +44,33 @@ int main() {
         }
     };
 
-    // Initialize OpenSSL
-    SSL_library_init();
-    SSL_load_error_strings();
+    // Initializes the SSL library
+    if (OpenSSL_version_num() < 0x10100000L) {
+        // Old version, deprecated as of version 1.1.0
+        SSL_library_init();
 
-    // Create new SSL context
+        // Loads human readable error strings
+        // Automatically initialized in newer versions
+        SSL_load_error_strings();
+    } else {
+        // New version
+        // Initializes both SSL and crypto and is generally better
+        OPENSSL_init_ssl(0, nullptr);
+    }
+
+    // Create new SSL context with client side connections and save it to a
+    // pointer
     SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
     if (!ctx) {
-        cout << "Creation of SSL context failed" << endl;
+        cout << "Creation of SSL context failed: " << getCtxError() << endl;
+        return -1;
     }
 
     // Load the server's certificate into context
-    if (SSL_CTX_load_verify_locations(
-            ctx, "./ssl/server.crt", nullptr) <= 0) {
-            cout << "SSL load failed" << endl;
+    // Returns 1 on success, otherwise check error stack
+    if (SSL_CTX_load_verify_locations(ctx, "./ssl/server.crt", nullptr) <= 0) {
+        cout << "Certificate load failed: " << getCtxError() << endl;
+        return -1;
     }
 
     // Create SSL object
@@ -81,7 +114,8 @@ int main() {
         cout << endl;
         message.username = "Client 1";
 
-        SSL_write(ssl, message.toString().data(), strlen(message.toString().data()));
+        SSL_write(ssl, message.toString().data(),
+                  strlen(message.toString().data()));
     }
 
     // Clean up

src/server/main.cc

@@ -57,6 +57,7 @@ int main() {
     // If it's null, then an error occurred
     if (!ctx) {
         cout << "Creation of SSL context failed: " << getCtxError() << endl;
+        return -1;
     }
 
     // Load certificate into the context