Add cdns-blocks cli tool

cdns-blocks command line tool prints summary information about
individual Blocks in C-DNS file.

CMakeLists.txt

@@ -72,7 +72,11 @@ if (BUILD_CLI_TOOLS)
     add_executable(cdns-preamble src/bin/cdns_preamble.cpp)
     target_link_libraries(cdns-preamble PUBLIC cdns)
 
-    install(TARGETS cdns-merge cdns-itemcount cdns-preamble RUNTIME)
+    # cdns-blocks cli tool
+    add_executable(cdns-blocks src/bin/cdns_blocks.cpp)
+    target_link_libraries(cdns-blocks PUBLIC cdns)
+
+    install(TARGETS cdns-merge cdns-itemcount cdns-preamble cdns-blocks RUNTIME)
 endif(BUILD_CLI_TOOLS)
 
 if (BUILD_PYTHON_BINDINGS)

src/bin/cdns_blocks.cpp

+/**
+ * Copyright © 2024 CZ.NIC, z. s. p. o.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include <iostream>
+#include <istream>
+#include <string>
+#include <getopt.h>
+
+#include "../cdns.h"
+
+
+/**
+ * @file cdns_blocks.cpp
+ * @brief Implementation of cdns-blocks command line tool.
+ *
+ * cdns-blocks command line tool prints summary information about individual Blocks in C-DNS file. \n
+ * Usage: cdns-blocks [-n <BLOCK_NUMBER>] [-h] <INPUT_FILE> \n
+ * Options: \n
+ *      -n <BLOCK_NUMBER>   : Print information only for specific block (starts at 0) \n
+ *      -h                  : Print this help message and exit \n
+ */
+
+static void print_help()
+{
+    std::cout << "cdns-blocks:" << std::endl;
+    std::cout << "Prints summary information about individual Blocks in C-DNS file" << std::endl;
+    std::cout << "Usage: cdns-blocks [-n <BLOCK_NUMBER>] [-h] <INPUT_FILE>" << std::endl;
+    std::cout << "Options:" << std::endl;
+    std::cout << "\t-n <BLOCK_NUMBER>   : Print information only for specific block (starts at 0)" << std::endl;
+    std::cout << "\t-h                  : Print this help message and exit" << std::endl;
+}
+
+int main(int argc, char** argv)
+{
+    std::string input_file;
+    bool one_block = false;
+    unsigned block_number = 0;
+    int opt;
+
+    // Parse command line arguments
+    while ((opt = getopt(argc, argv, "n:h")) != EOF) {
+        switch (opt) {
+            case 'n':
+                one_block = true;
+                block_number = std::stoul(optarg);
+                break;
+            case 'h':
+                print_help();
+                exit(EXIT_SUCCESS);
+                break;
+            default:
+                print_help();
+                exit(EXIT_FAILURE);
+                break;
+        }
+    }
+
+    if (optind == argc) {
+        std::cerr << "No input file specified!" << std::endl << std::endl;
+        print_help();
+        return 1;
+    }
+
+    input_file = std::string(argv[optind++]);
+
+    if (optind < argc) {
+        std::cerr << "Invalid extra arguments!" << std::endl << std::endl;
+        print_help();
+        return 1;
+    }
+
+    try {
+        std::ifstream ifs(input_file, std::ifstream::binary);
+        CDNS::CdnsReader reader(ifs);
+        bool end = false;
+        unsigned i = 0;
+
+        while (true) {
+            auto block = reader.read_block(end);
+
+            if (end)
+                break;
+
+            if (one_block && block_number != i) {
+                i++;
+                continue;
+            }
+
+            std::cout << "Block " << std::to_string(i) << ": " << std::endl;
+            std::cout << block.string() << std::endl;
+
+            i++;
+        }
+    }
+    catch (std::exception& e) {
+        std::cerr << "Couldn't process input file " << input_file << "! Reason: " << e.what() << std::endl;
+    }
+
+    return 0;
+}