X-Git-Url: https://git.ralfj.de/dyn-nsupdate.git/blobdiff_plain/88af7a47fc7194a1bd4c699f1da55e86f4576dec..ecc6d7d76571926b6011a3396b5b8d9458d713fc:/dyn-nsupdate.cpp

diff --git a/dyn-nsupdate.cpp b/dyn-nsupdate.cpp
index e378082..b0a7aed 100644
--- a/dyn-nsupdate.cpp
+++ b/dyn-nsupdate.cpp
@@ -1,37 +1,122 @@
 #include <iostream>
+#include <fstream>
+#include <sys/wait.h>
+
+#include <boost/regex.hpp>
 #include <boost/property_tree/ptree.hpp>
 #include <boost/property_tree/ini_parser.hpp>
+#include <boost/iostreams/device/file_descriptor.hpp>
+#include <boost/iostreams/stream.hpp>
 
-#include <sys/stat.h>
+using namespace boost;
+typedef property_tree::ptree::path_type path;
 
-int main(int argc, const char **argv)
+static void write(int fd, const char *str)
 {
-	if (argc < 2) {
-		std::cerr << "Usage: " << argv[0] << " <configuration file>" << std::endl;
-		return 1;
+	size_t len = strlen(str);
+	ssize_t written = write(fd, str, len);
+	if (written < 0 || (size_t)written != len) {
+		std::cerr << "Error writing pipe." << std::endl;
+		exit(1);
 	}
-	const char *filename = argv[1];
+}
+
+int main(int argc, const char ** argv)
+{
+	static const regex regex_ip("\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}");
+	static const regex regex_password("[a-zA-Z0-9.:;,_-]+");
+	static const regex regex_domain("[a-zA-Z0-9.]+");
+	
 	
-	struct stat file_stat;
-	int ret = lstat(filename, &file_stat);
-	if (ret != 0) {
-		std::cerr << "Unable to stat " << filename << "." << std::endl;
+	if (argc != 4) {
+		std::cerr << "Usage: " << argv[0] << " <domain> <password> <IP address>" << std::endl;
 		return 1;
 	}
-	/* Check if the file is suited */
-	if (!S_ISREG(file_stat.st_mode)) {
-		std::cerr << filename << " is not a file." << std::endl;
-		return 1;
+	
+	/* Obtain input */
+	std::string domain = argv[1];
+	std::string password = argv[2];
+	std::string ip = argv[3];
+	
+	/* Validate input */
+	if (!regex_match(ip, regex_ip)) {
+		std::cerr << "Invalid IP address " << ip << "." << std::endl;
+		exit(1);
 	}
-	if (file_stat.st_uid != geteuid()) {
-		std::cerr << filename << " must be owned by user executing " << argv[0] << "." << std::endl;
-		return 1;
+	if (!regex_match(domain, regex_domain)) {
+		std::cerr << "Invalid domain " << domain << "." << std::endl;
+		exit(1);
 	}
-	if (file_stat.st_mode & (S_IWGRP | S_IWOTH)) { /* can be written by group/others */
-		std::cerr << filename << " must not be writeable by group or others." << std::endl;
-		return 1;
+	if (!regex_match(password, regex_password)) {
+		std::cerr << "Invalid password " << password << "." << std::endl;
+		exit(1);
+	}
+	
+	/* read configuration */
+	property_tree::ptree config;
+	property_tree::ini_parser::read_ini(CONFIG_FILE, config);
+	std::string nsupdate = config.get<std::string>("nsupdate");
+	unsigned server_port = config.get<unsigned>("port", 53);
+	
+	/* Given the domain, check whether the password matches */
+	optional<std::string> correct_password = config.get_optional<std::string>(path(domain+"/password", '/'));
+	if (!correct_password || *correct_password != password) {
+		std::cerr << "Password incorrect." << std::endl;
+		exit(1);
+	}
+	
+	/* preapre the pipe */
+	int pipe_ends[2];
+	if (pipe(pipe_ends) < 0) {
+		std::cerr << "Error opening pipe." << std::endl;
+		exit(1);
+	}
+
+	/* Launch nsupdate */
+	pid_t child_pid = fork();
+	if (child_pid < 0) {
+		std::cerr << "Error while forking." << std::endl;
+		exit(1);
+	}
+	if (child_pid == 0) {
+		/* We're in the child */
+		/* Close write end, use read end as stdin */
+		close(pipe_ends[1]);
+		if (dup2(pipe_ends[0], fileno(stdin)) < 0) {
+			std::cerr << "There was an error redirecting stdin." << std::endl;
+			exit(1);
+		}
+		/* exec nsupdate */
+		execl(nsupdate.c_str(), nsupdate.c_str(), "-p", std::to_string(server_port).c_str(), "-l", (char *)NULL);
+		/* There was an error */
+		std::cerr << "There was an error executing nsupdate." << std::endl;
+		exit(1);
+	}
+	
+	/* Send it the command */
+	write(pipe_ends[1], "update delete ");
+	write(pipe_ends[1], domain.c_str());
+	write(pipe_ends[1], ". A\n");
+	
+	write(pipe_ends[1], "update add ");
+	write(pipe_ends[1], domain.c_str());
+	write(pipe_ends[1], ". 60 A ");
+	write(pipe_ends[1], ip.c_str());
+	write(pipe_ends[1], "\n");
+	
+	write(pipe_ends[1], "send\n");
+	
+	/* Close both ends */
+	close(pipe_ends[0]);
+	close(pipe_ends[1]);
+	
+	/* Wait for child to be gone */
+	int child_status;
+	waitpid(child_pid, &child_status, 0);
+	if (child_status != 0) {
+		std::cerr << "There was an error in the child." << std::endl;
+		exit(1);
 	}
 	
-	std::cout << "Hi world!" << std::endl;
 	return 0;
 }