allow configuring the port

[dyn-nsupdate.git] / dyn-nsupdate.cpp

diff --git a/dyn-nsupdate.cpp b/dyn-nsupdate.cpp
index e378082c30ea4c9f0471e830f983c72535944621..b0a7aed0d8e51185d9838ce64ecff16e79bc2242 100644 (file)
--- 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;
 }