run nsupdate as child and send it the update commands

diff --git a/dyn-nsupdate.cpp b/dyn-nsupdate.cpp
index cdd1dc493db31a9859108ddadd94e9328ba7bfac..4cb7ead86ec2ff1c178cffedee3cbb7037b66597 100644 (file)
--- a/dyn-nsupdate.cpp
+++ b/dyn-nsupdate.cpp
@@ -1,12 +1,25 @@
 #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>
 
 using namespace boost;
 
+static void write(int fd, const char *str)
+{
+       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);
+       }
+}
+
 int main(int argc, const char ** argv)
 {
        static const regex regex_ip("\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}");
@@ -26,31 +39,78 @@ int main(int argc, const char ** argv)
        
        if (!regex_match(ip, regex_ip)) {
                std::cerr << "Invalid IP address " << ip << "." << std::endl;
-               return 1;
+               exit(1);
        }
        if (!regex_match(user, regex_user)) {
                std::cerr << "Invalid username " << user << "." << std::endl;
-               return 1;
+               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");
        std::string keyfile = config.get<std::string>("key");
        
        /* Check username, password, domain */
        optional<std::string> correct_password = config.get_optional<std::string>(user+".password");
        if (!correct_password || *correct_password != password) {
                std::cerr << "Username or password incorrect." << std::endl;
-               return 1;
+               exit(1);
        }
        if (config.get<std::string>(user+".domain") != domain) {
                std::cerr << "Domain incorrect." << std::endl;
-               return 1;
+               exit(1);
        }
        
-       std::cout << "It's all right, using key " << keyfile << std::endl;
+       /* preapre the pipe */
+       int pipe_ends[] = {0,0};
+       pipe(pipe_ends);
+
+       /* 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 and as stdin */
+               close(pipe_ends[1]);
+               dup2(pipe_ends[0], fileno(stdin));
+               /* exec nsupdate */
+               execl(nsupdate.c_str(), nsupdate.c_str(), "-k", keyfile.c_str(), 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], "server localhost\n");
+       
+       write(pipe_ends[1], "update delete ");
+       write(pipe_ends[1], domain.c_str());
+       write(pipe_ends[1], ".\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);
+       }
        
        return 0;
 }