initial checkin of c-implementaion of door_damon

[svn42.git] / door_daemon / daemon.h

diff --git a/door_daemon/daemon.h b/door_daemon/daemon.h
new file mode 100644 (file)
index 0000000..ac0516e
--- /dev/null
+++ b/door_daemon/daemon.h
@@ -0,0 +1,172 @@
+/*
+ *  uAnytun
+ *
+ *  uAnytun is a tiny implementation of SATP. Unlike Anytun which is a full
+ *  featured implementation uAnytun has no support for multiple connections
+ *  or synchronisation. It is a small single threaded implementation intended
+ *  to act as a client on small platforms.
+ *  The secure anycast tunneling protocol (satp) defines a protocol used
+ *  for communication between any combination of unicast and anycast
+ *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
+ *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
+ *  ethernet, ip, arp ...). satp directly includes cryptography and
+ *  message authentication based on the methodes used by SRTP.  It is
+ *  intended to deliver a generic, scaleable and secure solution for
+ *  tunneling and relaying of packets of any protocol.
+ *  
+ *
+ *  Copyright (C) 2007-2008 Christian Pointner <equinox@anytun.org>
+ *
+ *  This file is part of uAnytun.
+ *
+ *  uAnytun is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 3 as
+ *  published by the Free Software Foundation.
+ *
+ *  uAnytun is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with uAnytun. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _DAEMON_H_
+#define _DAEMON_H_
+
+#include <poll.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <grp.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+struct priv_info_struct {
+  struct passwd* pw_;
+  struct group* gr_;
+};
+typedef struct priv_info_struct priv_info_t;
+
+int priv_init(priv_info_t* priv, const char* username, const char* groupname)
+{
+  if(!priv)
+    return -1;
+
+  priv->pw_ = NULL;
+  priv->gr_ = NULL;
+
+  priv->pw_ = getpwnam(username);
+  if(!priv->pw_) {
+    log_printf(ERROR, "unkown user %s", username);
+    return -1;
+  }
+
+  if(groupname)
+    priv->gr_ = getgrnam(groupname);
+  else
+    priv->gr_ = getgrgid(priv->pw_->pw_gid);
+
+  if(!priv->gr_) {
+    log_printf(ERROR, "unkown group %s", groupname);
+    return -1;
+  }
+
+  return 0;
+}
+
+int priv_drop(priv_info_t* priv)
+{
+  if(!priv || !priv->pw_ || !priv->gr_) {
+    log_printf(ERROR, "privileges not initialized properly");
+    return -1;
+  }
+
+  if(setgid(priv->gr_->gr_gid))  {
+    log_printf(ERROR, "setgid('%s') failed: %s", priv->gr_->gr_name, strerror(errno));
+    return -1;
+  }
+
+  gid_t gr_list[1];
+  gr_list[0] = priv->gr_->gr_gid;
+  if(setgroups (1, gr_list)) {
+    log_printf(ERROR, "setgroups(['%s']) failed: %s", priv->gr_->gr_name, strerror(errno));
+    return -1;
+  }
+
+  if(setuid(priv->pw_->pw_uid)) {
+    log_printf(ERROR, "setuid('%s') failed: %s", priv->pw_->pw_name, strerror(errno));
+    return -1;
+  }
+
+  log_printf(NOTICE, "dropped privileges to %s:%s", priv->pw_->pw_name, priv->gr_->gr_name);
+  return 0;
+}
+
+
+int do_chroot(const char* chrootdir)
+{
+  if(getuid() != 0) {
+    log_printf(ERROR, "this programm has to be run as root in order to run in a chroot");
+    return -1;
+  }
+
+  if(chroot(chrootdir)) {
+    log_printf(ERROR, "can't chroot to %s: %s", chrootdir, strerror(errno));
+    return -1;
+  }
+  log_printf(NOTICE, "we are in chroot jail (%s) now", chrootdir);
+  if(chdir("/")) {
+    log_printf(ERROR, "can't change to /: %s", strerror(errno));
+    return -1;
+  }
+}
+
+void daemonize()
+{
+  pid_t pid;
+
+  pid = fork();
+  if(pid < 0) {
+    log_printf(ERROR, "daemonizing failed at fork(): %s, exitting", strerror(errno));
+    exit(-1);
+  }
+  if(pid) exit(0);
+
+  umask(0);
+
+  if(setsid() < 0) {
+    log_printf(ERROR, "daemonizing failed at setsid(): %s, exitting", strerror(errno));
+    exit(-1);
+  }
+
+  pid = fork();
+  if(pid < 0) {
+    log_printf(ERROR, "daemonizing failed at fork(): %s, exitting", strerror(errno));
+    exit(-1);
+  }
+  if(pid) exit(0);
+
+  if ((chdir("/")) < 0) {
+    log_printf(ERROR, "daemonizing failed at chdir(): %s, exitting", strerror(errno));
+    exit(-1);
+  }
+
+  int fd;
+  for (fd=0;fd<=2;fd++) // close all file descriptors
+    close(fd);
+  fd = open("/dev/null",O_RDWR);        // stdin
+  if(fd == -1)
+    log_printf(WARNING, "can't open stdin (chroot and no link to /dev/null?)");
+  else {
+    if(dup(fd) == -1)   // stdout
+      log_printf(WARNING, "can't open stdout");
+    if(dup(fd) == -1)   // stderr
+      log_printf(WARNING, "can't open stderr");
+  }
+  umask(027);
+}
+
+#endif
+