added initial code - based on rharchive

1 files changed, 168 insertions, 0 deletions

diff --git a/src/daemon.h b/src/daemon.h
new file mode 100644
index 0000000..b7c2880
--- /dev/null
+++ b/src/daemon.h
@@ -0,0 +1,168 @@
+/*
+ *  sydra
+ *
+ *  sydra is a toolbox which allows you to set up multiple bidirectional
+ *  Video/Audio streams from external locations.
+ *  sydra has been written to be used for the Elevate Festival in Graz
+ *  Austria in order to involve external locations to present themselves
+ *  at the festival.
+ *  Sydra is based on GStreamer and is written in C.
+ *
+ *
+ *  Copyright (C) 2014 Christian Pointner <equinox@helsinki.at>
+ *
+ *  This file is part of sydra.
+ *
+ *  sydra is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  any later version.
+ *
+ *  sydra 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 sydra. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef SYDRA_daemon_h_INCLUDED
+#define SYDRA_daemon_h_INCLUDED
+
+#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, "unknown 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, "unknown 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 program 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;
+  }
+
+  return 0;
+}
+
+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