196 lines
7 KiB
C++
196 lines
7 KiB
C++
/// \file server_setup.cpp
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/// Contains generic functions for setting up a DDVTECH Connector.
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#ifndef MAINHANDLER
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/// Handler that is called for accepted incoming connections.
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#define MAINHANDLER NoHandler
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#error "No handler was set!"
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#endif
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#ifndef DEFAULT_PORT
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/// Default port for this server.
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#define DEFAULT_PORT 0
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#error "No default port was set!"
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#endif
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#ifndef CONFIGSECT
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/// Configuration file section for this server.
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#define CONFIGSECT None
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#error "No configuration file section was set!"
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#endif
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#include "socket.h" //Socket library
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#include <signal.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include <fstream>
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#define defstr(x) #x ///< converts a define name to string
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#define defstrh(x) "[" defstr(x) "]" ///< converts define name to [string]
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Socket::Server server_socket(-1); ///< Placeholder for the server socket
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/// Basic signal handler. Disconnects the server_socket if it receives
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/// a SIGINT, SIGHUP or SIGTERM signal, but does nothing for SIGPIPE.
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/// Disconnecting the server_socket will terminate the main listening loop
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/// and cleanly shut down the process.
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void signal_handler (int signum){
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switch (signum){
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case SIGINT: break;
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case SIGHUP: break;
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case SIGTERM: break;
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case SIGCHLD:
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wait(0);
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return;
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break;
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default: return; break;
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}
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if (!server_socket.connected()) return;
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server_socket.close();
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}//signal_handler
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/// Generic main entry point and loop for DDV Connectors.
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/// This sets up the proper termination handler, checks commandline options,
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/// parses config files and opens a listening socket on the requested port.
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/// Any incoming connections will be accepted and start up the function #MAINHANDLER,
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/// which should be defined before including server_setup.cpp.
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/// The default port is set by define #DEFAULT_PORT.
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/// The configuration file section is set by define #CONFIGSECT.
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int main(int argc, char ** argv){
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Socket::Connection S;//placeholder for incoming connections
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//setup signal handler
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struct sigaction new_action;
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new_action.sa_handler = signal_handler;
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sigemptyset (&new_action.sa_mask);
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new_action.sa_flags = 0;
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sigaction(SIGINT, &new_action, NULL);
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sigaction(SIGHUP, &new_action, NULL);
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sigaction(SIGTERM, &new_action, NULL);
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sigaction(SIGPIPE, &new_action, NULL);
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sigaction(SIGCHLD, &new_action, NULL);
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//default values
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int listen_port = DEFAULT_PORT;
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bool daemon_mode = true;
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std::string interface = "0.0.0.0";
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std::string configfile = "/etc/ddvtech.conf";
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std::string username = "root";
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bool ignore_daemon = false;
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bool ignore_interface = false;
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bool ignore_port = false;
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bool ignore_user = false;
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int opt = 0;
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static const char *optString = "ndp:i:u:c:h?";
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static const struct option longOpts[] = {
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{"help",0,0,'h'},
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{"port",1,0,'p'},
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{"interface",1,0,'i'},
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{"username",1,0,'u'},
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{"no-daemon",0,0,'n'},
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{"daemon",0,0,'d'},
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{"configfile",1,0,'c'}
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};
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while ((opt = getopt_long(argc, argv, optString, longOpts, 0)) != -1){
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switch (opt){
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case 'p': listen_port = atoi(optarg); ignore_port = true; break;
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case 'i': interface = optarg; ignore_interface = true; break;
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case 'n': daemon_mode = false; ignore_daemon = true; break;
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case 'd': daemon_mode = true; ignore_daemon = true; break;
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case 'c': configfile = optarg; break;
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case 'u': username = optarg; ignore_user = true; break;
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case 'h':
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case '?':
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printf("Options: -h[elp], -?, -n[odaemon], -d[aemon], -p[ort] VAL, -i[nterface] VAL, -c[onfigfile] VAL, -u[sername] VAL\n");
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printf("Defaults:\n interface: 0.0.0.0\n port: %i\n daemon mode: true\n configfile: /etc/ddvtech.conf\n username: root\n", listen_port);
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printf("Username root means no change to UID, no matter what the UID is.\n");
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printf("If the configfile exists, it is always loaded first. Commandline settings then overwrite the config file.\n");
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printf("\nThis process takes it directives from the %s section of the configfile.\n", defstrh(CONFIGSECT));
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return 1;
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break;
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}
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}//commandline options parser
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std::ifstream conf(configfile.c_str(), std::ifstream::in);
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std::string tmpstr;
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bool acc_comm = false;
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size_t foundeq;
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if (conf.fail()){
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#if DEBUG >= 3
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fprintf(stderr, "Configuration file %s not found - using build-in defaults...\n", configfile.c_str());
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#endif
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}else{
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while (conf.good()){
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getline(conf, tmpstr);
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if (tmpstr[0] == '['){//new section? check if we care.
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if (tmpstr == defstrh(CONFIGSECT)){acc_comm = true;}else{acc_comm = false;}
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}else{
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if (!acc_comm){break;}//skip all lines in this section if we do not care about it
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foundeq = tmpstr.find('=');
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if (foundeq != std::string::npos){
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if ((tmpstr.substr(0, foundeq) == "port") && !ignore_port){listen_port = atoi(tmpstr.substr(foundeq+1).c_str());}
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if ((tmpstr.substr(0, foundeq) == "interface") && !ignore_interface){interface = tmpstr.substr(foundeq+1);}
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if ((tmpstr.substr(0, foundeq) == "username") && !ignore_user){username = tmpstr.substr(foundeq+1);}
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if ((tmpstr.substr(0, foundeq) == "daemon") && !ignore_daemon){daemon_mode = true;}
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if ((tmpstr.substr(0, foundeq) == "nodaemon") && !ignore_daemon){daemon_mode = false;}
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}//found equals sign
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}//section contents
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}//configfile line loop
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}//configuration
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//setup a new server socket, for the correct interface and port
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server_socket = Socket::Server(listen_port, interface);
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#if DEBUG >= 3
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fprintf(stderr, "Made a listening socket on %s:%i...\n", interface.c_str(), listen_port);
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#endif
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if (server_socket.connected()){
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//if setup success, enter daemon mode if requested
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if (daemon_mode){
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daemon(1, 0);
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#if DEBUG >= 3
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fprintf(stderr, "Going into background mode...\n");
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#endif
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}
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}else{
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#if DEBUG >= 1
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fprintf(stderr, "Error: could not make listening socket\n");
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#endif
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return 1;
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}
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if (username != "root"){
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struct passwd * user_info = getpwnam(username.c_str());
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if (!user_info){
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#if DEBUG >= 1
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fprintf(stderr, "Error: could not setuid %s: could not get PID\n", username.c_str());
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#endif
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return 1;
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}else{
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if (setuid(user_info->pw_uid) != 0){
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#if DEBUG >= 1
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fprintf(stderr, "Error: could not setuid %s: not allowed\n", username.c_str());
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#endif
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}else{
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#if DEBUG >= 3
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fprintf(stderr, "Changed user to %s\n", username.c_str());
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#endif
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}
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}
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}
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while (server_socket.connected()){
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S = server_socket.accept();
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if (S.connected()){//check if the new connection is valid
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pid_t myid = fork();
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if (myid == 0){//if new child, start MAINHANDLER
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return MAINHANDLER(S);
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}else{//otherwise, do nothing or output debugging text
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#if DEBUG >= 3
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fprintf(stderr, "Spawned new process %i for socket %i\n", (int)myid, S.getSocket());
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#endif
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}
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}
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}//while connected
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return 0;
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}//main
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