Index: /trunk/ntripserver/ntripserver.c
===================================================================
--- /trunk/ntripserver/ntripserver.c	(revision 485)
+++ /trunk/ntripserver/ntripserver.c	(revision 485)
@@ -0,0 +1,1671 @@
+/*
+ * $Id: NtripLinuxServer.c,v 1.32 2007/06/07 07:47:24 stoecker Exp $
+ *
+ * Copyright (c) 2003...2007
+ * German Federal Agency for Cartography and Geodesy (BKG)
+ *
+ * Developed for Networked Transport of RTCM via Internet Protocol (NTRIP)
+ * for streaming GNSS data over the Internet.
+ *
+ * Designed by Informatik Centrum Dortmund http://www.icd.de
+ *
+ * The BKG disclaims any liability nor responsibility to any person or
+ * entity with respect to any loss or damage caused, or alleged to be
+ * caused, directly or indirectly by the use and application of the NTRIP
+ * technology.
+ *
+ * For latest information and updates, access:
+ * http://igs.bkg.bund.de/index_ntrip_down.htm
+ *
+ * BKG, Frankfurt, Germany, February 2007
+ * E-mail: euref-ip@bkg.bund.de
+ *
+ * This program 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* CVS revision and version */
+static char revisionstr[] = "$Revision: 1.32 $";
+static char datestr[]     = "$Date: 2007/06/07 07:47:24 $";
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <netdb.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/termios.h>
+#include <sys/types.h>
+#include <sys/time.h>
+
+#ifndef COMPILEDATE
+#define COMPILEDATE " built " __DATE__
+#endif
+
+#ifndef MSG_DONTWAIT
+#define MSG_DONTWAIT 0 /* prevent compiler errors */
+#endif
+#ifndef O_EXLOCK
+#define O_EXLOCK 0 /* prevent compiler errors */
+#endif
+
+enum MODE { SERIAL = 1, TCPSOCKET = 2, INFILE = 3, SISNET = 4, UDPSOCKET = 5,
+CASTER = 6, LAST };
+
+enum OUTMODE { HTTP = 1, RTSP = 2, NTRIPV1 = 3, END };
+
+#define AGENTSTRING     "NTRIP NtripLinuxServer"
+#define BUFSZ           1024
+#define SZ              64
+
+/* default socket source */
+#define SERV_HOST_ADDR  "localhost"
+#define SERV_TCP_PORT   2101
+
+/* default destination */
+#define NTRIP_CASTER    "www.euref-ip.net"
+#define NTRIP_PORT      2101
+
+/* default sisnet source */
+#define SISNET_SERVER   "131.176.49.142"
+#define SISNET_PORT     7777
+
+#define ALARMTIME       60
+
+#define RTP_VERSION     2
+#define TIME_RESOLUTION 125
+
+static int ttybaud             = 19200;
+static const char *ttyport     = "/dev/gps";
+static const char *filepath    = "/dev/stdin";
+static enum MODE inputmode     = INFILE;
+static int sisnet              = 31;
+static int gpsfd               = -1;
+static int sigint_received     = 0;
+
+/* Forward references */
+static int  openserial(const char * tty, int blocksz, int baud);
+static void send_receive_loop(int sock, int fd, int outmode,
+  struct sockaddr * pcasterRTP, socklen_t length);
+static void usage(int, char *);
+static int  encode(char *buf, int size, const char *user, const char *pwd);
+static int  send_to_caster(char *input, int socket, int input_size);
+static void close_session(int sock_udp, int sock_tcp,
+  const char *caster_addr, const char *mountpoint, int cseq,
+  int session, char *rtsp_ext, int in_fd);
+
+/* Signal Handling */
+static void handle_sigint(int sig);
+static void setup_signal_handler(int sig, void (*handler)(int));
+static int  signal_was_caught(void);
+
+#ifdef __GNUC__
+static __attribute__ ((noreturn)) void sighandler_alarm(
+int sig __attribute__((__unused__)))
+#else /* __GNUC__ */
+static void sighandler_alarm(int sig)
+#endif /* __GNUC__ */
+{
+  fprintf(stderr, "ERROR: more than %d seconds no activity\n", ALARMTIME);
+  exit(1);
+}
+
+/*
+* main
+*
+* Main entry point for the program.  Processes command-line arguments and
+* prepares for action.
+*
+* Parameters:
+*     argc : integer        : Number of command-line arguments.
+*     argv : array of char  : Command-line arguments as an array of
+*                             zero-terminated pointers to strings.
+*
+* Return Value:
+*     The function does not return a value (although its return type is int).
+*
+* Remarks:
+*
+*/
+
+int main(int argc, char **argv)
+{
+  int                c;
+  int                size = 2048; /* for setting send buffer size */
+  struct             sockaddr_in caster;
+  const char *       proxyhost = "";
+  unsigned int       proxyport = 0;
+  /*** INPUT ***/
+  const char *       casterinhost = 0;
+  unsigned int       casterinport = 0;
+  const char *       inhost = 0;
+  unsigned int       inport = 0;
+
+  char               get_extension[SZ] = "";
+
+  struct hostent *   he;
+  const char *       mountpoint = NULL;
+
+  const char *       sisnetpassword = "";
+  const char *       sisnetuser = "";
+
+  const char *       stream_name = 0;
+  const char *       stream_user = 0;
+  const char *       stream_password = 0;
+
+  const char *       recvrid= 0;
+  const char *       recvrpwd = 0;
+
+  const char *       initfile = NULL;
+
+  int                bindmode = 0;
+
+  /*** OUTPUT ***/
+  const char *       casterouthost = NTRIP_CASTER;
+  unsigned int       casteroutport = NTRIP_PORT;
+  const char *       outhost = 0;
+  unsigned int       outport = 0;
+  char               post_extension[SZ] = "";
+  char               rtsp_extension[SZ] = "";
+
+  const char *       ntrip_str = "";
+
+  const char *       user = "";
+  const char *       password = "";
+
+  int                socket_tcp = 0;
+  int                outputmode = NTRIPV1;
+
+  struct sockaddr_in casterRTP;
+  struct sockaddr_in local;
+  int                socket_udp = 0;
+  int                client_port = 0;
+  int                server_port = 0;
+  int                session = 0;
+  int                cseq = 0;
+  socklen_t          len = 0;
+  int                i = 0;
+
+  char               szSendBuffer[BUFSZ];
+  char               authorization[SZ];
+  int                nBufferBytes = 0;
+  char *             dlim = " \r\n=";
+  char *             token;
+  char *             tok_buf[BUFSZ];
+
+  setbuf(stdout, 0);
+  setbuf(stdin, 0);
+  setbuf(stderr, 0);
+
+  {
+  char *a;
+  int i = 0;
+  for(a = revisionstr+11; *a && *a != ' '; ++a)
+    revisionstr[i++] = *a;
+  revisionstr[i] = 0;
+  datestr[0] = datestr[7];
+  datestr[1] = datestr[8];
+  datestr[2] = datestr[9];
+  datestr[3] = datestr[10];
+  datestr[5] = datestr[12];
+  datestr[6] = datestr[13];
+  datestr[8] = datestr[15];
+  datestr[9] = datestr[16];
+  datestr[4] = datestr[7] = '-';
+  datestr[10] = 0;
+  }
+
+  /* setup signal handler for timeout */
+  signal(SIGALRM,sighandler_alarm);
+  alarm(ALARMTIME);
+
+  /* get and check program arguments */
+  if(argc <= 1)
+  {
+    usage(2, argv[0]);
+    exit(1);
+  }
+  while((c = getopt(argc, argv,
+  "M:i:h:b:p:s:a:m:c:H:P:f:x:y:l:u:V:D:U:W:B:O:E:F:N:n:")) != EOF)
+  {
+    switch (c)
+    {
+    case 'M': /*** InputMode ***/
+      if(!strcmp(optarg, "serial"))         inputmode = SERIAL;
+      else if(!strcmp(optarg, "tcpsocket")) inputmode = TCPSOCKET;
+      else if(!strcmp(optarg, "file"))      inputmode = INFILE;
+      else if(!strcmp(optarg, "sisnet"))    inputmode = SISNET;
+      else if(!strcmp(optarg, "udpsocket")) inputmode = UDPSOCKET;
+      else if(!strcmp(optarg, "caster"))    inputmode = CASTER;
+      else inputmode = atoi(optarg);
+      if((inputmode == 0) || (inputmode >= LAST))
+      {
+        fprintf(stderr, "ERROR: can't convert <%s> to a valid InputMode\n",
+        optarg);
+        usage(-1, argv[0]);
+      }
+      break;
+    case 'i': /* serial input device */
+      ttyport = optarg;
+      break;
+    case 'B': /* bind to incoming UDP stream */
+      bindmode = 1;
+      break;
+    case 'V': /* Sisnet data server version number */
+      if(!strcmp("3.0", optarg))      sisnet = 30;
+      else if(!strcmp("3.1", optarg)) sisnet = 31;
+      else if(!strcmp("2.1", optarg)) sisnet = 21;
+      else
+      {
+        fprintf(stderr, "ERROR: unknown SISNeT version <%s>\n", optarg);
+        usage(-2, argv[0]);
+      }
+      break;
+    case 'b': /* serial input baud rate */
+      ttybaud = atoi(optarg);
+      if(ttybaud <= 1)
+      {
+        fprintf(stderr, "ERROR: can't convert <%s> to valid serial baud rate\n",
+          optarg);
+        usage(1, argv[0]);
+      }
+      break;
+    case 'a': /* Destination caster address */
+      casterouthost = optarg;
+      break;
+    case 'p': /* Destination caster port */
+      casteroutport = atoi(optarg);
+      if(casteroutport <= 1 || casteroutport > 65535)
+      {
+        fprintf(stderr,
+          "ERROR: can't convert <%s> to a valid HTTP server port\n", optarg);
+        usage(1, argv[0]);
+      }
+      break;
+    case 'm': /* Destination caster mountpoint for stream upload */
+      mountpoint = optarg;
+      break;
+    case 's': /* File name for input data simulation from file */
+      filepath = optarg;
+      break;
+    case 'f': /* name of an initialization file */
+      initfile = optarg;
+      break;
+    case 'x': /* user ID to access incoming stream */
+      recvrid = optarg;
+      break;
+    case 'y': /* password to access incoming stream */
+      recvrpwd = optarg;
+      break;
+    case 'u': /* Sisnet data server user ID */
+      sisnetuser = optarg;
+      break;
+    case 'l': /* Sisnet data server password */
+      sisnetpassword = optarg;
+      break;
+    case 'c': /* DestinationCaster password for stream upload to mountpoint */
+      password = optarg;
+      break;
+    case 'H': /* Input host address*/
+      casterinhost = optarg;
+      break;
+    case 'P': /* Input port */
+      casterinport = atoi(optarg);
+      if(casterinport <= 1 || casterinport > 65535)
+      {
+        fprintf(stderr, "ERROR: can't convert <%s> to a valid port number\n",
+          optarg);
+        usage(1, argv[0]);
+      }
+      break;
+    case 'D': /* Source caster mountpoint for stream input */
+     stream_name = optarg;
+     break;
+    case 'U': /* Source caster user ID for input stream access */
+     stream_user = optarg;
+     break;
+    case 'W': /* Source caster password for input stream access */
+     stream_password = optarg;
+     break;
+    case 'E': /* Proxy Server */
+      proxyhost = optarg;
+      break;
+    case 'F': /* Proxy port */
+      proxyport = atoi(optarg);
+      break;
+    case 'O': /* OutputMode */
+      outputmode = 0;
+      if (!strcmp(optarg,"n") || !strcmp(optarg,"ntrip1"))
+        outputmode = NTRIPV1;
+      else if(!strcmp(optarg,"h") || !strcmp(optarg,"http"))
+        outputmode = HTTP;
+      else if(!strcmp(optarg,"r") || !strcmp(optarg,"rtsp"))
+        outputmode = RTSP;
+      else outputmode = atoi(optarg);
+      if((outputmode == 0) || (outputmode >= END))
+      {
+        fprintf(stderr, "ERROR: can't convert <%s> to a valid OutputMode\n",
+        optarg);
+        usage(-1, argv[0]);
+      }
+      break;
+    case 'n': /* Destination caster user ID for stream upload to mountpoint */
+      user = optarg;
+      break;
+    case 'N': /* Ntrip-STR, optional for Ntrip Version 2.0 */
+      ntrip_str = optarg;
+      break;
+    case 'h': /* print help screen */
+    case '?':
+      usage(0, argv[0]);
+      break;
+    default:
+      usage(2, argv[0]);
+      break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  /*** argument analysis ***/
+  if(argc > 0)
+  {
+    fprintf(stderr, "ERROR: Extra args on command line: ");
+    for(; argc > 0; argc--)
+    {
+      fprintf(stderr, " %s", *argv++);
+    }
+    fprintf(stderr, "\n");
+    usage(1, argv[0]);                   /* never returns */
+  }
+
+  if(*ntrip_str && (outputmode == NTRIPV1))
+  {
+     fprintf(stderr, "WARNING: OutputMode is Ntrip version 1.0"
+     " - Ntrip-STR will not be considered\n");
+  }
+
+  if(!mountpoint)
+  {
+    fprintf(stderr, "ERROR: Missing mountpoint argument for stream upload\n");
+    exit(1);
+  }
+
+  if(!password[0])
+  {
+    fprintf(stderr, "WARNING: Missing password argument for stream upload - "
+    "are you really sure?\n");
+  }
+  else
+  {
+    nBufferBytes += encode(authorization, sizeof(authorization), user,
+    password);
+    if(nBufferBytes > (int)sizeof(authorization))
+    {
+      fprintf(stderr, "ERROR: user ID and/or password too long: %d (%d)\n"
+      "       user ID: %s \npassword: <%s>\n",
+      nBufferBytes, (int)sizeof(authorization), user, password);
+      exit(1);
+    }
+  }
+
+  if(stream_name && stream_user && !stream_password)
+  {
+    fprintf(stderr, "WARNING: Missing password argument for stream download"
+      " - are you really sure?\n");
+  }
+
+  /*** proxy server handling ***/
+  if(*proxyhost)
+  {
+    outhost = inhost = proxyhost;
+    outport = inport = proxyport;
+    i = snprintf(szSendBuffer, sizeof(szSendBuffer),"http://%s:%d",
+    casterouthost, casteroutport);
+    if((i > SZ) || (i < 0))
+    {
+      fprintf(stderr, "ERROR: Destination caster name/port to long - "
+      "length = %d (max: %d)\n", i, SZ);
+      exit(0);
+    }
+    else
+    {
+      strncpy(post_extension, szSendBuffer, (size_t)i);
+      strcpy(szSendBuffer, "");
+      i = snprintf(szSendBuffer, sizeof(szSendBuffer),":%d", casteroutport);
+      strncpy(rtsp_extension, szSendBuffer, SZ);
+      strcpy(szSendBuffer,""); i = 0;
+    }
+    i = snprintf(szSendBuffer, sizeof(szSendBuffer),"http://%s:%d", casterinhost, casterinport);
+    if((i > SZ) || (i < 0))
+    {
+      fprintf(stderr, "ERROR: Destination caster name/port to long - length = %d (max: %d)\n", i, SZ);
+      exit(0);
+    }
+    else
+    {
+      strncpy(get_extension, szSendBuffer, (size_t)i);
+      strcpy(szSendBuffer, "");
+      i = 0;
+    }
+  }
+  else
+  {
+    outhost   = casterouthost; outport = casteroutport;
+    inhost    = casterinhost;  inport  = casterinport;
+  }
+
+  /*** InputMode handling ***/
+  switch(inputmode)
+  {
+  case INFILE:
+    {
+      if((gpsfd = open(filepath, O_RDONLY)) < 0)
+      {
+        perror("ERROR: opening input file");
+        exit(1);
+      }
+      /* set blocking inputmode in case it was not set
+        (seems to be sometimes for fifo's) */
+      fcntl(gpsfd, F_SETFL, 0);
+      printf("file input: file = %s\n", filepath);
+    }
+    break;
+  case SERIAL: /* open serial port */
+    {
+      gpsfd = openserial(ttyport, 1, ttybaud);
+      if(gpsfd < 0)
+      {
+        exit(1);
+      }
+      printf("serial input: device = %s, speed = %d\n", ttyport, ttybaud);
+    }
+    break;
+  case TCPSOCKET: case UDPSOCKET: case SISNET: case CASTER:
+    {
+      if(inputmode == SISNET)
+      {
+        if(!inhost) inhost = SISNET_SERVER;
+        if(!inport) inport = SISNET_PORT;
+      }
+      else if(inputmode == CASTER)
+      {
+        if(!inport) inport = NTRIP_PORT;
+        if(!inhost) inhost = NTRIP_CASTER;
+      }
+      else if((inputmode == TCPSOCKET) || (inputmode == UDPSOCKET))
+      {
+        if(!inport) inport = SERV_TCP_PORT;
+        if(!inhost) inhost = SERV_HOST_ADDR;
+      }
+
+      if(!(he = gethostbyname(inhost)))
+      {
+        fprintf(stderr, "ERROR: Input host <%s> unknown\n", inhost);
+        usage(-2, argv[0]);
+      }
+
+      if((gpsfd = socket(AF_INET, inputmode == UDPSOCKET
+      ? SOCK_DGRAM : SOCK_STREAM, 0)) < 0)
+      {
+        fprintf(stderr,
+        "ERROR: can't create socket for incoming data stream\n");
+        exit(1);
+      }
+
+      memset((char *) &caster, 0x00, sizeof(caster));
+      if(!bindmode)
+        memcpy(&caster.sin_addr, he->h_addr, (size_t)he->h_length);
+      caster.sin_family = AF_INET;
+      caster.sin_port = htons(inport);
+
+      fprintf(stderr, "%s input: host = %s, port = %d, %s%s%s%s%s\n",
+      inputmode == CASTER ? "caster" : inputmode == SISNET ? "sisnet" :
+      inputmode == TCPSOCKET ? "tcp socket" : "udp socket",
+      bindmode ? "127.0.0.1" : inet_ntoa(caster.sin_addr),
+      inport, stream_name ? "stream = " : "", stream_name ? stream_name : "",
+      initfile ? ", initfile = " : "", initfile ? initfile : "",
+      bindmode ? "binding mode" : "");
+
+      if(bindmode)
+      {
+        if(bind(gpsfd, (struct sockaddr *) &caster, sizeof(caster)) < 0)
+        {
+          fprintf(stderr, "ERROR: can't bind input to port %d\n", inport);
+          exit(1);
+        }
+      } /* connect to input-caster or proxy server*/
+      else if(connect(gpsfd, (struct sockaddr *)&caster, sizeof(caster)) < 0)
+      {
+        fprintf(stderr, "ERROR: can't connect input to %s at port %d\n",
+        inet_ntoa(caster.sin_addr), inport);
+        exit(1);
+      }
+
+      if(stream_name) /* input from Ntrip Version 1.0 caster*/
+      {
+        int init = 0;
+
+        /* set socket buffer size */
+        setsockopt(gpsfd, SOL_SOCKET, SO_SNDBUF, (const char *) &size,
+          sizeof(const char *));
+        if(stream_user && stream_password)
+        {
+          /* leave some space for login */
+          nBufferBytes=snprintf(szSendBuffer, sizeof(szSendBuffer)-40,
+          "GET %s/%s HTTP/1.0\r\n"
+          "User-Agent: %s/%s\r\n"
+          "Authorization: Basic ", get_extension, stream_name,
+          AGENTSTRING, revisionstr);
+          /* second check for old glibc */
+          if(nBufferBytes > (int)sizeof(szSendBuffer)-40 || nBufferBytes < 0)
+          {
+            fprintf(stderr, "ERROR: Source caster request too long\n");
+            exit(1);
+          }
+          nBufferBytes += encode(szSendBuffer+nBufferBytes,
+            sizeof(szSendBuffer)-nBufferBytes-4, stream_user, stream_password);
+          if(nBufferBytes > (int)sizeof(szSendBuffer)-4)
+          {
+            fprintf(stderr,
+            "ERROR: Source caster user ID and/or password too long\n");
+            exit(1);
+          }
+          szSendBuffer[nBufferBytes++] = '\r';
+          szSendBuffer[nBufferBytes++] = '\n';
+          szSendBuffer[nBufferBytes++] = '\r';
+          szSendBuffer[nBufferBytes++] = '\n';
+        }
+        else
+        {
+          nBufferBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),
+          "GET %s/%s HTTP/1.0\r\n"
+          "User-Agent: %s/%s\r\n"
+          "\r\n", get_extension, stream_name, AGENTSTRING, revisionstr);
+        }
+        if((send(gpsfd, szSendBuffer, (size_t)nBufferBytes, 0))
+        != nBufferBytes)
+        {
+          fprintf(stderr, "ERROR: could not send Source caster request\n");
+          exit(1);
+        }
+        nBufferBytes = 0;
+        /* check Source caster's response */
+        while(!init && nBufferBytes < (int)sizeof(szSendBuffer)
+        && (nBufferBytes += recv(gpsfd, szSendBuffer,
+        sizeof(szSendBuffer)-nBufferBytes, 0)) > 0)
+        {
+          if(strstr(szSendBuffer, "\r\n"))
+          {
+            if(!strncmp(szSendBuffer, "ICY 200 OK\r\n", 10))
+              init = 1;
+            else
+            {
+              int k;
+              fprintf(stderr,
+              "ERROR: could not get requested data from Source caster: ");
+              for(k = 0; k < nBufferBytes && szSendBuffer[k] != '\n'
+              && szSendBuffer[k] != '\r'; ++k)
+              {
+                fprintf(stderr, "%c", isprint(szSendBuffer[k])
+                ? szSendBuffer[k] : '.');
+              }
+              fprintf(stderr, "\n");
+              exit(1);
+            }
+          }
+        }
+        if(!init)
+        {
+          fprintf(stderr, "ERROR: could not init Source caster download\n");
+          exit(1);
+        }
+      } /* end input from Ntrip Version 1.0 caster */
+
+      if(initfile && inputmode != SISNET)
+      {
+        char buffer[1024];
+        FILE *fh;
+        int i;
+
+        if((fh = fopen(initfile, "r")))
+        {
+          while((i = fread(buffer, 1, sizeof(buffer), fh)) > 0)
+          {
+            if((send(gpsfd, buffer, (size_t)i, 0)) != i)
+            {
+              perror("ERROR: sending init file");
+              exit(1);
+            }
+          }
+          if(i < 0)
+          {
+            perror("ERROR: reading init file");
+            exit(1);
+          }
+          fclose(fh);
+        }
+        else
+        {
+          fprintf(stderr, "ERROR: can't read init file <%s>\n", initfile);
+          exit(1);
+        }
+      }
+    }
+    if(inputmode == SISNET)
+    {
+      int i, j;
+      char buffer[1024];
+
+      i = snprintf(buffer, sizeof(buffer), sisnet >= 30 ? "AUTH,%s,%s\r\n"
+        : "AUTH,%s,%s", sisnetuser, sisnetpassword);
+      if((send(gpsfd, buffer, (size_t)i, 0)) != i)
+      {
+        perror("ERROR: sending authentication for SISNeT data server");
+        exit(1);
+      }
+      i = sisnet >= 30 ? 7 : 5;
+      if((j = recv(gpsfd, buffer, i, 0)) != i && strncmp("*AUTH", buffer, 5))
+      {
+        fprintf(stderr, "ERROR: SISNeT connect failed:");
+        for(i = 0; i < j; ++i)
+        {
+          if(buffer[i] != '\r' && buffer[i] != '\n')
+          {
+            fprintf(stderr, "%c", isprint(buffer[i]) ? buffer[i] : '.');
+          }
+        }
+        fprintf(stderr, "\n");
+        exit(1);
+      }
+      if(sisnet >= 31)
+      {
+        if((send(gpsfd, "START\r\n", 7, 0)) != i)
+        {
+          perror("ERROR: sending Sisnet start command");
+          exit(1);
+        }
+      }
+    }
+    /*** receiver authentication  ***/
+    if (recvrid && recvrpwd && ((inputmode == TCPSOCKET)
+    || (inputmode == UDPSOCKET)))
+    {
+      if (strlen(recvrid) > (BUFSZ-3))
+      {
+        fprintf(stderr, "ERROR: Receiver ID too long\n");
+        exit(0);
+      }
+      else
+      {
+        fprintf(stderr, "Sending user ID for receiver...\n");
+        nBufferBytes = read(gpsfd, szSendBuffer, BUFSZ);
+        strcpy(szSendBuffer, recvrid);
+        strcat(szSendBuffer,"\r\n");
+        send(gpsfd,szSendBuffer, strlen(szSendBuffer), MSG_DONTWAIT);
+      }
+
+      if (strlen(recvrpwd) > (BUFSZ-3))
+      {
+        fprintf(stderr, "ERROR: Receiver password too long\n");
+        exit(0);
+      }
+      else
+      {
+        fprintf(stderr, "Sending user password for receiver...\n");
+        nBufferBytes = read(gpsfd, szSendBuffer, BUFSZ);
+        strcpy(szSendBuffer, recvrpwd);
+        strcat(szSendBuffer,"\r\n");
+        send(gpsfd, szSendBuffer, strlen(szSendBuffer), MSG_DONTWAIT);
+      }
+    }
+    break;
+  default:
+    usage(-1, argv[0]);
+    break;
+  }
+
+  /* ----- main part ----- */
+  /* setup signal handler for CTRL+C */
+  setup_signal_handler(SIGINT,  handle_sigint);
+
+  while(outputmode != END)
+  {
+    if(signal_was_caught())
+    {
+      fprintf(stderr, "NtripLinuxServer terminates\n");
+      break;
+    }
+
+    if(!(he = gethostbyname(outhost)))
+    {
+      fprintf(stderr, "ERROR: Destination caster or proxy host <%s> unknown\n",
+      outhost);
+      usage(-2, argv[0]);
+    }
+
+    /* create socket */
+    if((socket_tcp = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+    {
+      perror("ERROR: tcp socket");
+      exit(2);
+    }
+
+    memset((char *) &caster, 0x00, sizeof(caster));
+    memcpy(&caster.sin_addr, he->h_addr, (size_t)he->h_length);
+    caster.sin_family = AF_INET;
+    caster.sin_port = htons(outport);
+
+    /* connect to Destination caster or Proxy server*/
+    fprintf(stderr, "caster output: host = %s, port = %d, mountpoint = %s"
+    ", mode = %s\n", inet_ntoa(caster.sin_addr), outport, mountpoint,
+    outputmode == NTRIPV1 ? "ntrip1" : outputmode == HTTP ? "http" : "rtsp");
+
+    if(connect(socket_tcp, (struct sockaddr *) &caster, sizeof(caster)) < 0)
+    {
+      fprintf(stderr, "ERROR: can't connect output to %s at port %d\n",
+        inet_ntoa(caster.sin_addr), outport);
+      if(close(socket_tcp)==-1) perror("ERROR: close tcp socket");
+      exit(3);
+    }
+
+    /*** OutputMode handling ***/
+    switch(outputmode){
+      case NTRIPV1: /*** OutputMode Ntrip Version 1.0 ***/
+        nBufferBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),
+          "SOURCE %s %s/%s\r\n"
+          "Source-Agent: %s\r\n\r\n",
+          password, post_extension, mountpoint, AGENTSTRING);
+        if((nBufferBytes > (int)sizeof(szSendBuffer)) || (nBufferBytes < 0))
+        {
+          fprintf(stderr, "ERROR: Destination caster request to long\n");
+          outputmode = END;
+          break;
+        }
+        if(!send_to_caster(szSendBuffer, socket_tcp, nBufferBytes))
+        {
+          outputmode = END;
+          break;
+        }
+        /* check Destination caster's response */
+        nBufferBytes = recv(socket_tcp, szSendBuffer, sizeof(szSendBuffer), 0);
+        szSendBuffer[nBufferBytes] = '\0';
+        if(!strstr(szSendBuffer, "OK"))
+        {
+          char *a;
+          fprintf(stderr,
+          "ERROR: Destination caster's or Proxy's reply is not OK: ");
+          for(a = szSendBuffer; *a && *a != '\n' && *a != '\r'; ++a)
+          {
+            fprintf(stderr, "%.1s", isprint(*a) ? a : ".");
+          }
+          fprintf(stderr, "\n");
+          outputmode = END;
+          break;
+        }
+#ifndef NDEBUG
+        else
+        {
+          fprintf(stderr,
+          "Destination caster response:\n%s\nconnection successfull\n",
+          szSendBuffer);
+        }
+#endif
+        send_receive_loop(socket_tcp, gpsfd, outputmode, NULL, 0);
+        break;
+      case HTTP: /*** Ntrip-Version 2.0 HTTP/1.1 ***/
+        nBufferBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),
+          "POST %s/%s HTTP/1.1\r\n"
+          "Host: %s\r\n"
+          "Ntrip-Version: Ntrip/2.0\r\n"
+          "User-Agent: %s/%s\r\n"
+          "Authorization: Basic %s\r\n"
+          "Ntrip-STR: %s\r\n"
+          "Transfer-Encoding: chunked\r\n\r\n",
+          post_extension, mountpoint, casterouthost, AGENTSTRING,
+          revisionstr, authorization, ntrip_str);
+        if((nBufferBytes > (int)sizeof(szSendBuffer)) || (nBufferBytes < 0))
+        {
+          fprintf(stderr, "ERROR: Destination caster request to long\n");
+          outputmode = END;
+          break;
+        }
+        if (!send_to_caster(szSendBuffer, socket_tcp, nBufferBytes))
+        {
+          outputmode = END;
+          break;
+        }
+        /* check Destination caster's response */
+        nBufferBytes = recv(socket_tcp, szSendBuffer, sizeof(szSendBuffer), 0);
+        szSendBuffer[nBufferBytes] = '\0';
+        if(!strstr(szSendBuffer, "HTTP/1.1 200 OK"))
+        {
+          char *a;
+          fprintf(stderr,
+          "ERROR: Destination caster's%s reply is not OK: ",
+          *proxyhost ? " or Proxy's" : "");
+          for(a = szSendBuffer; *a && *a != '\n' && *a != '\r'; ++a)
+          {
+            fprintf(stderr, "%.1s", isprint(*a) ? a : ".");
+          }
+          fprintf(stderr, "\n");
+          /* fallback if necessary */
+          if(!strstr(szSendBuffer,"Ntrip-Version: Ntrip/2.0\r\n"))
+          {
+            fprintf(stderr,
+            " Ntrip Version 2.0 not implemented at Destination caster"
+            " <%s>%s%s%s\n%s\n"
+            "caster fallback: Fallback to Ntrip Version 1.0\n",
+            casterouthost,
+            *proxyhost ? " or Proxy <" : "", proxyhost, *proxyhost ? ">" : "",
+            *proxyhost ? " or HTTP/1.1 not implemented at Proxy\n" : "");
+            outputmode = NTRIPV1;
+            break;
+          }
+          outputmode = END;
+          break;
+        }
+#ifndef NDEBUG
+        else
+        {
+          fprintf(stderr, "Destination caster response:\n%s\n"
+          "connection successfull\n",szSendBuffer);
+        }
+#endif
+        send_receive_loop(socket_tcp, gpsfd, outputmode, NULL, 0);
+        break;
+      case RTSP: /*** Ntrip-Version 2.0 RTSP / RTP ***/
+        if((socket_udp = socket(AF_INET, SOCK_DGRAM,0)) < 0)
+        {
+          perror("ERROR: udp socket");
+          exit(4);
+        }
+        /* fill structure with local address information for UDP */
+        memset(&local, 0, sizeof(local));
+        local.sin_family = AF_INET;
+        local.sin_port = htons(0);
+        local.sin_addr.s_addr = htonl(INADDR_ANY);
+        len = (socklen_t)sizeof(local);
+        /* bind() in order to get a random RTP client_port */
+        if((bind(socket_udp,(struct sockaddr *)&local, len)) < 0)
+        {
+          perror("ERROR: udp bind");
+          if(close(socket_udp)==-1) perror("ERROR: close udp socket");
+          if(close(socket_tcp)==-1) perror("ERROR: close tcp socket");
+          exit(4);
+        }
+        if((getsockname(socket_udp, (struct sockaddr*)&local, &len)) != -1)
+        {
+          client_port = (unsigned int)ntohs(local.sin_port);
+        }else{
+          perror("ERROR: getsockname(localhost)");
+          if(close(socket_udp)==-1) perror("ERROR: close udp socket");
+          if(close(socket_tcp)==-1) perror("ERROR: close tcp socket");
+          exit(4);
+        }
+        nBufferBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),
+          "SETUP rtsp://%s%s/%s RTSP/1.0\r\n"
+          "CSeq: 1\r\n"
+          "Ntrip-Version: Ntrip/2.0\r\n"
+          "Ntrip-Component: Ntripserver\r\n"
+          "User-Agent: %s/%s\r\n"
+          "Transport: RTP/GNSS;unicast;client_port=%u\r\n"
+          "Authorization: Basic %s\r\n"
+          "Ntrip-STR: %s\r\n\r\n",
+          casterouthost, rtsp_extension, mountpoint, AGENTSTRING, revisionstr,
+          client_port, authorization, ntrip_str);
+        if((nBufferBytes > (int)sizeof(szSendBuffer)) || (nBufferBytes < 0))
+        {
+          fprintf(stderr, "ERROR: Destination caster request to long\n");
+          outputmode = END;
+          break;
+        }
+        if (!send_to_caster(szSendBuffer, socket_tcp, nBufferBytes))
+        {
+          outputmode = END;
+          break;
+        }
+        while((nBufferBytes = recv(socket_tcp, szSendBuffer,
+        sizeof(szSendBuffer), 0)) > 0)
+        {
+          /* check Destination caster's response */
+          szSendBuffer[nBufferBytes] = '\0';
+          if(!strstr(szSendBuffer, "RTSP/1.0 200 OK"))
+          {
+            char *a;
+            fprintf(stderr,
+            "ERROR: Destination caster's%s reply is not OK: ",
+            *proxyhost ? " or Proxy's" : "");
+            for(a = szSendBuffer; *a && *a != '\n' && *a != '\r'; ++a)
+            {
+              fprintf(stderr, "%c", isprint(*a) ? *a : '.');
+            }
+            fprintf(stderr, "\n");
+            /* fallback if necessary */
+            if(strncmp(szSendBuffer, "RTSP",4) != 0)
+            {
+              if(strstr(szSendBuffer,"Ntrip-Version: Ntrip/2.0\r\n"))
+              {
+                fprintf(stderr,
+                " - RTSP not implemented at Destination caster <%s>%s%s%s\n\n"
+                "caster fallback: Fallback to Ntrip Version 2.0 in TCP/IP"
+                " mode\n\n", casterouthost,
+                *proxyhost ? " or Proxy <" :"", proxyhost, *proxyhost ? ">":"");
+                outputmode = HTTP;
+                break;
+              }
+              else
+              {
+                fprintf(stderr,
+                " Ntrip-Version 2.0 not implemented at Destination caster"
+                "<%s>%s%s%s\n%s"
+                " or RTSP/1.0 not implemented at Destination caster%s\n\n"
+                "caster fallback: Fallback to Ntrip Version 1.0\n",
+                casterouthost, *proxyhost ? " or Proxy <" :"", proxyhost,
+                *proxyhost ? ">":"",
+                *proxyhost ? " or HTTP/1.1 not implemented at Proxy\n" : "",
+                *proxyhost ? " or Proxy" :"");
+                outputmode = NTRIPV1;
+                break;
+              }
+            }
+            else
+            {
+              outputmode = END;
+              break;
+            }
+          }
+#ifndef NDEBUG
+          else
+          {
+            fprintf(stderr, "Destination caster response:\n%s\n",szSendBuffer);
+          }
+#endif
+          if((strstr(szSendBuffer,"RTSP/1.0 200 OK\r\n"))
+          && (strstr(szSendBuffer,"CSeq: 1\r\n")))
+          {
+            for(token = strtok(szSendBuffer, dlim); token != NULL;
+            token = strtok(NULL, dlim))
+            {
+              tok_buf[i] = token; i++;
+            }
+            session = atoi(tok_buf[6]);
+            server_port = atoi(tok_buf[10]);
+            nBufferBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),
+              "POST rtsp://%s%s/%s RTSP/1.0\r\n"
+              "CSeq: 2\r\n"
+              "Session: %d\r\n"
+              "\r\n",
+              casterouthost, rtsp_extension,  mountpoint,  session);
+            if((nBufferBytes >= (int)sizeof(szSendBuffer))
+            || (nBufferBytes < 0))
+            {
+              fprintf(stderr, "ERROR: Destination caster request to long\n");
+              outputmode = END;
+              break;
+            }
+            if(!send_to_caster(szSendBuffer, socket_tcp, nBufferBytes))
+            {
+               outputmode = END;
+               break;
+            }
+          }else if((strstr(szSendBuffer,"RTSP/1.0 200 OK\r\n")) && (strstr(szSendBuffer,"CSeq: 2\r\n"))) {
+            /* fill structure with caster address information for UDP */
+            memset(&casterRTP, 0, sizeof(casterRTP));
+            casterRTP.sin_family = AF_INET;
+            casterRTP.sin_port   = htons(((uint16_t)server_port));
+            if((he = gethostbyname(outhost))== NULL) {
+              fprintf(stderr, "ERROR: Destination caster unknown\n");
+              if(close(socket_udp)==-1) perror("ERROR: close udp socket");
+              if(close(socket_tcp)==-1) perror("ERROR: close tcp socket");
+              exit(4);
+            }else{
+              memcpy((char *)&casterRTP.sin_addr.s_addr,
+              he->h_addr_list[0], (size_t)he->h_length);
+            }
+            cseq = 2;
+            len = (socklen_t)sizeof(casterRTP);
+            send_receive_loop(socket_udp, gpsfd, outputmode, (struct sockaddr *)&casterRTP, (socklen_t)len);
+            break;
+          }else{break;}
+        }
+        break;
+    }
+  }
+  close_session(socket_udp, socket_tcp, casterouthost, mountpoint, cseq, session, rtsp_extension, gpsfd);
+  return 0;
+}
+
+static void send_receive_loop(int sock, int fd, int outmode, struct sockaddr* pcasterRTP,
+socklen_t length)
+{
+  int nodata = 0;
+  char buffer[BUFSZ] = { 0 };
+  char sisnetbackbuffer[200];
+  char szSendBuffer[BUFSZ] = "";
+  int nBufferBytes = 0;
+
+   /* RTSP / RTP Mode */
+  int    isfirstpacket = 1;
+  struct timeval now;
+  struct timeval last = {0,0};
+  long int sendtimediff;
+  int rtpseq = 0;
+  int rtpssrc = 0;
+  int rtptime = 0;
+
+  /* data transmission */
+  fprintf(stderr,"transfering data ...\n");
+
+  while(1)
+  {
+    /* signal handling*/
+    if(signal_was_caught())
+    {
+      fprintf(stderr, "NtripLinuxServer exits send-receive mode\n");
+      break;
+    }
+    if(!nodata) alarm(ALARMTIME);
+    else nodata = 0;
+
+    if(!nBufferBytes)
+    {
+      if(inputmode == SISNET && sisnet <= 30)
+      {
+        int i;
+        /* a somewhat higher rate than 1 second to get really each block */
+        /* means we need to skip double blocks sometimes */
+        struct timeval tv = {0,700000};
+        select(0, 0, 0, 0, &tv);
+        memcpy(sisnetbackbuffer, buffer, sizeof(sisnetbackbuffer));
+        i = (sisnet >= 30 ? 5 : 3);
+        if((send(gpsfd, "MSG\r\n", i, 0)) != i)
+        {
+          perror("ERROR: sending SISNeT data request");
+          exit(1);
+        }
+      }
+      /*** receiving data ****/
+      nBufferBytes = read(fd, buffer, sizeof(buffer));
+      if(!nBufferBytes)
+      {
+        printf("WARNING: no data received from input\n");
+        sleep(3);
+        nodata = 1;
+        continue;
+      }
+      else if(nBufferBytes < 0)
+      {
+        perror("ERROR: reading input failed");
+        exit(1);
+      }
+      /* we can compare the whole buffer, as the additional bytes
+         remain unchanged */
+      if(inputmode == SISNET && sisnet <= 30 &&
+      !memcmp(sisnetbackbuffer, buffer, sizeof(sisnetbackbuffer)))
+      {
+        nBufferBytes = 0;
+      }
+    }
+    /**  send data ***/
+    if((nBufferBytes)  && (outmode == NTRIPV1)) /*** Ntrip-Version 1.0 ***/
+    {
+      int i;
+      if((i = send(sock, buffer, (size_t)nBufferBytes, MSG_DONTWAIT))
+      != nBufferBytes)
+      {
+        if(i < 0)
+        {
+          if(errno != EAGAIN)
+          {
+            perror("WARNING: could not send data to Destination caster"
+            " - retry connection");
+            close(sock);
+            sleep(5);
+            return;
+          }
+        }
+        else if(i)
+        {
+          memmove(buffer, buffer+i, (size_t)(nBufferBytes-i));
+          nBufferBytes -= i;
+        }
+      }else
+      {
+        nBufferBytes = 0;
+      }
+    }
+    /*** Ntrip-Version 2.0 HTTP/1.1 ***/
+    else if((nBufferBytes)  && (outmode == HTTP))
+    {
+      int i, nChunkBytes, j = 1;
+      nChunkBytes = snprintf(szSendBuffer, sizeof(szSendBuffer),"%x\r\n",
+      nBufferBytes);
+      send(sock, szSendBuffer, nChunkBytes, MSG_DONTWAIT);
+      if((i = send(sock, buffer, (size_t)nBufferBytes, MSG_DONTWAIT))
+      != nBufferBytes)
+      {
+        if(i < 0)
+        {
+          if(errno != EAGAIN)
+          {
+            perror("WARNING: could not send data to Destination caster"
+            " - retry connection");
+            close(sock);
+            sleep(5);
+            return;
+          }
+        }
+        else if(i)
+        {
+          while(j>0)
+          {
+            j = send(sock, buffer, (size_t)BUFSZ, MSG_DONTWAIT);
+          }
+        }
+      }
+      else
+      {
+        send(sock, "\r\n", strlen("\r\n"), MSG_DONTWAIT);
+        nBufferBytes = 0;
+      }
+    }
+    /*** Ntrip-Version 2.0 RTSP(TCP) / RTP(UDP) ***/
+    else if((nBufferBytes)  && (outmode == RTSP))
+    {
+      char rtpbuffer[BUFSZ+12];
+      int i, j;
+      /* Signal Handling */
+      if(signal_was_caught())
+      {
+        fprintf(stderr, "NtripLinuxServer exits send-receive mode\n");
+        break;
+      }
+      gettimeofday(&now, NULL);
+      /* RTP data packet generation*/
+      if(isfirstpacket){
+        rtpseq = rand();
+        rtptime = rand();
+        rtpssrc = rand();
+        last = now;
+        isfirstpacket = 0;
+      }
+      else
+      {
+        ++rtpseq;
+        sendtimediff = (((now.tv_sec - last.tv_sec)*1000000)
+        + (now.tv_usec - last.tv_usec));
+        rtptime += sendtimediff/TIME_RESOLUTION;
+      }
+      rtpbuffer[0] = (RTP_VERSION<<6);
+      /* padding, extension, csrc are empty */
+      rtpbuffer[1] = 96;
+      /* marker is empty */
+      rtpbuffer[2] = rtpseq>>8;
+      rtpbuffer[3] = rtpseq;
+      rtpbuffer[4] = rtptime>>24;
+      rtpbuffer[5] = rtptime>>16;
+      rtpbuffer[6] = rtptime>>8;
+      rtpbuffer[7] = rtptime;
+      rtpbuffer[8] = rtpssrc>>24;
+      rtpbuffer[9] = rtpssrc>>16;
+      rtpbuffer[10] = rtpssrc>>8;
+      rtpbuffer[11] = rtpssrc;
+      for(j=0; j<nBufferBytes; j++) {rtpbuffer[12+j] = buffer[j];}
+      last.tv_sec  = now.tv_sec;
+      last.tv_usec = now.tv_usec;
+
+      if ((i = sendto(sock, rtpbuffer, 12 + nBufferBytes, 0, pcasterRTP,
+      length)) != (nBufferBytes + 12))
+      {
+        if(i < 0)
+        {
+          if(errno != EAGAIN)
+          {
+            perror("WARNING: could not send data to Destination caster - retry connection");
+            close(sock);
+            sleep(5);
+            return;
+          }
+        }
+        else if(i)
+        {
+          memmove(buffer, buffer+(i-12), (size_t)(nBufferBytes-(i-12)));
+          nBufferBytes -= i-12;
+        }
+      }
+      else
+      {
+        nBufferBytes = 0;
+      }
+    }
+  }
+  return;
+}
+
+
+/********************************************************************
+ * openserial
+ *
+ * Open the serial port with the given device name and configure it for
+ * reading NMEA data from a GPS receiver.
+ *
+ * Parameters:
+ *     tty     : pointer to    : A zero-terminated string containing the device
+ *               unsigned char   name of the appropriate serial port.
+ *     blocksz : integer       : Block size for port I/O
+ *     baud :    integer       : Baud rate for port I/O
+ *
+ * Return Value:
+ *     The function returns a file descriptor for the opened port if successful.
+ *     The function returns -1 in the event of an error.
+ *
+ * Remarks:
+ *
+ ********************************************************************/
+
+static int openserial(const char * tty, int blocksz, int baud)
+{
+  int fd;
+  struct termios termios;
+
+  fd = open(tty, O_RDWR | O_NONBLOCK | O_EXLOCK);
+  if(fd < 0)
+  {
+    perror("ERROR: opening serial connection");
+    return (-1);
+  }
+  if(tcgetattr(fd, &termios) < 0)
+  {
+    perror("ERROR: get serial attributes");
+    return (-1);
+  }
+  termios.c_iflag = 0;
+  termios.c_oflag = 0;          /* (ONLRET) */
+  termios.c_cflag = CS8 | CLOCAL | CREAD;
+  termios.c_lflag = 0;
+  {
+    int cnt;
+    for(cnt = 0; cnt < NCCS; cnt++)
+      termios.c_cc[cnt] = -1;
+  }
+  termios.c_cc[VMIN] = blocksz;
+  termios.c_cc[VTIME] = 2;
+
+#if (B4800 != 4800)
+/* Not every system has speed settings equal to absolute speed value. */
+
+  switch (baud)
+  {
+  case 300:
+    baud = B300;
+    break;
+  case 1200:
+    baud = B1200;
+    break;
+  case 2400:
+    baud = B2400;
+    break;
+  case 4800:
+    baud = B4800;
+    break;
+  case 9600:
+    baud = B9600;
+    break;
+  case 19200:
+    baud = B19200;
+    break;
+  case 38400:
+    baud = B38400;
+    break;
+#ifdef B57600
+  case 57600:
+    baud = B57600;
+    break;
+#endif
+#ifdef B115200
+  case 115200:
+    baud = B115200;
+    break;
+#endif
+#ifdef B230400
+  case 230400:
+    baud = B230400;
+    break;
+#endif
+  default:
+    fprintf(stderr, "WARNING: Baud settings not useful, using 19200\n");
+    baud = B19200;
+    break;
+  }
+#endif
+
+  if(cfsetispeed(&termios, baud) != 0)
+  {
+    perror("ERROR: setting serial speed with cfsetispeed");
+    return (-1);
+  }
+  if(cfsetospeed(&termios, baud) != 0)
+  {
+    perror("ERROR: setting serial speed with cfsetospeed");
+    return (-1);
+  }
+  if(tcsetattr(fd, TCSANOW, &termios) < 0)
+  {
+    perror("ERROR: setting serial attributes");
+    return (-1);
+  }
+  if(fcntl(fd, F_SETFL, 0) == -1)
+  {
+    perror("WARNING: setting blocking inputmode failed");
+  }
+  return (fd);
+} /* openserial */
+
+/********************************************************************
+* usage
+*
+* Send a usage message to standard error and quit the program.
+*
+* Parameters:
+*     None.
+*
+* Return Value:
+*     The function does not return a value.
+*
+* Remarks:
+*
+*********************************************************************/
+static
+#ifdef __GNUC__
+__attribute__ ((noreturn))
+#endif /* __GNUC__ */
+void usage(int rc, char *name)
+{
+  fprintf(stderr, "Version %s (%s) GPL" COMPILEDATE "\nUsage:\n%s [OPTIONS]\n",
+    revisionstr, datestr, name);
+  fprintf(stderr, "PURPOSE\n");
+  fprintf(stderr, "   The purpose of this program is to pick up a GNSS data stream (Input, Source)\n");
+  fprintf(stderr, "   from either\n\n");
+  fprintf(stderr, "     1. a Serial port, or\n");
+  fprintf(stderr, "     2. an IP server, or\n");
+  fprintf(stderr, "     3. a File, or\n");
+  fprintf(stderr, "     4. a SISNeT Data Server, or\n");
+  fprintf(stderr, "     5. a UDP server, or\n");
+  fprintf(stderr, "     6. an NTRIP Version 1.0 Caster\n\n");
+  fprintf(stderr, "   and forward that incoming stream (Output, Destination) to either\n\n");
+  fprintf(stderr, "     - an NTRIP Version 1.0 Caster, or\n");
+  fprintf(stderr, "     - an NTRIP Version 2.0 Caster via TCP/IP or RTSP/RTP.\n\n\n");
+  fprintf(stderr, "OPTIONS\n");
+  fprintf(stderr, "   -h|? print this help screen\n\n");
+  fprintf(stderr, "    -E <ProxyHost>       Proxy server host name or address, required i.e. when\n");
+  fprintf(stderr, "                         running the program in a proxy server protected LAN,\n");
+  fprintf(stderr, "                         optional\n");
+  fprintf(stderr, "    -F <ProxyPort>       Proxy server IP port, required i.e. when running\n");
+  fprintf(stderr, "                         the program in a proxy server protected LAN, optional\n\n");
+  fprintf(stderr, "    -M <InputMode> Sets the input mode (1 = Serial Port, 2 = IP server,\n");
+  fprintf(stderr, "       3 = File, 4 = SISNeT Data Server, 5 = UDP server, 6 = NTRIP Caster),\n");
+  fprintf(stderr, "       mandatory\n\n");
+  fprintf(stderr, "       <InputMode> = 1 (Serial Port):\n");
+  fprintf(stderr, "       -i <Device>       Serial input device, default: /dev/gps, mandatory if\n");
+  fprintf(stderr, "                         <InputMode>=1\n");
+  fprintf(stderr, "       -b <BaudRate>     Serial input baud rate, default: 19200 bps, mandatory\n");
+  fprintf(stderr, "                         if <InputMode>=1\n\n");
+  fprintf(stderr, "       <InputMode> = 2|5 (IP port | UDP port):\n");
+  fprintf(stderr, "       -H <ServerHost>   Input host name or address, default: 127.0.0.1,\n");
+  fprintf(stderr, "                         mandatory if <InputMode> = 2|5\n");
+  fprintf(stderr, "       -P <ServerPort>   Input port, default: 1025, mandatory if <InputMode>= 2|5\n");
+  fprintf(stderr, "       -f <ServerFile>   Name of initialization file to be send to server,\n");
+  fprintf(stderr, "                         optional\n");
+  fprintf(stderr, "       -x <ServerUser>   User ID to access incoming stream, optional\n");
+  fprintf(stderr, "       -y <ServerPass>   Password, to access incoming stream, optional\n");
+  fprintf(stderr, "       -B Bind to incoming UDP stream, optional for <InputMode> = 5\n\n");
+  fprintf(stderr, "       <InputMode> = 3 (File):\n");
+  fprintf(stderr, "       -s <File>         File name to simulate stream by reading data from (log)\n");
+  fprintf(stderr, "                         file, default is /dev/stdin, mandatory for <InputMode> = 3\n\n");
+  fprintf(stderr, "       <InputMode> = 4 (SISNeT Data Server):\n");
+  fprintf(stderr, "       -H <SisnetHost>   SISNeT Data Server name or address,\n");
+  fprintf(stderr, "                         default: 131.176.49.142, mandatory if <InputMode> = 4\n");
+  fprintf(stderr, "       -P <SisnetPort>   SISNeT Data Server port, default: 7777, mandatory if\n");
+  fprintf(stderr, "                         <InputMode> = 4\n");
+  fprintf(stderr, "       -u <SisnetUser>   SISNeT Data Server user ID, mandatory if <InputMode> = 4\n");
+  fprintf(stderr, "       -l <SisnetPass>   SISNeT Data Server password, mandatory if <InputMode> = 4\n");
+  fprintf(stderr, "       -V <SisnetVers>   SISNeT Data Server Version number, options are 2.1, 3.0\n");
+  fprintf(stderr, "                         or 3.1, default: 3.1, mandatory if <InputMode> = 4\n\n");
+  fprintf(stderr, "       <InputMode> = 6 (NTRIP Version 1.0 Caster):\n");
+  fprintf(stderr, "       -H <SourceHost>   Source caster name or address, default: 127.0.0.1,\n");
+  fprintf(stderr, "                         mandatory if <InputMode> = 6\n");
+  fprintf(stderr, "       -P <SourcePort>   Source caster port, default: 2101, mandatory if\n");
+  fprintf(stderr, "                         <InputMode> = 6\n");
+  fprintf(stderr, "       -D <SourceMount>  Source caster mountpoint for stream input, mandatory if\n");
+  fprintf(stderr, "                         <InputMode> = 6\n");
+  fprintf(stderr, "       -U <SourceUser>   Source caster user Id for input stream access, mandatory\n");
+  fprintf(stderr, "                         for protected streams if <InputMode> = 6\n");
+  fprintf(stderr, "       -W <SourcePass>   Source caster password for input stream access, mandatory\n");
+  fprintf(stderr, "                         for protected streams if <InputMode> = 6\n\n");
+  fprintf(stderr, "    -O <OutputMode> Sets output mode for communatation with destination caster\n");
+  fprintf(stderr, "       0 = h = http: Ntrip Version 2.0 Caster in TCP/IP mode\n");
+  fprintf(stderr, "       1 = r = rtsp: NTRIP Version 2.0 Caster in RTSP/RTP mode\n");
+  fprintf(stderr, "       2 = n = ntrip1: NTRIP Version 1.0 Caster\n\n");
+  fprintf(stderr, "       Defaults to NTRIP1.0, but wil change to 2.0 in future versions\n");
+  fprintf(stderr, "       Note that the program automatically falls back from mode r to mode t and\n");
+  fprintf(stderr, "       further to mode f if necessary.\n\n");
+  fprintf(stderr, "       -a <DestHost>     Destination caster name or address, default: 127.0.0.1,\n");
+  fprintf(stderr, "                         mandatory\n");
+  fprintf(stderr, "       -p <DestPort>     Destination caster port, default: 2101, mandatory\n");
+  fprintf(stderr, "       -m <DestMount>    Destination caster mountpoint for stream upload,\n");
+  fprintf(stderr, "                         mandatory\n");
+  fprintf(stderr, "       -n <DestUser>     Destination caster user ID for stream upload to\n");
+  fprintf(stderr, "                         mountpoint, only for NTRIP Version 2.0 destination\n");
+  fprintf(stderr, "                         casters, mandatory\n");
+  fprintf(stderr, "       -c <DestPass>     Destination caster password for stream upload to\n");
+  fprintf(stderr, "                         mountpoint, mandatory\n");
+  fprintf(stderr, "       -N <STR-record>   Sourcetable STR-record\n");
+  fprintf(stderr, "                         optional for Ntrip Version 2.0 in RTSP/RTP and TCP/IP mode\n\n");
+  exit(rc);
+} /* usage */
+
+
+/********************************************************************/
+/* signal handling                                                  */
+/********************************************************************/
+#ifdef __GNUC__
+static void handle_sigint(int sig __attribute__((__unused__)))
+#else /* __GNUC__ */
+static void handle_sigint(int sig)
+#endif /* __GNUC__ */
+{sigint_received  = 1;}
+
+static void setup_signal_handler(int sig, void (*handler)(int))
+{
+#if _POSIX_VERSION > 198800L
+  struct sigaction action;
+
+  action.sa_handler = handler;
+  sigemptyset(&(action.sa_mask));
+  sigaddset(&(action.sa_mask), sig);
+  action.sa_flags = 0;
+  sigaction(sig, &action, 0);
+#else
+  signal(sig, handler);
+#endif
+  return;
+} /* setupsignal_handler */
+
+static int signal_was_caught(void)
+{
+  fflush(stdout);
+  if(sigint_received)
+    fprintf(stderr, "SIGINT received: ");
+
+  return (sigint_received);
+} /* signal_was_caught */
+
+/********************************************************************
+ * base64-encoding                                                  *
+*******************************************************************/
+static const char encodingTable [64] =
+{
+  'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
+  'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
+  'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
+  'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/'
+};
+
+/* does not buffer overrun, but breaks directly after an error */
+/* returns the number of required bytes */
+static int encode(char *buf, int size, const char *user, const char *pwd)
+{
+  unsigned char inbuf[3];
+  char *out = buf;
+  int i, sep = 0, fill = 0, bytes = 0;
+
+  while(*user || *pwd)
+  {
+    i = 0;
+    while(i < 3 && *user) inbuf[i++] = *(user++);
+    if(i < 3 && !sep)    {inbuf[i++] = ':'; ++sep; }
+    while(i < 3 && *pwd)  inbuf[i++] = *(pwd++);
+    while(i < 3)         {inbuf[i++] = 0; ++fill; }
+    if(out-buf < size-1)
+      *(out++) = encodingTable[(inbuf [0] & 0xFC) >> 2];
+    if(out-buf < size-1)
+      *(out++) = encodingTable[((inbuf [0] & 0x03) << 4)
+               | ((inbuf [1] & 0xF0) >> 4)];
+    if(out-buf < size-1)
+    {
+      if(fill == 2)
+        *(out++) = '=';
+      else
+        *(out++) = encodingTable[((inbuf [1] & 0x0F) << 2)
+                 | ((inbuf [2] & 0xC0) >> 6)];
+    }
+    if(out-buf < size-1)
+    {
+      if(fill >= 1)
+        *(out++) = '=';
+      else
+        *(out++) = encodingTable[inbuf [2] & 0x3F];
+    }
+    bytes += 4;
+  }
+  if(out-buf < size)
+    *out = 0;
+  return bytes;
+}/* base64 Encoding */
+
+
+/********************************************************************
+ * send message to caster                                           *
+*********************************************************************/
+static int send_to_caster(char *input, int socket, int input_size)
+{
+ int send_error = 1;
+
+  if((send(socket, input, (size_t)input_size, 0)) != input_size)
+  {
+    fprintf(stderr, "ERROR: could not send full header to Destination caster\n");
+    send_error = 0;
+  }
+#ifndef NDEBUG
+  else
+  {
+    fprintf(stderr, "\nDestination caster request:\n");
+    fprintf(stderr, "%s", input);
+  }
+#endif
+  return send_error;
+}/* send_to_caster */
+
+
+/********************************************************************
+ * close session                                                    *
+*********************************************************************/
+static void close_session(int sock_udp, int sock_tcp,
+const char *caster_addr, const char *mountpoint, int cseq,
+int session, char *rtsp_ext, int in_fd)
+{
+  int  size_send_buf;
+  char send_buf[BUFSZ];
+
+  if(in_fd)
+  {
+    if(close(in_fd)==-1)
+    {
+      perror("ERROR: close input device ");
+      exit(0);
+    }
+#ifndef NDEBUG
+    else
+    {
+      fprintf(stderr, "\nclose input device: successful\n");
+    }
+#endif
+  }
+
+  if(sock_udp  != 0)
+  {
+    if(cseq == 2)
+    {
+      size_send_buf = snprintf(send_buf, sizeof(send_buf),
+        "TEARDOWN rtsp://%s%s/%s RTSP/1.0\r\n"
+        "CSeq: 2\r\n"
+        "Session: %d\r\n"
+        "\r\n",
+        caster_addr, rtsp_ext, mountpoint, session);
+      if((size_send_buf >= (int)sizeof(send_buf)) || (size_send_buf < 0))
+      {
+        fprintf(stderr, "ERROR: Destination caster request to long\n");
+        exit(0);
+      }
+      send_to_caster(send_buf, sock_tcp, size_send_buf); strcpy(send_buf,"");
+      size_send_buf = recv(sock_tcp, send_buf, sizeof(send_buf), 0);
+      send_buf[size_send_buf] = '\0';
+#ifndef NDEBUG
+      fprintf(stderr, "Destination caster response:\n%s", send_buf);
+#endif
+    }
+    if(close(sock_udp)==-1)
+    {
+      perror("ERROR: close udp socket");
+      exit(0);
+    }
+#ifndef NDEBUG
+    else
+    {
+      fprintf(stderr, "close udp socket:   successful\n");
+    }
+#endif
+  }
+
+  if(close(sock_tcp)==-1)
+  {
+    perror("ERROR: close tcp socket");
+    exit(0);
+  }
+#ifndef NDEBUG
+  else
+  {
+    fprintf(stderr, "close tcp socket:   successful\n\n");
+  }
+#endif
+} /* close_session */