/**
   * astriumnet protocoll. This is the protocoll understood by the newest version 
   * of Astrium choppers with the Beckhoff server backend. There are a number of 
   * peculaties here: 
   *
   * On connecting there is an authorisation exchange. This, the client, has to send a 
   * challenge. The server responds with a random hash code. Then a password is encrypted 
   * with the hashcode and sent to the server. Who, hopefully, will respond with an AuthOK 
   * message. 
   * 
   * Furtheron the message exchange happens in an XML like format. But implemented in a 
   * slightly strange way in that everything is done through attributes. 
   * 
   * For more information, see the documentation by Astrium.
   *
   * copyright: see file COPYRIGHT
   *
   * Mark Koennecke, April 2014
   */
#include <errno.h>
#include <math.h>
#include <ascon.h>
#include <ascon.i>
#include <stptok.h>
#include <dynstring.h>
#include <mxml.h>


extern char *trim(char *);

typedef struct {
  char password[132];
  int authState;
  pDynString buffer;
}Astriumnet, *pAstriumnet;

#define AUTHSEND   4
#define AUTHSTART  0
#define WAITHASH   1
#define WAITOK     2  
#define AUTHOK     3
/*-----------------------------------------------------------------------*/
const char *AstriumWS(mxml_node_t* node, int where)
{
  /*
   * do not want whitespace in there anywhere
   */
  return NULL;
}
/*-----------------------------------------------------------------------*/
void ptToKomma(char *txt)
{
  int i;

  for(i = 0; i < strlen(txt); i++){
    if(txt[i] == '.'){
      txt[i] = ',';
    }
  }
}
/*-----------------------------------------------------------------------*/
void kommaToPt(char *txt)
{
  int i;

  for(i = 0; i < strlen(txt); i++){
    if(txt[i] == ','){
      txt[i] = '.';
    }
  }
}
/*-----------------------------------------------------------------------*/
static void encodeXML(Ascon *a)
{
  char *pPtr, *equal, *close;
  mxml_node_t *root, *msg, *sys, *param;
  char token[132];

  pPtr = GetCharArray(a->wrBuffer);
  root = mxmlNewXML("1.0");
  msg = mxmlNewElement(root,"Msg");
  
  /*
   * The first element must be the system name
   */
  pPtr = stptok(pPtr,token,sizeof(token),":");
  sys = mxmlNewElement(msg,"SysName");
  mxmlNewText(sys,0,token);

  param = mxmlNewElement(msg,"Param");
  while((pPtr = stptok(pPtr,token,sizeof(token),":")) != NULL){
    equal = strchr(token,(int)'=');
    if(equal != NULL){
      *equal = '\0';
      equal++;
      /*      ptToKomma(equal);*/
      mxmlElementSetAttr(param,token,equal);
    } else {
      mxmlElementSetAttr(param,token,NULL);
    }
  }
  
  mxmlSetWrapMargin(0);
  pPtr = mxmlSaveAllocString(root,AstriumWS);
  /*
   * Skip the <?XML=1.0 bla bla ?> string
   */
  close = strchr(pPtr,(int)'>');
  DynStringCopy(a->wrBuffer,"#CRQ#");
  DynStringConcat(a->wrBuffer,trim(close+1));
  free(pPtr);
  mxmlDelete(root);
}
/*-----------------------------------------------------------------------*/
static int decodeXML(Ascon *a)
{
  pDynString xmlBuffer;
  mxml_node_t *root, *param;
  mxml_attr_t attr;

  int i;

  /*
   * prepend the XML prefix to make mxml a happy library
   */ 
  xmlBuffer = CreateDynString(128,128);
  DynStringCopy(xmlBuffer,"<?xml version=\"1.0\" encoding=\"utf-8\"?>");
  DynStringConcat(xmlBuffer,GetCharArray(a->rdBuffer)+5);
  
  root = mxmlLoadString(NULL,GetCharArray(xmlBuffer),MXML_TEXT_CALLBACK);
  if(root == NULL){
    AsconError(a,"Astrium returned invalid XML",0);
    return 0;
  }
  
  DynStringClear(a->rdBuffer);
  param = mxmlFindElement(root,root,"Param",NULL,NULL,MXML_DESCEND);
  if(param == NULL){
    AsconError(a,"No Param node found",0);
    return 0;
  }
  
  for(i = 0; i < param->value.element.num_attrs; i++){
    attr = param->value.element.attrs[i];
    DynStringConcat(a->rdBuffer,attr.name);
    if(attr.value != NULL){
      DynStringConcat(a->rdBuffer,"=");
      kommaToPt(attr.value);
      DynStringConcat(a->rdBuffer,attr.value);
    } 
    DynStringConcat(a->rdBuffer,":");
  }
  DeleteDynString(xmlBuffer);
  mxmlDelete(root);

  return 1;
}
/*-----------------------------------------------------------------------
This code and the function below is sensitive to int sizes. The hash must 
be a 64bit int. This is long on OSX and long long on SL6 32 bit. Setting 
this to int64_t as defined in stdint.h does not solve the problem because 
of the conversions to and from strings involved.   
------------------------------------------------------------------------- */
static long long calculateToken(char *password, long long hash)
{
  long long tmp;
  int i;

  assert(sizeof(hash) == 8);

  tmp = hash ^ 0x80AA80AA;
  for(i = 0; i < strlen(password); i++){
    tmp += password[i] * (long long)pow(2,i);
    tmp -= password[i] * (long long)pow(2,31-i);
  } 
  return tmp ^ hash;
}
/*------------------------------------------------------------------------*/
static int doWaitHash(Ascon *a)
{
  pAstriumnet priv = NULL;
  int ret;
  char chr;
  long long hash;
  char token[50], *pPtr, *endptr;

  priv = (pAstriumnet)a->private;
  ret = AsconReadChar(a->fd,&chr);
  if(ret < 0){
    AsconError(a, "ASC5", errno);
    return 0;
  }
  if(ret == 1 && (int)chr != 0x16) {
    DynStringConcatChar(a->rdBuffer,chr);
  }
  if(strstr(GetCharArray(a->rdBuffer),"</Hash>") != NULL ) {
    pPtr = GetCharArray(a->rdBuffer);
    pPtr += 6;
    endptr = strchr(pPtr,(int)'<');
    *endptr = '\0';
    hash = strtoll(pPtr, &endptr,0);
    hash = calculateToken(priv->password,hash);
    DynStringCopy(priv->buffer,"<AuthToken>");
    snprintf(token,sizeof(token),"%lld",hash);
    DynStringConcat(priv->buffer,token);
    ret = AsconWriteChars(a->fd, GetCharArray(priv->buffer), 
			  GetDynStringLength(priv->buffer));
    if (ret < 0) {
      AsconError(a, "ASC4", errno); /* sets state to AsconFailed */ 
      return 0;
    }
    DynStringClear(a->rdBuffer);
    priv->authState = WAITOK;
  }
  return 1; 
}
/*------------------------------------------------------------------------*/
static int doWaitOK(Ascon *a)
{
  pAstriumnet priv = NULL;
  int ret;
  char chr;

  priv = (pAstriumnet)a->private;
  ret = AsconReadChar(a->fd,&chr);
  if(ret < 0){
    AsconError(a, "ASC5", errno);
    return 0;
  }
  if(ret == 1 && (int)chr != 0x16) {
    DynStringConcatChar(a->rdBuffer,chr);
  }
  if(strchr(GetCharArray(a->rdBuffer),(int)'>') != NULL) {
      if(strstr(GetCharArray(a->rdBuffer),"AuthOK") == NULL){
	AsconError(a,"Token authorisation failed",0);
	return 0;
      }
      priv->authState = AUTHOK;
      a->state = AsconConnectDone;
  }
  return 1; 
}

/*------------------------------------------------------------------------*/
static int AstriumnetHandler(Ascon *a)
{
  pAstriumnet priv = NULL;
  int ret;
  char chr;

  priv = (pAstriumnet)a->private;

  switch(a->state){
  case AsconConnectStart:
    AsconBaseHandler(a);
    if(a->state == AsconConnecting){
      DynStringCopy(priv->buffer,"<AuthReq>");
      priv->authState = AUTHSEND;
      return 1;
    } else {
      return 0;
    }
    break;
  case AsconConnecting:
    if(priv->authState == AUTHSEND){
      ret = AsconWriteChars(a->fd, GetCharArray(priv->buffer), 
			    GetDynStringLength(priv->buffer));
      if (ret < 0) {
	if(errno == EINPROGRESS){
	  return 1;
	}
	AsconError(a, "ASC4", errno); /* sets state to AsconFailed */ 
	return 0;
      }
      priv->authState = WAITHASH;
      DynStringClear(a->rdBuffer);
      return 1;
    } else if(priv->authState == WAITHASH){
      return doWaitHash(a);
    } else if(priv->authState == WAITOK){
      return doWaitOK(a);
    } else {
      AsconError(a,"Invalid authentication state",0);
      return 0;
    }
    break;
  case AsconWriteStart:
    encodeXML(a);
    a->state = AsconWriting;
    a->wrPos = 0;
    return 1;
    break;
  case AsconReading:
    ret = AsconReadChar(a->fd,&chr);
    if(ret < 0){
      AsconError(a, "ASC5", errno);
      return 0;
    }
    if(ret == 1 && (int)chr != 0x16) {
      DynStringConcatChar(a->rdBuffer,chr);
    }
    if(strstr(GetCharArray(a->rdBuffer),"</Msg>") != NULL) {
      decodeXML(a);
      a->state = AsconReadDone;
    }
    return 1;
    break;
  }
  return AsconBaseHandler(a);
}
/*------------------------------------------------------------------------*/
static int AstriumnetInit(Ascon * a, SConnection * con, int argc, char *argv[])
{
	  pAstriumnet priv = NULL;

	  if(argc < 3){
	    SCPrintf(con,eError,"ERROR: missing password argument to Astriumnet");
	    return 0;
          }
	  priv = calloc(sizeof(Astriumnet), 1);
	  a->fd = -1;
	  a->state = AsconConnectStart;
	  a->reconnectInterval = 10;
	  a->hostport = strdup(argv[1]);
	  a->private = priv;
	  a->killPrivate = free;
	  strncpy(priv->password,argv[2],sizeof(priv->password));
          priv->authState = AUTHSTART;
          priv->buffer = CreateDynString(128,128);
	  if(priv->buffer == NULL){
	    return 0;
          }
	  return 1;
}
/*------------------------------------------------------------------------*/
void AddAstriumnetProtocoll()
{
  AsconProtocol *prot = NULL;

  prot = calloc(sizeof(AsconProtocol), 1);
  prot->name = strdup("astriumnet");
  prot->init = AstriumnetInit;
  prot->handler = AstriumnetHandler;
  AsconInsertProtocol(prot);
}