/* path.cc   handles source routes   $Id: path.cc,v 1.7 1998/05/13 16:17:51 dmaltz Exp $*/extern "C" {#include <assert.h>#include <stdio.h>}#include <packet.h>#include <ip.h>#include <cmu/dsr/hdr_sr.h>#include "path.h"/*===========================================================================  global statics---------------------------------------------------------------------------*/ID invalid_addr(0xffffffff,::NONE);ID IP_broadcast(IP_BROADCAST,::IP);/*===========================================================================  ID methods---------------------------------------------------------------------------*/voidID::unparse(FILE *out) const{  fprintf(out,"%d",(int) addr);}char *ID::dump() const{  static char buf[MAX_SR_LEN+1][50];  static int which = 0;  char *ptr = buf[which];  which = (which + 1) % (MAX_SR_LEN+1);  assert(type == ::NONE || type == ::MAC || type == ::IP);  if (type == ::IP)    sprintf(ptr,"%d",(int) addr);  else if (type == ::NONE)    sprintf(ptr,"NONE");  else    sprintf(ptr,"0x%x",(int) addr);  return ptr;}/*===========================================================================  Path methods---------------------------------------------------------------------------*//* rep invariants:   -1 <= cur_index <= len  (neither bound is really hard)   0 <= len < MAX_SR_LEN*/Path::Path(int route_len, const ID *route){  path = new ID[MAX_SR_LEN];  assert(route_len <= MAX_SR_LEN);  //  route_len = (route == NULL : 0 ? route_len);   // a more cute solution, follow the above with the then clause  if (route != NULL)    {      for (int c = 0; c < route_len; c++)        {	  path[c] = route[c];        }      len = route_len;    }  else    {      len = 0;    }  cur_index = 0;}Path::Path(){  path = new ID[MAX_SR_LEN];  len = 0;  cur_index = 0;}Path::Path(const struct sr_addr *addrs, int len){ /* make a path from the bits of an NS source route header */  assert(len <= MAX_SR_LEN);  path = new ID[MAX_SR_LEN];  for (int i = 0 ; i < len ; i++)    path[i] = ID(addrs[i]);  this->len = len;  cur_index = 0;}Path::Path(const struct hdr_sr *srh){ /* make a path from the bits of an NS source route header */  path = new ID[MAX_SR_LEN];  if (!srh->valid_)    {      len = 0;      cur_index = 0;      return;    }  len = srh->num_addrs_;  cur_index = srh->cur_addr_;  assert(len <= MAX_SR_LEN);  for (int i = 0 ; i < len ; i++)    path[i] = ID(srh->addrs[i]);}voidPath::fillSR(struct hdr_sr *srh){  for (int i = 0 ; i < len ; i++)    {      path[i].fillSRAddr(srh->addrs[i]);    }  srh->num_addrs() = len;  srh->cur_addr() = cur_index;}Path::Path(const Path& old){  path = new ID[MAX_SR_LEN];  if (old.path != NULL)    {      for (int c = 0; c < old.len; c++)	path[c] = old.path[c];      len = old.len;    }  else    {      len = 0;    }  cur_index = old.cur_index;  path_owner = old.path_owner;}Path::~Path(){  delete[] path;}voidPath::operator=(const Path &rhs)     // makes the lhs a copy of the rhs: lhs may share data with     // the rhs such that changes to one will be seen by the other     // use the provided copy operation if you don't want this.{/* OLD  NOTE:  we save copying the path by doing a delete[] path; path = rhs.path;   but then the following code will be fatal (it calls delete[]   twice on the same address)     { Path p1();       { Path p2();         p2 = p1;       }     }   you'd have to implement reference counts on the path array to   save copying the path.   NEW NOTE: we just copy like everything else*/  if (this != &rhs)    {// beware of path = path (see Stroustrup p. 238)      cur_index = rhs.cur_index;      path_owner = rhs.path_owner;      len = rhs.len;      for (int c = 0 ; c < len ; c++)	path[c] = rhs.path[c];    }  // note: i don't return *this cause I don't think assignments should  // be expressions (and it has slightly incorrect semantics: (a=b) should  // have the value of b, not the new value of a)}boolPath::operator==(const Path &rhs){  int c;  if (len != rhs.len) return false;  for (c = 0; c < len; c++)    if (path[c] != rhs.path[c]) return false;  return true;} void Path::appendPath(Path& p){  int i;  for (i = 0; i < p.length() ; i++)    {      path[len] = p[i];      len++;      if (len > MAX_SR_LEN)	{	  fprintf(stderr,"DFU: overflow in appendPath len2 %d\n",		  p.length());	  len--;	  return;	}    }}void Path::removeSection(int from, int to)  // the elements at indices from -> to-1 are removed from the path{  int i,j;  if (to <= from) return;  if (cur_index > from) cur_index = cur_index - (to - from);  for (i = to, j = 0; i < len ; i++, j++)    path[from + j] = path[i];  len = from + j;}PathPath::copy() const{  Path p(len,path);  p.cur_index = cur_index;  p.path_owner = path_owner;  return p;}voidPath::copyInto(Path& to) const{  to.cur_index = cur_index;  to.len = len;  for (int c = 0 ; c < len ; c++)    to.path[c] = path[c];    to.path_owner = path_owner;}PathPath::reverse() const     // return an identical path with the index pointing to the same     // host, but the path in reverse order{  if (len == 0) return *this;  Path p;  int from, to;  for (from = 0, to = (len-1) ; from < len ; from++,to--)    p.path[to] = path[from];  p.len = len;  p.cur_index = (len - 1) - cur_index;  return p;}voidPath::reverseInPlace(){  if (len == 0) return;  int fp,bp;	   // forward ptr, back ptr  ID temp;  for (fp = 0, bp = (len-1) ; fp < bp ; fp++, bp--)    {      temp = path[fp];      path[fp] = path[bp];      path[bp] = temp;    }  cur_index = (len - 1) - cur_index;}intPath::size() const{  // this should be more clever and ask the id's what their sizes are.  return len*4;}boolPath::member(const ID& id) const// rtn true iff id is in path{  return member(id, invalid_addr);  }boolPath::member(const ID& id, const ID& MAC_id) const// rtn true iff id or MAC_id is in path{  for (int c = 0; c < len ; c++)    if (path[c] == id || path[c] == MAC_id)      return true;  return false;}voidPath::unparse(FILE *out) const{  // change to put ()'s around the cur_index entry?  if (len==0)    {      fprintf(out,"<empty path>");      return;    }  for (int c = 0 ; c < len-1 ; c ++)    {      if (c == cur_index) fprintf(out,"(");      path[c].unparse(out);      if (c == cur_index) fprintf(out,")");      fprintf(out,",");    }  if (len-1 == cur_index) fprintf(out,"(");  path[len-1].unparse(out);  if (len-1 == cur_index) fprintf(out,")");}char *Path::dump() const{  static which = 0;  static char buf[4][100];  char *ptr = buf[which];  char *rtn_buf = ptr;  which = (which + 1) % 4;    if (len == 0)    {      sprintf(rtn_buf,"[<empty path>]");      return rtn_buf;    }  *ptr++ = '[';  for (int c = 0 ; c < len ; c ++)    {      if (c == cur_index) *ptr++ = '(';      ptr += sprintf(ptr,"%s%s ",path[c].dump(), c == cur_index ? ")" : "");    }  *ptr++ = ']';  *ptr++ = '\0';  return rtn_buf;}voidcompressPath(Path &path)// take a path and remove any double backs from it// eg:  A B C B D --> A B D{  // idea: walk one pointer from begining  //  for each elt1 start at end of path and walk a pointer backwards (elt2)  //   if forward pointer = backward pointer, go on and walk foward one more  //   if elt1 = elt2 then append {(elt2 + 1) to end} after forward pointer  //    update length of path (we just cut out a loopback) and walk forward  //  when forward walking pointer reaches end of path we're done  int fp = 0, bp; // the forward walking ptr and the back walking ptr  while (fp < path.len)    {      for (bp = path.len - 1; bp != fp; bp--)	{	  if (path.path[fp] == path.path[bp])	    { int from, to;	      for (from = bp, to = fp;		   from < path.len ;		   from++, to++)		path.path[to] = path.path[from];	      path.len = to;	      break;	    } // end of removing double back	} // end of scaning to check for double back      fp++; // advance the forward moving pointer    }}void CopyIntoPath(Path& to, const Path& from, int start, int stop)// sets to[0->(stop-start)] = from[start->stop]{  assert(start >= 0 && stop < from.len);  int f, t,c ;			// from and to indices  for(f = start, t = 0; f <= stop; f++, t++)    to.path[t] = from.path[f];  if (to.len < stop - start + 1) to.len = stop - start + 1;  for (c = to.len - 1; c >= 0; c--)    {      if (to.path[c] == to.owner()) break;      if (to.path[c] == ((Path &)from).owner()) 	{	  to.owner() = ((Path &)from).owner();	  break;	}    } }voidPath::checkpath() const{  for(int c = 0; c < MAX_SR_LEN; c++)    {           assert(path[c].type == NONE ||             path[c].type == MAC ||             path[c].type == IP);    }}