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AnonymizeIPAddr_A50 Class Reference

#include <Anon.h>

Inheritance diagram for AnonymizeIPAddr_A50:

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Collaboration diagram for AnonymizeIPAddr_A50:

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List of all members.

Public Member Functions

 AnonymizeIPAddr_A50 ()
 ~AnonymizeIPAddr_A50 ()
ipaddr32_t anonymize (ipaddr32_t addr)
int PreservePrefix (ipaddr32_t input, int num_bits)

Protected Member Functions

void init ()
Node * new_node ()
Node * new_node_block ()
void free_node (Node *)
ipaddr32_t make_output (ipaddr32_t, int) const
Node * make_peer (ipaddr32_t, Node *)
Node * find_node (ipaddr32_t)

Protected Attributes

int method
int before_anonymization
int new_mapping
Node * root
Node * next_free_node
std::vector< Node * > blocks
Node special_nodes [2]

Constructor & Destructor Documentation

AnonymizeIPAddr_A50::AnonymizeIPAddr_A50 (   )  [inline]
 

Definition at line 94 of file Anon.h.

References init(). 

00094 { init(); }

AnonymizeIPAddr_A50::~AnonymizeIPAddr_A50 (   ) 
 

Definition at line 122 of file Anon.cc.

References blocks. 

00123         {
00124         for ( unsigned int i = 0; i < blocks.size(); ++i )
00125                 delete [] blocks[i];
00126 
00127         blocks.clear();
00128         }

Member Function Documentation

ipaddr32_t AnonymizeIPAddr_A50::anonymize (  ipaddr32_t  addr  )  [virtual]
 

Implements AnonymizeIPAddr.

Definition at line 174 of file Anon.cc.

References before_anonymization, find_node(), ipaddr32_t, new_mapping, and AnonymizeIPAddr_A50::Node::output. 

00175         {
00176         before_anonymization = 0;
00177         new_mapping = 0;
00178 
00179         if ( Node* n = find_node(ntohl(a)) )
00180                 {
00181                 ipaddr32_t output = htonl(n->output);
00182                 return output;
00183                 }
00184         else
00185                 return 0;
00186         }

AnonymizeIPAddr_A50::Node * AnonymizeIPAddr_A50::find_node (  ipaddr32_t   )  [protected]
 

Definition at line 284 of file Anon.cc.

References bi_ffs(), AnonymizeIPAddr_A50::Node::child, AnonymizeIPAddr_A50::Node::input, internal_error(), ipaddr32_t, make_peer(), new_node(), AnonymizeIPAddr_A50::Node::output, rand32(), root, and special_nodes.

Referenced by anonymize(), and PreservePrefix(). 

00285         {
00286         // Watch out for special IP addresses, which never make it
00287         // into the tree.
00288         if ( a == 0 || a == 0xFFFFFFFFU )
00289                 return &special_nodes[a & 1];
00290 
00291         if ( ! root )
00292                 {
00293                 root = new_node();
00294                 root->input = a;
00295                 root->output = rand32();
00296                 root->child[0] = root->child[1] = 0;
00297 
00298                 return root;
00299                 }
00300 
00301         // Straight from tcpdpriv.
00302         Node* n = root;
00303         while ( n )
00304                 {
00305                 if ( n->input == a )
00306                         return n;
00307 
00308                 if ( ! n->child[0] )
00309                         n = make_peer(a, n);
00310 
00311                 else
00312                         {
00313                         // swivel is the first bit in which the two children
00314                         // differ.
00315                         int swivel =
00316                                 bi_ffs(n->child[0]->input ^ n->child[1]->input);
00317 
00318                         if ( bi_ffs(a ^ n->input) < swivel )
00319                                 // Input differs earlier.
00320                                 n = make_peer(a, n);
00321 
00322                         else if ( a & (1 << (32 - swivel)) )
00323                                 n = n->child[1];
00324 
00325                         else
00326                                 n = n->child[0];
00327                         }
00328                 }
00329 
00330         internal_error("out of memory!");
00331         return 0;
00332         }

void AnonymizeIPAddr_A50::free_node (  Node *   )  [inline, protected]
 

Definition at line 222 of file Anon.cc.

References AnonymizeIPAddr_A50::Node::child, and next_free_node.

Referenced by make_peer(). 

00223         {
00224         n->child[0] = next_free_node;
00225         next_free_node = n;
00226         }

void AnonymizeIPAddr_A50::init (   )  [protected]
 

Definition at line 130 of file Anon.cc.

References before_anonymization, AnonymizeIPAddr_A50::Node::input, next_free_node, AnonymizeIPAddr_A50::Node::output, root, and special_nodes.

Referenced by AnonymizeIPAddr_A50(). 

00131         {
00132         root = next_free_node = 0;
00133 
00134         // Prepare special nodes for 0.0.0.0 and 255.255.255.255.
00135         memset(&special_nodes[0], 0, sizeof(special_nodes));
00136         special_nodes[0].input = special_nodes[0].output = 0;
00137         special_nodes[1].input = special_nodes[1].output = 0xFFFFFFFF;
00138 
00139         before_anonymization = 1;
00140         }

ipaddr32_t AnonymizeIPAddr_A50::make_output (  ipaddr32_t  ,
int 
)  const [protected]
 

Definition at line 228 of file Anon.cc.

References ipaddr32_t, and rand32().

Referenced by make_peer(). 

00229         {
00230         // -A50 anonymization
00231         if ( swivel == 32 )
00232                 return old_output ^ 1;
00233         else
00234                 {
00235                 // Bits up to swivel are unchanged; bit swivel is flipped.
00236                 ipaddr32_t known_part =
00237                         ((old_output >> (32 - swivel)) ^ 1) << (32 - swivel);
00238 
00239                 // Remainder of bits are random.
00240                 return known_part | ((rand32() & 0x7FFFFFFF) >> swivel);
00241                 }
00242         }

AnonymizeIPAddr_A50::Node * AnonymizeIPAddr_A50::make_peer (  ipaddr32_t  ,
Node * 
)  [protected]
 

Definition at line 244 of file Anon.cc.

References bi_ffs(), AnonymizeIPAddr_A50::Node::child, free_node(), AnonymizeIPAddr_A50::Node::input, internal_error(), ipaddr32_t, make_output(), new_node(), and AnonymizeIPAddr_A50::Node::output.

Referenced by find_node(). 

00245         {
00246         if ( a == 0 || a == 0xFFFFFFFFU )
00247                 internal_error("0.0.0.0 and 255.255.255.255 should never get into the tree");
00248 
00249         // Become a peer.
00250         // Algorithm: create two nodes, the two peers.  Leave orig node as
00251         // the parent of the two new ones.
00252 
00253         Node* down[2];
00254 
00255         if ( ! (down[0] = new_node()) )
00256                 return 0;
00257 
00258         if ( ! (down[1] = new_node()) )
00259                 {
00260                 free_node(down[0]);
00261                 return 0;
00262                 }
00263 
00264         // swivel is first bit 'a' and 'old->input' differ.
00265         int swivel = bi_ffs(a ^ n->input);
00266 
00267         // bitvalue is the value of that bit of 'a'.
00268         int bitvalue = (a >> (32 - swivel)) & 1;
00269 
00270         down[bitvalue]->input = a;
00271         down[bitvalue]->output = make_output(n->output, swivel);
00272         down[bitvalue]->child[0] = down[bitvalue]->child[1] = 0;
00273 
00274         *down[1 - bitvalue] = *n;       // copy orig node down one level
00275 
00276         n->input = down[1]->input;      // NB: 1s to the right (0s to the left)
00277         n->output = down[1]->output;
00278         n->child[0] = down[0];          // point to children
00279         n->child[1] = down[1];
00280 
00281         return down[bitvalue];
00282         }

AnonymizeIPAddr_A50::Node * AnonymizeIPAddr_A50::new_node (   )  [inline, protected]
 

Definition at line 208 of file Anon.cc.

References AnonymizeIPAddr_A50::Node::child, new_mapping, new_node_block(), and next_free_node.

Referenced by find_node(), and make_peer(). 

00209         {
00210         new_mapping = 1;
00211 
00212         if ( next_free_node )
00213                 {
00214                 Node* n = next_free_node;
00215                 next_free_node = n->child[0];
00216                 return n;
00217                 }
00218         else
00219                 return new_node_block();
00220         }

AnonymizeIPAddr_A50::Node * AnonymizeIPAddr_A50::new_node_block (   )  [protected]
 

Definition at line 188 of file Anon.cc.

References blocks, AnonymizeIPAddr_A50::Node::child, internal_error(), and next_free_node.

Referenced by new_node(). 

00189         {
00190         assert(! next_free_node);
00191 
00192         int block_size = 1024;
00193         Node* block = new Node[block_size];
00194         if ( ! block )
00195                 internal_error("out of memory!");
00196 
00197         blocks.push_back(block);
00198 
00199         for ( int i = 1; i < block_size - 1; ++i )
00200                 block[i].child[0] = &block[i+1];
00201 
00202         block[block_size - 1].child[0] = 0;
00203         next_free_node = &block[1];
00204 
00205         return &block[0];
00206         }

int AnonymizeIPAddr_A50::PreservePrefix (  ipaddr32_t  input,
int  num_bits
)  [virtual]
 

Reimplemented from AnonymizeIPAddr.

Definition at line 142 of file Anon.cc.

References before_anonymization, DEBUG_MSG, dotted_addr(), find_node(), first_n_bit_mask, fmt(), ipaddr32_t, AnonymizeIPAddr_A50::Node::output, rand32(), run_time(), and uint32. 

00143         {
00144         DEBUG_MSG(fmt("%s/%d\n", dotted_addr(input), num_bits));
00145 
00146         if ( ! before_anonymization )
00147                 {
00148                 run_time("prefix perservation specified after anonymization begun");
00149                 return 0;
00150                 }
00151 
00152         input = ntohl(input);
00153 
00154         // Sanitize input.
00155         input = input & first_n_bit_mask(num_bits);
00156 
00157         Node* n = find_node(input);
00158 
00159         // Preserve the first num_bits bits of addr.
00160         if ( num_bits == 32 )
00161                 n->output = input;
00162 
00163         else if ( num_bits > 0 )
00164                 {
00165                 assert((0xFFFFFFFFU >> 1) == 0x7FFFFFFFU);
00166                 uint32 suffix_mask = (0xFFFFFFFFU >> num_bits);
00167                 uint32 prefix_mask = ~suffix_mask;
00168                 n->output = (input & prefix_mask) | (rand32() & suffix_mask);
00169                 }
00170 
00171         return 1;
00172         }

Member Data Documentation

int AnonymizeIPAddr_A50::before_anonymization [protected]
 

Definition at line 108 of file Anon.h.

Referenced by anonymize(), init(), and PreservePrefix().

std::vector<Node*> AnonymizeIPAddr_A50::blocks [protected]
 

Definition at line 116 of file Anon.h.

Referenced by new_node_block(), and ~AnonymizeIPAddr_A50().

int AnonymizeIPAddr_A50::method [protected]
 

Definition at line 107 of file Anon.h.

int AnonymizeIPAddr_A50::new_mapping [protected]
 

Definition at line 109 of file Anon.h.

Referenced by anonymize(), and new_node().

Node* AnonymizeIPAddr_A50::next_free_node [protected]
 

Definition at line 115 of file Anon.h.

Referenced by free_node(), init(), new_node(), and new_node_block().

Node* AnonymizeIPAddr_A50::root [protected]
 

Definition at line 112 of file Anon.h.

Referenced by find_node(), and init().

Node AnonymizeIPAddr_A50::special_nodes[2] [protected]
 

Definition at line 119 of file Anon.h.

Referenced by find_node(), and init().

The documentation for this class was generated from the following files:
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