src/acl/Random.cc

   1 /*
   2  * Copyright (C) 1996-2022 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* DEBUG: section 28    Access Control */
  10
  11 #include "squid.h"
  12 #include "acl/FilledChecklist.h"
  13 #include "acl/Random.h"
  14 #include "debug/Stream.h"
  15 #include "Parsing.h"
  16 #include "wordlist.h"
  17
  18 #include <random>
  19
  20 ACLRandom::ACLRandom(char const *theClass) : data(0.0), class_(theClass)
  21 {
  22     memset(pattern, 0, sizeof(pattern));
  23 }
  24
  25 ACLRandom::~ACLRandom()
  26 { }
  27
  28 char const *
  29 ACLRandom::typeString() const
  30 {
  31     return class_;
  32 }
  33
  34 bool
  35 ACLRandom::empty () const
  36 {
  37     return data == 0.0;
  38 }
  39
  40 bool
  41 ACLRandom::valid() const
  42 {
  43     return !empty();
  44 }
  45
  46 /*******************/
  47 /* aclParseRandomList */
  48 /*******************/
  49 void
  50 ACLRandom::parse()
  51 {
  52     char bufa[256], bufb[256];
  53
  54     char *t = ConfigParser::strtokFile();
  55     if (!t) {
  56         debugs(28, DBG_PARSE_NOTE(DBG_IMPORTANT), "ERROR: ACL random missing pattern");
  57         return;
  58     }
  59
  60     debugs(28, 5, "aclParseRandomData: " << t);
  61
  62     // seed random generator ...
  63     srand(time(nullptr));
  64
  65     if (sscanf(t, "%[0-9]:%[0-9]", bufa, bufb) == 2) {
  66         int a = xatoi(bufa);
  67         int b = xatoi(bufb);
  68         if (a <= 0 || b <= 0) {
  69             debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  70             return;
  71         } else
  72             data = a / (double)(a+b);
  73     } else if (sscanf(t, "%[0-9]/%[0-9]", bufa, bufb) == 2) {
  74         int a = xatoi(bufa);
  75         int b = xatoi(bufb);
  76         if (a <= 0 || b <= 0 || a > b) {
  77             debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  78             return;
  79         } else
  80             data = (double) a / (double) b;
  81     } else if (sscanf(t, "0.%[0-9]", bufa) == 1) {
  82         data = atof(t);
  83     } else {
  84         debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  85         return;
  86     }
  87
  88     // save the exact input pattern. so we can display it later.
  89     memcpy(pattern, t, min(sizeof(pattern)-1,strlen(t)));
  90 }
  91
  92 int
  93 ACLRandom::match(ACLChecklist *)
  94 {
  95     // make up the random value.
  96     // The fixed-value default seed is fine because we are
  97     // actually matching whether the random value is above
  98     // or below the configured threshold ratio.
  99     static std::mt19937 mt;
 100     static std::uniform_real_distribution<> dist(0, 1);
 101
 102     const double random = dist(mt);
 103
 104     debugs(28, 3, "ACL Random: " << name << " " << pattern << " test: " << data << " > " << random << " = " << ((data > random)?"MATCH":"NO MATCH") );
 105     return (data > random)?1:0;
 106 }
 107
 108 SBufList
 109 ACLRandom::dump() const
 110 {
 111     SBufList sl;
 112     sl.push_back(SBuf(pattern));
 113     return sl;
 114 }
 115