src/acl/Random.cc

   1 /*
   2  * Copyright (C) 1996-2020 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.h"
  15 #include "Parsing.h"
  16 #include "wordlist.h"
  17
  18 #include <random>
  19
  20 ACL *
  21 ACLRandom::clone() const
  22 {
  23     return new ACLRandom(*this);
  24 }
  25
  26 ACLRandom::ACLRandom(char const *theClass) : data(0.0), class_(theClass)
  27 {
  28     memset(pattern, 0, sizeof(pattern));
  29 }
  30
  31 ACLRandom::ACLRandom(ACLRandom const & old) : data(old.data), class_(old.class_)
  32 {
  33     memcpy(pattern, old.pattern, sizeof(pattern));
  34 }
  35
  36 ACLRandom::~ACLRandom()
  37 { }
  38
  39 char const *
  40 ACLRandom::typeString() const
  41 {
  42     return class_;
  43 }
  44
  45 bool
  46 ACLRandom::empty () const
  47 {
  48     return data == 0.0;
  49 }
  50
  51 bool
  52 ACLRandom::valid() const
  53 {
  54     return !empty();
  55 }
  56
  57 /*******************/
  58 /* aclParseRandomList */
  59 /*******************/
  60 void
  61 ACLRandom::parse()
  62 {
  63     char bufa[256], bufb[256];
  64
  65     char *t = ConfigParser::strtokFile();
  66     if (!t) {
  67         debugs(28, DBG_PARSE_NOTE(DBG_IMPORTANT), "ACL random missing pattern");
  68         return;
  69     }
  70
  71     debugs(28, 5, "aclParseRandomData: " << t);
  72
  73     // seed random generator ...
  74     srand(time(NULL));
  75
  76     if (sscanf(t, "%[0-9]:%[0-9]", bufa, bufb) == 2) {
  77         int a = xatoi(bufa);
  78         int b = xatoi(bufb);
  79         if (a <= 0 || b <= 0) {
  80             debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  81             return;
  82         } else
  83             data = a / (double)(a+b);
  84     } else if (sscanf(t, "%[0-9]/%[0-9]", bufa, bufb) == 2) {
  85         int a = xatoi(bufa);
  86         int b = xatoi(bufb);
  87         if (a <= 0 || b <= 0 || a > b) {
  88             debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  89             return;
  90         } else
  91             data = (double) a / (double) b;
  92     } else if (sscanf(t, "0.%[0-9]", bufa) == 1) {
  93         data = atof(t);
  94     } else {
  95         debugs(28, DBG_CRITICAL, "ERROR: ACL random with bad pattern: '" << t << "'");
  96         return;
  97     }
  98
  99     // save the exact input pattern. so we can display it later.
 100     memcpy(pattern, t, min(sizeof(pattern)-1,strlen(t)));
 101 }
 102
 103 int
 104 ACLRandom::match(ACLChecklist *)
 105 {
 106     // make up the random value.
 107     // The fixed-value default seed is fine because we are
 108     // actually matching whether the random value is above
 109     // or below the configured threshold ratio.
 110     static std::mt19937 mt;
 111     static xuniform_real_distribution<> dist(0, 1);
 112
 113     const double random = dist(mt);
 114
 115     debugs(28, 3, "ACL Random: " << name << " " << pattern << " test: " << data << " > " << random << " = " << ((data > random)?"MATCH":"NO MATCH") );
 116     return (data > random)?1:0;
 117 }
 118
 119 SBufList
 120 ACLRandom::dump() const
 121 {
 122     SBufList sl;
 123     sl.push_back(SBuf(pattern));
 124     return sl;
 125 }
 126