net/djbdns/patches/200-dnscache-cname-handling.patch

   1 --- a/query.c
   2 +++ b/query.c
   3 @@ -91,6 +91,21 @@ static void cleanup(struct query *z)
   4    }
   5  }
   6
   7 +static int move_name_to_alias(struct query *z,uint32 ttl)
   8 +{
   9 +  int j ;
  10 +
  11 +  if (z->alias[QUERY_MAXALIAS - 1]) return 0 ;
  12 +  for (j = QUERY_MAXALIAS - 1;j > 0;--j)
  13 +    z->alias[j] = z->alias[j - 1];
  14 +  for (j = QUERY_MAXALIAS - 1;j > 0;--j)
  15 +    z->aliasttl[j] = z->aliasttl[j - 1];
  16 +  z->alias[0] = z->name[0];
  17 +  z->aliasttl[0] = ttl;
  18 +  z->name[0] = 0;
  19 +  return 1 ;
  20 +}
  21 +
  22  static int rqa(struct query *z)
  23  {
  24    int i;
  25 @@ -123,7 +138,6 @@ static int globalip(char *d,char ip[4])
  26  static char *t1 = 0;
  27  static char *t2 = 0;
  28  static char *t3 = 0;
  29 -static char *cname = 0;
  30  static char *referral = 0;
  31  static unsigned int *records = 0;
  32
  33 @@ -179,15 +193,14 @@ static int doit(struct query *z,int stat
  34    uint16 datalen;
  35    char *control;
  36    char *d;
  37 +  char *owner_name = 0 ;
  38    const char *dtype;
  39    unsigned int dlen;
  40    int flagout;
  41 -  int flagcname;
  42    int flagreferral;
  43    int flagsoa;
  44    uint32 ttl;
  45    uint32 soattl;
  46 -  uint32 cnamettl;
  47    int i;
  48    int j;
  49    int k;
  50 @@ -253,7 +266,10 @@ static int doit(struct query *z,int stat
  51
  52      byte_copy(key,2,DNS_T_CNAME);
  53      cached = cache_get(key,dlen + 2,&cachedlen,&ttl);
  54 -    if (cached) {
  55 +    /* A previous explicit query might have caused an empty RRSet to have been
  56 +    ** cached.  Take care to ignore such a thing.
  57 +    */
  58 +    if (cached && cachedlen) {
  59        if (typematch(DNS_T_CNAME,dtype)) {
  60          log_cachedanswer(d,DNS_T_CNAME);
  61          if (!rqa(z)) goto DIE;
  62 @@ -262,8 +278,11 @@ static int doit(struct query *z,int stat
  63         return 1;
  64        }
  65        log_cachedcname(d,cached);
  66 -      if (!dns_domain_copy(&cname,cached)) goto DIE;
  67 -      goto CNAME;
  68 +      if (!z->level) {
  69 +       if (!move_name_to_alias(z,ttl)) goto DIE ;
  70 +      }
  71 +      if (!dns_domain_copy(&z->name[z->level],cached)) goto DIE;
  72 +      goto NEWNAME;
  73      }
  74
  75      if (typematch(DNS_T_NS,dtype)) {
  76 @@ -352,7 +371,7 @@ static int doit(struct query *z,int stat
  77        }
  78      }
  79
  80 -    if (!typematch(DNS_T_ANY,dtype) && !typematch(DNS_T_AXFR,dtype) && !typematch(DNS_T_CNAME,dtype) && !typematch(DNS_T_NS,dtype) && !typematch(DNS_T_PTR,dtype) && !typematch(DNS_T_A,dtype) && !typematch(DNS_T_MX,dtype)) {
  81 +    if (!typematch(DNS_T_ANY,dtype) && !typematch(DNS_T_AXFR,dtype) && !typematch(DNS_T_NS,dtype) && !typematch(DNS_T_PTR,dtype) && !typematch(DNS_T_A,dtype) && !typematch(DNS_T_MX,dtype)) {
  82        byte_copy(key,2,dtype);
  83        cached = cache_get(key,dlen + 2,&cachedlen,&ttl);
  84        if (cached && (cachedlen || byte_diff(dtype,2,DNS_T_ANY))) {
  85 @@ -473,29 +492,31 @@ static int doit(struct query *z,int stat
  86
  87    cachettl = 0;
  88    flagout = 0;
  89 -  flagcname = 0;
  90    flagreferral = 0;
  91    flagsoa = 0;
  92    soattl = 0;
  93 -  cnamettl = 0;
  94 +  if (!dns_domain_copy(&owner_name,d)) goto DIE;
  95 +  /* This code assumes that the CNAME chain is presented in the correct
  96 +  ** order.  The example algorithm in RFC 1034 will actually result in this
  97 +  ** being the case, but the words do not require it to be so.
  98 +  */
  99    for (j = 0;j < numanswers;++j) {
 100      pos = dns_packet_getname(buf,len,pos,&t1); if (!pos) goto DIE;
 101      pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) goto DIE;
 102
 103 -    if (dns_domain_equal(t1,d))
 104 +    if (dns_domain_equal(t1,owner_name))
 105        if (byte_equal(header + 2,2,DNS_C_IN)) { /* should always be true */
 106          if (typematch(header,dtype))
 107            flagout = 1;
 108          else if (typematch(header,DNS_T_CNAME)) {
 109 -          if (!dns_packet_getname(buf,len,pos,&cname)) goto DIE;
 110 -          flagcname = 1;
 111 -         cnamettl = ttlget(header + 4);
 112 +          if (!dns_packet_getname(buf,len,pos,&owner_name)) goto DIE;
 113          }
 114        }
 115
 116      uint16_unpack_big(header + 8,&datalen);
 117      pos += datalen;
 118    }
 119 +  dns_domain_free(&owner_name) ;
 120    posauthority = pos;
 121
 122    for (j = 0;j < numauthority;++j) {
 123 @@ -522,15 +543,6 @@ static int doit(struct query *z,int stat
 124    }
 125    posglue = pos;
 126
 127 -
 128 -  if (!flagcname && !rcode && !flagout && flagreferral && !flagsoa)
 129 -    if (dns_domain_equal(referral,control) || !dns_domain_suffix(referral,control)) {
 130 -      log_lame(whichserver,control,referral);
 131 -      byte_zero(whichserver,4);
 132 -      goto HAVENS;
 133 -    }
 134 -
 135 -
 136    if (records) { alloc_free(records); records = 0; }
 137
 138    k = numanswers + numauthority + numglue;
 139 @@ -677,24 +689,36 @@ static int doit(struct query *z,int stat
 140
 141    alloc_free(records); records = 0;
 142
 143 +  if (byte_diff(DNS_T_CNAME,2,dtype)) {
 144 +    /* This code assumes that the CNAME chain is presented in the correct
 145 +    ** order.  The example algorithm in RFC 1034 will actually result in this
 146 +    ** being the case, but the words do not require it to be so.
 147 +    */
 148 +    pos = posanswers;
 149 +    for (j = 0;j < numanswers;++j) {
 150 +      pos = dns_packet_getname(buf,len,pos,&t1); if (!pos) goto DIE;
 151 +      pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) goto DIE;
 152 +
 153 +      if (dns_domain_equal(t1,d))
 154 +       if (byte_equal(header + 2,2,DNS_C_IN)) { /* should always be true */
 155 +         if (typematch(header,DNS_T_CNAME)) {
 156 +           ttl = ttlget(header + 4);
 157 +           if (z->level == 0) {
 158 +             if (!move_name_to_alias(z,ttl)) goto DIE ;
 159 +           }
 160 +           if (!dns_packet_getname(buf,len,pos,&z->name[z->level])) goto DIE;
 161 +           d = z->name[z->level];
 162 +           if (!dns_domain_suffix(d,control) || !roots_same(d,control))
 163 +             goto NEWNAME ;  /* Cannot trust the chain further - restart using current name */
 164 +         }
 165 +       }
 166
 167 -  if (flagcname) {
 168 -    ttl = cnamettl;
 169 -    CNAME:
 170 -    if (!z->level) {
 171 -      if (z->alias[QUERY_MAXALIAS - 1]) goto DIE;
 172 -      for (j = QUERY_MAXALIAS - 1;j > 0;--j)
 173 -        z->alias[j] = z->alias[j - 1];
 174 -      for (j = QUERY_MAXALIAS - 1;j > 0;--j)
 175 -        z->aliasttl[j] = z->aliasttl[j - 1];
 176 -      z->alias[0] = z->name[0];
 177 -      z->aliasttl[0] = ttl;
 178 -      z->name[0] = 0;
 179 +      uint16_unpack_big(header + 8,&datalen);
 180 +      pos += datalen;
 181      }
 182 -    if (!dns_domain_copy(&z->name[z->level],cname)) goto DIE;
 183 -    goto NEWNAME;
 184    }
 185
 186 +  /* A "no such name" error applies to the end of any CNAME chain, not to the start. */
 187    if (rcode == 3) {
 188      log_nxdomain(whichserver,d,cachettl);
 189      cachegeneric(DNS_T_ANY,d,"",0,cachettl);
 190 @@ -707,10 +731,26 @@ static int doit(struct query *z,int stat
 191      return 1;
 192    }
 193
 194 +  /* We check for a lame server _after_ we have cached any records that it
 195 +  ** might have returned to us.  This copes better with the incorrect
 196 +  ** behaviour of one content DNS server software that doesn't return
 197 +  ** complete CNAME chains but instead returns only the first link in a
 198 +  ** chain followed by a lame delegation to the same server.
 199 +  ** Also: We check for a lame server _after_ following the CNAME chain.  The
 200 +  ** delegation in a referral answer applies to the _end_ of the chain, not
 201 +  ** to the beginning.
 202 +  */
 203 +  if (!rcode && !flagout && flagreferral && !flagsoa)
 204 +    if (dns_domain_equal(referral,control) || !dns_domain_suffix(referral,control)) {
 205 +      log_lame(whichserver,control,referral);
 206 +      byte_zero(whichserver,4);
 207 +      goto HAVENS;
 208 +    }
 209 +
 210    if (!flagout && flagsoa)
 211 +    /* Don't save empty RRSets for those types that we use as special markers. */
 212      if (byte_diff(DNS_T_ANY,2,dtype))
 213 -      if (byte_diff(DNS_T_AXFR,2,dtype))
 214 -        if (byte_diff(DNS_T_CNAME,2,dtype)) {
 215 +      if (byte_diff(DNS_T_AXFR,2,dtype)) {
 216            save_start();
 217            save_finish(dtype,d,soattl);
 218           log_nodata(whichserver,d,dtype,soattl);
 219 @@ -822,6 +862,7 @@ static int doit(struct query *z,int stat
 220    DIE:
 221    cleanup(z);
 222    if (records) { alloc_free(records); records = 0; }
 223 +  dns_domain_free(&owner_name) ;
 224    return -1;
 225  }
 226