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227 lines
7.5 KiB
Diff
227 lines
7.5 KiB
Diff
--- a/query.c
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+++ b/query.c
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@@ -91,6 +91,21 @@ static void cleanup(struct query *z)
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}
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}
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+static int move_name_to_alias(struct query *z,uint32 ttl)
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+{
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+ int j ;
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+
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+ if (z->alias[QUERY_MAXALIAS - 1]) return 0 ;
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+ for (j = QUERY_MAXALIAS - 1;j > 0;--j)
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+ z->alias[j] = z->alias[j - 1];
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+ for (j = QUERY_MAXALIAS - 1;j > 0;--j)
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+ z->aliasttl[j] = z->aliasttl[j - 1];
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+ z->alias[0] = z->name[0];
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+ z->aliasttl[0] = ttl;
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+ z->name[0] = 0;
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+ return 1 ;
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+}
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+
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static int rqa(struct query *z)
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{
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int i;
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@@ -123,7 +138,6 @@ static int globalip(char *d,char ip[4])
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static char *t1 = 0;
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static char *t2 = 0;
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static char *t3 = 0;
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-static char *cname = 0;
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static char *referral = 0;
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static unsigned int *records = 0;
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@@ -179,15 +193,14 @@ static int doit(struct query *z,int stat
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uint16 datalen;
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char *control;
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char *d;
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+ char *owner_name = 0 ;
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const char *dtype;
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unsigned int dlen;
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int flagout;
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- int flagcname;
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int flagreferral;
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int flagsoa;
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uint32 ttl;
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uint32 soattl;
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- uint32 cnamettl;
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int i;
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int j;
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int k;
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@@ -253,7 +266,10 @@ static int doit(struct query *z,int stat
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byte_copy(key,2,DNS_T_CNAME);
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cached = cache_get(key,dlen + 2,&cachedlen,&ttl);
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- if (cached) {
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+ /* A previous explicit query might have caused an empty RRSet to have been
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+ ** cached. Take care to ignore such a thing.
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+ */
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+ if (cached && cachedlen) {
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if (typematch(DNS_T_CNAME,dtype)) {
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log_cachedanswer(d,DNS_T_CNAME);
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if (!rqa(z)) goto DIE;
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@@ -262,8 +278,11 @@ static int doit(struct query *z,int stat
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return 1;
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}
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log_cachedcname(d,cached);
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- if (!dns_domain_copy(&cname,cached)) goto DIE;
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- goto CNAME;
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+ if (!z->level) {
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+ if (!move_name_to_alias(z,ttl)) goto DIE ;
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+ }
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+ if (!dns_domain_copy(&z->name[z->level],cached)) goto DIE;
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+ goto NEWNAME;
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}
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if (typematch(DNS_T_NS,dtype)) {
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@@ -352,7 +371,7 @@ static int doit(struct query *z,int stat
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}
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}
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- 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)) {
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+ 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)) {
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byte_copy(key,2,dtype);
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cached = cache_get(key,dlen + 2,&cachedlen,&ttl);
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if (cached && (cachedlen || byte_diff(dtype,2,DNS_T_ANY))) {
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@@ -473,29 +492,31 @@ static int doit(struct query *z,int stat
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cachettl = 0;
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flagout = 0;
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- flagcname = 0;
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flagreferral = 0;
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flagsoa = 0;
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soattl = 0;
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- cnamettl = 0;
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+ if (!dns_domain_copy(&owner_name,d)) goto DIE;
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+ /* This code assumes that the CNAME chain is presented in the correct
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+ ** order. The example algorithm in RFC 1034 will actually result in this
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+ ** being the case, but the words do not require it to be so.
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+ */
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for (j = 0;j < numanswers;++j) {
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pos = dns_packet_getname(buf,len,pos,&t1); if (!pos) goto DIE;
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pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) goto DIE;
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- if (dns_domain_equal(t1,d))
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+ if (dns_domain_equal(t1,owner_name))
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if (byte_equal(header + 2,2,DNS_C_IN)) { /* should always be true */
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if (typematch(header,dtype))
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flagout = 1;
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else if (typematch(header,DNS_T_CNAME)) {
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- if (!dns_packet_getname(buf,len,pos,&cname)) goto DIE;
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- flagcname = 1;
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- cnamettl = ttlget(header + 4);
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+ if (!dns_packet_getname(buf,len,pos,&owner_name)) goto DIE;
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}
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}
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uint16_unpack_big(header + 8,&datalen);
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pos += datalen;
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}
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+ dns_domain_free(&owner_name) ;
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posauthority = pos;
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for (j = 0;j < numauthority;++j) {
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@@ -522,15 +543,6 @@ static int doit(struct query *z,int stat
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}
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posglue = pos;
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-
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- if (!flagcname && !rcode && !flagout && flagreferral && !flagsoa)
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- if (dns_domain_equal(referral,control) || !dns_domain_suffix(referral,control)) {
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- log_lame(whichserver,control,referral);
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- byte_zero(whichserver,4);
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- goto HAVENS;
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- }
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-
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-
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if (records) { alloc_free(records); records = 0; }
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k = numanswers + numauthority + numglue;
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@@ -677,24 +689,36 @@ static int doit(struct query *z,int stat
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alloc_free(records); records = 0;
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+ if (byte_diff(DNS_T_CNAME,2,dtype)) {
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+ /* This code assumes that the CNAME chain is presented in the correct
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+ ** order. The example algorithm in RFC 1034 will actually result in this
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+ ** being the case, but the words do not require it to be so.
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+ */
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+ pos = posanswers;
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+ for (j = 0;j < numanswers;++j) {
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+ pos = dns_packet_getname(buf,len,pos,&t1); if (!pos) goto DIE;
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+ pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) goto DIE;
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+
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+ if (dns_domain_equal(t1,d))
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+ if (byte_equal(header + 2,2,DNS_C_IN)) { /* should always be true */
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+ if (typematch(header,DNS_T_CNAME)) {
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+ ttl = ttlget(header + 4);
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+ if (z->level == 0) {
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+ if (!move_name_to_alias(z,ttl)) goto DIE ;
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+ }
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+ if (!dns_packet_getname(buf,len,pos,&z->name[z->level])) goto DIE;
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+ d = z->name[z->level];
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+ if (!dns_domain_suffix(d,control) || !roots_same(d,control))
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+ goto NEWNAME ; /* Cannot trust the chain further - restart using current name */
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+ }
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+ }
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- if (flagcname) {
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- ttl = cnamettl;
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- CNAME:
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- if (!z->level) {
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- if (z->alias[QUERY_MAXALIAS - 1]) goto DIE;
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- for (j = QUERY_MAXALIAS - 1;j > 0;--j)
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- z->alias[j] = z->alias[j - 1];
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- for (j = QUERY_MAXALIAS - 1;j > 0;--j)
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- z->aliasttl[j] = z->aliasttl[j - 1];
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- z->alias[0] = z->name[0];
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- z->aliasttl[0] = ttl;
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- z->name[0] = 0;
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+ uint16_unpack_big(header + 8,&datalen);
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+ pos += datalen;
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}
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- if (!dns_domain_copy(&z->name[z->level],cname)) goto DIE;
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- goto NEWNAME;
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}
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+ /* A "no such name" error applies to the end of any CNAME chain, not to the start. */
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if (rcode == 3) {
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log_nxdomain(whichserver,d,cachettl);
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cachegeneric(DNS_T_ANY,d,"",0,cachettl);
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@@ -707,10 +731,26 @@ static int doit(struct query *z,int stat
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return 1;
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}
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+ /* We check for a lame server _after_ we have cached any records that it
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+ ** might have returned to us. This copes better with the incorrect
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+ ** behaviour of one content DNS server software that doesn't return
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+ ** complete CNAME chains but instead returns only the first link in a
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+ ** chain followed by a lame delegation to the same server.
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+ ** Also: We check for a lame server _after_ following the CNAME chain. The
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+ ** delegation in a referral answer applies to the _end_ of the chain, not
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+ ** to the beginning.
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+ */
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+ if (!rcode && !flagout && flagreferral && !flagsoa)
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+ if (dns_domain_equal(referral,control) || !dns_domain_suffix(referral,control)) {
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+ log_lame(whichserver,control,referral);
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+ byte_zero(whichserver,4);
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+ goto HAVENS;
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+ }
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+
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if (!flagout && flagsoa)
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+ /* Don't save empty RRSets for those types that we use as special markers. */
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if (byte_diff(DNS_T_ANY,2,dtype))
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- if (byte_diff(DNS_T_AXFR,2,dtype))
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- if (byte_diff(DNS_T_CNAME,2,dtype)) {
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+ if (byte_diff(DNS_T_AXFR,2,dtype)) {
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save_start();
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save_finish(dtype,d,soattl);
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log_nodata(whichserver,d,dtype,soattl);
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@@ -822,6 +862,7 @@ static int doit(struct query *z,int stat
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DIE:
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cleanup(z);
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if (records) { alloc_free(records); records = 0; }
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+ dns_domain_free(&owner_name) ;
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return -1;
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}
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