diff options
Diffstat (limited to 'tdlookup.c')
| -rw-r--r-- | tdlookup.c | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/tdlookup.c b/tdlookup.c new file mode 100644 index 0000000..da7420d --- /dev/null +++ b/tdlookup.c @@ -0,0 +1,310 @@ +#include <unistd.h> +#include "uint16.h" +#include "open.h" +#include "tai.h" +#include "cdb.h" +#include "byte.h" +#include "case.h" +#include "dns.h" +#include "seek.h" +#include "response.h" + +static int want(const char *owner,const char type[2]) +{ + unsigned int pos; + static char *d; + char x[10]; + uint16 datalen; + + pos = dns_packet_skipname(response,response_len,12); if (!pos) return 0; + pos += 4; + + while (pos < response_len) { + pos = dns_packet_getname(response,response_len,pos,&d); if (!pos) return 0; + pos = dns_packet_copy(response,response_len,pos,x,10); if (!pos) return 0; + if (dns_domain_equal(d,owner)) + if (byte_equal(type,2,x)) + return 0; + uint16_unpack_big(x + 8,&datalen); + pos += datalen; + } + return 1; +} + +static char *d1; + +static char clientloc[2]; +static struct tai now; +static struct cdb c; + +static char data[32767]; +static uint32 dlen; +static unsigned int dpos; +static char type[2]; +static uint32 ttl; + +static int find(char *d,int flagwild) +{ + int r; + char ch; + struct tai cutoff; + char ttd[8]; + char ttlstr[4]; + char recordloc[2]; + double newttl; + + for (;;) { + r = cdb_findnext(&c,d,dns_domain_length(d)); + if (r <= 0) return r; + dlen = cdb_datalen(&c); + if (dlen > sizeof data) return -1; + if (cdb_read(&c,data,dlen,cdb_datapos(&c)) == -1) return -1; + dpos = dns_packet_copy(data,dlen,0,type,2); if (!dpos) return -1; + dpos = dns_packet_copy(data,dlen,dpos,&ch,1); if (!dpos) return -1; + if ((ch == '=' + 1) || (ch == '*' + 1)) { + --ch; + dpos = dns_packet_copy(data,dlen,dpos,recordloc,2); if (!dpos) return -1; + if (byte_diff(recordloc,2,clientloc)) continue; + } + if (flagwild != (ch == '*')) continue; + dpos = dns_packet_copy(data,dlen,dpos,ttlstr,4); if (!dpos) return -1; + uint32_unpack_big(ttlstr,&ttl); + dpos = dns_packet_copy(data,dlen,dpos,ttd,8); if (!dpos) return -1; + if (byte_diff(ttd,8,"\0\0\0\0\0\0\0\0")) { + tai_unpack(ttd,&cutoff); + if (ttl == 0) { + if (tai_less(&cutoff,&now)) continue; + tai_sub(&cutoff,&cutoff,&now); + newttl = tai_approx(&cutoff); + if (newttl <= 2.0) newttl = 2.0; + if (newttl >= 3600.0) newttl = 3600.0; + ttl = newttl; + } + else + if (!tai_less(&cutoff,&now)) continue; + } + return 1; + } +} + +static int dobytes(unsigned int len) +{ + char buf[20]; + if (len > 20) return 0; + dpos = dns_packet_copy(data,dlen,dpos,buf,len); + if (!dpos) return 0; + return response_addbytes(buf,len); +} + +static int doname(void) +{ + dpos = dns_packet_getname(data,dlen,dpos,&d1); + if (!dpos) return 0; + return response_addname(d1); +} + +static int doit(char *q,char qtype[2]) +{ + unsigned int bpos; + unsigned int anpos; + unsigned int aupos; + unsigned int arpos; + char *control; + char *wild; + int flaggavesoa; + int flagfound; + int r; + int flagns; + int flagauthoritative; + char x[20]; + uint16 u16; + char addr[8][4]; + int addrnum; + uint32 addrttl; + int i; + + anpos = response_len; + + control = q; + for (;;) { + flagns = 0; + flagauthoritative = 0; + cdb_findstart(&c); + while (r = find(control,0)) { + if (r == -1) return 0; + if (byte_equal(type,2,DNS_T_SOA)) flagauthoritative = 1; + if (byte_equal(type,2,DNS_T_NS)) flagns = 1; + } + if (flagns) break; + if (!*control) return 0; /* q is not within our bailiwick */ + control += *control; + control += 1; + } + + if (!flagauthoritative) { + response[2] &= ~4; + goto AUTHORITY; /* q is in a child zone */ + } + + + flaggavesoa = 0; + flagfound = 0; + wild = q; + + for (;;) { + addrnum = 0; + addrttl = 0; + cdb_findstart(&c); + while (r = find(wild,wild != q)) { + if (r == -1) return 0; + flagfound = 1; + if (flaggavesoa && byte_equal(type,2,DNS_T_SOA)) continue; + if (byte_diff(type,2,qtype) && byte_diff(qtype,2,DNS_T_ANY) && byte_diff(type,2,DNS_T_CNAME)) continue; + if (byte_equal(type,2,DNS_T_A) && (dlen - dpos == 4)) { + addrttl = ttl; + i = dns_random(addrnum + 1); + if (i < 8) { + if ((i < addrnum) && (addrnum < 8)) + byte_copy(addr[addrnum],4,addr[i]); + byte_copy(addr[i],4,data + dpos); + } + if (addrnum < 1000000) ++addrnum; + continue; + } + if (!response_rstart(q,type,ttl)) return 0; + if (byte_equal(type,2,DNS_T_NS) || byte_equal(type,2,DNS_T_CNAME) || byte_equal(type,2,DNS_T_PTR)) { + if (!doname()) return 0; + } + else if (byte_equal(type,2,DNS_T_MX)) { + if (!dobytes(2)) return 0; + if (!doname()) return 0; + } + else if (byte_equal(type,2,DNS_T_SOA)) { + if (!doname()) return 0; + if (!doname()) return 0; + if (!dobytes(20)) return 0; + flaggavesoa = 1; + } + else + if (!response_addbytes(data + dpos,dlen - dpos)) return 0; + response_rfinish(RESPONSE_ANSWER); + } + for (i = 0;i < addrnum;++i) + if (i < 8) { + if (!response_rstart(q,DNS_T_A,addrttl)) return 0; + if (!response_addbytes(addr[i],4)) return 0; + response_rfinish(RESPONSE_ANSWER); + } + + if (flagfound) break; + if (wild == control) break; + if (!*wild) break; /* impossible */ + wild += *wild; + wild += 1; + } + + if (!flagfound) + response_nxdomain(); + + + AUTHORITY: + aupos = response_len; + + if (flagauthoritative && (aupos == anpos)) { + cdb_findstart(&c); + while (r = find(control,0)) { + if (r == -1) return 0; + if (byte_equal(type,2,DNS_T_SOA)) { + if (!response_rstart(control,DNS_T_SOA,ttl)) return 0; + if (!doname()) return 0; + if (!doname()) return 0; + if (!dobytes(20)) return 0; + response_rfinish(RESPONSE_AUTHORITY); + break; + } + } + } + else + if (want(control,DNS_T_NS)) { + cdb_findstart(&c); + while (r = find(control,0)) { + if (r == -1) return 0; + if (byte_equal(type,2,DNS_T_NS)) { + if (!response_rstart(control,DNS_T_NS,ttl)) return 0; + if (!doname()) return 0; + response_rfinish(RESPONSE_AUTHORITY); + } + } + } + + arpos = response_len; + + bpos = anpos; + while (bpos < arpos) { + bpos = dns_packet_skipname(response,arpos,bpos); if (!bpos) return 0; + bpos = dns_packet_copy(response,arpos,bpos,x,10); if (!bpos) return 0; + if (byte_equal(x,2,DNS_T_NS) || byte_equal(x,2,DNS_T_MX)) { + if (byte_equal(x,2,DNS_T_NS)) { + if (!dns_packet_getname(response,arpos,bpos,&d1)) return 0; + } + else + if (!dns_packet_getname(response,arpos,bpos + 2,&d1)) return 0; + case_lowerb(d1,dns_domain_length(d1)); + if (want(d1,DNS_T_A)) { + cdb_findstart(&c); + while (r = find(d1,0)) { + if (r == -1) return 0; + if (byte_equal(type,2,DNS_T_A)) { + if (!response_rstart(d1,DNS_T_A,ttl)) return 0; + if (!dobytes(4)) return 0; + response_rfinish(RESPONSE_ADDITIONAL); + } + } + } + } + uint16_unpack_big(x + 8,&u16); + bpos += u16; + } + + if (flagauthoritative && (response_len > 512)) { + byte_zero(response + RESPONSE_ADDITIONAL,2); + response_len = arpos; + if (response_len > 512) { + byte_zero(response + RESPONSE_AUTHORITY,2); + response_len = aupos; + } + } + + return 1; +} + +int respond(char *q,char qtype[2],char ip[4]) +{ + int fd; + int r; + char key[6]; + + tai_now(&now); + fd = open_read("data.cdb"); + if (fd == -1) return 0; + cdb_init(&c,fd); + + byte_zero(clientloc,2); + key[0] = 0; + key[1] = '%'; + byte_copy(key + 2,4,ip); + r = cdb_find(&c,key,6); + if (!r) r = cdb_find(&c,key,5); + if (!r) r = cdb_find(&c,key,4); + if (!r) r = cdb_find(&c,key,3); + if (!r) r = cdb_find(&c,key,2); + if (r == -1) return 0; + if (r && (cdb_datalen(&c) == 2)) + if (cdb_read(&c,clientloc,2,cdb_datapos(&c)) == -1) return 0; + + r = doit(q,qtype); + + cdb_free(&c); + close(fd); + return r; +} |