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#include "fmt.h"
#include "iobuf.h"
#include "ipv4.h"
#include "msg.h"
#include "socket.h"
#include "uint16.h"
#include "uint32.h"
#include <sys/wait.h>
#define DUMP void dump_rrs(int count, const union dns_result_rrs* rr)
#define NODUMP DUMP { (void)count; (void)rr; }
#define RESPONSE static const struct dns_response
extern DUMP;
static int dns_responder_pid = 0;
extern ipv4port dns_use_port;
struct dns_response_rr
{
const char* name;
uint16 namelen;
uint16 type;
uint16 class;
uint32 ttl;
const char* rdata;
uint16 rdatalen;
};
struct dns_response
{
uint16 ancount, nscount, arcount;
struct dns_response_rr rr[8];
};
static long dump_name(const unsigned char* data)
{
long o = 0;
unsigned char l;
while ((l = data[o++]) > 0) {
obuf_write(&outbuf, (const char*)data+o, l);
obuf_putc(&outbuf, '.');
o += l;
};
return o;
}
static long dump_request(const unsigned char* packet, long len)
{
uint16 first = uint16_get_msb(packet+2);
uint16 qdcount = uint16_get_msb(packet+4);
uint16 ancount = uint16_get_msb(packet+6);
uint16 nscount = uint16_get_msb(packet+8);
uint16 arcount = uint16_get_msb(packet+10);
long o = 12;
obuf_putf(&outbuf, "d{: ID=XX QR=}d{ opcode=}d{ AA=}d{ TC=}d{ RD=}d{ RA=}d{ Z=}d{ RCODE=}d{ QDCOUNT=}d{ ANCOUNT=}d{ NSCOUNT=}d{ ARCOUNT=}d{\n}",
len,
first >> 15, /* QR */
(first >> 11) & 0xf, /* Opcode */
(first >> 10) & 1, /* AA */
(first >> 9) & 1, /* TC */
(first >> 8) & 1, /* RD */
(first >> 7) & 1, /* RA */
(first >> 4) & 7, /* Z */
first & 0xf, /* RCODE */
qdcount, ancount, nscount, arcount);
for (; qdcount > 0; qdcount--) {
obuf_puts(&outbuf, "Question: ");
o += dump_name(packet+o);
obuf_putf(&outbuf, "{ QTYPE=}d{ QCLASS=}d{\n}", uint16_get_msb(packet+o), uint16_get_msb(packet+o+2));
o += 4;
}
obuf_flush(&outbuf);
return o;
}
static int make_response(unsigned char* buf, int offset, const struct dns_response* response)
{
int r;
uint16_pack_msb(response->ancount, buf+6);
uint16_pack_msb(response->nscount, buf+8);
uint16_pack_msb(response->arcount, buf+10);
for (r = 0; r < response->ancount + response->nscount + response->arcount; r++) {
const struct dns_response_rr* rr = &response->rr[r];
memcpy((char*)buf+offset, rr->name, rr->namelen);
offset += rr->namelen;
uint16_pack_msb(rr->type, buf+offset);
uint16_pack_msb(rr->class, buf+offset+2);
uint32_pack_msb(rr->ttl, buf+offset+4);
uint16_pack_msb(rr->rdatalen, buf+offset+8);
offset += 10;
memcpy((char*)buf+offset, rr->rdata, rr->rdatalen);
offset += rr->rdatalen;
}
return offset;
}
static void start_dns_responder(const struct dns_response* response, int count)
{
int sockfd;
ipv4addr addr;
ipv4port port;
unsigned char buf[512];
long r;
long offset;
if ((sockfd = socket_udp()) < 0)
die1sys(111, "Could not create DNS socket");
ipv4_scan("127.0.0.1", &addr);
if (!socket_bind4(sockfd, &addr, 0))
die1sys(111, "Could not bind DNS socket");
if (!socket_getaddr4(sockfd, &addr, &port))
die1sys(111, "Could not get DNS socket address");
if (0 && !socket_listen(sockfd, 0))
die1sys(111, "Could not listen to DNS socket");
dns_use_port = port;
buf[fmt_sdec((char*)buf, port)] = 0;
if (setenv("DNSCACHEIP", "127.0.0.1", 1) < 0
|| setenv("DNSCACHEPORT", (char*)buf, 1) < 0)
die1sys(111, "Could not set up DNS responder environment variables");
if ((dns_responder_pid = fork()) < 0)
die1sys(111, "Could not fork");
if (dns_responder_pid != 0)
return;
for (; count > 0; ++response, --count) {
if ((r = socket_recv4(sockfd, (char*)buf, sizeof buf, &addr, &port)) < 0)
die1sys(111, "Could not receive DNS packet");
offset = dump_request(buf, r);
offset = make_response(buf, offset, response);
if ((r = socket_send4(sockfd, (char*)buf, offset, &addr, port)) != offset)
die1sys(111, "Could not send DNS response");
}
exit(0);
}
static void wait_dns_responder(void)
{
waitpid(dns_responder_pid, NULL, 0);
}
void do_dns_test(const char* fqdn, int (*fn)(struct dns_result*, const char*))
{
struct dns_result out = {0};
debugfn(fn(&out, fqdn));
obuf_putf(&outbuf, "s{: count=}d{\n}", fqdn, out.count);
dump_rrs(out.count, &out.rr);
}
void do_dns_respond_tests(int (*fn)(struct dns_result*, const char*),
const char** fqdn,
const struct dns_response* responses, int count)
{
start_dns_responder(responses, count);
while (*fqdn) {
do_dns_test(*fqdn++, fn);
obuf_flush(&outbuf);
}
wait_dns_responder();
}
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