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#include "links.h"
struct dnsentry {
struct dnsentry *next;
struct dnsentry *prev;
ttime get_time;
ip addr;
char name[1];
};
#define DNS_PIPE_BUFFER 32
struct dnsquery {
void (*fn)(void *, int);
void *data;
void (*xfn)(struct dnsquery *, int);
int h;
struct dnsquery **s;
ip *addr;
char name[1];
};
struct list_head dns_cache = {&dns_cache, &dns_cache};
int do_real_lookup(unsigned char *name, ip *host)
{
struct hostent *hst;
if (!(hst = gethostbyname(name))) return -1;
memcpy(host, hst->h_addr_list[0], sizeof(ip));
return 0;
}
void lookup_fn(unsigned char *name, int h)
{
ip host;
if (do_real_lookup(name, &host)) return;
write(h, &host, sizeof(ip));
}
void end_real_lookup(struct dnsquery *q)
{
int r = 1;
if (read(q->h, q->addr, sizeof(ip)) != sizeof(ip)) goto end;
r = 0;
end:
set_handlers(q->h, NULL, NULL, NULL, NULL);
close(q->h);
q->xfn(q, r);
}
void failed_real_lookup(struct dnsquery *q)
{
set_handlers(q->h, NULL, NULL, NULL, NULL);
close(q->h);
q->xfn(q, -1);
}
void do_lookup(struct dnsquery *q, void (*fn)(struct dnsquery *, int))
{
struct hostent *host;
#ifndef NO_ASYNC_LOOKUP
if (!async_lookup) {
#endif
int r;
sync_lookup:
r = do_real_lookup(q->name, q->addr);
fn(q, r);
#ifndef NO_ASYNC_LOOKUP
} else {
if ((q->h = start_thread((void (*)(void *, int))lookup_fn, q->name, strlen(q->name) + 1)) == -1) goto sync_lookup;
q->xfn = fn;
set_handlers(q->h, (void (*)(void *))end_real_lookup, NULL, (void (*)(void *))failed_real_lookup, q);
}
#endif
}
int find_in_dns_cache(char *name, struct dnsentry **dnsentry)
{
struct dnsentry *e;
foreach(e, dns_cache)
if (!strcasecmp(e->name, name)) {
del_from_list(e);
add_to_list(dns_cache, e);
*dnsentry=e;
return 0;
}
return -1;
}
void end_dns_lookup(struct dnsquery *q, int a)
{
struct dnsentry *dnsentry;
void (*fn)(void *, int);
void *data;
if (!find_in_dns_cache(q->name, &dnsentry)) {
if (a) {
memcpy(q->addr, &dnsentry->addr, sizeof(ip));
a = 0;
goto e;
}
del_from_list(dnsentry);
mem_free(dnsentry);
}
if (a) goto e;
if ((dnsentry = mem_alloc(sizeof(struct dnsentry) + strlen(q->name) + 1))) {
strcpy(dnsentry->name, q->name);
memcpy(&dnsentry->addr, q->addr, sizeof(ip));
dnsentry->get_time = get_time();
add_to_list(dns_cache, dnsentry);
}
e:
if (q->s) *q->s = NULL;
fn = q->fn;
data = q->data;
mem_free(q);
fn(data, a);
}
void find_host_no_cache(unsigned char *name, ip *addr, void **qp, void (*fn)(void *, int), void *data)
{
struct dnsquery *q;
if (!(q = mem_alloc(sizeof(struct dnsquery) + strlen(name) + 1))) {
fn(data, -1);
return;
}
q->fn = fn;
q->data = data;
q->s = (struct dnsquery **)qp;
q->addr = addr;
strcpy(q->name, name);
if (qp) *(struct dnsquery **) qp = q;
do_lookup(q, end_dns_lookup);
}
void find_host(unsigned char *name, ip *addr, void **qp, void (*fn)(void *, int), void *data)
{
struct dnsentry *dnsentry;
if (qp) *qp = NULL;
if (!find_in_dns_cache(name, &dnsentry)) {
if (dnsentry->get_time + DNS_TIMEOUT < get_time()) goto timeout;
memcpy(addr, &dnsentry->addr, sizeof(ip));
fn(data, 0);
return;
}
timeout:
find_host_no_cache(name, addr, qp, fn, data);
}
void kill_dns_request(void **qp)
{
struct dnsquery *q = *qp;
set_handlers(q->h, NULL, NULL, NULL, NULL);
close(q->h);
mem_free(q);
*qp = NULL;
}
void shrink_dns_cache(int u)
{
struct dnsentry *d, *e;
foreach(d, dns_cache) if (u || d->get_time + DNS_TIMEOUT < get_time()) {
e = d;
d = d->prev;
del_from_list(e);
mem_free(e);
}
}
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