int
mdns_serve(struct mdns_ctx *ctx, mdns_stop_func stop, void *p_cookie)
{
int r;
struct mdns_svc *svc;
struct mdns_hdr qhdr = {0};
struct rr_entry *question;
if (setsockopt(ctx->sock, SOL_SOCKET, SO_RCVTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
return (MDNS_NETERR);
if (setsockopt(ctx->sock, SOL_SOCKET, SO_SNDTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
return (MDNS_NETERR);
for (; stop(p_cookie) == false;) {
r = mdns_recv(ctx, &qhdr, &question);
if (r == MDNS_NETERR)
continue;
if (qhdr.num_qn == 0)
goto again;
for (svc = ctx->services; svc; svc = svc->next) {
if (!strrcmp(question->name, svc->name) && question->type == svc->type) {
svc->callback(svc->p_cookie, r, question);
goto again;
}
}
again:
mdns_free(question);
}
return (0);
}
int
mdns_recv(const struct mdns_ctx *ctx, struct mdns_hdr *hdr, struct rr_entry **entries)
{
uint8_t buf[MDNS_PKT_MAXSZ];
size_t num_entry, n;
ssize_t length;
struct rr_entry *entry;
*entries = NULL;
if ((length = recv(ctx->sock, (char *) buf, sizeof(buf), 0)) < 0)
return (MDNS_NETERR);
const uint8_t *ptr = mdns_read_header(buf, length, hdr);
num_entry = hdr->num_qn + hdr->num_ans_rr + hdr->num_add_rr;
for (size_t i = 0; i < num_entry; ++i) {
entry = calloc(1, sizeof(struct rr_entry));
if (!entry)
goto err;
ptr = rr_read(ptr, &n, buf, entry, (hdr->flags & FLAG_QR) > 0);
if (!ptr) {
errno = ENOSPC;
goto err;
}
entry->next = *entries;
*entries = entry;
}
if (*entries == NULL) {
return (MDNS_STDERR);
}
return (0);
err:
mdns_free(*entries);
return (MDNS_STDERR);
}
int
mdns_listen(const struct mdns_ctx *ctx, const char *name, enum rr_type type, unsigned int interval,
mdns_stop_func stop, mdns_callback callback, void *p_cookie)
{
int r;
time_t t1, t2;
struct mdns_hdr hdr = {0};
struct rr_entry qn = {0};
hdr.num_qn = 1;
qn.name = (char *)name;
qn.type = type;
qn.rr_class = RR_IN;
if (setsockopt(ctx->sock, SOL_SOCKET, SO_RCVTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
return (MDNS_NETERR);
if (setsockopt(ctx->sock, SOL_SOCKET, SO_SNDTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
return (MDNS_NETERR);
if ((r = mdns_send(ctx, &hdr, &qn)) < 0) // send a first probe request
callback(p_cookie, r, NULL);
for (t1 = t2 = time(NULL); stop(p_cookie) == false; t2 = time(NULL)) {
struct mdns_hdr ahdr = {0};
struct rr_entry *entries;
if (difftime(t2, t1) >= (double) interval) {
if ((r = mdns_send(ctx, &hdr, &qn)) < 0) {
callback(p_cookie, r, NULL);
continue;
}
t1 = t2;
}
r = mdns_recv(ctx, &ahdr, &entries);
if (r == MDNS_NETERR && os_wouldblock())
continue;
if (ahdr.num_ans_rr + ahdr.num_add_rr == 0)
continue;
for (struct rr_entry *entry = entries; entry; entry = entry->next) {
if (!strrcmp(entry->name, name)) {
callback(p_cookie, r, entries);
break;
}
}
mdns_free(entries);
}
return (0);
}
int
mdns_listen(const struct mdns_ctx *ctx, const char *const names[],
unsigned int nb_names, enum rr_type type, unsigned int interval,
mdns_stop_func stop, mdns_callback callback, void *p_cookie)
{
int r;
time_t t1, t2;
struct mdns_hdr hdr = {0};
struct rr_entry *qns = malloc(nb_names * sizeof(struct rr_entry));
if (qns == NULL)
return (MDNS_STDERR);
memset(qns, 0, nb_names * sizeof(struct rr_entry));
hdr.num_qn = nb_names;
for (unsigned int i = 0; i < nb_names; ++i)
{
qns[i].name = (char *)names[i];
qns[i].type = type;
qns[i].rr_class = RR_IN;
if (i + 1 < nb_names)
qns[i].next = &qns[i+1];
}
if (setsockopt(ctx->sock, SOL_SOCKET, SO_RCVTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
{
free(qns);
return (MDNS_NETERR);
}
if (setsockopt(ctx->sock, SOL_SOCKET, SO_SNDTIMEO, (const void *) &os_deadline, sizeof(os_deadline)) < 0)
{
free(qns);
return (MDNS_NETERR);
}
if ((r = mdns_entries_send(ctx, &hdr, qns)) < 0) // send a first probe request
callback(p_cookie, r, NULL);
for (t1 = t2 = time(NULL); stop(p_cookie) == false; t2 = time(NULL)) {
struct mdns_hdr ahdr = {0};
struct rr_entry *entries;
if (difftime(t2, t1) >= (double) interval) {
if ((r = mdns_entries_send(ctx, &hdr, qns)) < 0) {
callback(p_cookie, r, NULL);
continue;
}
t1 = t2;
}
r = mdns_recv(ctx, &ahdr, &entries);
if (r == MDNS_NETERR && os_wouldblock())
{
mdns_free(entries);
continue;
}
if (ahdr.num_ans_rr + ahdr.num_add_rr == 0)
{
mdns_free(entries);
continue;
}
for (struct rr_entry *entry = entries; entry; entry = entry->next) {
for (unsigned int i = 0; i < nb_names; ++i) {
if (!strrcmp(entry->name, names[i])) {
callback(p_cookie, r, entries);
break;
}
}
}
mdns_free(entries);
}
free(qns);
return (0);
}
