#include <netinet/tcp.h>

#include "alloc-util.h"

#include "fd-util.h"

#include "io-util.h"

#include "missing.h"

#include "resolved-dns-stream.h"

#define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC)

#define DNS_STREAMS_MAX 128

static void dns_stream_stop(DnsStream *s) {

assert(s);

s->io_event_source = sd_event_source_unref(s->io_event_source);

s->timeout_event_source = sd_event_source_unref(s->timeout_event_source);

s->fd = safe_close(s->fd);

}

static int dns_stream_update_io(DnsStream *s) {

int f = 0;

assert(s);

if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size)

f |= EPOLLOUT;

if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size)

f |= EPOLLIN;

return sd_event_source_set_io_events(s->io_event_source, f);

}

static int dns_stream_complete(DnsStream *s, int error) {

assert(s);

dns_stream_stop(s);

if (s->complete)

s->complete(s, error);

else

dns_stream_free(s);

return 0;

}

static int dns_stream_identify(DnsStream *s) {

union {

struct cmsghdr header; /* For alignment */

uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))

+ EXTRA_CMSG_SPACE /* kernel appears to require extra space */];

} control;

struct msghdr mh = {};

struct cmsghdr *cmsg;

socklen_t sl;

int r;

assert(s);

if (s->identified)

return 0;

/* Query the local side */

s->local_salen = sizeof(s->local);

r = getsockname(s->fd, &s->local.sa, &s->local_salen);

if (r < 0)

return -errno;

if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0)

s->ifindex = s->local.in6.sin6_scope_id;

/* Query the remote side */

s->peer_salen = sizeof(s->peer);

r = getpeername(s->fd, &s->peer.sa, &s->peer_salen);

if (r < 0)

return -errno;

if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0)

s->ifindex = s->peer.in6.sin6_scope_id;

/* Check consistency */

assert(s->peer.sa.sa_family == s->local.sa.sa_family);

assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6));

/* Query connection meta information */

sl = sizeof(control);

if (s->peer.sa.sa_family == AF_INET) {

r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl);

if (r < 0)

return -errno;

} else if (s->peer.sa.sa_family == AF_INET6) {

r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl);

if (r < 0)

return -errno;

} else

return -EAFNOSUPPORT;

mh.msg_control = &control;

mh.msg_controllen = sl;

CMSG_FOREACH(cmsg, &mh) {

if (cmsg->cmsg_level == IPPROTO_IPV6) {

assert(s->peer.sa.sa_family == AF_INET6);

switch (cmsg->cmsg_type) {

case IPV6_PKTINFO: {

struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);

if (s->ifindex <= 0)

s->ifindex = i->ipi6_ifindex;

break;

}

case IPV6_HOPLIMIT:

s->ttl = *(int *) CMSG_DATA(cmsg);

break;

}

} else if (cmsg->cmsg_level == IPPROTO_IP) {

assert(s->peer.sa.sa_family == AF_INET);

switch (cmsg->cmsg_type) {

case IP_PKTINFO: {

struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);

if (s->ifindex <= 0)

s->ifindex = i->ipi_ifindex;

break;

}

case IP_TTL:

s->ttl = *(int *) CMSG_DATA(cmsg);

break;

}

}

}

/* The Linux kernel sets the interface index to the loopback

if (s->ifindex == LOOPBACK_IFINDEX)

s->ifindex = 0;

/* If we don't know the interface index still, we look for the

if (s->ifindex <= 0)

s->ifindex = manager_find_ifindex(s->manager, s->local.sa.sa_family, s->local.sa.sa_family == AF_INET ? (union in_addr_union*) &s->local.in.sin_addr : (union in_addr_union*) &s->local.in6.sin6_addr);

if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) {

uint32_t ifindex = htobe32(s->ifindex);

/* Make sure all packets for this connection are sent on the same interface */

if (s->local.sa.sa_family == AF_INET) {

r = setsockopt(s->fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex));

if (r < 0)

log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF: %m");

} else if (s->local.sa.sa_family == AF_INET6) {

r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex));

if (r < 0)

log_debug_errno(errno, "Failed to invoke IPV6_UNICAST_IF: %m");

}

}

s->identified = true;

return 0;

}

static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) {

DnsStream *s = userdata;

assert(s);

return dns_stream_complete(s, ETIMEDOUT);

}

static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) {

DnsStream *s = userdata;

int r;

assert(s);

r = dns_stream_identify(s);

if (r < 0)

return dns_stream_complete(s, -r);

if ((revents & EPOLLOUT) &&

s->write_packet &&

s->n_written < sizeof(s->write_size) + s->write_packet->size) {

struct iovec iov[2];

ssize_t ss;

iov[0].iov_base = &s->write_size;

iov[0].iov_len = sizeof(s->write_size);

iov[1].iov_base = DNS_PACKET_DATA(s->write_packet);

iov[1].iov_len = s->write_packet->size;

IOVEC_INCREMENT(iov, 2, s->n_written);

ss = writev(fd, iov, 2);

if (ss < 0) {

if (errno != EINTR && errno != EAGAIN)

return dns_stream_complete(s, errno);

} else

s->n_written += ss;

/* Are we done? If so, disable the event source for EPOLLOUT */

if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) {

r = dns_stream_update_io(s);

if (r < 0)

return dns_stream_complete(s, -r);

}

}

if ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&

(!s->read_packet ||

s->n_read < sizeof(s->read_size) + s->read_packet->size)) {

if (s->n_read < sizeof(s->read_size)) {

ssize_t ss;

ss = read(fd, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read);

if (ss < 0) {

if (errno != EINTR && errno != EAGAIN)

return dns_stream_complete(s, errno);

} else if (ss == 0)

return dns_stream_complete(s, ECONNRESET);

else

s->n_read += ss;

}

if (s->n_read >= sizeof(s->read_size)) {

if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE)

return dns_stream_complete(s, EBADMSG);

if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) {

ssize_t ss;

if (!s->read_packet) {

r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size));

if (r < 0)

return dns_stream_complete(s, -r);

s->read_packet->size = be16toh(s->read_size);

s->read_packet->ipproto = IPPROTO_TCP;

s->read_packet->family = s->peer.sa.sa_family;

s->read_packet->ttl = s->ttl;

s->read_packet->ifindex = s->ifindex;

if (s->read_packet->family == AF_INET) {

s->read_packet->sender.in = s->peer.in.sin_addr;

s->read_packet->sender_port = be16toh(s->peer.in.sin_port);

s->read_packet->destination.in = s->local.in.sin_addr;

s->read_packet->destination_port = be16toh(s->local.in.sin_port);

} else {

assert(s->read_packet->family == AF_INET6);

s->read_packet->sender.in6 = s->peer.in6.sin6_addr;

s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port);

s->read_packet->destination.in6 = s->local.in6.sin6_addr;

s->read_packet->destination_port = be16toh(s->local.in6.sin6_port);

if (s->read_packet->ifindex == 0)

s->read_packet->ifindex = s->peer.in6.sin6_scope_id;

if (s->read_packet->ifindex == 0)

s->read_packet->ifindex = s->local.in6.sin6_scope_id;

}

}

ss = read(fd,

(uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size),

sizeof(s->read_size) + be16toh(s->read_size) - s->n_read);

if (ss < 0) {

if (errno != EINTR && errno != EAGAIN)

return dns_stream_complete(s, errno);

} else if (ss == 0)

return dns_stream_complete(s, ECONNRESET);

else

s->n_read += ss;

}

/* Are we done? If so, disable the event source for EPOLLIN */

if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) {

r = dns_stream_update_io(s);

if (r < 0)

return dns_stream_complete(s, -r);

/* If there's a packet handler

if (s->on_packet)

return s->on_packet(s);

}

}

}

if ((s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) &&

(s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size))

return dns_stream_complete(s, 0);

return 0;

}

DnsStream *dns_stream_free(DnsStream *s) {

if (!s)

return NULL;

dns_stream_stop(s);

if (s->manager) {

LIST_REMOVE(streams, s->manager->dns_streams, s);

s->manager->n_dns_streams--;

}

dns_packet_unref(s->write_packet);

dns_packet_unref(s->read_packet);

free(s);

return 0;

}

DEFINE_TRIVIAL_CLEANUP_FUNC(DnsStream*, dns_stream_free);

int dns_stream_new(Manager *m, DnsStream **ret, DnsProtocol protocol, int fd) {

_cleanup_(dns_stream_freep) DnsStream *s = NULL;

int r;

assert(m);

assert(fd >= 0);

if (m->n_dns_streams > DNS_STREAMS_MAX)

return -EBUSY;

s = new0(DnsStream, 1);

if (!s)

return -ENOMEM;

s->fd = -1;

s->protocol = protocol;

r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s);

if (r < 0)

return r;

(void) sd_event_source_set_description(s->io_event_source, "dns-stream-io");

r = sd_event_add_time(

m->event,

&s->timeout_event_source,

clock_boottime_or_monotonic(),

now(clock_boottime_or_monotonic()) + DNS_STREAM_TIMEOUT_USEC, 0,

on_stream_timeout, s);

if (r < 0)

return r;

(void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout");

LIST_PREPEND(streams, m->dns_streams, s);

s->manager = m;

s->fd = fd;

m->n_dns_streams++;

*ret = s;

s = NULL;

return 0;

}

int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {

assert(s);

if (s->write_packet)

return -EBUSY;

s->write_packet = dns_packet_ref(p);

s->write_size = htobe16(p->size);

s->n_written = 0;

return dns_stream_update_io(s);

}