#include <linux/rtnetlink.h>
#endif
+#include "mdns.h"
#include "meshlink_internal.h"
#include "event.h"
#include "discovery.h"
#include "netutl.h"
#include "node.h"
#include "connection.h"
+#include "utils.h"
#include "xalloc.h"
#define MESHLINK_MDNS_SERVICE_TYPE "_%s._tcp"
#define MESHLINK_MDNS_NAME_KEY "name"
#define MESHLINK_MDNS_FINGERPRINT_KEY "fingerprint"
+static const sockaddr_t mdns_address_ipv4 = {
+ .in.sin_family = AF_INET,
+ .in.sin_addr.s_addr = 0xfb0000e0,
+ .in.sin_port = 0xe914,
+};
+
+static const sockaddr_t mdns_address_ipv6 = {
+ .in6.sin6_family = AF_INET6,
+ .in6.sin6_addr.s6_addr[0x0] = 0xfd,
+ .in6.sin6_addr.s6_addr[0x1] = 0x02,
+ .in6.sin6_addr.s6_addr[0xf] = 0xfb,
+ .in6.sin6_port = 0xe914,
+};
+
static void generate_rand_string(meshlink_handle_t *mesh, char *buffer, size_t size) {
assert(size);
abort();
}
+#if 1
+ // bypass Catta
+ pthread_cond_broadcast(&mesh->discovery_cond);
+ pthread_mutex_unlock(&mesh->discovery_mutex);
+ return NULL;
+#endif
+
// handle catta logs
catta_set_log_function(discovery_log_cb);
return sockaddrcmp_noport(&a->address, &b->address);
}
+static void send_mdns_packet_ipv4(meshlink_handle_t *mesh, int fd, int index, const sockaddr_t *src, const sockaddr_t *dest, void *data, size_t len) {
+#ifdef IP_PKTINFO
+ struct iovec iov = {
+ .iov_base = data,
+ .iov_len = len,
+ };
+
+ struct in_pktinfo pkti = {
+ .ipi_ifindex = index,
+ .ipi_addr = src->in.sin_addr,
+ };
+
+ union {
+ char buf[CMSG_SPACE(sizeof(pkti))];
+ struct cmsghdr align;
+ } u;
+
+ struct msghdr msg = {
+ .msg_name = (struct sockaddr *) &dest->sa,
+ .msg_namelen = SALEN(dest->sa),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = u.buf,
+ .msg_controllen = sizeof(u.buf),
+ };
+
+
+ struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = IPPROTO_IP;
+ cmsg->cmsg_type = IP_PKTINFO;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
+ memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
+
+ // Send the packet
+ ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
+#else
+ // Send the packet
+ ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
+#endif
+
+ if(result <= 0) {
+ logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
+ }
+}
+
+static void send_mdns_packet_ipv6(meshlink_handle_t *mesh, int fd, int index, const sockaddr_t *src, const sockaddr_t *dest, void *data, size_t len) {
+#ifdef IPV6_PKTINFO
+ struct iovec iov = {
+ .iov_base = data,
+ .iov_len = len,
+ };
+
+ struct in6_pktinfo pkti = {
+ .ipi6_ifindex = index,
+ .ipi6_addr = src->in6.sin6_addr,
+ };
+
+ union {
+ char buf[CMSG_SPACE(sizeof(pkti))];
+ struct cmsghdr align;
+ } u;
+
+ memset(&u, 0, sizeof u);
+
+ struct msghdr msg = {
+ .msg_name = (struct sockaddr *) &dest->sa,
+ .msg_namelen = SALEN(dest->sa),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = u.buf,
+ .msg_controllen = CMSG_LEN(sizeof(pkti)),
+ };
+
+ struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = IPPROTO_IPV6;
+ cmsg->cmsg_type = IPV6_PKTINFO;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
+ memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
+
+ // Send the packet
+ ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
+#else
+ // Send the packet
+ ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
+#endif
+
+ if(result <= 0) {
+ logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
+ }
+}
+
static void send_mdns_packet(meshlink_handle_t *mesh, const discovery_address_t *addr) {
char *host = NULL, *port = NULL;
sockaddr2str(&addr->address, &host, &port);
fprintf(stderr, "Sending on iface %d %s port %s\n", addr->index, host, port);
free(host);
free(port);
+
+ // Configure the socket to send the packet to the right interface
+ int fd;
+ uint8_t data[1024];
+ char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
+ const char *keys[] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
+ const char *values[] = {mesh->name, fingerprint};
+ size_t size = prepare_packet(data, sizeof data, fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, values);
+
+ switch(addr->address.sa.sa_family) {
+ case AF_INET:
+ fd = mesh->discovery_sockets[0].fd;
+#ifdef IP_MULTICAST_IF
+ {
+ struct ip_mreqn mreq = {
+ .imr_address = addr->address.in.sin_addr,
+ .imr_ifindex = addr->index,
+ };
+
+ if(setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) != 0) {
+ logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv4 socket");
+ return;
+ }
+ }
+
+#endif
+
+ send_mdns_packet_ipv4(mesh, fd, addr->index, &addr->address, &mdns_address_ipv4, data, size);
+ break;
+
+ case AF_INET6:
+ fd = mesh->discovery_sockets[1].fd;
+#ifdef IPV6_MULTICAST_IF
+
+ if(setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &addr->index, sizeof(addr->index)) != 0) {
+ logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv6 socket");
+ return;
+ }
+
+#endif
+
+ send_mdns_packet_ipv6(mesh, fd, addr->index, &addr->address, &mdns_address_ipv6, data, size);
+ break;
+
+ default:
+ break;
+ }
+}
+
+static void mdns_io_handler(event_loop_t *loop, void *data, int flags) {
+ (void)flags;
+ meshlink_handle_t *mesh = loop->data;
+ io_t *io = data;
+ uint8_t buf[1024];
+ sockaddr_t sa;
+ socklen_t sl = sizeof(sa);
+
+ ssize_t len = recvfrom(io->fd, buf, sizeof(buf), MSG_DONTWAIT, &sa.sa, &sl);
+
+ if(len == -1) {
+ if(!sockwouldblock(errno)) {
+ fprintf(stderr, "Error reading from discovery socket: %s\n", strerror(errno));
+ logger(mesh, MESHLINK_ERROR, "Error reading from mDNS discovery socket: %s", strerror(errno));
+ io_set(loop, io, 0);
+ }
+
+ return;
+ }
+
+ char *name = NULL;
+ uint16_t port = 0;
+ const char *keys[2] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
+ char *values[2] = {NULL, NULL};
+
+ if(parse_packet(buf, len, &name, mesh->appname, "tcp", &port, 2, keys, values)) {
+ node_t *n = (node_t *)meshlink_get_node(mesh, values[0]);
+
+ if(n) {
+ logger(mesh, MESHLINK_INFO, "Node %s is part of the mesh network.\n", n->name);
+
+ switch(sa.sa.sa_family) {
+ case AF_INET:
+ sa.in.sin_port = port;
+ break;
+
+ case AF_INET6:
+ sa.in6.sin6_port = port;
+ break;
+
+ default:
+ logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", n->name);
+ sa.sa.sa_family = AF_UNKNOWN;
+ break;
+ }
+
+ if(sa.sa.sa_family != AF_UNKNOWN) {
+ n->catta_address = sa;
+ node_add_recent_address(mesh, n, &sa);
+
+ connection_t *c = n->connection;
+
+ if(c && c->outgoing && !c->status.active) {
+ c->outgoing->timeout = 0;
+
+ if(c->outgoing->ev.cb) {
+ timeout_set(&mesh->loop, &c->outgoing->ev, &(struct timespec) {
+ 0, 0
+ });
+ }
+
+ c->last_ping_time = -3600;
+ }
+ }
+ } else {
+ logger(mesh, MESHLINK_WARNING, "Node %s is not part of the mesh network.\n", values[0]);
+ }
+
+ fprintf(stderr, "Got packet from %s port %u\n%s=%s\n%s=%s\n", name, port, keys[0], values[0], keys[1], values[1]);
+ }
+
+ free(name);
+
+ for(int i = 0; i < 2; i++) {
+ free(values[i]);
+ }
}
static void iface_up(meshlink_handle_t *mesh, int index) {
mesh->discovery_ifaces[mesh->discovery_iface_count - 1] = index;
qsort(mesh->discovery_ifaces, mesh->discovery_iface_count, sizeof(*p), iface_compare);
- for(int i = 0; i < mesh->discovery_iface_count; i++) {
- fprintf(stderr, "%d", mesh->discovery_ifaces[i]);
- }
+ // Add multicast membership
+ struct ip_mreqn mreq4 = {
+ .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
+ .imr_ifindex = index,
+ };
+ setsockopt(mesh->discovery_sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
+ setsockopt(mesh->discovery_sockets[0].fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq4, sizeof(mreq4));
+
+ struct ipv6_mreq mreq6 = {
+ .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
+ .ipv6mr_interface = index,
+ };
+ setsockopt(mesh->discovery_sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
+ setsockopt(mesh->discovery_sockets[1].fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6));
// Send an announcement for all addresses associated with this interface
for(int i = 0; i < mesh->discovery_address_count; i++) {
send_mdns_packet(mesh, &mesh->discovery_addresses[i]);
}
}
+
+ handle_network_change(mesh, true);
}
static void iface_down(meshlink_handle_t *const mesh, int index) {
- int *p = bsearch(&index, mesh->discovery_ifaces, mesh->discovery_iface_count, sizeof(int), iface_compare);
+ int *p = bsearch(&index, mesh->discovery_ifaces, mesh->discovery_iface_count, sizeof(*p), iface_compare);
if(!p) {
return;
}
+ // Drop multicast membership
+ struct ip_mreqn mreq4 = {
+ .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
+ .imr_ifindex = index,
+ };
+ setsockopt(mesh->discovery_sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
+
+ struct ipv6_mreq mreq6 = {
+ .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
+ .ipv6mr_interface = index,
+ };
+ setsockopt(mesh->discovery_sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
+
fprintf(stderr, "iface %d down\n", index);
- memmove(p, p + 1, --mesh->discovery_iface_count * sizeof(*p));
+ memmove(p, p + 1, (mesh->discovery_ifaces + --mesh->discovery_iface_count - p) * sizeof(*p));
+
+ handle_network_change(mesh, mesh->discovery_iface_count);
}
static void addr_add(meshlink_handle_t *mesh, const discovery_address_t *addr) {
- discovery_address_t *p = bsearch(addr, mesh->discovery_addresses, mesh->discovery_address_count, sizeof(int), address_compare);
+ discovery_address_t *p = bsearch(addr, mesh->discovery_addresses, mesh->discovery_address_count, sizeof(*p), address_compare);
if(p) {
return;
}
- bool up = bsearch(&addr->index, mesh->discovery_ifaces, mesh->discovery_iface_count, sizeof(*p), iface_compare);
+ bool up = bsearch(&addr->index, mesh->discovery_ifaces, mesh->discovery_iface_count, sizeof(int), iface_compare);
char *host = NULL, *port = NULL;
sockaddr2str(&addr->address, &host, &port);
fprintf(stderr, "address %d %s port %s up %d\n", addr->index, host, port, up);
mesh->discovery_addresses = xrealloc(mesh->discovery_addresses, ++mesh->discovery_address_count * sizeof(*p));
mesh->discovery_addresses[mesh->discovery_address_count - 1] = *addr;
- qsort(mesh->discovery_addresses, mesh->discovery_address_count, sizeof(*p), address_compare);
-
mesh->discovery_addresses[mesh->discovery_address_count - 1].up = up;
if(up) {
send_mdns_packet(mesh, &mesh->discovery_addresses[mesh->discovery_address_count - 1]);
}
+
+ qsort(mesh->discovery_addresses, mesh->discovery_address_count, sizeof(*p), address_compare);
}
static void addr_del(meshlink_handle_t *mesh, const discovery_address_t *addr) {
free(host);
free(port);
- memmove(p, p + 1, --mesh->discovery_address_count * sizeof(*p));
+ memmove(p, p + 1, (mesh->discovery_addresses + --mesh->discovery_address_count - p) * sizeof(*p));
}
#if defined(__linux)
mesh->discovery_threadstarted = true;
+ // Set up multicast sockets for mDNS
+ static const int one = 1;
+ static const int ttl = 255;
+
+ int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+ sockaddr_t sa4 = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = ntohs(5353),
+ };
+ setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+ bind(fd, &sa4.sa, SALEN(sa4.sa));
+ setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
+ setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
+ io_add(&mesh->loop, &mesh->discovery_sockets[0], mdns_io_handler, &mesh->discovery_sockets[0], fd, IO_READ);
+
+ sockaddr_t sa6 = {
+ .in6.sin6_family = AF_INET6,
+ .in6.sin6_port = ntohs(5353),
+ };
+ fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+ setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+ setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
+ bind(fd, &sa6.sa, SALEN(sa6.sa));
+ setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
+ setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
+ io_add(&mesh->loop, &mesh->discovery_sockets[1], mdns_io_handler, &mesh->discovery_sockets[1], fd, IO_READ);
+
#if defined(__linux)
int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
io_del(&mesh->loop, &mesh->pfroute_io);
}
+ for(int i = 0; i < 2; i++) {
+ if(mesh->discovery_sockets[i].cb) {
+ close(mesh->discovery_sockets[i].fd);
+ io_del(&mesh->loop, &mesh->discovery_sockets[i]);
+ }
+ }
+
// Shut down
if(mesh->catta_poll) {
catta_simple_poll_quit(mesh->catta_poll);
--- /dev/null
+// SPDX-FileCopyrightText: 2020 Guus Sliepen <guus@meshlink.io>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "system.h"
+
+#include <stddef.h>
+
+#include "mdns.h"
+#include "xalloc.h"
+
+// Creating a buffer
+
+typedef struct {
+ uint8_t *ptr;
+ ptrdiff_t len;
+} buf_t;
+
+static void buf_add(buf_t *buf, const void *data, uint32_t len) {
+ if(buf->len >= len) {
+ memcpy(buf->ptr, data, len);
+ buf->ptr += len;
+ buf->len -= len;
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_add_uint8(buf_t *buf, uint8_t val) {
+ if(buf->len >= 1) {
+ buf->ptr[0] = val;
+ buf->ptr++;
+ buf->len--;
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_add_uint16(buf_t *buf, uint16_t val) {
+ uint16_t nval = htons(val);
+ buf_add(buf, &nval, sizeof(nval));
+}
+
+static void buf_add_uint32(buf_t *buf, uint32_t val) {
+ uint32_t nval = htonl(val);
+ buf_add(buf, &nval, sizeof(nval));
+}
+
+static void buf_add_label(buf_t *buf, const char *str) {
+ size_t len = strlen(str);
+
+ if(len < 256) {
+ buf_add_uint8(buf, len);
+ buf_add(buf, str, len);
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_add_ulabel(buf_t *buf, const char *str) {
+ size_t len = strlen(str);
+
+ if(len + 1 < 256) {
+ buf_add_uint8(buf, len + 1);
+ buf_add_uint8(buf, '_');
+ buf_add(buf, str, len);
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_add_kvp(buf_t *buf, const char *key, const char *val) {
+ size_t key_len = strlen(key);
+ size_t val_len = strlen(val);
+
+ if(key_len + val_len + 1 < 256) {
+ buf_add_uint8(buf, key_len + val_len + 1);
+ buf_add(buf, key, key_len);
+ buf_add_uint8(buf, '=');
+ buf_add(buf, val, val_len);
+ } else {
+ buf->len = -1;
+ }
+}
+
+static uint8_t *buf_len_start(buf_t *buf) {
+ if(buf->len < 2) {
+ buf->len = -1;
+ return NULL;
+ } else {
+ uint8_t *ptr = buf->ptr;
+ buf->ptr += 2;
+ buf->len -= 2;
+ return ptr;
+ }
+}
+
+static void buf_len_end(buf_t *buf, uint8_t *ptr) {
+ if(buf->len < 0) {
+ return;
+ }
+
+ uint16_t len = htons(buf->ptr - ptr - 2);
+ memcpy(ptr, &len, sizeof(len));
+}
+
+// Functions reading a buffer
+
+typedef struct {
+ const uint8_t *ptr;
+ ptrdiff_t len;
+} cbuf_t;
+
+static void buf_check(cbuf_t *buf, const void *data, uint32_t len) {
+ if(buf->len >= len && !memcmp(buf->ptr, data, len)) {
+ buf->ptr += len;
+ buf->len -= len;
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_check_uint8(cbuf_t *buf, uint8_t val) {
+ if(buf->len >= 1 && buf->ptr[0] == val) {
+ buf->ptr++;
+ buf->len--;
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_check_uint16(cbuf_t *buf, uint16_t val) {
+ uint16_t nval = htons(val);
+ buf_check(buf, &nval, sizeof(nval));
+}
+
+static uint16_t buf_get_uint16(cbuf_t *buf) {
+ uint16_t nval;
+
+ if(buf->len >= 2) {
+ memcpy(&nval, buf->ptr, 2);
+ buf->ptr += 2;
+ buf->len -= 2;
+ return ntohs(nval);
+ } else {
+ buf->len = -1;
+ return 0;
+ }
+}
+
+static void buf_check_uint32(cbuf_t *buf, uint32_t val) {
+ uint32_t nval = htonl(val);
+ buf_check(buf, &nval, sizeof(nval));
+}
+
+static void buf_check_label(cbuf_t *buf, const char *str) {
+ size_t len = strlen(str);
+
+ if(len < 256) {
+ buf_check_uint8(buf, len);
+ buf_check(buf, str, len);
+ } else {
+ buf->len = -1;
+ }
+}
+
+static char *buf_get_label(cbuf_t *buf) {
+ if(buf->len < 1) {
+ buf->len = -1;
+ return NULL;
+ }
+
+ uint8_t len = buf->ptr[0];
+ buf->ptr++;
+ buf->len--;
+
+ if(buf->len < len) {
+ buf->len = -1;
+ return NULL;
+ }
+
+ char *label = xmalloc(len + 1);
+ memcpy(label, buf->ptr, len);
+ label[len] = 0;
+ buf->ptr += len;
+ buf->len -= len;
+ return label;
+}
+
+static void buf_check_ulabel(cbuf_t *buf, const char *str) {
+ size_t len = strlen(str);
+
+ if(len + 1 < 256) {
+ buf_check_uint8(buf, len + 1);
+ buf_check_uint8(buf, '_');
+ buf_check(buf, str, len);
+ } else {
+ buf->len = -1;
+ }
+}
+
+static void buf_get_kvp(cbuf_t *buf, const char *key, char **val) {
+ char *kvp = buf_get_label(buf);
+
+ if(buf->len == -1) {
+ return;
+ }
+
+ char *split = strchr(kvp, '=');
+
+ if(!split) {
+ buf->len = -1;
+ return;
+ }
+
+ *split++ = 0;
+
+ if(strcmp(kvp, key)) {
+ buf->len = -1;
+ return;
+ }
+
+ memmove(kvp, split, strlen(split) + 1);
+ *val = kvp;
+}
+
+static const uint8_t *buf_check_len_start(cbuf_t *buf) {
+ if(buf->len < 2) {
+ buf->len = -1;
+ return NULL;
+ } else {
+ const uint8_t *ptr = buf->ptr;
+ buf->ptr += 2;
+ buf->len -= 2;
+ return ptr;
+ }
+}
+
+static void buf_check_len_end(cbuf_t *buf, const uint8_t *ptr) {
+ if(buf->len < 0) {
+ return;
+ }
+
+ uint16_t len = htons(buf->ptr - ptr - 2);
+
+ if(memcmp(ptr, &len, sizeof(len))) {
+ buf->len = -1;
+ }
+}
+
+size_t prepare_packet(void *vdata, size_t size, const char *name, const char *protocol, const char *transport, uint16_t port, int nkeys, const char **keys, const char **values) {
+ // Create the request/response packet right now
+ uint8_t *data = vdata;
+ buf_t buf = {data, size};
+
+ // Header
+ buf_add_uint16(&buf, 0); // TX ID
+ buf_add_uint16(&buf, 0); // flags
+ buf_add_uint16(&buf, 1); // 1 question
+ buf_add_uint16(&buf, 1); // 1 answer RR
+ buf_add_uint16(&buf, 0); // 0 authority RRs
+ buf_add_uint16(&buf, 2); // 1 additional RR
+
+ // Question section: _protocol._transport.local PTR IN
+ buf_add_ulabel(&buf, protocol);
+ buf_add_ulabel(&buf, transport);
+ uint16_t local = buf.ptr - data;
+ buf_add_label(&buf, "local");
+ buf_add_uint8(&buf, 0);
+ buf_add_uint16(&buf, 0xc); // PTR
+ buf_add_uint16(&buf, 0x1); // IN
+
+ // Answer section: _protocol._transport local PTR IN 3600 name._protocol._transport
+ buf_add_uint16(&buf, 0xc00c); // _protocol._transport.local
+ buf_add_uint16(&buf, 0xc); // PTR
+ buf_add_uint16(&buf, 0x1); // IN
+ buf_add_uint32(&buf, 3600); // TTL
+ uint8_t *len_ptr = buf_len_start(&buf);
+ uint16_t full_name = buf.ptr - data; // remember start of full name
+ buf_add_label(&buf, name);
+ buf_add_uint16(&buf, 0xc00c); // _protocol._transport.local
+ buf_len_end(&buf, len_ptr);
+
+ // Add the SRV record: name._protocol._transport.local SRV IN 120 0 0 port name.local
+ buf_add_uint16(&buf, 0xc000 | full_name);
+ buf_add_uint16(&buf, 0x21); // SRV
+ buf_add_uint16(&buf, 0x1); // IN
+ buf_add_uint32(&buf, 120); // TTL
+ len_ptr = buf_len_start(&buf);
+ buf_add_uint16(&buf, 0); // priority
+ buf_add_uint16(&buf, 0); // weight
+ buf_add_uint16(&buf, port); // port
+ buf_add_label(&buf, name);
+ buf_add_uint16(&buf, 0xc000 | local);
+ buf_len_end(&buf, len_ptr);
+
+ // Add the TXT records: name._protocol._transport.local TXT IN 3600 key=value...
+ buf_add_uint16(&buf, 0xc000 | full_name);
+ buf_add_uint16(&buf, 0x10); // TXT
+ buf_add_uint16(&buf, 0x1); // IN
+ buf_add_uint32(&buf, 3600); // TTL
+ len_ptr = buf_len_start(&buf);
+
+ for(int i = 0; i < nkeys; i++) {
+ buf_add_kvp(&buf, keys[i], values[i]);
+ }
+
+ buf_len_end(&buf, len_ptr);
+
+ // Done.
+ if(buf.len < 0) {
+ return 0;
+ } else {
+ return buf.ptr - data;
+ }
+}
+
+bool parse_packet(const void *vdata, size_t size, char **name, const char *protocol, const char *transport, uint16_t *port, int nkeys, const char **keys, char **values) {
+ const uint8_t *data = vdata;
+ cbuf_t buf = {data, size};
+
+ // Header
+ buf_check_uint16(&buf, 0); // TX ID
+ buf_check_uint16(&buf, 0); // flags
+ buf_check_uint16(&buf, 1); // 1 question
+ buf_check_uint16(&buf, 1); // 1 answer RR
+ buf_check_uint16(&buf, 0); // 0 authority RRs
+ buf_check_uint16(&buf, 2); // 1 checkitional RR
+
+ if(buf.len == -1) {
+ return false;
+ }
+
+ // Question section: _protocol._transport.local PTR IN
+ buf_check_ulabel(&buf, protocol);
+ buf_check_ulabel(&buf, transport);
+ uint16_t local = buf.ptr - data;
+ buf_check_label(&buf, "local");
+ buf_check_uint8(&buf, 0);
+ buf_check_uint16(&buf, 0xc); // PTR
+ buf_check_uint16(&buf, 0x1); // IN
+
+ if(buf.len == -1) {
+ return false;
+ }
+
+ // Answer section: _protocol._transport local PTR IN 3600 name._protocol._transport
+ buf_check_uint16(&buf, 0xc00c); // _protocol._transport.local
+ buf_check_uint16(&buf, 0xc); // PTR
+ buf_check_uint16(&buf, 0x1); // IN
+ buf_check_uint32(&buf, 3600); // TTL
+ const uint8_t *len_ptr = buf_check_len_start(&buf);
+ uint16_t full_name = buf.ptr - data; // remember start of full name
+ *name = buf_get_label(&buf);
+ buf_check_uint16(&buf, 0xc00c); // _protocol._transport.local
+ buf_check_len_end(&buf, len_ptr);
+
+ if(buf.len == -1) {
+ return false;
+ }
+
+ // Check the SRV record: name._protocol._transport.local SRV IN 120 0 0 port name.local
+ buf_check_uint16(&buf, 0xc000 | full_name);
+ buf_check_uint16(&buf, 0x21); // SRV
+ buf_check_uint16(&buf, 0x1); // IN
+ buf_check_uint32(&buf, 120); // TTL
+ len_ptr = buf_check_len_start(&buf);
+ buf_check_uint16(&buf, 0); // priority
+ buf_check_uint16(&buf, 0); // weight
+ *port = buf_get_uint16(&buf); // port
+ buf_check_label(&buf, *name);
+ buf_check_uint16(&buf, 0xc000 | local);
+ buf_check_len_end(&buf, len_ptr);
+
+ if(buf.len == -1) {
+ return false;
+ }
+
+ // Check the TXT records: name._protocol._transport.local TXT IN 3600 key=value...
+ buf_check_uint16(&buf, 0xc000 | full_name);
+ buf_check_uint16(&buf, 0x10); // TXT
+ buf_check_uint16(&buf, 0x1); // IN
+ buf_check_uint32(&buf, 3600); // TTL
+ len_ptr = buf_check_len_start(&buf);
+
+ for(int i = 0; i < nkeys; i++) {
+ buf_get_kvp(&buf, keys[i], &values[i]);
+ }
+
+ buf_check_len_end(&buf, len_ptr);
+
+ // Done.
+ return buf.len == 0;
+}
projects / meshlink / commitdiff