Adding upstream version 3.2.6.upstream/3.2.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 896 insertions, 0 deletions

diff --git a/src/utils/common/netio.c b/src/utils/common/netio.c
new file mode 100644
index 0000000..4f31551
--- /dev/null
+++ b/src/utils/common/netio.c
@@ -0,0 +1,896 @@
+/*  Copyright (C) 2023 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <netinet/in.h>
+#include <sys/types.h>   // OpenBSD
+#include <netinet/tcp.h> // TCP_FASTOPEN
+#include <sys/socket.h>
+
+#ifdef HAVE_SYS_UIO_H
+#include <sys/uio.h>
+#endif
+
+#include "utils/common/netio.h"
+#include "utils/common/msg.h"
+#include "utils/common/tls.h"
+#include "libknot/libknot.h"
+#include "contrib/proxyv2/proxyv2.h"
+#include "contrib/sockaddr.h"
+
+srv_info_t *srv_info_create(const char *name, const char *service)
+{
+	if (name == NULL || service == NULL) {
+		DBG_NULL;
+		return NULL;
+	}
+
+	// Create output structure.
+	srv_info_t *server = calloc(1, sizeof(srv_info_t));
+
+	// Check output.
+	if (server == NULL) {
+		return NULL;
+	}
+
+	// Fill output.
+	server->name = strdup(name);
+	server->service = strdup(service);
+
+	if (server->name == NULL || server->service == NULL) {
+		srv_info_free(server);
+		return NULL;
+	}
+
+	// Return result.
+	return server;
+}
+
+void srv_info_free(srv_info_t *server)
+{
+	if (server == NULL) {
+		DBG_NULL;
+		return;
+	}
+
+	free(server->name);
+	free(server->service);
+	free(server);
+}
+
+int get_iptype(const ip_t ip, const srv_info_t *server)
+{
+	bool unix_socket = (server->name[0] == '/');
+
+	switch (ip) {
+	case IP_4:
+		return AF_INET;
+	case IP_6:
+		return AF_INET6;
+	default:
+		return unix_socket ? AF_UNIX : AF_UNSPEC;
+	}
+}
+
+int get_socktype(const protocol_t proto, const uint16_t type)
+{
+	switch (proto) {
+	case PROTO_TCP:
+		return SOCK_STREAM;
+	case PROTO_UDP:
+		return SOCK_DGRAM;
+	default:
+		if (type == KNOT_RRTYPE_AXFR || type == KNOT_RRTYPE_IXFR) {
+			return SOCK_STREAM;
+		} else {
+			return SOCK_DGRAM;
+		}
+	}
+}
+
+const char *get_sockname(const int socktype)
+{
+	switch (socktype) {
+	case SOCK_STREAM:
+		return "TCP";
+	case SOCK_DGRAM:
+		return "UDP";
+	default:
+		return "UNKNOWN";
+	}
+}
+
+static int get_addr(const srv_info_t *server,
+                    const int        iptype,
+                    const int        socktype,
+                    struct addrinfo  **info)
+{
+	struct addrinfo hints;
+
+	// Set connection hints.
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = iptype;
+	hints.ai_socktype = socktype;
+
+	// Get connection parameters.
+	int ret = getaddrinfo(server->name, server->service, &hints, info);
+	switch (ret) {
+	case 0:
+		return 0;
+#ifdef EAI_ADDRFAMILY	/* EAI_ADDRFAMILY isn't implemented in FreeBSD/macOS anymore. */
+	case EAI_ADDRFAMILY:
+		break;
+#else			/* FreeBSD, macOS, and likely others return EAI_NONAME instead. */
+	case EAI_NONAME:
+		if (iptype != AF_UNSPEC) {
+			break;
+		}
+		/* FALLTHROUGH */
+#endif	/* EAI_ADDRFAMILY */
+	default:
+		ERR("%s for %s@%s", gai_strerror(ret), server->name, server->service);
+	}
+	return -1;
+}
+
+void get_addr_str(const struct sockaddr_storage *ss,
+                  const int                     socktype,
+                  char                          **dst)
+{
+	char addr_str[SOCKADDR_STRLEN] = {0};
+
+	// Get network address string and port number.
+	sockaddr_tostr(addr_str, sizeof(addr_str), ss);
+
+	// Calculate needed buffer size
+	const char *sock_name = get_sockname(socktype);
+	size_t buflen = strlen(addr_str) + strlen(sock_name) + 3 /* () */;
+
+	// Free previous string if any and write result
+	free(*dst);
+	*dst = malloc(buflen);
+	if (*dst != NULL) {
+		int ret = snprintf(*dst, buflen, "%s(%s)", addr_str, sock_name);
+		if (ret <= 0 || ret >= buflen) {
+			**dst = '\0';
+		}
+	}
+}
+
+int net_init(const srv_info_t      *local,
+             const srv_info_t      *remote,
+             const int             iptype,
+             const int             socktype,
+             const int             wait,
+             const net_flags_t     flags,
+             const tls_params_t    *tls_params,
+             const https_params_t  *https_params,
+             const quic_params_t   *quic_params,
+             const struct sockaddr *proxy_src,
+             const struct sockaddr *proxy_dst,
+             net_t                 *net)
+{
+	if (remote == NULL || net == NULL) {
+		DBG_NULL;
+		return KNOT_EINVAL;
+	}
+
+	// Clean network structure.
+	memset(net, 0, sizeof(*net));
+	net->sockfd = -1;
+
+	if (iptype == AF_UNIX) {
+		struct addrinfo *info = calloc(1, sizeof(struct addrinfo));
+		info->ai_addr = calloc(1, sizeof(struct sockaddr_storage));
+		info->ai_addrlen = sizeof(struct sockaddr_un);
+		info->ai_socktype = socktype;
+		info->ai_family = iptype;
+		int ret = sockaddr_set_raw((struct sockaddr_storage *)info->ai_addr,
+		                           AF_UNIX, (const uint8_t *)remote->name,
+		                           strlen(remote->name));
+		if (ret != KNOT_EOK) {
+			free(info->ai_addr);
+			free(info);
+			return ret;
+		}
+		net->remote_info = info;
+	} else {
+		// Get remote address list.
+		if (get_addr(remote, iptype, socktype, &net->remote_info) != 0) {
+			net_clean(net);
+			return KNOT_NET_EADDR;
+		}
+	}
+
+	// Set current remote address.
+	net->srv = net->remote_info;
+
+	// Get local address if specified.
+	if (local != NULL) {
+		if (get_addr(local, iptype, socktype, &net->local_info) != 0) {
+			net_clean(net);
+			return KNOT_NET_EADDR;
+		}
+	}
+
+	// Store network parameters.
+	net->sockfd = -1;
+	net->iptype = iptype;
+	net->socktype = socktype;
+	net->wait = wait;
+	net->local = local;
+	net->remote = remote;
+	net->flags = flags;
+	net->proxy.src = proxy_src;
+	net->proxy.dst = proxy_dst;
+
+	if ((bool)(proxy_src == NULL) != (bool)(proxy_dst == NULL) ||
+	    (proxy_src != NULL && proxy_src->sa_family != proxy_dst->sa_family)) {
+		net_clean(net);
+		return KNOT_EINVAL;
+	}
+
+	// Prepare for TLS.
+	if (tls_params != NULL && tls_params->enable) {
+		int ret = 0;
+#ifdef LIBNGHTTP2
+		// Prepare for HTTPS.
+		if (https_params != NULL && https_params->enable) {
+			ret = tls_ctx_init(&net->tls, tls_params,
+			                   GNUTLS_NONBLOCK, net->wait);
+			if (ret != KNOT_EOK) {
+				net_clean(net);
+				return ret;
+			}
+			ret = https_ctx_init(&net->https, &net->tls, https_params);
+			if (ret != KNOT_EOK) {
+				net_clean(net);
+				return ret;
+			}
+		} else
+#endif //LIBNGHTTP2
+#ifdef ENABLE_QUIC
+		if (quic_params != NULL && quic_params->enable) {
+			ret = tls_ctx_init(&net->tls, tls_params,
+			        GNUTLS_NONBLOCK | GNUTLS_ENABLE_EARLY_DATA |
+			        GNUTLS_NO_END_OF_EARLY_DATA, net->wait);
+			if (ret != KNOT_EOK) {
+				net_clean(net);
+				return ret;
+			}
+			ret = quic_ctx_init(&net->quic, &net->tls, quic_params);
+			if (ret != KNOT_EOK) {
+				net_clean(net);
+				return ret;
+			}
+		} else
+#endif //ENABLE_QUIC
+		{
+			ret = tls_ctx_init(&net->tls, tls_params,
+			                   GNUTLS_NONBLOCK, net->wait);
+			if (ret != KNOT_EOK) {
+				net_clean(net);
+				return ret;
+			}
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+/*!
+ * Connect with TCP Fast Open.
+ */
+static int fastopen_connect(int sockfd, const struct addrinfo *srv)
+{
+#if defined( __FreeBSD__)
+	const int enable = 1;
+	return setsockopt(sockfd, IPPROTO_TCP, TCP_FASTOPEN, &enable, sizeof(enable));
+#elif defined(__APPLE__)
+	// connection is performed lazily when first data are sent
+	struct sa_endpoints ep = {0};
+	ep.sae_dstaddr = srv->ai_addr;
+	ep.sae_dstaddrlen = srv->ai_addrlen;
+	int flags =  CONNECT_DATA_IDEMPOTENT|CONNECT_RESUME_ON_READ_WRITE;
+
+	return connectx(sockfd, &ep, SAE_ASSOCID_ANY, flags, NULL, 0, NULL, NULL);
+#elif defined(__linux__)
+	// connect() will be called implicitly with sendto(), sendmsg()
+	return 0;
+#else
+	errno = ENOTSUP;
+	return -1;
+#endif
+}
+
+/*!
+ * Sends data with TCP Fast Open.
+ */
+static int fastopen_send(int sockfd, const struct msghdr *msg, int timeout)
+{
+#if defined(__FreeBSD__) || defined(__APPLE__)
+	return sendmsg(sockfd, msg, 0);
+#elif defined(__linux__)
+	int ret = sendmsg(sockfd, msg, MSG_FASTOPEN);
+	if (ret == -1 && errno == EINPROGRESS) {
+		struct pollfd pfd = {
+			.fd = sockfd,
+			.events = POLLOUT,
+			.revents = 0,
+		};
+		if (poll(&pfd, 1, 1000 * timeout) != 1) {
+			errno = ETIMEDOUT;
+			return -1;
+		}
+		ret = sendmsg(sockfd, msg, 0);
+	}
+	return ret;
+#else
+	errno = ENOTSUP;
+	return -1;
+#endif
+}
+
+static char *net_get_remote(const net_t *net)
+{
+	if (net->tls.params->sni != NULL) {
+		return net->tls.params->sni;
+	} else if (net->tls.params->hostname != NULL) {
+		return net->tls.params->hostname;
+	} else if (strchr(net->remote_str, ':') == NULL) {
+		char *at = strchr(net->remote_str, '@');
+		if (at != NULL && strncmp(net->remote->name, net->remote_str,
+		                          at - net->remote_str)) {
+			return net->remote->name;
+		}
+	}
+	return NULL;
+}
+
+#ifdef ENABLE_QUIC
+static int fd_set_recv_ecn(int fd, int family)
+{
+	unsigned int tos = 1;
+	switch (family) {
+	case AF_INET:
+#ifdef IP_RECVTOS
+		if (setsockopt(fd, IPPROTO_IP, IP_RECVTOS, &tos, sizeof(tos)) == -1) {
+			return knot_map_errno();
+		}
+#endif
+		break;
+	case AF_INET6:
+		if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVTCLASS, &tos, sizeof(tos)) == -1) {
+			return knot_map_errno();
+		}
+		break;
+	default:
+		return KNOT_EINVAL;
+	}
+	return KNOT_EOK;
+}
+#endif
+
+
+int net_connect(net_t *net)
+{
+	if (net == NULL || net->srv == NULL) {
+		DBG_NULL;
+		return KNOT_EINVAL;
+	}
+
+	// Set remote information string.
+	get_addr_str((struct sockaddr_storage *)net->srv->ai_addr,
+	             net->socktype, &net->remote_str);
+
+	// Create socket.
+	int sockfd = socket(net->srv->ai_family, net->socktype, 0);
+	if (sockfd == -1) {
+		WARN("can't create socket for %s", net->remote_str);
+		return KNOT_NET_ESOCKET;
+	}
+
+	// Initialize poll descriptor structure.
+	struct pollfd pfd = {
+		.fd = sockfd,
+		.events = POLLOUT,
+		.revents = 0,
+	};
+
+	// Set non-blocking socket.
+	if (fcntl(sockfd, F_SETFL, O_NONBLOCK) == -1) {
+		WARN("can't set non-blocking socket for %s", net->remote_str);
+		return KNOT_NET_ESOCKET;
+	}
+
+	// Bind address to socket if specified.
+	if (net->local_info != NULL) {
+		if (bind(sockfd, net->local_info->ai_addr,
+		         net->local_info->ai_addrlen) == -1) {
+			WARN("can't assign address %s", net->local->name);
+			return KNOT_NET_ESOCKET;
+		}
+	} else {
+		// Ensure source port is always randomized (even for TCP).
+		struct sockaddr_storage local = { .ss_family = net->srv->ai_family };
+		(void)bind(sockfd, (struct sockaddr *)&local, sockaddr_len(&local));
+	}
+
+	int ret = 0;
+	if (net->socktype == SOCK_STREAM) {
+		int  cs = 1, err;
+		socklen_t err_len = sizeof(err);
+		bool fastopen = net->flags & NET_FLAGS_FASTOPEN;
+
+#ifdef TCP_NODELAY
+		(void)setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, &cs, sizeof(cs));
+#endif
+
+		// Establish a connection.
+		if (net->tls.params == NULL || !fastopen) {
+			if (fastopen) {
+				ret = fastopen_connect(sockfd, net->srv);
+			} else {
+				ret = connect(sockfd, net->srv->ai_addr, net->srv->ai_addrlen);
+			}
+			if (ret != 0 && errno != EINPROGRESS) {
+				WARN("can't connect to %s", net->remote_str);
+				close(sockfd);
+				return KNOT_NET_ECONNECT;
+			}
+
+			// Check for connection timeout.
+			if (!fastopen && poll(&pfd, 1, 1000 * net->wait) != 1) {
+				WARN("connection timeout for %s", net->remote_str);
+				close(sockfd);
+				return KNOT_NET_ECONNECT;
+			}
+
+			// Check if NB socket is writeable.
+			cs = getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &err, &err_len);
+			if (cs < 0 || err != 0) {
+				WARN("can't connect to %s", net->remote_str);
+				close(sockfd);
+				return KNOT_NET_ECONNECT;
+			}
+		}
+
+		if (net->tls.params != NULL) {
+#ifdef LIBNGHTTP2
+			if (net->https.params.enable) {
+				// Establish HTTPS connection.
+				char *remote = net_get_remote(net);
+				ret = tls_ctx_setup_remote_endpoint(&net->tls, &doh_alpn, 1, NULL,
+				        remote);
+				if (ret != 0) {
+					close(sockfd);
+					return ret;
+				}
+				if (remote && net->https.authority == NULL) {
+					net->https.authority = strdup(remote);
+				}
+				ret = https_ctx_connect(&net->https, sockfd, fastopen,
+				        (struct sockaddr_storage *)net->srv->ai_addr);
+			} else
+#endif //LIBNGHTTP2
+			{
+				// Establish TLS connection.
+				ret = tls_ctx_setup_remote_endpoint(&net->tls, &dot_alpn, 1, NULL,
+				        net_get_remote(net));
+				if (ret != 0) {
+					close(sockfd);
+					return ret;
+				}
+				ret = tls_ctx_connect(&net->tls, sockfd, fastopen,
+				        (struct sockaddr_storage *)net->srv->ai_addr);
+			}
+			if (ret != KNOT_EOK) {
+				close(sockfd);
+				return ret;
+			}
+		}
+	}
+#ifdef ENABLE_QUIC
+	else if (net->socktype == SOCK_DGRAM) {
+		if (net->quic.params.enable) {
+			// Establish QUIC connection.
+			ret = fd_set_recv_ecn(sockfd, net->srv->ai_family);
+			if (ret != KNOT_EOK) {
+				close(sockfd);
+				return ret;
+			}
+			ret = tls_ctx_setup_remote_endpoint(&net->tls,
+			        doq_alpn, 4, QUIC_PRIORITY, net_get_remote(net));
+			if (ret != 0) {
+				close(sockfd);
+				return ret;
+			}
+			ret = quic_ctx_connect(&net->quic, sockfd,
+			        (struct addrinfo *)net->srv);
+			if (ret != KNOT_EOK) {
+				close(sockfd);
+				return ret;
+			}
+		}
+	}
+#endif
+
+	// Store socket descriptor.
+	net->sockfd = sockfd;
+
+	return KNOT_EOK;
+}
+
+int net_set_local_info(net_t *net)
+{
+	if (net == NULL) {
+		DBG_NULL;
+		return KNOT_EINVAL;
+	}
+
+	socklen_t local_addr_len = sizeof(struct sockaddr_storage);
+
+	struct addrinfo *new_info = calloc(1, sizeof(*new_info) + local_addr_len);
+	if (new_info == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	new_info->ai_addr = (struct sockaddr *)(new_info + 1);
+	new_info->ai_family = net->srv->ai_family;
+	new_info->ai_socktype = net->srv->ai_socktype;
+	new_info->ai_protocol = net->srv->ai_protocol;
+	new_info->ai_addrlen = local_addr_len;
+
+	if (getsockname(net->sockfd, new_info->ai_addr,	&local_addr_len) == -1) {
+		WARN("can't get local address");
+		free(new_info);
+		return KNOT_NET_ESOCKET;
+	}
+
+	if (net->local_info != NULL) {
+		if (net->local == NULL) {
+			free(net->local_info);
+		} else {
+			freeaddrinfo(net->local_info);
+		}
+	}
+
+	net->local_info = new_info;
+
+	get_addr_str((struct sockaddr_storage *)net->local_info->ai_addr,
+	             net->socktype, &net->local_str);
+
+	return KNOT_EOK;
+}
+
+int net_send(const net_t *net, const uint8_t *buf, const size_t buf_len)
+{
+	if (net == NULL || buf == NULL) {
+		DBG_NULL;
+		return KNOT_EINVAL;
+	}
+
+#ifdef ENABLE_QUIC
+	// Send data over QUIC.
+	if (net->quic.params.enable) {
+		int ret = quic_send_dns_query((quic_ctx_t *)&net->quic,
+		                              net->sockfd, net->srv, buf, buf_len);
+		if (ret != KNOT_EOK) {
+			WARN("can't send query to %s", net->remote_str);
+			return KNOT_NET_ESEND;
+		}
+	} else
+#endif
+	// Send data over UDP.
+	if (net->socktype == SOCK_DGRAM) {
+		char proxy_buf[PROXYV2_HEADER_MAXLEN];
+		struct iovec iov[2] = {
+			{ .iov_base = proxy_buf, .iov_len = 0 },
+			{ .iov_base = (void *)buf, .iov_len = buf_len }
+		};
+
+		struct msghdr msg = {
+			.msg_name = net->srv->ai_addr,
+			.msg_namelen = net->srv->ai_addrlen,
+			.msg_iov = &iov[1],
+			.msg_iovlen = 1
+		};
+
+		if (net->proxy.src != NULL && net->proxy.src->sa_family != 0) {
+			int ret = proxyv2_write_header(proxy_buf, sizeof(proxy_buf),
+			                               SOCK_DGRAM, net->proxy.src,
+			                               net->proxy.dst);
+			if (ret < 0) {
+				WARN("can't send proxied query to %s", net->remote_str);
+				return KNOT_NET_ESEND;
+			}
+			iov[0].iov_len = ret;
+			msg.msg_iov--;
+			msg.msg_iovlen++;
+		}
+
+		ssize_t total = iov[0].iov_len + iov[1].iov_len;
+
+		if (sendmsg(net->sockfd, &msg, 0) != total) {
+			WARN("can't send query to %s", net->remote_str);
+			return KNOT_NET_ESEND;
+		}
+#ifdef LIBNGHTTP2
+	// Send data over HTTPS
+	} else if (net->https.params.enable) {
+		int ret = https_send_dns_query((https_ctx_t *)&net->https, buf, buf_len);
+		if (ret != KNOT_EOK) {
+			WARN("can't send query to %s", net->remote_str);
+			return KNOT_NET_ESEND;
+		}
+#endif //LIBNGHTTP2
+	// Send data over TLS.
+	} else if (net->tls.params != NULL) {
+		int ret = tls_ctx_send((tls_ctx_t *)&net->tls, buf, buf_len);
+		if (ret != KNOT_EOK) {
+			WARN("can't send query to %s", net->remote_str);
+			return KNOT_NET_ESEND;
+		}
+	// Send data over TCP.
+	} else {
+		bool fastopen = net->flags & NET_FLAGS_FASTOPEN;
+
+		char proxy_buf[PROXYV2_HEADER_MAXLEN];
+		uint16_t pktsize = htons(buf_len); // Leading packet length bytes.
+		struct iovec iov[3] = {
+			{ .iov_base = proxy_buf, .iov_len = 0 },
+			{ .iov_base = &pktsize, .iov_len = sizeof(pktsize) },
+			{ .iov_base = (void *)buf, .iov_len = buf_len }
+		};
+
+		struct msghdr msg = {
+			.msg_name = net->srv->ai_addr,
+			.msg_namelen = net->srv->ai_addrlen,
+			.msg_iov = &iov[1],
+			.msg_iovlen = 2
+		};
+
+		if (net->srv->ai_addr->sa_family == AF_UNIX) {
+			msg.msg_name = NULL;
+		}
+
+		if (net->proxy.src != NULL && net->proxy.src->sa_family != 0) {
+			int ret = proxyv2_write_header(proxy_buf, sizeof(proxy_buf),
+			                               SOCK_STREAM, net->proxy.src,
+			                               net->proxy.dst);
+			if (ret < 0) {
+				WARN("can't send proxied query to %s", net->remote_str);
+				return KNOT_NET_ESEND;
+			}
+			iov[0].iov_len = ret;
+			msg.msg_iov--;
+			msg.msg_iovlen++;
+		}
+
+		ssize_t total = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
+
+		int ret = 0;
+		if (fastopen) {
+			ret = fastopen_send(net->sockfd, &msg, net->wait);
+		} else {
+			ret = sendmsg(net->sockfd, &msg, 0);
+		}
+		if (ret != total) {
+			WARN("can't send query to %s", net->remote_str);
+			return KNOT_NET_ESEND;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+int net_receive(const net_t *net, uint8_t *buf, const size_t buf_len)
+{
+	if (net == NULL || buf == NULL) {
+		DBG_NULL;
+		return KNOT_EINVAL;
+	}
+
+	// Initialize poll descriptor structure.
+	struct pollfd pfd = {
+		.fd = net->sockfd,
+		.events = POLLIN,
+		.revents = 0,
+	};
+
+#ifdef ENABLE_QUIC
+	// Receive data over QUIC.
+	if (net->quic.params.enable) {
+		int ret = quic_recv_dns_response((quic_ctx_t *)&net->quic, buf,
+		                                 buf_len, net->srv);
+		if (ret < 0) {
+			WARN("can't receive reply from %s", net->remote_str);
+			return KNOT_NET_ERECV;
+		}
+		return ret;
+	} else
+#endif
+	// Receive data over UDP.
+	if (net->socktype == SOCK_DGRAM) {
+		struct sockaddr_storage from;
+		memset(&from, '\0', sizeof(from));
+
+		// Receive replies unless correct reply or timeout.
+		while (true) {
+			socklen_t from_len = sizeof(from);
+
+			// Wait for datagram data.
+			if (poll(&pfd, 1, 1000 * net->wait) != 1) {
+				WARN("response timeout for %s",
+				     net->remote_str);
+				return KNOT_NET_ETIMEOUT;
+			}
+
+			// Receive whole UDP datagram.
+			ssize_t ret = recvfrom(net->sockfd, buf, buf_len, 0,
+			                       (struct sockaddr *)&from, &from_len);
+			if (ret <= 0) {
+				WARN("can't receive reply from %s",
+				     net->remote_str);
+				return KNOT_NET_ERECV;
+			}
+
+			// Compare reply address with the remote one.
+			if (from_len > sizeof(from) ||
+			    memcmp(&from, net->srv->ai_addr, from_len) != 0) {
+				char *src = NULL;
+				get_addr_str(&from, net->socktype, &src);
+				WARN("unexpected reply source %s", src);
+				free(src);
+				continue;
+			}
+
+			return ret;
+		}
+#ifdef LIBNGHTTP2
+	// Receive data over HTTPS.
+	} else if (net->https.params.enable) {
+		int ret = https_recv_dns_response((https_ctx_t *)&net->https, buf, buf_len);
+		if (ret < 0) {
+			WARN("can't receive reply from %s", net->remote_str);
+			return KNOT_NET_ERECV;
+		}
+		return ret;
+#endif //LIBNGHTTP2
+	// Receive data over TLS.
+	} else if (net->tls.params != NULL) {
+		int ret = tls_ctx_receive((tls_ctx_t *)&net->tls, buf, buf_len);
+		if (ret < 0) {
+			WARN("can't receive reply from %s", net->remote_str);
+			return KNOT_NET_ERECV;
+		}
+		return ret;
+	// Receive data over TCP.
+	} else {
+		uint32_t total = 0;
+
+		uint16_t msg_len = 0;
+		// Receive TCP message header.
+		while (total < sizeof(msg_len)) {
+			if (poll(&pfd, 1, 1000 * net->wait) != 1) {
+				WARN("response timeout for %s",
+				     net->remote_str);
+				return KNOT_NET_ETIMEOUT;
+			}
+
+			// Receive piece of message.
+			ssize_t ret = recv(net->sockfd, (uint8_t *)&msg_len + total,
+				           sizeof(msg_len) - total, 0);
+			if (ret <= 0) {
+				WARN("can't receive reply from %s",
+				     net->remote_str);
+				return KNOT_NET_ERECV;
+			}
+			total += ret;
+		}
+
+		// Convert number to host format.
+		msg_len = ntohs(msg_len);
+		if (msg_len > buf_len) {
+			return KNOT_ESPACE;
+		}
+
+		total = 0;
+
+		// Receive whole answer message by parts.
+		while (total < msg_len) {
+			if (poll(&pfd, 1, 1000 * net->wait) != 1) {
+				WARN("response timeout for %s",
+				     net->remote_str);
+				return KNOT_NET_ETIMEOUT;
+			}
+
+			// Receive piece of message.
+			ssize_t ret = recv(net->sockfd, buf + total, msg_len - total, 0);
+			if (ret <= 0) {
+				WARN("can't receive reply from %s",
+				     net->remote_str);
+				return KNOT_NET_ERECV;
+			}
+			total += ret;
+		}
+
+		return total;
+	}
+
+	return KNOT_NET_ERECV;
+}
+
+void net_close(net_t *net)
+{
+	if (net == NULL) {
+		DBG_NULL;
+		return;
+	}
+
+#ifdef ENABLE_QUIC
+	if (net->quic.params.enable) {
+		quic_ctx_close(&net->quic);
+	}
+#endif
+	tls_ctx_close(&net->tls);
+	close(net->sockfd);
+	net->sockfd = -1;
+}
+
+void net_clean(net_t *net)
+{
+	if (net == NULL) {
+		DBG_NULL;
+		return;
+	}
+
+	free(net->local_str);
+	free(net->remote_str);
+	net->local_str = NULL;
+	net->remote_str = NULL;
+
+	if (net->local_info != NULL) {
+		if (net->local == NULL) {
+			free(net->local_info);
+		} else {
+			freeaddrinfo(net->local_info);
+		}
+		net->local_info = NULL;
+	}
+
+	if (net->remote_info != NULL) {
+		if (net->remote_info->ai_addr->sa_family == AF_UNIX) {
+			free(net->remote_info->ai_addr);
+			free(net->remote_info);
+		} else {
+			freeaddrinfo(net->remote_info);
+		}
+		net->remote_info = NULL;
+	}
+
+#ifdef LIBNGHTTP2
+	https_ctx_deinit(&net->https);
+#endif
+#ifdef ENABLE_QUIC
+	quic_ctx_deinit(&net->quic);
+#endif
+	tls_ctx_deinit(&net->tls);
+}