Merge pull request #16705 from miri64/gcoap_dns/feat/initial

gcoap_dns: initial import of a DNS over CoAP (DoC) client

makefiles/pseudomodules.inc.mk

@@ -67,6 +67,10 @@ PSEUDOMODULES += fmt_%
 PSEUDOMODULES += gcoap_forward_proxy
 PSEUDOMODULES += gcoap_fileserver
 PSEUDOMODULES += gcoap_dtls
+## Enable @ref net_gcoap_dns
+PSEUDOMODULES += gcoap_dns
+## Enable the @ref gcoap_dns_server_proxy_set function
+PSEUDOMODULES += gcoap_dns_proxied
 PSEUDOMODULES += fido2_tests
 PSEUDOMODULES += gnrc_dhcpv6_%
 PSEUDOMODULES += gnrc_ipv6_auto_subnets_auto_init

sys/Makefile.dep

@@ -676,6 +676,15 @@ ifneq (,$(filter gcoap,$(USEMODULE)))
   USEMODULE += random
 endif
 
+ifneq (,$(filter gcoap_dns,$(USEMODULE)))
+  USEMODULE += dns_msg
+  USEMODULE += gcoap
+  USEMODULE += ipv4_addr
+  USEMODULE += ipv6_addr
+  USEMODULE += uri_parser
+  USEMODULE += sock_util
+endif
+
 ifneq (,$(filter luid,$(USEMODULE)))
   FEATURES_OPTIONAL += periph_cpuid
 endif

sys/include/net/coap.h

@@ -154,6 +154,7 @@ extern "C" {
 #define COAP_FORMAT_SENSML_EXI              (115)
 #define COAP_FORMAT_SENML_XML               (310)
 #define COAP_FORMAT_SENSML_XML              (311)
+#define COAP_FORMAT_DNS_MESSAGE           (65053)       /**< NON STANDARD! */
 /** @} */
 
 /**

sys/include/net/gcoap/dns.h

@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2021 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup net_gcoap_dns  DNS over CoAP client implementation
+ * @ingroup  net_gcoap
+ *
+ * @brief   A DNS over CoAP client prototype based on gCoAP.
+ *
+ * DNS over CoAP allows a node to use a CoAP server to resolve DNS request, following
+ * [draft-lenders-dns-over-coap](https://datatracker.ietf.org/doc/draft-lenders-dns-over-coap/).
+ *
+ * The `gcoap_dns` module does not replace the @ref sock_dns_query function when built, and is not
+ * used as a back-end to @ref netutils_get_ipv6 automatically. It does, however, provide a drop-in
+ * replacement for @ref sock_dns_query in its @ref gcoap_dns_query function.
+ *
+ * @{
+ *
+ * @file
+ * @brief   `gcoap_dns` definitions
+ *
+ * @author  Martine Lenders <[email protected]>
+ */
+#ifndef NET_GCOAP_DNS_H
+#define NET_GCOAP_DNS_H
+
+#include <stdint.h>
+
+#include "mutex.h"
+#include "net/credman.h"
+#include "net/coap.h"
+#include "net/gcoap.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup    gcoap_dns_config    GCoAP DNS over CoAP client configuration
+ * @ingroup     config
+ * @{
+ */
+/**
+ * @brief   maximum length of the URI for the DNS server
+ */
+#ifndef CONFIG_GCOAP_DNS_SERVER_URI_LEN
+#define CONFIG_GCOAP_DNS_SERVER_URI_LEN     64U
+#endif
+
+/**
+ * @brief   maximum number of credentials that can be added with @ref gcoap_dns_cred_add()
+ */
+#ifndef CONFIG_GCOAP_DNS_CREDS_MAX
+#if IS_USED(MODULE_GCOAP_DTLS) || defined(DOXYGEN)
+#define CONFIG_GCOAP_DNS_CREDS_MAX          1U
+#else
+#define CONFIG_GCOAP_DNS_CREDS_MAX          0U
+#endif
+#endif
+
+/**
+ * @brief   size of the buffer used to build a CoAP request
+ */
+#ifndef CONFIG_GCOAP_DNS_PDU_BUF_SIZE
+#define CONFIG_GCOAP_DNS_PDU_BUF_SIZE       128U
+#endif
+
+/**
+ * @brief   block-size used for requests (both Block2 control and Block1)
+ *
+ * Should be less than @ref CONFIG_GCOAP_DNS_PDU_BUF_SIZE or
+ * @ref CONFIG_GCOAP_PDU_BUF_SIZE and must be a power
+ * of 2
+ */
+#ifndef CONFIG_GCOAP_DNS_BLOCK_SIZE
+#define CONFIG_GCOAP_DNS_BLOCK_SIZE         64U
+#endif
+/** @} */
+
+/**
+ * @brief   Query a domain name via CoAP synchronously
+ *
+ * @param[in] domain_name   A '\0'-terminated domain name. Must not be NULL.
+ * @param[out] addr_out     The resolved address. Must not be NULL.
+ * @param[in] family        The desired address family for @p addr_out.
+ *                          @ref AF_UNSPEC for any address family (an IPv6
+ *                          address will take preference over an IPv4 address).
+ *
+ * @return  length of @p addr_out in bytes on success
+ * @return  -EAFNOSUPPORT, if the hostname of the URI resolves to an unknown address family.
+ * @return  -EBADMSG, when receiving erroneous response or response containing
+ *          an error code.
+ * @return  -ECONNABORTED, if CoAP request cannot be sent.
+ * @return  -ECONNREFUSED, if no URI is set for the client (see @ref gcoap_dns_server_uri_set()).
+ * @return  -EDESTADDRREQ, if CoAP response was received from an unexpected
+ *          remote.
+ * @return  -EHOSTUNREACH, if the hostname of the URI can not be resolved
+ * @return  -ENOBUFS, if there was not enough buffer space for the request.
+ * @return  -ENOBUFS, if length of received CoAP body is greater than
+ *          @ref CONFIG_DNS_MSG_LEN.
+ * @return  -ENOENT, if Zone-ID of the URI can not be found locally.
+ * @return  -ENOMSG, if CoAP response did not contain a DNS response.
+ * @return  -ENOTRECOVERABLE, on gCoAP-internal error.
+ * @return  -ENOTSUP, if credential can not be added for to client.
+ * @return  -ETIMEDOUT, if CoAP request timed out.
+ */
+int gcoap_dns_query(const char *domain_name, void *addr_out, int family);
+
+/**
+ * @brief   Sets and checks a URI for a DoC server
+ *
+ * @param[in] uri   A URI. May be NULL to remove the URI.
+                    Unless the @ref net_sock_dns module is also used, the host
+                    component of the URI needs to be an IP literal.
+ *
+ * @return  length of @p uri on success (0 when URI is removed).
+ * @return  -EINVAL, if @p uri is not a valid URI for DNS over CoAP.
+ * @return  -ENOBUFS, if the client implementation has not enough buffer space
+ *          to process the URI.
+ */
+int gcoap_dns_server_uri_set(const char *uri);
+
+/**
+ * @brief   Checks if the URI for the DoC server is set.
+ *
+ * @retval true     A URI for the DoC server is set.
+ * @retval false    There is no URI set for the DoC server.
+ */
+bool gcoap_dns_server_uri_is_set(void);
+
+/**
+ * @brief   Gets the URI for the DoC server
+ *
+ * @param[out] uri      The current URI for the DoC server
+ * @param[in] uri_len   Maximum length for @p uri
+ *
+ * @return  Length of the @p uri on return. 0, if no URI is set.
+ * @return  -ENOBUFS, if the configured URI is longer than @p uri_len.
+ */
+ssize_t gcoap_dns_server_uri_get(char *uri, size_t uri_len);
+
+/**
+ * @brief   Deletes all added credentials
+ *
+ * This also removes the credentials from the @ref net_credman and the GCoAP DTLS sock.
+ */
+void gcoap_dns_cred_reset(void);
+
+/**
+ * @brief   Adds a credential for the use with the configured DoC server.
+ *
+ * @pre creds != NULL.
+ *
+ * @param[in] creds     A crential. May not be NULL.
+ *
+ * @return 0 on success
+ * @return -ENOTSUP if DTLS is not supported (because `gcoap_dtls` is not compiled in)
+ * @return -ENOMEM if @ref CONFIG_GCOAP_DNS_CREDS_MAX is exceeded (duplicates may be added).
+ * @return -EBADF if the credential can not be added to @ref net_credman or the GCoAP DTLS sock.
+ */
+int gcoap_dns_cred_add(credman_credential_t *creds);
+
+/**
+ * @brief   Remove a credential for the use with the configured DoC server
+ *
+ * This also removes the credentials from the @ref net_credman and the GCoAP DTLS sock.
+ *
+ * @param[in] tag   The tag of the credential.
+ * @param[in] type  The type of the credential.
+ */
+void gcoap_dns_cred_remove(credman_tag_t tag, credman_type_t type);
+
+/**
+ * @brief   Deletes the proxy URI.
+ */
+void gcoap_dns_server_proxy_reset(void);
+
+/**
+ * @brief   Sets and checks a proxy URI.
+ *
+ * @param[in] proxy     A proxy URI. Must contain a `dns` query variable.
+ *
+ * @return  length of @p proxy on success.
+ * @return  -ENOBUFS, if the client implementation has not enough buffer space
+ *          to process the proxy URI.
+ * @return  -ENOSUP, if module `gcoap_dns_proxied` is not compiled in.
+ */
+int gcoap_dns_server_proxy_set(const char *proxy);
+
+/**
+ * @brief   Checks if a proxy URI is set.
+ *
+ * @retval true     A proxy URI is set.
+ * @retval false    There is no URI set for the DoC server.
+ */
+bool gcoap_dns_server_proxy_is_set(void);
+
+/**
+ * @brief   Gets the proxy URI
+ *
+ * @param[out] proxy    The current proxy URI
+ * @param[in] proxy_len Maximum length for @p proxy
+ *
+ * @return  Length of the @p proxy on return. 0, if no URI is set.
+ * @return  -ENOBUFS, if the configured URI is longer than @p proxy_len.
+ */
+ssize_t gcoap_dns_server_proxy_get(char *proxy, size_t proxy_len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GCOAP_DNS_H */
+/** @} */

sys/net/application_layer/gcoap/Kconfig

@@ -13,6 +13,37 @@ menuconfig KCONFIG_USEMODULE_GCOAP
 
 if KCONFIG_USEMODULE_GCOAP
 
+menuconfig KCONFIG_USEMODULE_GCOAP_DNS
+    bool "Configure DNS-over-CoAPS implementation in GCoAP"
+    depends on USEMODULE_GCOAP_DNS
+    help
+        Configure DNS-over-CoAPS submodule of Gcoap using Kconfig. If not set
+        default values and CFLAGS will be used.
+
+if KCONFIG_USEMODULE_GCOAP_DNS
+config GCOAP_DNS_SERVER_URI_LEN
+    int "Maximum length of the URI template for the DNS server"
+    default 64
+    range 9 65535  # 14 == len("coaps:///")
+
+config GCOAP_DNS_CREDS_MAX
+    int "Maximum number of credentials that can be added with @ref gcoap_dns_cred_add()"
+    default 1 if USEMODULE_GCOAP_DTLS
+    default 0
+
+config GCOAP_DNS_PDU_BUF_SIZE
+    int "Size of the buffer used to build a CoAP request"
+    default 128
+
+config GCOAP_DNS_BLOCK_SIZE
+    int "Block-size used for requests (both Block2 control and Block1)"
+    default 64
+    help
+        Should be less than @ref CONFIG_GCOAP_DNS_PDU_BUF_SIZE or
+        @ref CONFIG_GCOAP_PDU_BUF_SIZE and must be a power
+
+endif # KCONFIG_USEMODULE_GCOAP_DNS
+
 menu "DTLS options"
 config GCOAP_DTLS_CREDENTIAL_TAG
     int "Credential tag"