Add mDNS module.

Cherry-picked from 86623e8, massaged to
build on IDFv4. Documentation NOT updated to match limitations of this
IDF version.

components/modules/CMakeLists.txt

@@ -15,6 +15,7 @@ set(module_srcs
   "i2c_hw_master.c"
   "i2c_hw_slave.c"
   "ledc.c"
+  "mdns.c"
   "mqtt.c"
   "net.c"
   "node.c"
@@ -87,6 +88,7 @@ idf_component_register(
     "libsodium"
     "lua"
     "mbedtls"
+    "mdns"
     "mqtt"
     "platform"
     "qrcodegen"

components/modules/Kconfig

@@ -116,6 +116,12 @@ menu "NodeMCU modules"
         help
             Includes the LEDC module.
 
+    config NODEMCU_CMODULE_MDNS
+        bool "mDNS module"
+        default "n"
+        help
+            Includes the mDNS module.
+
     config NODEMCU_CMODULE_MQTT
         bool "MQTT module"
         default "n"

components/modules/mdns.c

@@ -0,0 +1,305 @@
+#include "module.h"
+#include "lauxlib.h"
+#include "ip_fmt.h"
+
+#include "esp_err.h"
+#include "mdns.h"
+
+// Table key names
+static const char *HOSTNAME = "hostname";
+static const char *INSTANCE_NAME = "instance_name";
+static const char *SERVICES = "services";
+static const char *SERVICE_TYPE = "service_type";
+static const char *PROTO = "protocol";
+static const char *PORT = "port";
+static const char *TXT = "txt";
+#if ESP_IDF_VERSION_MAJOR >= 5
+static const char *SUBTYPE = "subtype";
+#else
+# warning "Reduced mDNS support on IDF<5.0"
+#endif
+static const char *QUERY_TYPE = "query_type";
+static const char *NAME = "name";
+static const char *TIMEOUT = "timeout";
+static const char *MAX_RESULTS = "max_results";
+static const char *ADDRESSES = "addresses";
+
+#define DEFAULT_TIMEOUT_MS 2000
+#define DEFAULT_MAX_RESULTS 10
+
+static bool started;
+
+static bool valid_query_type(int t)
+{
+  switch(t)
+  {
+    case MDNS_TYPE_A:
+    case MDNS_TYPE_PTR:
+    case MDNS_TYPE_TXT:
+    case MDNS_TYPE_AAAA:
+    case MDNS_TYPE_SRV:
+    //case MDNS_TYPE_OPT:
+    //case MDNS_TYPE_NSEC:
+    case MDNS_TYPE_ANY: return true;
+    default: return false;
+  }
+}
+
+
+static int lmdns_start(lua_State *L)
+{
+  luaL_checktable(L, 1);
+  lua_settop(L, 1);
+
+  if (started)
+    return luaL_error(L, "already started");
+
+  bool inited = false;
+  esp_err_t err = mdns_init();
+  if (err != ESP_OK)
+    goto mdns_err;
+  inited = true;
+
+  // Hostname
+  lua_getfield(L, 1, HOSTNAME);
+  const char *hostname = luaL_optstring(L, -1, NULL);
+  if (hostname)
+  {
+    err = mdns_hostname_set(hostname);
+    if (err != ESP_OK)
+      goto mdns_err;
+  }
+  lua_pop(L, 1);
+
+  // Instance name
+  lua_getfield(L, 1, INSTANCE_NAME);
+  const char *instname = luaL_optstring(L, -1, NULL);
+  if (instname)
+  {
+    err = mdns_instance_name_set(instname);
+    if (err != ESP_OK)
+      goto mdns_err;
+  }
+  lua_pop(L, 1);
+
+  // Services
+  lua_getfield(L, 1, SERVICES);
+  unsigned i = 1;
+  if (!lua_isnoneornil(L, 2)) // array of service entries
+  {
+    luaL_checktable(L, 2);
+    for (i = 1; true; ++i)
+    {
+      lua_rawgeti(L, 2, i);
+      if (!lua_istable(L, 3))
+        break;
+
+      lua_getfield(L, 3, SERVICE_TYPE);
+      const char *svctype = luaL_checkstring(L, -1);
+
+      lua_getfield(L, 3, PROTO);
+      const char *proto = luaL_checkstring(L, -1);
+
+      lua_getfield(L, 3, PORT);
+      int port = luaL_checkint(L, -1);
+
+      lua_getfield(L, 3, INSTANCE_NAME);
+      const char *instname2 = luaL_optstring(L, -1, NULL);
+
+      // Note: we add txt entries iteratively to avoid having to size and
+      // allocate a buffer to hold them all.
+      err = mdns_service_add(instname2, svctype, proto, port, NULL, 0);
+      if (err != ESP_OK)
+        goto mdns_err;
+
+      lua_pop(L, 4); // svctype, proto, port, instname2
+
+      lua_getfield(L, 3, TXT);
+      if (lua_istable(L, 4))
+      {
+        lua_pushnil(L); // 5 is now table key
+        while(lua_next(L, 4)) // replaces 5 with actual key
+        {
+          // copy key, value so we can safely tostring() them
+          lua_pushvalue(L, 5);
+          lua_pushvalue(L, 6);
+
+          const char *key = luaL_checkstring(L, -2);
+          const char *val = luaL_checkstring(L, -1);
+
+          err = mdns_service_txt_item_set_for_host(
+#if ESP_IDF_VERSION_MAJOR >= 5
+            instname2,
+#endif
+            svctype, proto, hostname, key, val);
+          if (err != ESP_OK)
+            goto mdns_err;
+
+          lua_pop(L, 3); // value, key, value
+        }
+      }
+      lua_pop(L, 1); // txt table
+
+#if ESP_IDF_VERSION_MAJOR >= 5
+      // Subtype
+      lua_getfield(L, 1, SUBTYPE);
+      const char *subtype = luaL_optstring(L, -1, NULL);
+      if (subtype)
+      {
+        err = mdns_service_subtype_add_for_host(
+          instname2, svctype, proto, hostname, subtype);
+        if (err != ESP_OK)
+          goto mdns_err;
+      }
+      lua_pop(L, 1); // subtype
+#endif
+
+      lua_pop(L, 1); // services[i] table
+    }
+  }
+  lua_pop(L, 1); // services array
+
+  started = true;
+
+  // Return number of services we added
+  lua_pushinteger(L, i - 1);
+  return 1;
+
+mdns_err:
+  if (inited)
+  {
+    mdns_service_remove_all();
+    mdns_free();
+  }
+  return luaL_error(L, "mdns error: %s", esp_err_to_name(err));
+}
+
+
+static int lmdns_stop(lua_State *L)
+{
+  if (started)
+  {
+    mdns_service_remove_all();
+    started = false;
+  }
+  mdns_free();
+  return 0;
+}
+
+
+static int lmdns_query(lua_State *L)
+{
+  luaL_checktable(L, 1);
+  lua_settop(L, 1);
+
+  lua_getfield(L, 1, NAME);
+  const char *name = luaL_optstring(L, -1, NULL);
+
+  lua_getfield(L, 1, SERVICE_TYPE);
+  const char *svctype = luaL_optstring(L, -1, NULL);
+
+  lua_getfield(L, 1, PROTO);
+  const char *proto = luaL_optstring(L, -1, NULL);
+
+  lua_getfield(L, 1, QUERY_TYPE);
+  int qtype = luaL_checkint(L, -1);
+  if (!valid_query_type(qtype))
+    return luaL_error(L, "unknown mDNS query type");
+
+  lua_getfield(L, 1, TIMEOUT);
+  int timeout = luaL_optinteger(L, -1, DEFAULT_TIMEOUT_MS);
+
+  lua_getfield(L, 1, MAX_RESULTS);
+  int max_results = luaL_optinteger(L, -1, DEFAULT_MAX_RESULTS);
+
+  mdns_result_t *res = NULL;
+  esp_err_t err =
+    mdns_query(name, svctype, proto, qtype, timeout, max_results, &res);
+  if (err != ESP_OK)
+    return luaL_error(L, "mdns error: %s", esp_err_to_name(err));
+
+  lua_settop(L, 0);
+  lua_createtable(L, max_results, 0); // results array at idx 1
+
+  for (int n = 1; res; ++n, res = res->next)
+  {
+    // Reserve 5 slots, for SRV result host/port/instance/service_type/proto
+    lua_createtable(L, 0, 5); // result entry table at idx 2
+
+    if (res->instance_name)
+    {
+      lua_pushstring(L, res->instance_name);
+      lua_setfield(L, 2, INSTANCE_NAME);
+    }
+    if (res->service_type)
+    {
+      lua_pushstring(L, res->service_type);
+      lua_setfield(L, 2, SERVICE_TYPE);
+    }
+    if (res->proto)
+    {
+      lua_pushstring(L, res->proto);
+      lua_setfield(L, 2, PROTO);
+    }
+    if (res->hostname)
+    {
+      lua_pushstring(L, res->hostname);
+      lua_setfield(L, 2, HOSTNAME);
+    }
+    if (res->port)
+    {
+      lua_pushinteger(L, res->port);
+      lua_setfield(L, 2, PORT);
+    }
+    if (res->txt)
+    {
+      lua_createtable(L, 0, res->txt_count); // txt table at idx 3
+      for (int i = 0; i < res->txt_count; ++i)
+      {
+        lua_pushstring(L, res->txt[i].key);
+        if (res->txt[i].value)
+          lua_pushlstring(L, res->txt[i].value, res->txt_value_len[i]);
+        else
+          lua_pushliteral(L, "");
+        lua_settable(L, 3);
+      }
+      lua_setfield(L, 2, TXT);
+    }
+    if (res->addr)
+    {
+      lua_createtable(L, 1, 0); // address array table at idx 3
+      int i = 1;
+      for (mdns_ip_addr_t *a = res->addr; a; ++i, a = a->next)
+      {
+        char buf[IP_STR_SZ];
+        ipstr_esp(buf, &a->addr);
+        lua_pushstring(L, buf);
+        lua_rawseti(L, 3, i);
+      }
+      lua_setfield(L, 2, ADDRESSES);
+    }
+
+    lua_rawseti(L, 1, n); // insert into array of results
+  }
+
+  mdns_query_results_free(res);
+  return 1;
+}
+
+
+LROT_BEGIN(mdns, NULL, 0)
+  LROT_FUNCENTRY( start,     lmdns_start    )
+  LROT_FUNCENTRY( query,     lmdns_query    )
+  LROT_FUNCENTRY( stop,      lmdns_stop     )
+
+  LROT_NUMENTRY( TYPE_A,     MDNS_TYPE_A    )
+  LROT_NUMENTRY( TYPE_PTR,   MDNS_TYPE_PTR  )
+  LROT_NUMENTRY( TYPE_TXT,   MDNS_TYPE_TXT  )
+  LROT_NUMENTRY( TYPE_AAAA,  MDNS_TYPE_AAAA )
+  LROT_NUMENTRY( TYPE_SRV,   MDNS_TYPE_SRV  )
+  //LROT_NUMENTRY( TYPE_OPT,   MDNS_TYPE_OPT  )
+  //LROT_NUMENTRY( TYPE_NSEC,  MDNS_TYPE_NSEC )
+  LROT_NUMENTRY( TYPE_ANY,   MDNS_TYPE_ANY  )
+LROT_END(mdns, NULL, 0)
+
+NODEMCU_MODULE(MDNS, "mdns", mdns, NULL);