mdns-search: add an example using the lwip mDNS service search code.

examples/mdns-search/.gitignore

@@ -0,0 +1 @@
+!local.mk

examples/mdns-search/FreeRTOSConfig.h

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+#define configUSE_TRACE_FACILITY 1
+#define configGENERATE_RUN_TIME_STATS 1
+#define portGET_RUN_TIME_COUNTER_VALUE() (RTC.COUNTER)
+#define portCONFIGURE_TIMER_FOR_RUN_TIME_STATS() {}
+
+/* Use the defaults for everything else */
+#include_next<FreeRTOSConfig.h>

examples/mdns-search/Makefile

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+# Makefile for mDNS search example
+PROGRAM=mdns-search
+EXTRA_COMPONENTS=extras/dhcpserver extras/wificfg
+
+# For the mDNS responder included with lwip:
+EXTRA_CFLAGS += -DLWIP_MDNS_RESPONDER=1 -DLWIP_NUM_NETIF_CLIENT_DATA=1 -DLWIP_NETIF_EXT_STATUS_CALLBACK=1 -DLWIP_MDNS_SEARCH=1
+
+# Avoid writing the wifi state to flash when using wificfg.
+EXTRA_CFLAGS += -DWIFI_PARAM_SAVE=0
+
+include ../../common.mk

examples/mdns-search/local.mk

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+FLASH_SIZE ?= 32

examples/mdns-search/mdsn-search.c

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+/*
+ * Example mDNS service search.
+ *
+ * Copyright (C) 2019 OurAirQuality.org
+ *
+ * Licensed under the Apache License, Version 2.0, January 2004 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *      http://www.apache.org/licenses/
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS WITH THE SOFTWARE.
+ *
+ */
+
+#include <string.h>
+#include <ctype.h>
+
+#include <espressif/esp_common.h>
+#include <espressif/user_interface.h>
+#include <esp/uart.h>
+#include <FreeRTOS.h>
+#include <task.h>
+
+#include "lwip/sockets.h"
+#include "lwip/apps/mdns.h"
+#include "lwip/prot/dns.h"
+#include "lwip/ip6.h"
+#include "lwip/ip6_addr.h"
+
+#include "wificfg/wificfg.h"
+
+#if !LWIP_MDNS_SEARCH
+#error "The LWIP_MDNS_SEARCH feature must be set."
+#endif
+
+#define SEARCH_SERVICE "_http"
+#define SEARCH_PROTO DNSSD_PROTO_TCP
+
+static void print_domain(const u8_t *src)
+{
+  u8_t i;
+
+  while (*src) {
+    u8_t label_len = *src;
+    src++;
+    for (i = 0; i < label_len; i++) {
+        putchar(src[i]);
+    }
+    src += label_len;
+    printf(".");
+  }
+}
+
+void result_fn(struct mdns_answer *answer, const char *varpart,
+               int varlen, int flags, void *arg)
+{
+    size_t i;
+
+    printf("Domain ");
+    print_domain(answer->info.domain->name);
+    printf(" ");
+
+    switch (answer->info.type) {
+    case DNS_RRTYPE_PTR:
+        printf("PTR ");
+        print_domain((u8_t *)varpart);
+        printf("\n");
+        break;
+
+    case DNS_RRTYPE_SRV:
+        /* Priority, weight, port fields. */
+        printf("SRV ");
+        print_domain((u8_t *)varpart + 6);
+        printf(" port %u\n", ((u16_t)varpart[4] << 8) | varpart[5]);
+        break;
+
+    case DNS_RRTYPE_TXT:
+        printf("TXT \"%s\"\n", varpart);
+        break;
+
+    case DNS_RRTYPE_A:
+        if (varlen == sizeof(ip4_addr_t)) {
+            ip4_addr_t addr;
+            char buf[16];
+            char *p;
+            SMEMCPY(&addr, varpart, sizeof(ip4_addr_t));
+            p = ip4addr_ntoa_r(&addr, buf, sizeof(buf));
+            if (p) printf("A %s\n", p);
+        }
+        break;
+
+#if LWIP_IPV6
+    case DNS_RRTYPE_AAAA:
+        if (varlen == sizeof(ip6_addr_p_t)) {
+            ip6_addr_p_t addrp;
+            ip6_addr_t addr;
+            char buf[64];
+            char *p;
+            SMEMCPY(addrp.addr, varpart, sizeof(ip6_addr_p_t));
+            ip6_addr_copy_from_packed(addr, addrp);
+            p = ip6addr_ntoa_r(&addr, buf, sizeof(buf));
+            if (p) printf("AAAA %s\n", p);
+        }
+        break;
+#endif
+
+    default:
+        printf("Unexpected type %u class %u, ans %p, part %p, len %d, flags %x, arg %p\n", answer->info.type, answer->info.klass, answer, varpart, varlen, flags, arg);
+        for (i = 0; i < varlen; i++)
+            printf(" %02x", varpart[i]);
+        printf("\n");
+    }
+}
+
+static void mdns_search_task(void *pvParameters)
+{
+    err_t err;
+    s8_t request_id;
+    struct netif *station_netif = sdk_system_get_netif(STATION_IF);
+
+    if (station_netif == NULL) {
+        vTaskDelete(NULL);
+    }
+
+    for (;;) {
+        printf("Starting mDNS search for %s : ", SEARCH_SERVICE);
+        LOCK_TCPIP_CORE();
+        err = mdns_search_service(NULL, SEARCH_SERVICE,
+                                  SEARCH_PROTO,
+                                  station_netif,
+                                  result_fn, NULL,
+                                  &request_id);
+        UNLOCK_TCPIP_CORE();
+        printf("request_id %d, error %d\n", request_id, err);
+
+        vTaskDelay(10000 / portTICK_PERIOD_MS);
+        printf("Stopping mDNS search\n");
+
+        LOCK_TCPIP_CORE();
+        mdns_search_stop(request_id);
+        UNLOCK_TCPIP_CORE();
+    }
+}
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+    printf("SDK version:%s\n", sdk_system_get_sdk_version());
+
+    wificfg_init(80, NULL);
+
+    xTaskCreate(&mdns_search_task, "mDNS search", 384, NULL, 1, NULL);
+}