Extend platform for hostname resolution functionality

platform/linux.c

@@ -1,14 +1,22 @@
+#include<string.h>
+#include<sys/socket.h>
+#include<errno.h>
+#include<netdb.h>
+#include<arpa/inet.h>
+
 #include <pthread.h>
 #include <stdlib.h>
 
 #include "platform.h"
 
+const size_t max_receive_buffer_size = 4 * 4096; // 16 KB
+
 struct _PlatformData {
     pthread_t read_thread;
 };
 
 void initialize_platform(MQTTHandle *handle) {
-    handle->platform = calloc(sizeof(struct _PlatformData), 1);
+    handle->platform = calloc(1, sizeof(struct _PlatformData));
 }
 
 MQTTStatus run_read_task(MQTTHandle *handle, Reader reader) {
@@ -20,11 +28,38 @@ MQTTStatus run_read_task(MQTTHandle *handle, Reader reader) {
 }
 
 MQTTStatus join_read_task(MQTTHandle *handle) {
-    pthread_join(handle->platform->read_thread, NULL);
-
+    if (handle->platform->read_thread) {
+        pthread_join(handle->platform->read_thread, NULL);
+        handle->platform->read_thread = 0;
+    }
     return MQTT_STATUS_OK;
 }
 
 void release_platform(MQTTHandle *handle) {
     free(handle->platform);
 }
+
+
+bool hostname_to_ip(char *hostname , char *ip) {
+    struct addrinfo hints, *servinfo;
+    struct sockaddr_in *h;
+ 
+    memset(&hints, 0, sizeof(struct addrinfo));
+    hints.ai_family = AF_UNSPEC; // use AF_INET6 to force IPv6
+    hints.ai_socktype = SOCK_STREAM;
+ 
+    int ret = getaddrinfo(hostname, NULL, &hints, &servinfo);
+    if (ret != 0) {
+        // fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return false;
+    }
+ 
+    // loop through all the results and connect to the first we can
+    for(struct addrinfo *p = servinfo; p != NULL; p = p->ai_next) {
+        h = (struct sockaddr_in *)p->ai_addr;
+        strcpy(ip , inet_ntoa( h->sin_addr ) );
+    }
+     
+    freeaddrinfo(servinfo); // all done with this structure
+    return true;
+}

platform/platform.h

@@ -5,6 +5,12 @@
 
 typedef void (*Reader)(MQTTHandle *handle);
 
+/** maximum receiver buffer size, defined by platform */
+extern const size_t max_receive_buffer_size;
+
+
+bool hostname_to_ip(char *hostname, char *ip);
+
 /**
  * Initialize platform specific data
  *