[PATCH v2] tools/hv: async name resolution in kvp_daemon

@@ -22,6 +22,8 @@ ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
 
 ALL_SCRIPTS := hv_get_dhcp_info.sh hv_get_dns_info.sh hv_set_ifconfig.sh
 
+$(OUTPUT)hv_kvp_daemon: LDFLAGS += -lpthread
+
 all: $(ALL_PROGRAMS)
 
 export srctree OUTPUT CC LD CFLAGS

@@ -41,6 +41,7 @@
 #include <net/if.h>
 #include <limits.h>
 #include <getopt.h>
+#include <pthread.h>
 
 /*
  * KVP protocol: The user mode component first registers with the

@@ -85,7 +86,7 @@ static char *processor_arch;
 static char *os_build;
 static char *os_version;
 static char *lic_version = "Unknown version";
-static char full_domain_name[HV_KVP_EXCHANGE_MAX_VALUE_SIZE];
+static char *full_domain_name;
 static struct utsname uts_buf;
 
 /*

@@ -1327,27 +1328,53 @@ static int kvp_set_ip_info(char *if_name, struct hv_kvp_ipaddr_value *new_val)
 	return error;
 }
 
-
-static void
-kvp_get_domain_name(char *buffer, int length)
+/*
+ * Async retrival of Fully Qualified Domain Name because getaddrinfo takes an
+ * unpredictable amount of time to finish.
+ */
+static void *kvp_getaddrinfo(void *p)
 {
-	struct addrinfo	hints, *info ;
-	int error = 0;
+	char *tmp, **str_ptr = (char **)p;
+	char hostname[HOST_NAME_MAX + 1];
+	struct addrinfo	*info, hints = {
+		.ai_family = AF_INET, /* Get only ipv4 addrinfo. */
+		.ai_socktype = SOCK_STREAM,
+		.ai_flags = AI_CANONNAME,
+	};
+	int ret;
+
+	if (gethostname(hostname, sizeof(hostname) - 1) < 0)
+		goto out;
 
-	gethostname(buffer, length);
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_family = AF_INET; /*Get only ipv4 addrinfo. */
-	hints.ai_socktype = SOCK_STREAM;
-	hints.ai_flags = AI_CANONNAME;
+	do {
+		ret = getaddrinfo(hostname, NULL, &hints, &info);
+		if (ret)
+			sleep(1);
+	} while (ret);
+
+	ret = asprintf(&tmp, "%s", info->ai_canonname);
+	freeaddrinfo(info);
+	if (ret <= 0)
+		goto out;
 
-	error = getaddrinfo(buffer, NULL, &hints, &info);
-	if (error != 0) {
-		snprintf(buffer, length, "getaddrinfo failed: 0x%x %s",
-			error, gai_strerror(error));
+	if (ret > HV_KVP_EXCHANGE_MAX_VALUE_SIZE)
+		tmp[HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1] = '\0';
+	*str_ptr = tmp;
+
+out:
+	pthread_exit(NULL);
+}
+
+static void kvp_obtain_domain_name(char **str_ptr)
+{
+	pthread_t t;
+
+	if (pthread_create(&t, NULL, kvp_getaddrinfo, str_ptr)) {
+		syslog(LOG_ERR, "pthread_create failed; error: %d %s",
+			errno, strerror(errno));
 		return;
 	}
-	snprintf(buffer, length, "%s", info->ai_canonname);
-	freeaddrinfo(info);
+	pthread_detach(t);
 }
 
 void print_usage(char *argv[])

@@ -1404,11 +1431,7 @@ int main(int argc, char *argv[])
 	 * Retrieve OS release information.
 	 */
 	kvp_get_os_info();
-	/*
-	 * Cache Fully Qualified Domain Name because getaddrinfo takes an
-	 * unpredictable amount of time to finish.
-	 */
-	kvp_get_domain_name(full_domain_name, sizeof(full_domain_name));
+	kvp_obtain_domain_name(&full_domain_name);
 
 	if (kvp_file_init()) {
 		syslog(LOG_ERR, "Failed to initialize the pools");

@@ -1573,7 +1596,7 @@ int main(int argc, char *argv[])
 
 		switch (hv_msg->body.kvp_enum_data.index) {
 		case FullyQualifiedDomainName:
-			strcpy(key_value, full_domain_name);
+			strcpy(key_value, full_domain_name ? : "");
 			strcpy(key_name, "FullyQualifiedDomainName");
 			break;
 		case IntegrationServicesVersion: