Code

Squashed-Commit: Cleanup consts/enums, reduced magic const usage, NULL
authorClaudius Zingerli <gitmail@zeuz.ch>
Sun, 6 Sep 2015 16:27:52 +0000 (18:27 +0200)
committerClaudius Zingerli <gitmail@zeuz.ch>
Fri, 29 Apr 2016 15:34:30 +0000 (17:34 +0200)
checks, Added sequence number randomization, Fixed 32bit builds, Fixed
reachability checks (push NAN data if clock source is not reachable)
Doc: Removed comments about seq nr check (implemented randomization)

src/chrony.c

index 261f67cf0385e951cb1124d30922ca932109fb8a..1a17cda0774d27ba2c6699418bcfbddb84d8bbcd 100644 (file)
@@ -1,13 +1,14 @@
 /* chrony plugin for collectd
    (c) 2015 by Claudius M Zingerli, ZSeng
    Internas roughly based on the ntpd plugin
+   Some functions copied from chronyd/web (marked)
    License: GPL2
 */
 /* TODO:
  *     - More robust udp parsing (using offsets instead of structs?)
+ *       -> Currently chrony parses its data the same way as we do (using structs)
  *     - Plausibility checks on values received
- *
- *
+ *       -> Done at higher levels
  */
 
 /* getaddrinfo */
 #include <sys/socket.h>
 #include <netdb.h>
 
+#include <arpa/inet.h> /* ntohs/ntohl */
+
 #include "collectd.h"
 #include "common.h" /* auxiliary functions */
 #include "plugin.h" /* plugin_register_*, plugin_dispatch_values */
 
+#define CONFIG_KEY_HOST    "Host"
+#define CONFIG_KEY_PORT    "Port"
+#define CONFIG_KEY_TIMEOUT "Timeout"
+
+#define URAND_DEVICE_PATH "/dev/urandom" /* Used to initialize seq nr generator*/
+#define RAND_DEVICE_PATH  "/dev/random"  /* Used to initialize seq nr generator (fall back)*/
+
 static const char *g_config_keys[] =
 {
-        "Host",
-        "Port",
-       "Timeout"
+        CONFIG_KEY_HOST,
+        CONFIG_KEY_PORT,
+       CONFIG_KEY_TIMEOUT
 };
 
-static int g_config_keys_num = STATIC_ARRAY_SIZE (g_config_keys);
-
-# define CHRONY_DEFAULT_HOST "localhost"
-# define CHRONY_DEFAULT_PORT "323"
-# define CHRONY_DEFAULT_TIMEOUT 2
-
-/* Copied from chrony/candm.h */
+static int    g_config_keys_num = STATIC_ARRAY_SIZE (g_config_keys);
+static int    g_is_connected    =  0;
+static int    g_chrony_socket   = -1;
+static time_t g_chrony_timeout  = -1;
+static char  *g_chrony_host     =  NULL;
+static char  *g_chrony_port     =  NULL;
+static char  *g_plugin_instance =  NULL;
+static uint32_t g_chrony_rand   =  1;
+static uint32_t g_chrony_seq_is_initialized = 0;
+
+#define PLUGIN_NAME_SHORT "chrony"
+#define PLUGIN_NAME       PLUGIN_NAME_SHORT " plugin"
+#define DAEMON_NAME       PLUGIN_NAME_SHORT
+#define CHRONY_DEFAULT_HOST "localhost"
+#define CHRONY_DEFAULT_PORT "323"
+#define CHRONY_DEFAULT_TIMEOUT 2
+
+/* Return codes (collectd expects non-zero on errors) */
+#define CHRONY_RC_OK    (int)0
+#define CHRONY_RC_FAIL  (int)1
+
+/* Variables adapted from chrony/candm.h */
 /*BEGIN*/
 #define PROTO_VERSION_NUMBER 6
+#define IPADDR_UNSPEC 0
+#define IPADDR_INET4  1
+#define IPADDR_INET6  2
+#define IPV6_STR_MAX_SIZE (8*4+7+1)
 
-enum
+typedef enum
+{
+       PKT_TYPE_CMD_REQUEST = 1,
+       PKT_TYPE_CMD_REPLY   = 2
+} ePacketType;
+
+typedef enum
 {
        REQ_N_SOURCES    = 14,
        REQ_SOURCE_DATA  = 15,
@@ -44,20 +79,17 @@ enum
        REQ_SOURCE_STATS = 34
 } eDaemonRequests;
 
-#define PKT_TYPE_CMD_REQUEST 1
-#define PKT_TYPE_CMD_REPLY 2
 
-#define RPY_NULL 1
-#define RPY_N_SOURCES 2
-#define RPY_SOURCE_DATA 3
-#define RPY_MANUAL_TIMESTAMP 4
-#define RPY_TRACKING 5
-#define RPY_SOURCE_STATS 6
-#define RPY_RTC 7
-
-#define IPADDR_UNSPEC 0
-#define IPADDR_INET4 1
-#define IPADDR_INET6 2
+typedef enum
+{
+       RPY_NULL             = 1,
+       RPY_N_SOURCES        = 2,
+       RPY_SOURCE_DATA      = 3,
+       RPY_MANUAL_TIMESTAMP = 4,
+       RPY_TRACKING         = 5,
+       RPY_SOURCE_STATS     = 6,
+       RPY_RTC              = 7
+} eDaemonReplies;
 
 #define ATTRIB_PACKED __attribute__((packed))
 typedef struct ATTRIB_PACKED
@@ -71,42 +103,42 @@ typedef struct ATTRIB_PACKED
        uint32_t tv_sec_low;
        uint32_t tv_nsec;
 } tTimeval;
-
 /*END*/
 
 typedef enum
 {
-       STT_SUCCESS = 0,
-       STT_FAILED  = 1,
-       STT_UNAUTH  = 2,
-       STT_INVALID = 3,
-       STT_NOSUCHSOURCE = 4,
-       STT_INVALIDTS  = 5,
-       STT_NOTENABLED = 6,
-       STT_BADSUBNET  = 7,
-       STT_ACCESSALLOWED = 8,
-       STT_ACCESSDENIED  = 9,
-       STT_NOHOSTACCESS  = 10,
+       STT_SUCCESS        =  0,
+       STT_FAILED         =  1,
+       STT_UNAUTH         =  2,
+       STT_INVALID        =  3,
+       STT_NOSUCHSOURCE   =  4,
+       STT_INVALIDTS      =  5,
+       STT_NOTENABLED     =  6,
+       STT_BADSUBNET      =  7,
+       STT_ACCESSALLOWED  =  8,
+       STT_ACCESSDENIED   =  9,
+       STT_NOHOSTACCESS   = 10,
        STT_SOURCEALREADYKNOWN = 11,
        STT_TOOMANYSOURCES = 12,
-       STT_NORTC      = 13,
-       STT_BADRTCFILE = 14,
-       STT_INACTIVE   = 15,
-       STT_BADSAMPLE  = 16,
-       STT_INVALIDAF  = 17,
-       STT_BADPKTVERSION = 18,
-       STT_BADPKTLENGTH = 19,
+       STT_NORTC          = 13,
+       STT_BADRTCFILE     = 14,
+       STT_INACTIVE       = 15,
+       STT_BADSAMPLE      = 16,
+       STT_INVALIDAF      = 17,
+       STT_BADPKTVERSION  = 18,
+       STT_BADPKTLENGTH   = 19
 } eChrony_Status;
 
+/* Chrony client request packets */
 typedef struct ATTRIB_PACKED
 {
-       uint8_t f_dummy0[80];
+       uint8_t f_dummy0[80]; //Chrony expects 80bytes dummy data (Avoiding UDP Amplification)
 } tChrony_Req_Tracking;
 
 typedef struct ATTRIB_PACKED
 {
        uint32_t f_n_sources;
-} tChrony_N_Sources;
+} tChrony_Req_N_Sources;
 
 typedef struct ATTRIB_PACKED
 {
@@ -120,13 +152,43 @@ typedef struct ATTRIB_PACKED
        uint8_t f_dummy0[56];
 } tChrony_Req_Source_stats;
 
-#define IPV6_STR_MAX_SIZE 40
+typedef struct ATTRIB_PACKED
+{
+       struct
+       {
+               uint8_t  f_version;
+               uint8_t  f_type;
+               uint8_t  f_dummy0;
+               uint8_t  f_dummy1;
+               uint16_t f_cmd;
+               uint16_t f_cmd_try;
+               uint32_t f_seq;
+
+               uint32_t f_dummy2;
+               uint32_t f_dummy3;
+       } header; /* Packed: 20Bytes */
+       union
+       {
+               tChrony_Req_N_Sources    n_sources;
+               tChrony_Req_Source_data  source_data;
+               tChrony_Req_Source_stats source_stats;
+               tChrony_Req_Tracking     tracking;
+       } body;
+       uint8_t padding[4+16]; /* Padding to match minimal response size */
+} tChrony_Request;
+
+/* Chrony daemon response packets */
+typedef struct ATTRIB_PACKED
+{
+       uint32_t f_n_sources;
+} tChrony_Resp_N_Sources;
+
 typedef struct ATTRIB_PACKED
 {
        union
        {
                uint32_t ip4;
-               uint8_t ip6[16];
+               uint8_t  ip6[16];
        } addr;
        uint16_t f_family;
 } tChrony_IPAddr;
@@ -134,41 +196,41 @@ typedef struct ATTRIB_PACKED
 typedef struct ATTRIB_PACKED
 {
        tChrony_IPAddr addr;
-       uint16_t dummy; /* FIXME: Strange dummy space. Needed on gcc 4.8.3 on x86_64 */
-       int16_t  f_poll;    // 2^f_poll = Time between polls (s)
-       uint16_t f_stratum; //Remote clock stratum
-       uint16_t f_state;   //0 = RPY_SD_ST_SYNC,    1 = RPY_SD_ST_UNREACH,   2 = RPY_SD_ST_FALSETICKER
-                                   //3 = RPY_SD_ST_JITTERY, 4 = RPY_SD_ST_CANDIDATE, 5 = RPY_SD_ST_OUTLIER
-       uint16_t f_mode;    //0 = RPY_SD_MD_CLIENT,  1 = RPY_SD_MD_PEER,      2 = RPY_SD_MD_REF
-       uint16_t f_flags;   //unused
-       uint16_t f_reachability; //???
-
-       uint32_t f_since_sample; //Time since last sample (s)
-       tFloat   f_origin_latest_meas; //
-       tFloat   f_latest_meas;        //
-       tFloat   f_latest_meas_err;    //
+       uint16_t dummy;     /* FIXME: Strange dummy space. Needed on gcc 4.8.3/clang 3.4.1 on x86_64 */
+       int16_t  f_poll;    /* 2^f_poll = Time between polls (s) */
+       uint16_t f_stratum; /* Remote clock stratum */
+       uint16_t f_state;   /* 0 = RPY_SD_ST_SYNC,    1 = RPY_SD_ST_UNREACH,   2 = RPY_SD_ST_FALSETICKER */
+                                   /* 3 = RPY_SD_ST_JITTERY, 4 = RPY_SD_ST_CANDIDATE, 5 = RPY_SD_ST_OUTLIER     */
+       uint16_t f_mode;    /* 0 = RPY_SD_MD_CLIENT,  1 = RPY_SD_MD_PEER,      2 = RPY_SD_MD_REF         */
+       uint16_t f_flags;   /* unused */
+       uint16_t f_reachability;       /* Bit mask of successfull tries to reach the source */
+
+       uint32_t f_since_sample;       /* Time since last sample (s) */
+       tFloat   f_origin_latest_meas; /*  */
+       tFloat   f_latest_meas;        /*  */
+       tFloat   f_latest_meas_err;    /*  */
 } tChrony_Resp_Source_data;
 
 typedef struct ATTRIB_PACKED
 {
        uint32_t f_ref_id;
        tChrony_IPAddr addr;
-       uint16_t dummy; /* FIXME: Strange dummy space. Needed on gcc 4.8.3 on x86_64 */
-       uint32_t f_n_samples;     //Number of measurements done
-       uint32_t f_n_runs;        //How many measurements to come
-       uint32_t f_span_seconds;  //For how long we're measuring
-       tFloat   f_rtc_seconds_fast;  //???
-       tFloat   f_rtc_gain_rate_ppm; //Estimated relative frequency error
-       tFloat   f_skew_ppm;          //Clock skew (ppm) (worst case freq est error (skew: peak2peak))
-       tFloat   f_est_offset;        //Estimated offset of source
-       tFloat   f_est_offset_err;    //Error of estimation
+       uint16_t dummy;               /* FIXME: Strange dummy space. Needed on gcc 4.8.3/clang 3.4.1 on x86_64 */
+       uint32_t f_n_samples;         /* Number of measurements done   */
+       uint32_t f_n_runs;            /* How many measurements to come */
+       uint32_t f_span_seconds;      /* For how long we're measuring  */
+       tFloat   f_rtc_seconds_fast;  /* ??? */
+       tFloat   f_rtc_gain_rate_ppm; /* Estimated relative frequency error */
+       tFloat   f_skew_ppm;          /* Clock skew (ppm) (worst case freq est error (skew: peak2peak)) */
+       tFloat   f_est_offset;        /* Estimated offset of source */
+       tFloat   f_est_offset_err;    /* Error of estimation        */
 } tChrony_Resp_Source_stats;
 
 typedef struct ATTRIB_PACKED
 {
        uint32_t f_ref_id;
        tChrony_IPAddr addr;
-       uint16_t dummy; /* FIXME: Strange dummy space. Needed on gcc 4.8.3 on x86_64 */
+       uint16_t dummy;     /* FIXME: Strange dummy space. Needed on gcc 4.8.3/clang 3.4.1 on x86_64 */
        uint16_t f_stratum;
        uint16_t f_leap_status;
        tTimeval f_ref_time;
@@ -183,31 +245,6 @@ typedef struct ATTRIB_PACKED
        tFloat   f_last_update_interval;
 } tChrony_Resp_Tracking;
 
-typedef struct ATTRIB_PACKED
-{
-       struct
-       {
-               uint8_t  f_version;
-               uint8_t  f_type;
-               uint8_t  f_dummy0;
-               uint8_t  f_dummy1;
-               uint16_t f_cmd;
-               uint16_t f_cmd_try;
-               uint32_t f_seq;
-
-               uint32_t f_dummy2;
-               uint32_t f_dummy3;
-       } header; /* Packed: 20Bytes */
-       union
-       {
-               tChrony_N_Sources        n_sources;
-               tChrony_Req_Source_data  source_data;
-               tChrony_Req_Source_stats source_stats;
-               tChrony_Req_Tracking     tracking;
-       } body;
-       uint8_t padding[4+16]; /* Padding to match minimal response size */
-} tChrony_Request;
-
 typedef struct ATTRIB_PACKED
 {
        struct
@@ -229,7 +266,7 @@ typedef struct ATTRIB_PACKED
 
        union
        {
-               tChrony_N_Sources         n_sources;
+               tChrony_Resp_N_Sources         n_sources;
                tChrony_Resp_Source_data  source_data;
                tChrony_Resp_Source_stats source_stats;
                tChrony_Resp_Tracking     tracking;
@@ -238,37 +275,30 @@ typedef struct ATTRIB_PACKED
        uint8_t padding[1024];
 } tChrony_Response;
 
-static int g_is_connected = 0;
-static int g_chrony_socket = -1;
-static time_t g_chrony_timeout = 0;
-static char *g_chrony_host = NULL;
-static char *g_chrony_port = NULL;
-static uint32_t g_chrony_seq = 0;
 
 /*****************************************************************************/
 /* Internal functions */
 /*****************************************************************************/
-/* Code from: http://long.ccaba.upc.edu/long/045Guidelines/eva/ipv6.html#daytimeClient6 */
+/* Code adapted from: http://long.ccaba.upc.edu/long/045Guidelines/eva/ipv6.html#daytimeClient6 */
 /*BEGIN*/
-static int
-connect_client (const char *p_hostname,
-                const char *service,
-                int         family,
-                int         socktype)
+static int connect_client (const char *p_hostname,
+                const char *p_service,
+                int         p_family,
+                int         p_socktype)
 {
-       struct addrinfo hints, *res, *ressave;
+       struct addrinfo hints, *res=NULL, *ressave=NULL;
        int n, sockfd;
 
        memset(&hints, 0, sizeof(struct addrinfo));
 
-       hints.ai_family family;
-       hints.ai_socktype = socktype;
+       hints.ai_family   = p_family;
+       hints.ai_socktype = p_socktype;
 
-       n = getaddrinfo(p_hostname, service, &hints, &res);
+       n = getaddrinfo(p_hostname, p_service, &hints, &res);
 
        if (n <0)
        {
-               ERROR ("chrony plugin: getaddrinfo error:: [%s]", gai_strerror(n));
+               ERROR (PLUGIN_NAME ": getaddrinfo error:: [%s]", gai_strerror(n));
                return -1;
        }
 
@@ -278,13 +308,14 @@ connect_client (const char *p_hostname,
        while (res)
        {
                sockfd = socket(res->ai_family,
-               res->ai_socktype,
-               res->ai_protocol);
+                               res->ai_socktype,
+                               res->ai_protocol);
 
                if (!(sockfd < 0))
                {
                        if (connect(sockfd, res->ai_addr, res->ai_addrlen) == 0)
                        {
+                               /* Success */
                                break;
                        }
 
@@ -297,17 +328,19 @@ connect_client (const char *p_hostname,
        freeaddrinfo(ressave);
        return sockfd;
 }
+
 /*Code originally from: git://git.tuxfamily.org/gitroot/chrony/chrony.git:util.c */
 /*char * UTI_IPToString(IPAddr *addr)*/
-char * niptoha(const tChrony_IPAddr *addr,char *p_buf, size_t p_buf_size)
+static char * niptoha(const tChrony_IPAddr *addr,char *p_buf, size_t p_buf_size)
 {
+       int rc=1;
        unsigned long a, b, c, d, ip;
        const uint8_t *ip6;
 
        switch (ntohs(addr->f_family))
        {
        case IPADDR_UNSPEC:
-               snprintf(p_buf, p_buf_size, "[UNSPEC]");
+               rc=snprintf(p_buf, p_buf_size, "[UNSPEC]");
        break;
        case IPADDR_INET4:
                ip = ntohl(addr->addr.ip4);
@@ -315,35 +348,38 @@ char * niptoha(const tChrony_IPAddr *addr,char *p_buf, size_t p_buf_size)
                b = (ip>>16) & 0xff;
                c = (ip>> 8) & 0xff;
                d = (ip>> 0) & 0xff;
-               snprintf(p_buf, p_buf_size, "%ld.%ld.%ld.%ld", a, b, c, d);
+               rc=snprintf(p_buf, p_buf_size, "%ld.%ld.%ld.%ld", a, b, c, d);
        break;
        case IPADDR_INET6:
                ip6 = addr->addr.ip6;
 
 #ifdef FEAT_IPV6
-               inet_ntop(AF_INET6, ip6, p_buf, p_bug_size);
+               rc=inet_ntop(AF_INET6, ip6, p_buf, p_bug_size);
+#else
+#if defined(BYTE_ORDER) && (BYTE_ORDER == BIG_ENDIAN)
+               rc=snprintf(p_buf, p_buf_size, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+                       ip6[15], ip6[14], ip6[13], ip6[12], ip6[11], ip6[10], ip6[9], ip6[8],
+                       ip6[7], ip6[6], ip6[5], ip6[4], ip6[3], ip6[2], ip6[1], ip6[0]);
 #else
-#if 0
-/* FIXME: Detect little endian systems */
-               snprintf(p_buf, p_buf_size, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+               rc=snprintf(p_buf, p_buf_size, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                        ip6[0], ip6[1], ip6[2], ip6[3], ip6[4], ip6[5], ip6[6], ip6[7],
                        ip6[8], ip6[9], ip6[10], ip6[11], ip6[12], ip6[13], ip6[14], ip6[15]);
-#else
-               snprintf(p_buf, p_buf_size, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
-                       ip6[5], ip6[4], ip6[3], ip6[2], ip6[1], ip6[0], ip6[9], ip6[8],
-                       ip6[7], ip6[6], ip6[5], ip6[4], ip6[3], ip6[2], ip6[1], ip6[0]);
 #endif
 #endif
        break;
        default:
-               snprintf(p_buf, p_buf_size, "[UNKNOWN]");
+               rc=snprintf(p_buf, p_buf_size, "[UNKNOWN]");
        }
+       assert(rc>0);
        return p_buf;
 }
 /*END*/
 
 static int chrony_set_timeout()
 {
+       /*Set the socket's  timeout to g_chrony_timeout; a value of 0 signals infinite timeout*/
+       /*Returns 0 on success, !0 on error (check errno)*/
+
        struct timeval tv;
        tv.tv_sec  = g_chrony_timeout;
        tv.tv_usec = 0;
@@ -351,54 +387,60 @@ static int chrony_set_timeout()
        assert(g_chrony_socket>=0);
        if (setsockopt(g_chrony_socket, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,sizeof(struct timeval)) < 0)
        {
-               return 1;
+               return CHRONY_RC_FAIL;
        }
-       return 0;
+       return CHRONY_RC_OK;
 }
 
 static int chrony_connect()
 {
+       /*Connects to the chrony daemon*/
+       /*Returns 0 on success, !0 on error (check errno)*/
+       int socket;
+
        if (g_chrony_host == NULL)
        {
                g_chrony_host = strdup(CHRONY_DEFAULT_HOST);
+               assert(g_chrony_host);
        }
        if (g_chrony_port == NULL)
        {
                g_chrony_port = strdup(CHRONY_DEFAULT_PORT);
+               assert(g_chrony_port);
        }
-       if (g_chrony_timeout <= 0)
+       if (g_chrony_timeout < 0)
        {
                g_chrony_timeout = CHRONY_DEFAULT_TIMEOUT;
+               assert(g_chrony_timeout>=0);
        }
        
 
-       DEBUG("chrony plugin: Connecting to %s:%s", g_chrony_host, g_chrony_port);
-       int socket = connect_client(g_chrony_host, g_chrony_port,  AF_UNSPEC, SOCK_DGRAM);
+       DEBUG(PLUGIN_NAME ": Connecting to %s:%s", g_chrony_host, g_chrony_port);
+       socket = connect_client(g_chrony_host, g_chrony_port,  AF_UNSPEC, SOCK_DGRAM);
        if (socket < 0)
        {
-               ERROR ("chrony plugin: Error connecting to daemon. Errno = %d", errno);
-               return 1;
+               ERROR (PLUGIN_NAME ": Error connecting to daemon. Errno = %d", errno);
+               return CHRONY_RC_FAIL;
        }
-       DEBUG("chrony plugin: Connected");
+       DEBUG(PLUGIN_NAME ": Connected");
        g_chrony_socket = socket;
 
        if (chrony_set_timeout())
        {
-               ERROR ("chrony plugin: Error setting timeout to %lds. Errno = %d", g_chrony_timeout, errno);
-               return 1;
+               ERROR (PLUGIN_NAME ": Error setting timeout to %lds. Errno = %d", g_chrony_timeout, errno);
+               return CHRONY_RC_FAIL;
        }
-       return 0;
+       return CHRONY_RC_OK;
 }
 
 static int chrony_send_request(const tChrony_Request *p_req, size_t p_req_size)
 {
        if (send(g_chrony_socket,p_req,p_req_size,0) < 0)
        {
-               ERROR ("chrony plugin: Error sending packet. Errno = %d", errno);
-               return 1;
-       } else {
-               return 0;
+               ERROR (PLUGIN_NAME ": Error sending packet. Errno = %d", errno);
+               return CHRONY_RC_FAIL;
        }
+       return CHRONY_RC_OK;
 }
 
 static int chrony_recv_response(tChrony_Response *p_resp, size_t p_resp_max_size, size_t *p_resp_size)
@@ -406,11 +448,11 @@ static int chrony_recv_response(tChrony_Response *p_resp, size_t p_resp_max_size
        ssize_t rc = recv(g_chrony_socket,p_resp,p_resp_max_size,0);
        if (rc <= 0)
        {
-               ERROR ("chrony plugin: Error receiving packet. Errno = %d", errno);
-               return 1;
+               ERROR (PLUGIN_NAME ": Error receiving packet: %s (%d)", strerror(errno), errno);
+               return CHRONY_RC_FAIL;
        } else {
                *p_resp_size = rc;
-               return 0;
+               return CHRONY_RC_OK;
        }
 }
 
@@ -427,8 +469,8 @@ static int chrony_query(const int p_command, tChrony_Request *p_req, tChrony_Res
                {
                        g_is_connected = 1;
                } else {
-                       ERROR ("chrony plugin: Unable to connect. Errno = %d", errno);
-                       return 1;
+                       ERROR (PLUGIN_NAME ": Unable to connect. Errno = %d", errno);
+                       return CHRONY_RC_FAIL;
                }
        }
 
@@ -466,7 +508,7 @@ static int chrony_query(const int p_command, tChrony_Request *p_req, tChrony_Res
                        valid_command = 1;
                break;
                default:
-                       ERROR ("chrony plugin: Unknown request command (Was: %d)", p_command);
+                       ERROR (PLUGIN_NAME ": Unknown request command (Was: %d)", p_command);
                break;
                }
 
@@ -475,74 +517,74 @@ static int chrony_query(const int p_command, tChrony_Request *p_req, tChrony_Res
                        break;
                }
 
+               uint32_t seq_nr = rand_r(&g_chrony_rand);
                p_req->header.f_cmd     = htons(p_command);
                p_req->header.f_cmd_try = 0;
-               p_req->header.f_seq     = htonl(g_chrony_seq++);
+               p_req->header.f_seq     = seq_nr;
                
-               DEBUG("chrony plugin: Sending request (.cmd = %d, .seq = %d)",p_command,g_chrony_seq-1);
+               DEBUG(PLUGIN_NAME ": Sending request (.cmd = %d, .seq = %d)",p_command,seq_nr);
                if (chrony_send_request(p_req,req_size) != 0)
                {
                        break;
                }
 
-               DEBUG("chrony plugin: Waiting for response");
+               DEBUG(PLUGIN_NAME ": Waiting for response");
                if (chrony_recv_response(p_resp,resp_size,p_resp_size) != 0)
                {
                        break;
                }
-               DEBUG("chrony plugin: Received response: .version = %u, .type = %u, .cmd = %u, .reply = %u, .status = %u, .seq = %u",
+               DEBUG(PLUGIN_NAME ": Received response: .version = %u, .type = %u, .cmd = %u, .reply = %u, .status = %u, .seq = %u",
                                p_resp->header.f_version,p_resp->header.f_type,ntohs(p_resp->header.f_cmd),
                                ntohs(p_resp->header.f_reply),ntohs(p_resp->header.f_status),ntohl(p_resp->header.f_seq));
 
                if (p_resp->header.f_version != p_req->header.f_version)
                {
-                       ERROR("chrony plugin: Wrong protocol version (Was: %d, expected: %d)", p_resp->header.f_version, p_req->header.f_version);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Wrong protocol version (Was: %d, expected: %d)", p_resp->header.f_version, p_req->header.f_version);
+                       return CHRONY_RC_FAIL;
                }
                if (p_resp->header.f_type != PKT_TYPE_CMD_REPLY)
                {
-                       ERROR("chrony plugin: Wrong packet type (Was: %d, expected: %d)", p_resp->header.f_type, PKT_TYPE_CMD_REPLY);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Wrong packet type (Was: %d, expected: %d)", p_resp->header.f_type, PKT_TYPE_CMD_REPLY);
+                       return CHRONY_RC_FAIL;
                }
-               if (p_resp->header.f_seq != p_req->header.f_seq)
+               if (p_resp->header.f_seq != seq_nr)
                {
                        /* FIXME: Implement sequence number handling */
-                       ERROR("chrony plugin: Unexpected sequence number (Was: %d, expected: %d)", p_resp->header.f_seq, p_req->header.f_seq);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Unexpected sequence number (Was: %d, expected: %d)", p_resp->header.f_seq, p_req->header.f_seq);
+                       return CHRONY_RC_FAIL;
                }
                if (p_resp->header.f_cmd != p_req->header.f_cmd)
                {
-                       ERROR("chrony plugin: Wrong reply command (Was: %d, expected: %d)", p_resp->header.f_cmd, p_req->header.f_cmd);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Wrong reply command (Was: %d, expected: %d)", p_resp->header.f_cmd, p_req->header.f_cmd);
+                       return CHRONY_RC_FAIL;
                }
 
                if (ntohs(p_resp->header.f_reply) !=  resp_code)
                {
-                       ERROR("chrony plugin: Wrong reply code (Was: %d, expected: %d)", ntohs(p_resp->header.f_reply), resp_code);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Wrong reply code (Was: %d, expected: %d)", ntohs(p_resp->header.f_reply), resp_code);
+                       return CHRONY_RC_FAIL;
                }
 
                switch (p_resp->header.f_status)
                {
                case STT_SUCCESS:
-                       DEBUG("chrony plugin: Reply packet status STT_SUCCESS");
+                       DEBUG(PLUGIN_NAME ": Reply packet status STT_SUCCESS");
                        break;
                default:
-                       ERROR("chrony plugin: Reply packet contains error status: %d (expected: %d)", p_resp->header.f_status, STT_SUCCESS);
-                       return 1;
+                       ERROR(PLUGIN_NAME ": Reply packet contains error status: %d (expected: %d)", p_resp->header.f_status, STT_SUCCESS);
+                       return CHRONY_RC_FAIL;
                }
 
-               //Good result
-               return 0;
+               /* Good result */
+               return CHRONY_RC_OK;
        } while (0);
        
-       //Some error occured
-       return 1;
+       /* Some error occured */
+       return CHRONY_RC_FAIL;
 }
 
 static void chrony_init_req(tChrony_Request *p_req)
 {
-       DEBUG("chrony plugin: Clearing %ld bytes",sizeof(*p_req));
        memset(p_req,0,sizeof(*p_req));
        p_req->header.f_version = PROTO_VERSION_NUMBER;
        p_req->header.f_type    = PKT_TYPE_CMD_REQUEST;
@@ -562,8 +604,10 @@ static void chrony_init_req(tChrony_Request *p_req)
 #define FLOAT_COEF_MAX (-FLOAT_COEF_MIN - 1)
 
 /* double UTI_tFloatNetworkToHost(tFloat f) */
-double ntohf(tFloat p_float)
+static double ntohf(tFloat p_float)
 {
+       /* Convert tFloat in Network-bit-order to double in host-bit-order */
+
        int32_t exp, coef;
        uint32_t uval;
 
@@ -574,7 +618,7 @@ double ntohf(tFloat p_float)
                exp -= 1 << FLOAT_EXP_BITS;
        }
 
-       //coef = (x << FLOAT_EXP_BITS) >> FLOAT_EXP_BITS;
+       /* coef = (x << FLOAT_EXP_BITS) >> FLOAT_EXP_BITS; */
        coef = uval % (1U << FLOAT_COEF_BITS);
        if (coef >= 1 << (FLOAT_COEF_BITS - 1))
        {
@@ -584,26 +628,87 @@ double ntohf(tFloat p_float)
 }
 /*END*/
 
-/* Code from: collectd/src/ntpd.c (MIT) */
-/*BEGIN*/
-static void chrony_push_data(char *type, char *type_inst, double value)
+static void chrony_push_data(char *p_type, char *p_type_inst, double p_value)
 {
        value_t values[1];
        value_list_t vl = VALUE_LIST_INIT;
 
-       values[0].gauge = value; //TODO: Check type??? (counter, gauge, derive, absolute)
+       values[0].gauge = p_value; /* TODO: Check type??? (counter, gauge, derive, absolute) */
 
        vl.values     = values;
        vl.values_len = 1;
-       sstrncpy (vl.host,            hostname_g, sizeof (vl.host));
-       sstrncpy (vl.plugin,          "chrony",   sizeof (vl.plugin));
-       sstrncpy (vl.plugin_instance, "",         sizeof (vl.plugin_instance));
-       sstrncpy (vl.type,            type,       sizeof (vl.type));
-       sstrncpy (vl.type_instance,   type_inst,  sizeof (vl.type_instance));
+
+       /* XXX: Shall g_chrony_host/g_chrony_port be reflected in the plugin's output? */
+       /* hostname_g is set in daemon/collectd.c (from config, via gethostname or by resolving localhost) */
+       /* defined as: char hostname_g[DATA_MAX_NAME_LEN]; (never NULL) */
+                                      { sstrncpy (vl.host,            hostname_g,          sizeof (vl.host)); }
+                                      { sstrncpy (vl.plugin,          PLUGIN_NAME_SHORT,   sizeof (vl.plugin)); }
+       if (g_plugin_instance != NULL) { sstrncpy (vl.plugin_instance, g_plugin_instance,   sizeof (vl.plugin_instance)); }
+       if (p_type            != NULL) { sstrncpy (vl.type,            p_type,              sizeof (vl.type)); }
+       if (p_type_inst       != NULL) { sstrncpy (vl.type_instance,   p_type_inst,         sizeof (vl.type_instance)); }
 
        plugin_dispatch_values (&vl);
 }
-/*END*/
+
+
+static void chrony_push_data_valid(char *p_type, char *p_type_inst, const int p_is_valid, double p_value)
+{
+       /* Push real value if p_is_valid is true, push NAN if p_is_valid is not true (idea from ntp plugin)*/
+       if (p_is_valid == 0)
+       {
+               p_value = NAN;
+       }
+       chrony_push_data(p_type, p_type_inst, p_value);
+}
+
+
+static int chrony_init_seq()
+{
+       /* Initialize the sequence number generator from /dev/urandom */
+
+       /* Try urandom */
+       int fh = open(URAND_DEVICE_PATH, O_RDONLY);
+       if (fh >= 0)
+       {
+               ssize_t rc = read(fh, &g_chrony_rand, sizeof(g_chrony_rand));
+               if (rc != sizeof(g_chrony_rand))
+               {
+                       ERROR (PLUGIN_NAME ": Reading from random source \'%s\'failed: %s (%d)", URAND_DEVICE_PATH, strerror(errno), errno);
+                       close(fh);
+                       return CHRONY_RC_FAIL;
+               }
+               close(fh);
+               DEBUG(PLUGIN_NAME ": Seeding RNG from " URAND_DEVICE_PATH);
+       } else {
+               if (errno == ENOENT)
+               {
+                       /* URAND_DEVICE_PATH device not found. Try RAND_DEVICE_PATH as fall-back */
+                       int fh = open(RAND_DEVICE_PATH, O_RDONLY);
+                       if (fh >= 0)
+                       {
+                               ssize_t rc = read(fh, &g_chrony_rand, sizeof(g_chrony_rand));
+                               if (rc != sizeof(g_chrony_rand))
+                               {
+                                       ERROR (PLUGIN_NAME ": Reading from random source \'%s\'failed: %s (%d)", RAND_DEVICE_PATH, strerror(errno), errno);
+                                       close(fh);
+                                       return CHRONY_RC_FAIL;
+                               }
+                               close(fh);
+                               DEBUG(PLUGIN_NAME ": Seeding RNG from " RAND_DEVICE_PATH);
+                       } else {
+                               /* Error opening RAND_DEVICE_PATH. Try time(NULL) as fall-back */
+                               DEBUG(PLUGIN_NAME ": Seeding RNG from time(NULL)");
+                               g_chrony_rand = time(NULL) ^ getpid();
+                       }
+               } else {
+                       ERROR (PLUGIN_NAME ": Opening random source \'%s\' failed: %s (%d)", URAND_DEVICE_PATH, strerror(errno), errno);
+                       return CHRONY_RC_FAIL;
+               }
+       }
+
+
+       return CHRONY_RC_OK;
+}
 
 /*****************************************************************************/
 /* Exported functions */
@@ -613,7 +718,7 @@ static int chrony_config(const char *p_key, const char *p_value)
        assert(p_key);
        assert(p_value);
        /* Parse config variables */
-       if (strcasecmp(p_key, "Host") == 0)
+       if (strcasecmp(p_key, CONFIG_KEY_HOST) == 0)
        {
                if (g_chrony_host != NULL)
                {
@@ -621,10 +726,10 @@ static int chrony_config(const char *p_key, const char *p_value)
                }
                if ((g_chrony_host = strdup (p_value)) == NULL)
                {
-                       ERROR ("chrony plugin: Error duplicating host name");
-                       return 1;
+                       ERROR (PLUGIN_NAME ": Error duplicating host name");
+                       return CHRONY_RC_FAIL;
                }
-       } else if (strcasecmp(p_key, "Port") == 0)
+       } else if (strcasecmp(p_key, CONFIG_KEY_PORT) == 0)
        {
                if (g_chrony_port != NULL)
                {
@@ -632,106 +737,138 @@ static int chrony_config(const char *p_key, const char *p_value)
                }
                if ((g_chrony_port = strdup (p_value)) == NULL)
                {
-                       ERROR ("chrony plugin: Error duplicating port name");
-                       return 1;
+                       ERROR (PLUGIN_NAME ": Error duplicating port name");
+                       return CHRONY_RC_FAIL;
                }
-       } else if (strcasecmp(p_key, "Timeout") == 0)
+       } else if (strcasecmp(p_key, CONFIG_KEY_TIMEOUT) == 0)
        {
                time_t tosec = strtol(p_value,NULL,0);
                g_chrony_timeout = tosec;
        } else {
-               WARNING("chrony plugin: Unknown configuration variable: %s %s",p_key,p_value);
-               return 1;
+               WARNING(PLUGIN_NAME ": Unknown configuration variable: %s %s",p_key,p_value);
+               return CHRONY_RC_FAIL;
        }
+       /* XXX: We could set g_plugin_instance here to "g_chrony_host-g_chrony_port", but as multiple instances aren't yet supported, we skip this for now */
 
-       return 0;
+       return CHRONY_RC_OK;
 }
 
 
 static int chrony_request_daemon_stats()
 {
-       //Tracking request
+       /* Perform Tracking request */
+       int rc;
        size_t chrony_resp_size;
        tChrony_Request  chrony_req;
        tChrony_Response chrony_resp;
-       char src_addr[IPV6_STR_MAX_SIZE];
 
        chrony_init_req(&chrony_req);
-       int rc = chrony_query(REQ_TRACKING, &chrony_req, &chrony_resp, &chrony_resp_size);
+       rc = chrony_query(REQ_TRACKING, &chrony_req, &chrony_resp, &chrony_resp_size);
        if (rc != 0)
        {
-               ERROR ("chrony plugin: chrony_query (REQ_TRACKING) failed with status %i", rc);
+               ERROR (PLUGIN_NAME ": chrony_query (REQ_TRACKING) failed with status %i", rc);
                return rc;
        }
        
-       memset(src_addr, 0, sizeof(src_addr));
-       niptoha(&chrony_resp.body.tracking.addr, src_addr, sizeof(src_addr));
-       DEBUG("chrony plugin: Daemon stat: .addr = %s, .ref_id= %u, .stratum = %u, .leap_status = %u, .ref_time = %u, .current_correction = %f, .last_offset = %f, .rms_offset = %f, .freq_ppm = %f, .skew_ppm = %f, .root_delay = %f, .root_dispersion = %f, .last_update_interval = %f",
-               src_addr,
-               ntohs(chrony_resp.body.tracking.f_ref_id), //FIXME: 16bit
-               ntohs(chrony_resp.body.tracking.f_stratum),
-               ntohs(chrony_resp.body.tracking.f_leap_status),
-               ntohl(chrony_resp.body.tracking.f_ref_time.tv_sec_high), //tTimeval
-               ntohf(chrony_resp.body.tracking.f_current_correction),
-               ntohf(chrony_resp.body.tracking.f_last_offset),
-               ntohf(chrony_resp.body.tracking.f_rms_offset),
-               ntohf(chrony_resp.body.tracking.f_freq_ppm),
-               ntohf(chrony_resp.body.tracking.f_skew_ppm),
-               ntohf(chrony_resp.body.tracking.f_root_delay),
-               ntohf(chrony_resp.body.tracking.f_root_dispersion),
-               ntohf(chrony_resp.body.tracking.f_last_update_interval)
-       );
-#if 0
-       chrony_push_data("clock_skew_ppm",    src_addr,ntohf(chrony_resp.body.source_stats.f_skew_ppm));
-       chrony_push_data("frequency_error",   src_addr,ntohf(chrony_resp.body.source_stats.f_rtc_gain_rate_ppm)); /* unit: ppm */
-       chrony_push_data("time_offset",       src_addr,ntohf(chrony_resp.body.source_stats.f_est_offset)); /* unit: s */
+#if COLLECT_DEBUG
+       {
+               char src_addr[IPV6_STR_MAX_SIZE];
+               memset(src_addr, 0, sizeof(src_addr));
+               niptoha(&chrony_resp.body.tracking.addr, src_addr, sizeof(src_addr));
+               DEBUG(PLUGIN_NAME ": Daemon stat: .addr = %s, .ref_id= %u, .stratum = %u, .leap_status = %u, .ref_time = %u:%u:%u, .current_correction = %f, .last_offset = %f, .rms_offset = %f, .freq_ppm = %f, .skew_ppm = %f, .root_delay = %f, .root_dispersion = %f, .last_update_interval = %f",
+                       src_addr,
+                       ntohs(chrony_resp.body.tracking.f_ref_id), //FIXME: 16bit
+                       ntohs(chrony_resp.body.tracking.f_stratum),
+                       ntohs(chrony_resp.body.tracking.f_leap_status),
+                       ntohl(chrony_resp.body.tracking.f_ref_time.tv_sec_high),
+                       ntohl(chrony_resp.body.tracking.f_ref_time.tv_sec_low),
+                       ntohl(chrony_resp.body.tracking.f_ref_time.tv_nsec),
+                       ntohf(chrony_resp.body.tracking.f_current_correction),
+                       ntohf(chrony_resp.body.tracking.f_last_offset),
+                       ntohf(chrony_resp.body.tracking.f_rms_offset),
+                       ntohf(chrony_resp.body.tracking.f_freq_ppm),
+                       ntohf(chrony_resp.body.tracking.f_skew_ppm),
+                       ntohf(chrony_resp.body.tracking.f_root_delay),
+                       ntohf(chrony_resp.body.tracking.f_root_dispersion),
+                       ntohf(chrony_resp.body.tracking.f_last_update_interval)
+               );
+       }
 #endif
-       return 0;
+
+       double time_ref = ntohl(chrony_resp.body.tracking.f_ref_time.tv_nsec);
+       time_ref /= 1000000000.0;
+       time_ref += ntohl(chrony_resp.body.tracking.f_ref_time.tv_sec_low);
+       if (chrony_resp.body.tracking.f_ref_time.tv_sec_high)
+       {
+               double secs_high = ntohl(chrony_resp.body.tracking.f_ref_time.tv_sec_high);
+               secs_high *= 4294967296.0;
+               time_ref += secs_high;
+       }
+
+       /* Forward results to collectd-daemon */
+       /* Type_instance is always 'chrony' to tag daemon-wide data */
+       /*                Type               Type_instance  Value */
+       chrony_push_data("clock_stratum",    DAEMON_NAME,   ntohs(chrony_resp.body.tracking.f_stratum));
+       chrony_push_data("time_ref",         DAEMON_NAME,   time_ref); /* unit: s */
+       chrony_push_data("time_offset_ntp",  DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_current_correction)); /* Offset between system time and NTP, unit: s */ 
+       chrony_push_data("time_offset",      DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_last_offset)); /* Estimated Offset of the NTP time, unit: s */
+       chrony_push_data("time_offset_rms",  DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_rms_offset));  /* averaged value of the above, unit: s */
+       chrony_push_data("frequency_error",  DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_freq_ppm));    /* Frequency error of the local osc, unit: ppm */
+       chrony_push_data("clock_skew_ppm",   DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_skew_ppm)); 
+       chrony_push_data("root_delay",       DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_root_delay));  /* Network latency between local daemon and the current source */
+       chrony_push_data("root_dispersion",  DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_root_dispersion));
+       chrony_push_data("clock_last_update",DAEMON_NAME,   ntohf(chrony_resp.body.tracking.f_last_update_interval));
+
+       return CHRONY_RC_OK;
 }
 
 
 static int chrony_request_sources_count(unsigned int *p_count)
 {
+       /* Requests the number of time sources from the chrony daemon */
        int rc;
        size_t chrony_resp_size;
        tChrony_Request  chrony_req;
        tChrony_Response chrony_resp;
 
-       DEBUG("chrony plugin: Requesting data");
+       DEBUG(PLUGIN_NAME ": Requesting data");
        chrony_init_req(&chrony_req);
        rc = chrony_query (REQ_N_SOURCES, &chrony_req, &chrony_resp, &chrony_resp_size);
         if (rc != 0)
         {
-                ERROR ("chrony plugin: chrony_query (REQ_N_SOURCES) failed with status %i", rc);
+                ERROR (PLUGIN_NAME ": chrony_query (REQ_N_SOURCES) failed with status %i", rc);
                 return rc;
         }
        
        *p_count = ntohl(chrony_resp.body.n_sources.f_n_sources);
-       DEBUG("chrony plugin: Getting data of %d clock sources", *p_count);
+       DEBUG(PLUGIN_NAME ": Getting data of %d clock sources", *p_count);
 
-       return 0;
+       return CHRONY_RC_OK;
 }
 
 
-static int chrony_request_source_data(int p_src_idx)
+static int chrony_request_source_data(int p_src_idx, int *p_is_reachable)
 {
-       //Source data request
+       /* Perform Source data request for source #p_src_idx*/
+       int rc;
        size_t chrony_resp_size;
        tChrony_Request  chrony_req;
        tChrony_Response chrony_resp;
+
        char src_addr[IPV6_STR_MAX_SIZE];
+       memset(src_addr, 0, sizeof(src_addr));
 
        chrony_init_req(&chrony_req);
        chrony_req.body.source_data.f_index  = htonl(p_src_idx);
-       int rc = chrony_query(REQ_SOURCE_DATA, &chrony_req, &chrony_resp, &chrony_resp_size);
+       rc = chrony_query(REQ_SOURCE_DATA, &chrony_req, &chrony_resp, &chrony_resp_size);
        if (rc != 0)
        {
-               ERROR ("chrony plugin: chrony_query (REQ_SOURCE_DATA) failed with status %i", rc);
+               ERROR (PLUGIN_NAME ": chrony_query (REQ_SOURCE_DATA) failed with status %i", rc);
                return rc;
        }
-       memset(src_addr, 0, sizeof(src_addr));
+
        niptoha(&chrony_resp.body.source_data.addr, src_addr, sizeof(src_addr));
-       DEBUG("chrony plugin: Source[%d] data: .addr = %s, .poll = %u, .stratum = %u, .state = %u, .mode = %u, .flags = %u, .reach = %u, .latest_meas_ago = %u, .orig_latest_meas = %f, .latest_meas = %f, .latest_meas_err = %f",
+       DEBUG(PLUGIN_NAME ": Source[%d] data: .addr = %s, .poll = %u, .stratum = %u, .state = %u, .mode = %u, .flags = %u, .reach = %u, .latest_meas_ago = %u, .orig_latest_meas = %f, .latest_meas = %f, .latest_meas_err = %f",
                p_src_idx,
                src_addr,
                ntohs(chrony_resp.body.source_data.f_poll),
@@ -745,94 +882,133 @@ static int chrony_request_source_data(int p_src_idx)
                ntohf(chrony_resp.body.source_data.f_latest_meas),
                ntohf(chrony_resp.body.source_data.f_latest_meas_err)
        );
-       chrony_push_data("clock_stratum",     src_addr,ntohs(chrony_resp.body.source_data.f_stratum));
-       chrony_push_data("clock_state",       src_addr,ntohs(chrony_resp.body.source_data.f_state));
-       chrony_push_data("clock_mode",        src_addr,ntohs(chrony_resp.body.source_data.f_mode));
-       chrony_push_data("clock_reachability",src_addr,ntohs(chrony_resp.body.source_data.f_reachability));
-       chrony_push_data("clock_last_meas",   src_addr,ntohs(chrony_resp.body.source_data.f_since_sample));
 
-       return 0;
+       /* Push NaN if source is currently not reachable */
+       int is_reachable = ntohs(chrony_resp.body.source_data.f_reachability) & 0x01; 
+       *p_is_reachable = is_reachable;
+
+       /* Forward results to collectd-daemon */
+       chrony_push_data_valid("clock_stratum",     src_addr, is_reachable, ntohs(chrony_resp.body.source_data.f_stratum));
+       chrony_push_data_valid("clock_state",       src_addr, is_reachable, ntohs(chrony_resp.body.source_data.f_state));
+       chrony_push_data_valid("clock_mode",        src_addr, is_reachable, ntohs(chrony_resp.body.source_data.f_mode));
+       chrony_push_data_valid("clock_reachability",src_addr, is_reachable, ntohs(chrony_resp.body.source_data.f_reachability));
+       chrony_push_data_valid("clock_last_meas",   src_addr, is_reachable, ntohs(chrony_resp.body.source_data.f_since_sample));
+
+       return CHRONY_RC_OK;
 }
 
 
-static int chrony_request_source_stats(int p_src_idx)
+static int chrony_request_source_stats(int p_src_idx, const int *p_is_reachable)
 {
-       //Source stats request
+       /* Perform Source stats request for source #p_src_idx */
+       int rc;
        size_t chrony_resp_size;
        tChrony_Request  chrony_req;
        tChrony_Response chrony_resp;
+       double skew_ppm, frequency_error, time_offset;
+
        char src_addr[IPV6_STR_MAX_SIZE];
+       memset(src_addr, 0, sizeof(src_addr));
 
-       chrony_init_req(&chrony_req);
-       chrony_req.body.source_stats.f_index = htonl(p_src_idx);
-       int rc = chrony_query(REQ_SOURCE_STATS, &chrony_req, &chrony_resp, &chrony_resp_size);
-       if (rc != 0)
+       if (*p_is_reachable == 0)
        {
-               ERROR ("chrony plugin: chrony_query (REQ_SOURCE_STATS) failed with status %i", rc);
-               return rc;
-       }
+               skew_ppm        = 0;
+               frequency_error = 0;
+               time_offset     = 0;
+       } else {
+               chrony_init_req(&chrony_req);
+               chrony_req.body.source_stats.f_index = htonl(p_src_idx);
+               rc = chrony_query(REQ_SOURCE_STATS, &chrony_req, &chrony_resp, &chrony_resp_size);
+               if (rc != 0)
+               {
+                       ERROR (PLUGIN_NAME ": chrony_query (REQ_SOURCE_STATS) failed with status %i", rc);
+                       return rc;
+               }
 
-       memset(src_addr, 0, sizeof(src_addr));
-       niptoha(&chrony_resp.body.source_stats.addr, src_addr, sizeof(src_addr));
-       DEBUG("chrony plugin: Source[%d] stat: .addr = %s, .ref_id= %u, .n_samples = %u, .n_runs = %u, .span_seconds = %u, .rtc_seconds_fast = %f, .rtc_gain_rate_ppm = %f, .skew_ppm= %f, .est_offset = %f, .est_offset_err = %f",
-               p_src_idx,
-               src_addr,
-               ntohl(chrony_resp.body.source_stats.f_ref_id),
-               ntohl(chrony_resp.body.source_stats.f_n_samples),
-               ntohl(chrony_resp.body.source_stats.f_n_runs),
-               ntohl(chrony_resp.body.source_stats.f_span_seconds),
-               ntohf(chrony_resp.body.source_stats.f_rtc_seconds_fast),
-               ntohf(chrony_resp.body.source_stats.f_rtc_gain_rate_ppm),
-               ntohf(chrony_resp.body.source_stats.f_skew_ppm),
-               ntohf(chrony_resp.body.source_stats.f_est_offset),
-               ntohf(chrony_resp.body.source_stats.f_est_offset_err)
-       );
-       chrony_push_data("clock_skew_ppm",    src_addr,ntohf(chrony_resp.body.source_stats.f_skew_ppm));
-       chrony_push_data("frequency_error",   src_addr,ntohf(chrony_resp.body.source_stats.f_rtc_gain_rate_ppm)); /* unit: ppm */
-       chrony_push_data("time_offset",       src_addr,ntohf(chrony_resp.body.source_stats.f_est_offset)); /* unit: s */
-       return 0;
+               skew_ppm        = ntohf(chrony_resp.body.source_stats.f_skew_ppm);
+               frequency_error = ntohf(chrony_resp.body.source_stats.f_rtc_gain_rate_ppm);
+               time_offset     = ntohf(chrony_resp.body.source_stats.f_est_offset);
+
+               niptoha(&chrony_resp.body.source_stats.addr, src_addr, sizeof(src_addr));
+               DEBUG(PLUGIN_NAME ": Source[%d] stat: .addr = %s, .ref_id= %u, .n_samples = %u, " \
+                               ".n_runs = %u, .span_seconds = %u, .rtc_seconds_fast = %f, " \
+                               ".rtc_gain_rate_ppm = %f, .skew_ppm= %f, .est_offset = %f, .est_offset_err = %f",
+                       p_src_idx,
+                       src_addr,
+                       ntohl(chrony_resp.body.source_stats.f_ref_id),
+                       ntohl(chrony_resp.body.source_stats.f_n_samples),
+                       ntohl(chrony_resp.body.source_stats.f_n_runs),
+                       ntohl(chrony_resp.body.source_stats.f_span_seconds),
+                       ntohf(chrony_resp.body.source_stats.f_rtc_seconds_fast),
+                       frequency_error,
+                       skew_ppm,
+                       time_offset,
+                       ntohf(chrony_resp.body.source_stats.f_est_offset_err)
+               );
+
+       } //if (*is_reachable)
+
+       /* Forward results to collectd-daemon */
+       chrony_push_data_valid("clock_skew_ppm",    src_addr, *p_is_reachable, skew_ppm);
+       chrony_push_data_valid("frequency_error",   src_addr, *p_is_reachable, frequency_error); /* unit: ppm */
+       chrony_push_data_valid("time_offset",       src_addr, *p_is_reachable, time_offset); /* unit: s */
+
+       return CHRONY_RC_OK;
 }
 
-
 static int chrony_read()
 {
+       /* collectd read callback: Perform data acquisition */
        int  rc;
+       unsigned int now_src, n_sources;
 
-       //Get daemon stats
+       if (g_chrony_seq_is_initialized == 0)
+       {
+               /* Seed RNG for sequence number generation */
+               rc = chrony_init_seq();
+               if (rc != CHRONY_RC_OK)
+               {
+                       return rc;
+               }
+               g_chrony_seq_is_initialized = 1;
+       }
+       
+       /* Get daemon stats */
        rc = chrony_request_daemon_stats();
-       if (rc != 0)
+       if (rc != CHRONY_RC_OK)
        {
                return rc;
        }
 
-       //Get number of time sources, then check every source for status
-       unsigned int now_src, n_sources;
+       /* Get number of time sources, then check every source for status */
                rc = chrony_request_sources_count(&n_sources);
-       if (rc != 0)
+       if (rc != CHRONY_RC_OK)
        {
                return rc;
        }
 
        for (now_src = 0; now_src < n_sources; ++now_src)
        {
-               rc = chrony_request_source_data(now_src);
-               if (rc != 0)
+               int is_reachable;
+               rc = chrony_request_source_data(now_src, &is_reachable);
+               if (rc != CHRONY_RC_OK)
                {
                        return rc;
                }
 
-               rc = chrony_request_source_stats(now_src);
-               if (rc != 0)
+               rc = chrony_request_source_stats(now_src, &is_reachable);
+               if (rc != CHRONY_RC_OK)
                {
                        return rc;
                }
        }
-       return 0;
+       return CHRONY_RC_OK;
 }
 
 
 static int chrony_shutdown()
 {
+       /* Collectd shutdown callback: Free mem */
        if (g_is_connected != 0)
        {
                close(g_chrony_socket);
@@ -848,14 +1024,19 @@ static int chrony_shutdown()
                free (g_chrony_port);
                g_chrony_port = NULL;
        }
-       return 0;
+       if (g_plugin_instance != NULL)
+       {
+               free (g_plugin_instance);
+               g_plugin_instance = NULL;
+       }
+       return CHRONY_RC_OK;
 }
 
 
 void module_register (void)
 {
-       plugin_register_config(  "chrony", chrony_config, g_config_keys, g_config_keys_num);
-        plugin_register_read(    "chrony", chrony_read);
-       plugin_register_shutdown("chrony", chrony_shutdown);
+       plugin_register_config(  PLUGIN_NAME_SHORT, chrony_config, g_config_keys, g_config_keys_num);
+       plugin_register_read(    PLUGIN_NAME_SHORT, chrony_read);
+       plugin_register_shutdown(PLUGIN_NAME_SHORT, chrony_shutdown);
 }