Eliminated send_delay global (file) variable.

[icmpmonitor] / icmpmonitor.c

diff --git a/icmpmonitor.c b/icmpmonitor.c
index 36a1ce6..f2bf43e 100644 (file)
--- a/icmpmonitor.c
+++ b/icmpmonitor.c
@@ -1,9 +1,13 @@
 /*
 /*

- * Monitor hosts using ICMP "echo" and notify when down.
+ * ICMPmonitor
+ *
+ * Monitors hosts using ICMP 'echo', executing a user-specified command
+ * whenever hosts change state between responsive and unresponsive.

  *
  * © 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
  * © 1999 Vadim Zaliva <lord@crocodile.org>
  * © 1989 The Regents of the University of California & Mike Muuss
  *
  * © 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
  * © 1999 Vadim Zaliva <lord@crocodile.org>
  * © 1989 The Regents of the University of California & Mike Muuss

+ *

  * See LICENSE file for copyright and license details.
  */
 
  * See LICENSE file for copyright and license details.
  */
 


@@ -23,86 +27,80 @@
 #include <netinet/ip.h>
 #include <netinet/ip_icmp.h>
 #include <errno.h>
 #include <netinet/ip.h>
 #include <netinet/ip_icmp.h>
 #include <errno.h>

+#include <assert.h>
+
+#include "iniparser/iniparser.h"

 
 

-#include "cfg.h"
+#define VERSION 2

 
 #define MAXPACKETSIZE  (65536 - 60 - 8) /* TODO: What are the magic numbers? */
 #define DEFAULTDATALEN (64 - 8)         /* TODO: What are the magic numbers? */
 
 
 #define MAXPACKETSIZE  (65536 - 60 - 8) /* TODO: What are the magic numbers? */
 #define DEFAULTDATALEN (64 - 8)         /* TODO: What are the magic numbers? */
 

+/* ICMP header contains: type, code, checksum, identifier and sequence number. */
+#define ICMP_ECHO_HEADER_BYTES  8
+#define ICMP_ECHO_DATA_BYTES    sizeof(struct timeval)
+#define ICMP_ECHO_PACKET_BYTES  ICMP_ECHO_HEADER_BYTES + ICMP_ECHO_DATA_BYTES
+
+/* Minimum time in seconds between pings. If this value is increased above the */
+/* `ping_interval` for a given host, some pings to that host may not be sent.  */
+#define TIMER_RESOLUTION        1
+
+/* Must be larger than the length of the longest configuration key (currently 'start_condition'). */
+#define MAXCONFKEYLEN 20
+
+/* One struct per host as listed in the config file. */

 struct monitor_host {
     /* From the config file */
     char * name;
     int    ping_interval;
     int    max_delay;
 struct monitor_host {
     /* From the config file */
     char * name;
     int    ping_interval;
     int    max_delay;

-    char * upcmd;
-    char * downcmd;
+    char * up_cmd;
+    char * down_cmd;

 
     /* Calculated values */
     int                socket;
     struct timeval     last_ping_received;
     struct timeval     last_ping_sent;
 
     /* Calculated values */
     int                socket;
     struct timeval     last_ping_received;
     struct timeval     last_ping_sent;

-    bool               hostup;
+    bool               host_up;

     struct sockaddr_in dest;
     struct sockaddr_in dest;

-    unsigned int       sentpackets;
-    unsigned int       recvdpackets;

 
 

-    /* linked list */
+    /* Linked list */

     struct monitor_host * next;
 };
 
     struct monitor_host * next;
 };
 

-/* globals */
-static struct monitor_host ** hosts       = NULL;
-static int                    isVerbose   = 0;
-static int                    keepBanging = 0;
-static int                    send_delay  = 1;
+/* Globals */
+    /* Since the program is based around signals, a linked list of hosts is maintained here. */
+    static struct monitor_host * hosts          = NULL;
+    /* Set by command line flags. */
+    static bool                  verbose        = false;
+    static bool                  retry_down_cmd = false;

 
 /*
 
 /*

- * Checksum routine for Internet Protocol family headers
+ * Generate an Internet Checksum per RFC 1071.
+ *
+ * This is not a general purpose implementation of RFC 1071.  Since we only
+ * send ICMP echo packets, we assume 'data' will contain a specific number of
+ * bytes.

  */
  */

-static int
-in_cksum(unsigned short * addr, int len)
+uint16_t
+checksum(uint16_t * data)

 {
 {

-    int nleft = len;
-    unsigned short * w = addr;
-    int sum = 0;
-    unsigned short answer = 0;
-
-    /*
-     * Our algorithm is simple, using a 32 bit accumulator (sum), we add
-     * sequential 16 bit words to it, and at the end, fold back all the
-     * carry bits from the top 16 bits into the lower 16 bits.
-     */
-    while (nleft > 1) {
-        sum += *w++;
-        nleft -= 2;
+    uint32_t accumulator = 0;
+    for (size_t i = 0; i < ICMP_ECHO_PACKET_BYTES / 2; i++) {
+        accumulator += ntohs(data[i]);
+        if (accumulator > 0xffff) accumulator -= 0xffff;

     }
     }

-
-    /* mop up an odd byte, if necessary */
-    if (nleft == 1) {
-        *(u_char *)(&answer) = *(u_char *)w;
-        sum += answer;
-    }
-
-    /* add back carry outs from top 16 bits to low 16 bits */
-    sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
-    sum += (sum >> 16);                 /* add carry */
-    answer = ~sum;                      /* truncate to 16 bits */
-    return(answer);
+    return htons(~accumulator);

 }
 
 /*
 }
 
 /*

- * Subtracts two timeval structs.
- * Ensure out >= in.
- * Modifies out = out - in.
+ * Calculate difference between two timeval structs to within one second.

  */
  */

-static void
-tvsub(register struct timeval * out, register struct timeval * in)
+void
+timeval_diff(struct timeval * a, const struct timeval * b)

 {
 {

-    if ((out->tv_usec -= in->tv_usec) < 0) {
-        --out->tv_sec;
-        out->tv_usec += 1000000;
-    }
-    out->tv_sec -= in->tv_sec;
+    assert(a->tv_sec >= b->tv_sec);
+    a->tv_sec -= b->tv_sec;

 }
 
 /*
 }
 
 /*


@@ -115,25 +113,24 @@ tvsub(register struct timeval * out, register struct timeval * in)
 static void
 pinger(int ignore)
 {
 static void
 pinger(int ignore)
 {

-    int cc, i;
+    int i;

     struct icmp * icp;
     struct icmp * icp;

-    struct monitor_host * p;
-    u_char outpack[MAXPACKETSIZE];
+    struct monitor_host * p = hosts;
+    unsigned char outpack[MAXPACKETSIZE]; /* Use char so this can be aliased later. */

 
 

-    p = hosts[0];

     while (p) {
         if (p->socket != -1) {
             struct timeval now;
 
             gettimeofday(&now, (struct timezone *) NULL);
     while (p) {
         if (p->socket != -1) {
             struct timeval now;
 
             gettimeofday(&now, (struct timezone *) NULL);

-            tvsub(&now, &p->last_ping_received);
+            timeval_diff(&now, &p->last_ping_received);

 
             if (now.tv_sec > (p->max_delay + p->ping_interval)) {
 
             if (now.tv_sec > (p->max_delay + p->ping_interval)) {

-                if ((p->hostup) || keepBanging) {
-                    if (isVerbose) printf("INFO: Host %s stopped responding. Executing DOWN command.\n", p->name);
-                    p->hostup = false;
+                if ((p->host_up) || retry_down_cmd) {
+                    if (verbose) printf("INFO: Host %s stopped responding. Executing DOWN command.\n", p->name);
+                    p->host_up = false;

                     if (!fork()) {
                     if (!fork()) {

-                        system(p->downcmd);
+                        system(p->down_cmd);

                         exit(EXIT_SUCCESS);
                     } else {
                         wait(NULL);
                         exit(EXIT_SUCCESS);
                     } else {
                         wait(NULL);


@@ -142,7 +139,7 @@ pinger(int ignore)
             }
 
             gettimeofday(&now, (struct timezone *) NULL);
             }
 
             gettimeofday(&now, (struct timezone *) NULL);

-            tvsub(&now, &p->last_ping_sent);
+            timeval_diff(&now, &p->last_ping_sent);

 
             if (now.tv_sec > p->ping_interval) { /* Time to send ping */
                 icp = (struct icmp *) outpack;
 
             if (now.tv_sec > p->ping_interval) { /* Time to send ping */
                 icp = (struct icmp *) outpack;


@@ -152,14 +149,13 @@ pinger(int ignore)
                 icp->icmp_seq   = p->socket;
                 icp->icmp_id    = getpid() & 0xFFFF;
 
                 icp->icmp_seq   = p->socket;
                 icp->icmp_id    = getpid() & 0xFFFF;
 

-                if (isVerbose) printf("INFO: Sending ICMP packet to %s.\n", p->name);
+                if (verbose) printf("INFO: Sending ICMP packet to %s.\n", p->name);

 
                 gettimeofday((struct timeval *) &outpack[8], (struct timezone *) NULL);
 
 
                 gettimeofday((struct timeval *) &outpack[8], (struct timezone *) NULL);
 

-                cc = DEFAULTDATALEN + 8;  /* skips ICMP portion */
+                int cc = DEFAULTDATALEN + 8;  /* skips ICMP portion */

 
 

-                /* compute ICMP checksum */
-                icp->icmp_cksum = in_cksum((unsigned short *) icp, cc);
+                icp->icmp_cksum = checksum((uint16_t *) outpack);

 
                 i = sendto(p->socket, (char *) outpack, cc, 0, (const struct sockaddr *) (&p->dest), sizeof(struct sockaddr));
 
 
                 i = sendto(p->socket, (char *) outpack, cc, 0, (const struct sockaddr *) (&p->dest), sizeof(struct sockaddr));
 


@@ -168,14 +164,13 @@ pinger(int ignore)
                 if (i < 0 || i != cc) {
                     if (i<0) fprintf(stderr, "WARN: Failed sending ICMP packet to %s.\n", p->name);
                 }
                 if (i < 0 || i != cc) {
                     if (i<0) fprintf(stderr, "WARN: Failed sending ICMP packet to %s.\n", p->name);
                 }

-                p->sentpackets++;

             }
         }
         p = p->next;
     }
 
     signal(SIGALRM, pinger); /* restore handler */
             }
         }
         p = p->next;
     }
 
     signal(SIGALRM, pinger); /* restore handler */

-    alarm(send_delay);
+    alarm(TIMER_RESOLUTION);

 }
 
 static void
 }
 
 static void


@@ -208,19 +203,18 @@ read_icmp_data(struct monitor_host * p)
     }
 
     if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == p->socket) {
     }
 
     if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == p->socket) {

-        p->recvdpackets++;

 
         memcpy(&p->last_ping_received, &tv, sizeof(tv));
 
 
         memcpy(&p->last_ping_received, &tv, sizeof(tv));
 

-        tvsub(&tv, (struct timeval *) &icmp->icmp_data[0]);
+        timeval_diff(&tv, (struct timeval *) &icmp->icmp_data[0]);

         delay = tv.tv_sec * 1000 + (tv.tv_usec / 1000);
 
         delay = tv.tv_sec * 1000 + (tv.tv_usec / 1000);
 

-        if (isVerbose) printf("INFO: Got ICMP reply from %s in %d ms.\n", p->name, delay);
-        if (!p->hostup) {
-            if (isVerbose) printf("INFO: Host %s started responding. Executing UP command.\n", p->name);
-            p->hostup = true;
+        if (verbose) printf("INFO: Got ICMP reply from %s.\n", p->name);
+        if (!p->host_up) {
+            if (verbose) printf("INFO: Host %s started responding. Executing UP command.\n", p->name);
+            p->host_up = true;

             if (!fork()) {
             if (!fork()) {

-                system(p->upcmd);
+                system(p->up_cmd);

                 exit(EXIT_SUCCESS);
             } else {
                 wait(NULL);
                 exit(EXIT_SUCCESS);
             } else {
                 wait(NULL);


@@ -239,11 +233,11 @@ get_response(void)
     struct monitor_host * p;
 
     while (1) {
     struct monitor_host * p;
 
     while (1) {

-        p = hosts[0];
+        p = hosts;

         FD_ZERO(&rfds);
         while (p) {
             if (p->socket != -1) {
         FD_ZERO(&rfds);
         while (p) {
             if (p->socket != -1) {

-                if (p->socket > maxd) maxd=p->socket;
+                if (p->socket > maxd) maxd = p->socket;

                 FD_SET(p->socket, &rfds);
             }
             p = p->next;
                 FD_SET(p->socket, &rfds);
             }
             p = p->next;


@@ -254,7 +248,7 @@ get_response(void)
             /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */
         } else {
             if (retval > 0) {
             /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */
         } else {
             if (retval > 0) {

-                p = hosts[0];
+                p = hosts;

                 while (p) {
                     if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p);
                     p = p->next;
                 while (p) {
                     if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p);
                     p = p->next;


@@ -267,76 +261,88 @@ get_response(void)
 }
 
 static void
 }
 
 static void

-read_hosts(const char * cfg_file_name)
+parse_config(const char * conf_file)

 {
 {

-    int i, n = 0;
-    struct Cfg * cfg;
+    dictionary * conf = iniparser_load(conf_file);
+    if (conf == NULL) {
+        fprintf(stderr, "ERROR: Unable to parse configuration file %s.\n", conf_file);
+        exit(EXIT_FAILURE);
+    }

 
 

-    if ((cfg = readcfg(cfg_file_name)) == NULL) {
-        fprintf(stderr, "ERROR: Failed to read config.\n");
+    int host_count = iniparser_getnsec(conf);
+    if (host_count < 1 ) {
+        fprintf(stderr, "ERROR: Unable to determine number of hosts in configuration file.\n");

         exit(EXIT_FAILURE);
     }
 
         exit(EXIT_FAILURE);
     }
 

-    if (cfg->nelements) {
-        hosts = malloc(sizeof(struct monitor_host *) * cfg->nelements);
-        for (i = 0; i < cfg->nelements; i++) {
-            if (cfg->dict[i]->nvalues < 4) {
-                fprintf(stderr, "ERROR: Not enough fields in record %d of cfg file. Got %d.\n", n, cfg->dict[i]->nvalues+1);
-                exit(EXIT_FAILURE);
-            } else if (cfg->dict[i]->nvalues>5) {
-                fprintf(stderr, "ERROR: Too many fields in record %d of cfg file. Got %d.\n", n, cfg->dict[i]->nvalues+1);
-                exit(EXIT_FAILURE);
-            }
+    struct monitor_host * host_list_end = NULL;
+    for (int i=0; i < host_count; i++) {
+        /* Allocate a reusable buffer large enough to hold the full 'section:key' string. */
+        int section_len = strlen(iniparser_getsecname(conf, i));
+        char * key_buf = malloc(section_len + 1 + MAXCONFKEYLEN + 1);
+        strcpy(key_buf, iniparser_getsecname(conf, i));
+        key_buf[section_len++] = ':';

 
 

-            hosts[n]                = malloc(sizeof(struct monitor_host));
-            hosts[n]->name          = strdup(cfg->dict[i]->name);
-            hosts[n]->ping_interval = atoi  (cfg->dict[i]->value[0]);
-            hosts[n]->max_delay     = atoi  (cfg->dict[i]->value[1]);
-            hosts[n]->upcmd         = strdup(cfg->dict[i]->value[2]);
-            hosts[n]->downcmd       = strdup(cfg->dict[i]->value[3]);
-
-        if (cfg->dict[i]->nvalues == 4) {
-            hosts[n]->hostup = true;
-        } else if (strcmp(cfg->dict[i]->value[4], "up") == 0) {
-            hosts[n]->hostup = true;
-        } else if (strcmp(cfg->dict[i]->value[4], "down") == 0) {
-            hosts[n]->hostup = false;
-        } else if (strcmp(cfg->dict[i]->value[4], "auto") == 0) {
-            /* TODO: Send a ping and set initial state accordingly. */
-        } else {
-            fprintf(stderr, "ERROR: Illegal value %s in record %d for startup condition.\n", cfg->dict[i]->value[4], n);
+        struct monitor_host * cur_host = malloc(sizeof(struct monitor_host));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "host", MAXCONFKEYLEN);
+        cur_host->name = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "interval", MAXCONFKEYLEN);
+        cur_host->ping_interval = iniparser_getint(conf, key_buf, -1);
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "max_delay", MAXCONFKEYLEN);
+        cur_host->max_delay = iniparser_getint(conf, key_buf, -1);
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "up_cmd", MAXCONFKEYLEN);
+        cur_host->up_cmd = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "down_cmd", MAXCONFKEYLEN);
+        cur_host->down_cmd = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        /* TODO: Parse for up/down/auto in start_condition. */
+        /* TODO: Do a host up/down check if necessary. */
+        cur_host->host_up = true;
+
+        /* TODO: Do I want to make any checks for start_condition? */
+        if (cur_host->name == NULL || cur_host->ping_interval == -1 || cur_host->max_delay == -1) {
+            fprintf(stderr, "ERROR: Problems parsing section %s.\n", iniparser_getsecname(conf, i));

             exit(EXIT_FAILURE);
         }
             exit(EXIT_FAILURE);
         }

-            hosts[n]->sentpackets   = 0;
-            hosts[n]->recvdpackets  = 0;

 
 

-            hosts[n]->socket           = -1;
-            hosts[n]->next             = NULL;
-            if (n > 0) hosts[n-1]->next=hosts[n];
-            gettimeofday(&(hosts[n]->last_ping_received), (struct timezone *)NULL);
+        cur_host->socket = -1;
+        cur_host->next = NULL;
+        gettimeofday(&(cur_host->last_ping_received), (struct timezone *) NULL);

 
 

-            n++;
+        if (hosts == NULL) {
+            hosts = cur_host;
+            host_list_end = cur_host;
+        } else {
+            host_list_end->next = cur_host;
+            host_list_end = cur_host;

         }
         }

-    }
-
-    freecfg(cfg);

 
 

-    if (n <= 0) {
-        fprintf(stderr, "ERROR: No hosts defined in cfg file, exiting.\n");
-        exit(EXIT_FAILURE);
+        free(key_buf);

     }
     }

+    iniparser_freedict(conf);

 }
 
 static int
 }
 
 static int

-gethostaddr(const char * name)
+get_host_addr(const char * name)

 {
     static int res;
 {
     static int res;

-    struct hostent * he;
+    struct hostent * host_ent;

 
     if ((res = inet_addr(name)) < 0) {
 
     if ((res = inet_addr(name)) < 0) {

-    he = gethostbyname(name);
-        if (!he) return -1;
-        memcpy(&res, he->h_addr, he->h_length);
+        host_ent = gethostbyname(name);
+        if (!host_ent) return -1;
+        memcpy(&res, host_ent->h_addr, host_ent->h_length);

     }
     return(res);
 }
     }
     return(res);
 }


@@ -352,7 +358,7 @@ gcd(int x, int y)
 static void
 init_hosts(void)
 {
 static void
 init_hosts(void)
 {

-    struct monitor_host * p = hosts[0];
+    struct monitor_host * p = hosts;

     struct protoent * proto;
     int ok = 0;
 
     struct protoent * proto;
     int ok = 0;
 


@@ -364,7 +370,7 @@ init_hosts(void)
     while (p) {
         bzero(&p->dest, sizeof(p->dest));
         p->dest.sin_family = AF_INET;
     while (p) {
         bzero(&p->dest, sizeof(p->dest));
         p->dest.sin_family = AF_INET;

-        if ((p->dest.sin_addr.s_addr = gethostaddr(p->name)) <= 0) {
+        if ((p->dest.sin_addr.s_addr = get_host_addr(p->name)) <= 0) {

             fprintf(stderr, "WARN: Can't resolve host. Skipping client %s.\n", p->name);
             p->socket=-1;
         } else {
             fprintf(stderr, "WARN: Can't resolve host. Skipping client %s.\n", p->name);
             p->socket=-1;
         } else {


@@ -372,8 +378,8 @@ init_hosts(void)
                 fprintf(stderr, "WARN: Can't create socket. Skipping client %s.\n", p->name);
                 p->socket=-1;
             } else {
                 fprintf(stderr, "WARN: Can't create socket. Skipping client %s.\n", p->name);
                 p->socket=-1;
             } else {

-                if (ok == 0) send_delay = p->ping_interval;
-                else send_delay = gcd(send_delay, p->ping_interval);
+                //if (ok == 0) send_delay = p->ping_interval;
+                //else send_delay = gcd(send_delay, p->ping_interval);

                 ok++;
             }
         }
                 ok++;
             }
         }


@@ -386,42 +392,56 @@ init_hosts(void)
     }
 }
 
     }
 }
 

-int
-main(int argc, char ** argv)
+void
+print_usage(char ** argv)

 {
 {

-    extern char * optarg;
-    extern int optind;
-    char * cfgfile = NULL;
-    int param;
+    printf( "ICMPmonitor v%d (www.subgeniuskitty.com)\n"
+            "Usage: %s [-h] [-v] [-r] -f <file>\n"
+            "  -v         Verbose mode. Prints message for each packet sent and received.\n"
+            "  -r         Repeat down_cmd every time a host fails to respond to a packet.\n"
+            "             Note: Default behavior executes down_cmd only once, resetting once the host is back up.\n"
+            "  -h         Help (prints this message)\n"
+            "  -f <file>  Specify a configuration file.\n"
+            , VERSION, argv[0]);
+}

 
 

-    while ((param = getopt(argc, argv, "rvf:")) != -1) {
+void
+parse_params(int argc, char ** argv)
+{
+    int param;
+    while ((param = getopt(argc, argv, "hrvf:")) != -1) {

         switch(param) {
             case 'v':
         switch(param) {
             case 'v':

-                isVerbose = 1;
+                verbose = true;

                 break;
             case 'r':
                 break;
             case 'r':

-                keepBanging = 1;
+                retry_down_cmd = true;

                 break;
             case 'f':
                 break;
             case 'f':

-                cfgfile=strdup(optarg);
+                parse_config(optarg);

                 break;
                 break;

+            case 'h':

             default:
             default:

-                fprintf(stderr,"Usage: icmpmonitor [-v] [-r] [-f cfgfile]\n");
+                print_usage(argv);

                 exit(EXIT_FAILURE);
                 exit(EXIT_FAILURE);

+                break;

         }
     }
         }
     }

-
-    if (!cfgfile) {
-        fprintf(stderr, "ERROR: No config file specified.\n");
+    if (hosts == NULL) {
+        fprintf(stderr, "ERROR: Unable to parse a config file.\n");

         exit(EXIT_FAILURE);
     }
         exit(EXIT_FAILURE);
     }

+}

 
 

-    read_hosts(cfgfile);
+int
+main(int argc, char ** argv)
+{
+    parse_params(argc, argv);

 
     init_hosts();
 
     signal(SIGALRM, pinger);
 
     init_hosts();
 
     signal(SIGALRM, pinger);

-    alarm(send_delay);
+    alarm(TIMER_RESOLUTION);

 
     get_response();
 
 
     get_response();