Eliminated send_delay global (file) variable.

[icmpmonitor] / icmpmonitor.c

diff --git a/icmpmonitor.c b/icmpmonitor.c
index 284da67..f2bf43e 100644 (file)
--- a/icmpmonitor.c
+++ b/icmpmonitor.c
@@ -27,6 +27,7 @@
 #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 "iniparser/iniparser.h"
 


@@ -35,6 +36,15 @@
 #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
 
 /* Must be larger than the length of the longest configuration key (currently 'start_condition'). */
 #define MAXCONFKEYLEN 20
 


@@ -64,56 +74,33 @@ struct monitor_host {
     /* Set by command line flags. */
     static bool                  verbose        = false;
     static bool                  retry_down_cmd = false;
     /* Set by command line flags. */
     static bool                  verbose        = false;
     static bool                  retry_down_cmd = false;

-    /* TODO: Get rid of this global. */
-    static int                   send_delay     = 1;

 
 /*
 
 /*

- * 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;
-    }
-
-    /* mop up an odd byte, if necessary */
-    if (nleft == 1) {
-        *(u_char *)(&answer) = *(u_char *)w;
-        sum += answer;
+    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;

     }
     }

-
-    /* 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
-tv_sub(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;

 }
 
 /*
 }
 
 /*


@@ -129,14 +116,14 @@ pinger(int ignore)
     int i;
     struct icmp * icp;
     struct monitor_host * p = hosts;
     int i;
     struct icmp * icp;
     struct monitor_host * p = hosts;

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

 
     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);

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

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


@@ -152,7 +139,7 @@ pinger(int ignore)
             }
 
             gettimeofday(&now, (struct timezone *) NULL);
             }
 
             gettimeofday(&now, (struct timezone *) NULL);

-            tv_sub(&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;


@@ -168,8 +155,7 @@ pinger(int ignore)
 
                 int 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));
 


@@ -184,7 +170,7 @@ pinger(int ignore)
     }
 
     signal(SIGALRM, pinger); /* restore handler */
     }
 
     signal(SIGALRM, pinger); /* restore handler */

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

 }
 
 static void
 }
 
 static void


@@ -220,10 +206,10 @@ read_icmp_data(struct monitor_host * p)
 
         memcpy(&p->last_ping_received, &tv, sizeof(tv));
 
 
         memcpy(&p->last_ping_received, &tv, sizeof(tv));
 

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


@@ -392,8 +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++;
             }
         }


@@ -455,7 +441,7 @@ main(int argc, char ** argv)
     init_hosts();
 
     signal(SIGALRM, pinger);
     init_hosts();
 
     signal(SIGALRM, pinger);

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

 
     get_response();
 
 
     get_response();