alarm(TIMER_RESOLUTION);
}
-static void
-read_icmp_data(struct host_entry * p)
+void
+read_icmp_data(struct host_entry * host)
{
- int cc, iphdrlen, delay;
- socklen_t fromlen;
- struct sockaddr_in from;
- struct ip * ip;
- struct icmp * icmp;
- struct timeval tv;
- unsigned char buf[MAXPACKETSIZE];
-
- gettimeofday(&tv, (struct timezone *) NULL);
+ struct timeval now;
+ gettimeofday(&now, NULL);
- fromlen = sizeof(from);
- if ((cc = recvfrom(p->socket, buf, sizeof(buf), 0, (struct sockaddr *)&from, &fromlen)) < 0) {
- if (errno != EINTR) fprintf(stderr, "WARN: Error reading ICMP data from %s.\n", p->name);
+ struct sockaddr_in from;
+ socklen_t fromlen = sizeof(from);
+ int bytes;
+ unsigned char packet[IP_PACKET_MAX_BYTES]; /* Use char so this can be aliased later. */
+ if ((bytes = recvfrom(host->socket, packet, sizeof(packet), 0, (struct sockaddr *) &from, &fromlen)) < 0) {
+ if (errno != EINTR) fprintf(stderr, "WARN: Error reading ICMP data from %s.\n", host->name);
return;
}
- /* check IP header actual len */
- ip = (struct ip *) buf;
- iphdrlen = ip->ip_hl << 2;
- icmp = (struct icmp *) (buf + iphdrlen);
+ struct ip * ip = (struct ip *) packet;
+ int iphdrlen = ip->ip_hl << 2;
+ struct icmp * icmp = (struct icmp *) (packet + iphdrlen);
- if (cc < iphdrlen + ICMP_MINLEN) {
- fprintf(stderr, "WARN: Received short packet from %s.\n", p->name);
+ if (bytes < iphdrlen + ICMP_MINLEN) {
+ fprintf(stderr, "WARN: Received short packet from %s.\n", host->name);
return;
}
- if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == p->socket) {
-
- memcpy(&p->last_ping_received, &tv, sizeof(tv));
-
- timeval_diff(&tv, (struct timeval *) &icmp->icmp_data[0]);
- delay = tv.tv_sec * 1000 + (tv.tv_usec / 1000);
-
- 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 (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == host->socket) {
+ memcpy(&host->last_ping_received, &now, sizeof(now));
+ if (verbose) printf("INFO: Got ICMP reply from %s.\n", host->name);
+ if (!host->host_up) {
+ if (verbose) printf("INFO: Host %s started responding. Executing UP command.\n", host->name);
+ host->host_up = true;
if (!fork()) {
- system(p->up_cmd);
+ system(host->up_cmd);
exit(EXIT_SUCCESS);
- } else {
- wait(NULL);
}
}
} else {
- /* TODO: Do anything here? */
+ /* The packet isn't what we expected. Ignore it and move on. */
}
}
-static void
+/*
+ * This function contains the main program loop, listening for replies to pings
+ * sent from the signal-driven pinger().
+ */
+void
get_response(void)
{
- fd_set rfds;
- int retval, maxd = -1;
- struct host_entry * p;
-
- while (1) {
- p = first_host_in_list;
+ while (true) {
+ fd_set rfds;
FD_ZERO(&rfds);
- while (p) {
- if (p->socket != -1) {
- if (p->socket > maxd) maxd = p->socket;
- FD_SET(p->socket, &rfds);
- }
- p = p->next;
+
+ assert(first_host_in_list);
+ struct host_entry * host = first_host_in_list;
+
+ int max_fd = -1;
+ while (host) {
+ if (host->socket > max_fd) max_fd = host->socket;
+ FD_SET(host->socket, &rfds);
+ host = host->next;
}
- retval = select(maxd+1, &rfds, NULL, NULL, NULL);
- if (retval < 0) {
- /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */
- } else {
- if (retval > 0) {
- p = first_host_in_list;
- while (p) {
- if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p);
- p = p->next;
- }
- } else {
- /* TODO: How to handle this error? */
+ int retval;
+ if ((retval = select(max_fd+1, &rfds, NULL, NULL, NULL)) > 0) {
+ assert(first_host_in_list);
+ host = first_host_in_list;
+ while (host) {
+ if (FD_ISSET(host->socket, &rfds)) read_icmp_data(host);
+ host = host->next;
}
+ } else {
+ /* An error or interruption occurred. */
+ /* We can't do anything about it, so loop and try again. */
}
}
}
-static void
+/*
+ * Parse a configuration file using the `iniparser` library.
+ * See `icmpmonitor.ini` and `README.md` for examples and reference.
+ */
+void
parse_config(const char * conf_file)
{
dictionary * conf = iniparser_load(conf_file);
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);
+ char * key_buf = malloc(section_len + 1 + MAX_CONF_KEY_LEN + 1); /* +1 for ':' and '\0' */
strcpy(key_buf, iniparser_getsecname(conf, i));
key_buf[section_len++] = ':';
struct host_entry * cur_host = malloc(sizeof(struct host_entry));
key_buf[section_len] = '\0';
- strncat(key_buf, "host", MAXCONFKEYLEN);
+ strncat(key_buf, "host", MAX_CONF_KEY_LEN);
cur_host->name = strdup(iniparser_getstring(conf, key_buf, NULL));
key_buf[section_len] = '\0';
- strncat(key_buf, "interval", MAXCONFKEYLEN);
+ strncat(key_buf, "interval", MAX_CONF_KEY_LEN);
cur_host->ping_interval = iniparser_getint(conf, key_buf, -1);
key_buf[section_len] = '\0';
- strncat(key_buf, "max_delay", MAXCONFKEYLEN);
+ strncat(key_buf, "max_delay", MAX_CONF_KEY_LEN);
cur_host->max_delay = iniparser_getint(conf, key_buf, -1);
key_buf[section_len] = '\0';
- strncat(key_buf, "up_cmd", MAXCONFKEYLEN);
+ strncat(key_buf, "up_cmd", MAX_CONF_KEY_LEN);
cur_host->up_cmd = strdup(iniparser_getstring(conf, key_buf, NULL));
key_buf[section_len] = '\0';
- strncat(key_buf, "down_cmd", MAXCONFKEYLEN);
+ strncat(key_buf, "down_cmd", MAX_CONF_KEY_LEN);
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;
+ strncat(key_buf, "start_condition", MAX_CONF_KEY_LEN);
+ const char * value = iniparser_getstring(conf, key_buf, NULL);
+ if (value) cur_host->host_up = *value == 'u' ? true : false;
- /* 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);