X-Git-Url: http://git.subgeniuskitty.com/icmpmonitor/.git/blobdiff_plain/77b5f21a72d577b2f4e641a8710b32badf972f54..22e9f47e32f5905d2bd9ae5ee35020ace9091428:/icmpmonitor.c diff --git a/icmpmonitor.c b/icmpmonitor.c index 898fc80..462c920 100644 --- a/icmpmonitor.c +++ b/icmpmonitor.c @@ -171,94 +171,87 @@ pinger(int ignore) /* Dummy parameter since this function registers as a signal 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); @@ -277,38 +270,37 @@ parse_config(const char * 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);