X-Git-Url: http://git.subgeniuskitty.com/icmpmonitor/.git/blobdiff_plain/c9b16ece585295b83d84cc148d30071d49b87b2e..3900fd4332290428dea7ffaa693887e5f23f1a89:/icmpmonitor.c diff --git a/icmpmonitor.c b/icmpmonitor.c index 04aa91c..f2bf43e 100644 --- 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 * © 1999 Vadim Zaliva * © 1989 The Regents of the University of California & Mike Muuss + * * See LICENSE file for copyright and license details. */ @@ -23,87 +27,80 @@ #include #include #include +#include + +#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? */ +/* 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; - char * upcmd; - char * downcmd; + char * up_cmd; + char * down_cmd; /* Calculated values */ int socket; struct timeval last_ping_received; struct timeval last_ping_sent; - bool hostup; + bool host_up; struct sockaddr_in dest; - unsigned int sentpackets; - unsigned int recvdpackets; - /* linked list */ + /* Linked list */ struct monitor_host * next; }; -/* globals */ -static struct monitor_host ** hosts = NULL; -static int isVerbose = 0; -static int keepBanging = 0; -static unsigned short ident; -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; } /* @@ -116,25 +113,24 @@ tvsub(register struct timeval * out, register struct timeval * in) static void pinger(int ignore) { - int cc, i; + int i; 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); - tvsub(&now, &p->last_ping_received); + timeval_diff(&now, &p->last_ping_received); 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()) { - system(p->downcmd); + system(p->down_cmd); exit(EXIT_SUCCESS); } else { wait(NULL); @@ -143,7 +139,7 @@ pinger(int ignore) } 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; @@ -151,16 +147,15 @@ pinger(int ignore) icp->icmp_code = 0; icp->icmp_cksum = 0; icp->icmp_seq = p->socket; - icp->icmp_id = ident; + 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); - 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)); @@ -169,14 +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); } - p->sentpackets++; } } p = p->next; } signal(SIGALRM, pinger); /* restore handler */ - alarm(send_delay); + alarm(TIMER_RESOLUTION); } static void @@ -208,20 +202,19 @@ read_icmp_data(struct monitor_host * p) return; } - if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == ident && icmp->icmp_seq == p->socket) { - p->recvdpackets++; + if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == p->socket) { 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); - 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()) { - system(p->upcmd); + system(p->up_cmd); exit(EXIT_SUCCESS); } else { wait(NULL); @@ -240,11 +233,11 @@ get_response(void) struct monitor_host * p; while (1) { - p = hosts[0]; + p = hosts; 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; @@ -255,7 +248,7 @@ get_response(void) /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */ } else { if (retval > 0) { - p = hosts[0]; + p = hosts; while (p) { if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p); p = p->next; @@ -268,76 +261,88 @@ get_response(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); } - 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); } - 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 -gethostaddr(const char * name) +get_host_addr(const char * name) { static int res; - struct hostent * he; + struct hostent * host_ent; 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); } @@ -353,7 +358,7 @@ gcd(int x, int y) static void init_hosts(void) { - struct monitor_host * p = hosts[0]; + struct monitor_host * p = hosts; struct protoent * proto; int ok = 0; @@ -365,7 +370,7 @@ init_hosts(void) 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 { @@ -373,8 +378,8 @@ init_hosts(void) 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++; } } @@ -387,44 +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 \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 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': - isVerbose = 1; + verbose = true; break; case 'r': - keepBanging = 1; + retry_down_cmd = true; break; case 'f': - cfgfile=strdup(optarg); + parse_config(optarg); break; + case 'h': default: - fprintf(stderr,"Usage: icmpmonitor [-v] [-r] [-f cfgfile]\n"); + print_usage(argv); 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); } +} - read_hosts(cfgfile); +int +main(int argc, char ** argv) +{ + parse_params(argc, argv); init_hosts(); - ident = getpid() & 0xFFFF; - signal(SIGALRM, pinger); - alarm(send_delay); + alarm(TIMER_RESOLUTION); get_response();