X-Git-Url: http://git.subgeniuskitty.com/icmpmonitor/.git/blobdiff_plain/684f5d952a4ecfad2d2fad808498a87b5184035b..4a0d85a5f1ed0900bf617f86ee238b3c644fe7b8:/icmpmonitor.c diff --git a/icmpmonitor.c b/icmpmonitor.c index d222d61..284da67 100644 --- a/icmpmonitor.c +++ b/icmpmonitor.c @@ -1,14 +1,19 @@ /* - * 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. */ #include #include +#include #include #include #include @@ -23,95 +28,44 @@ #include #include -#include "cfg.h" +#include "iniparser/iniparser.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? */ +/* 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; - /* TODO: Replace the following two values with a single boolean */ - int up; - int down; + bool host_up; struct sockaddr_in dest; - unsigned int sentpackets; - unsigned int recvdpackets; - - /* linked list */ + + /* Linked list */ struct monitor_host * next; }; -/* protos */ -static int gethostaddr(const char * name); -static void read_hosts(const char * cfg_file_name); -static void init_hosts(void); -static void get_response(void); -static void pinger(int); -static int in_cksum(unsigned short * addr, int len); -static void read_icmp_data(struct monitor_host * p); -static void tvsub(struct timeval * out, struct timeval * in); -static int gcd(int x, int y); - -/* globals */ -static struct monitor_host ** hosts = NULL; -static int isVerbose = 0; -static int keepBanging = 0; -static unsigned short ident; -static int send_delay = 1; - -int -main(int argc, char ** argv) -{ - extern char * optarg; - extern int optind; - char * cfgfile = NULL; - int param; - - while ((param = getopt(argc, argv, "rvf:")) != -1) { - switch(param) { - case 'v': - isVerbose = 1; - break; - case 'r': - keepBanging = 1; - break; - case 'f': - cfgfile=strdup(optarg); - break; - default: - fprintf(stderr,"Usage: icmpmonitor [-v] [-r] [-f cfgfile]\n"); - exit(EXIT_FAILURE); - } - } - - if (!cfgfile) { - fprintf(stderr, "ERROR: No config file specified.\n"); - exit(EXIT_FAILURE); - } - - read_hosts(cfgfile); - - init_hosts(); - - ident = getpid() & 0xFFFF; - - signal(SIGALRM, pinger); - alarm(send_delay); - - get_response(); - - exit(EXIT_SUCCESS); -} +/* 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; + /* TODO: Get rid of this global. */ + static int send_delay = 1; /* * Checksum routine for Internet Protocol family headers @@ -123,7 +77,7 @@ in_cksum(unsigned short * addr, int 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 @@ -133,13 +87,13 @@ in_cksum(unsigned short * addr, int len) sum += *w++; nleft -= 2; } - + /* 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 */ @@ -147,6 +101,21 @@ in_cksum(unsigned short * addr, int len) return(answer); } +/* + * Subtracts two timeval structs. + * Ensure out >= in. + * Modifies out = out - in. + */ +static void +tv_sub(register struct timeval * out, register struct timeval * in) +{ + if ((out->tv_usec -= in->tv_usec) < 0) { + --out->tv_sec; + out->tv_usec += 1000000; + } + out->tv_sec -= in->tv_sec; +} + /* * Compose and transmit an ICMP ECHO REQUEST packet. The IP packet * will be added on by the kernel. The ID field is our UNIX process ID, @@ -157,106 +126,67 @@ in_cksum(unsigned short * addr, int len) static void pinger(int ignore) { - int cc, i; + int i; struct icmp * icp; - struct monitor_host * p; + struct monitor_host * p = hosts; u_char outpack[MAXPACKETSIZE]; - p = hosts[0]; while (p) { if (p->socket != -1) { struct timeval now; - + gettimeofday(&now, (struct timezone *) NULL); - tvsub(&now, &p->last_ping_received); - - if (now.tv_sec > (p->max_delay + p->ping_interval)) { - p->up = 0; - if ((!p->down) || keepBanging) { - p->down = 1; - - if (isVerbose) printf("INFO: Host %s is down. Executing DOWN command.\n", p->name); + tv_sub(&now, &p->last_ping_received); + + if (now.tv_sec > (p->max_delay + p->ping_interval)) { + 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); } } } - + gettimeofday(&now, (struct timezone *) NULL); - tvsub(&now, &p->last_ping_sent); - + tv_sub(&now, &p->last_ping_sent); + if (now.tv_sec > p->ping_interval) { /* Time to send ping */ icp = (struct icmp *) outpack; icp->icmp_type = ICMP_ECHO; icp->icmp_code = 0; icp->icmp_cksum = 0; icp->icmp_seq = p->socket; - icp->icmp_id = ident; + icp->icmp_id = getpid() & 0xFFFF; + + if (verbose) printf("INFO: Sending ICMP packet to %s.\n", p->name); - if (isVerbose) 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); - + i = sendto(p->socket, (char *) outpack, cc, 0, (const struct sockaddr *) (&p->dest), sizeof(struct sockaddr)); - + gettimeofday(&p->last_ping_sent, (struct timezone *) NULL); - + 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); } -static void -get_response(void) -{ - fd_set rfds; - int retval, maxd = -1; - struct monitor_host * p; - - while (1) { - p = hosts[0]; - FD_ZERO(&rfds); - while (p) { - if (p->socket != -1) { - if (p->socket > maxd) maxd=p->socket; - FD_SET(p->socket, &rfds); - } - p=p->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 = hosts[0]; - 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? */ - } - } - } -} - static void read_icmp_data(struct monitor_host * p) { @@ -265,42 +195,40 @@ read_icmp_data(struct monitor_host * p) struct sockaddr_in from; struct ip * ip; struct icmp * icmp; - struct timeval tv ; + struct timeval tv; unsigned char buf[MAXPACKETSIZE]; gettimeofday(&tv, (struct timezone *) 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); return; - } + } - /* check IP header actual len */ - ip = (struct ip *) buf; - iphdrlen = ip->ip_hl << 2; + /* check IP header actual len */ + ip = (struct ip *) buf; + iphdrlen = ip->ip_hl << 2; icmp = (struct icmp *) (buf + iphdrlen); - + if (cc < iphdrlen + ICMP_MINLEN) { fprintf(stderr, "WARN: Received short packet from %s.\n", p->name); 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]); + + tv_sub(&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); - p->down = 0; - if (!p->up) { - p->up = 1; - if (isVerbose) printf("INFO: Host %s is up. Executing UP command.\n", p->name); + + if (verbose) printf("INFO: Got ICMP reply from %s in %d ms.\n", p->name, delay); + 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); @@ -312,91 +240,139 @@ read_icmp_data(struct monitor_host * p) } static void -read_hosts(const char * cfg_file_name) +get_response(void) { - int i, n = 0; - struct Cfg * cfg; - - if ((cfg = readcfg(cfg_file_name)) == NULL) { - fprintf(stderr, "ERROR: Failed to read config.\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); + fd_set rfds; + int retval, maxd = -1; + struct monitor_host * p; + + while (1) { + p = hosts; + FD_ZERO(&rfds); + while (p) { + if (p->socket != -1) { + if (p->socket > maxd) maxd = p->socket; + FD_SET(p->socket, &rfds); } - - 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]->down = 0; - hosts[n]->up = 1; - } else if (strcmp(cfg->dict[i]->value[4], "up") == 0) { - hosts[n]->down = 0; - hosts[n]->up = 1; - } else if (strcmp(cfg->dict[i]->value[4], "down") == 0) { - hosts[n]->down = 1; - hosts[n]->up = 0; - } else if (strcmp(cfg->dict[i]->value[4], "auto") == 0) { - hosts[n]->down = 1; - hosts[n]->up = 1; - } else if (strcmp(cfg->dict[i]->value[4], "none") == 0) { - hosts[n]->down = 0; - hosts[n]->up = 0; + p = p->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 { - fprintf(stderr, "ERROR: Illegal value %s in record %d for startup condition.\n", cfg->dict[i]->value[4], n); - exit(EXIT_FAILURE); + if (retval > 0) { + p = hosts; + 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? */ + } } - 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); +static void +parse_config(const char * conf_file) +{ + dictionary * conf = iniparser_load(conf_file); + if (conf == NULL) { + fprintf(stderr, "ERROR: Unable to parse configuration file %s.\n", conf_file); + exit(EXIT_FAILURE); + } - 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); } - freecfg(cfg); + 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++] = ':'; - if (n <= 0) { - fprintf(stderr, "ERROR: No hosts defined in cfg file, exiting.\n"); - exit(EXIT_FAILURE); + 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); + } + + cur_host->socket = -1; + cur_host->next = NULL; + gettimeofday(&(cur_host->last_ping_received), (struct timezone *) NULL); + + if (hosts == NULL) { + hosts = cur_host; + host_list_end = cur_host; + } else { + host_list_end->next = cur_host; + host_list_end = cur_host; + } + + 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); } +static int +gcd(int x, int y) +{ + int remainder = x % y; + if (remainder == 0) return y; + return gcd(y, remainder); +} + static void init_hosts(void) { - struct monitor_host * p = hosts[0]; + struct monitor_host * p = hosts; struct protoent * proto; int ok = 0; @@ -404,11 +380,11 @@ init_hosts(void) fprintf(stderr, "ERROR: Unknown protocol: icmp.\n"); exit(EXIT_FAILURE); } - + 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 { @@ -430,25 +406,58 @@ init_hosts(void) } } -/* - * Subtracts two timeval structs. - * Ensure out >= in. - * Modifies out = out - in. - */ -static void -tvsub(register struct timeval * out, register struct timeval * in) +void +print_usage(char ** argv) { - if ((out->tv_usec -= in->tv_usec) < 0) { - --out->tv_sec; - out->tv_usec += 1000000; + 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]); +} + +void +parse_params(int argc, char ** argv) +{ + int param; + while ((param = getopt(argc, argv, "hrvf:")) != -1) { + switch(param) { + case 'v': + verbose = true; + break; + case 'r': + retry_down_cmd = true; + break; + case 'f': + parse_config(optarg); + break; + case 'h': + default: + print_usage(argv); + exit(EXIT_FAILURE); + break; + } + } + if (hosts == NULL) { + fprintf(stderr, "ERROR: Unable to parse a config file.\n"); + exit(EXIT_FAILURE); } - out->tv_sec -= in->tv_sec; } -static int -gcd(int x, int y) +int +main(int argc, char ** argv) { - int remainder = x % y; - if (remainder == 0) return y; - return gcd(y, remainder); + parse_params(argc, argv); + + init_hosts(); + + signal(SIGALRM, pinger); + alarm(send_delay); + + get_response(); + + exit(EXIT_SUCCESS); }