X-Git-Url: http://git.subgeniuskitty.com/icmpmonitor/.git/blobdiff_plain/8f7eee8c47253a145a06b143b8c869bb13c2d318..3900fd4332290428dea7ffaa693887e5f23f1a89:/icmpmonitor.c diff --git a/icmpmonitor.c b/icmpmonitor.c index 7d24d1a..f2bf43e 100644 --- a/icmpmonitor.c +++ b/icmpmonitor.c @@ -1,378 +1,222 @@ /* - * 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 #include #include #include #include #include -#include -#include #include -#include #include #include #include -#include #include #include -#include #include +#include -#include "cfg.h" +#include "iniparser/iniparser.h" -/* return codes */ -#define RET_OK 0 -#define RET_NO_HOSTS 1 -#define RET_INIT_ERROR 2 -#define RET_BAD_CFG 3 -#define RET_BAD_OPT 4 +#define VERSION 2 -#define MAXPACKET (65536 - 60 - 8) /* max packet size */ -#define DEFDATALEN (64 - 8) /* default data length */ +#define MAXPACKETSIZE (65536 - 60 - 8) /* TODO: What are the magic numbers? */ +#define DEFAULTDATALEN (64 - 8) /* TODO: What are the magic numbers? */ -#define VERSION "ICMPmonitor v1.2 by lord@crocodile.org" +/* 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 -# define icmphdr icmp +/* 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 -/* typedefs */ -typedef struct monitor_host -{ - /* following are coming from cfg */ - char *name; +/* 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; - - /* following values are calculated */ - int socket; - struct timeval last_ping_received; - struct timeval last_ping_sent; - int up; - int down; + char * up_cmd; + char * down_cmd; + + /* Calculated values */ + int socket; + struct timeval last_ping_received; + struct timeval last_ping_sent; + bool host_up; struct sockaddr_in dest; - unsigned int sentpackets ; - unsigned int recvdpackets; - - /* linked list */ - struct monitor_host *next; -} monitor_host_t; - -/* 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(u_short *addr, int len); -static void read_icmp_data(monitor_host_t *p); -static void tvsub(struct timeval *out, struct timeval *in); -static int gcd(int x, int y); - -/* globals */ - -static monitor_host_t **hosts = NULL; -static int isVerbose = 0; -static int keepBanging = 0; -static unsigned short ident; -static int send_delay = 1; - - - - + /* Linked list */ + struct monitor_host * next; +}; +/* 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; - - - - - - - -int main(int ac, char **av) +/* + * 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. + */ +uint16_t +checksum(uint16_t * data) { - extern char* optarg; - extern int optind; - char *cfgfile=NULL; - int param; - - while((param = getopt(ac, av, "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); + 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; } - - read_hosts(cfgfile); - - init_hosts(); - - ident=getpid() & 0xFFFF; - - (void)signal(SIGALRM, pinger); - alarm(send_delay); - - get_response(); - - exit(EXIT_SUCCESS); + return htons(~accumulator); } - /* - * in_cksum -- - * Checksum routine for Internet Protocol family headers (C Version) + * Calculate difference between two timeval structs to within one second. */ -static int -in_cksum(u_short *addr, int len) +void +timeval_diff(struct timeval * a, const struct timeval * b) { - register int nleft = len; - register u_short *w = addr; - register int sum = 0; - u_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; - } - - /* 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); + assert(a->tv_sec >= b->tv_sec); + a->tv_sec -= b->tv_sec; } /* - * pinger -- - * 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, - * and the sequence number is an ascending integer. The first 8 bytes + * 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, + * and the sequence number is an ascending integer. The first 8 bytes * of the data portion are used to hold a UNIX "timeval" struct in VAX * byte-order, to compute the round-trip time. */ -static void pinger(int ignore) +static void +pinger(int ignore) { - register struct icmphdr *icp; - register int cc; - int i; - monitor_host_t *p; - u_char outpack[MAXPACKET]; - - p=hosts[0]; - while(p) - { - if(p->socket!=-1) - { + int i; + struct icmp * icp; + struct monitor_host * p = hosts; + unsigned char outpack[MAXPACKETSIZE]; /* Use char so this can be aliased later. */ + + while (p) { + if (p->socket != -1) { struct timeval now; - - (void)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); - if(!fork()) - { - system(p->downcmd); - exit(0); - } else - { + + gettimeofday(&now, (struct timezone *) NULL); + 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 (verbose) printf("INFO: Host %s stopped responding. Executing DOWN command.\n", p->name); + p->host_up = false; + if (!fork()) { + system(p->down_cmd); + exit(EXIT_SUCCESS); + } else { wait(NULL); } } } - - (void)gettimeofday(&now,(struct timezone *)NULL); - tvsub(&now, &p->last_ping_sent); - - if(now.tv_sec > p->ping_interval) - { - /* Time to send ping */ - - icp = (struct icmphdr *)outpack; + + gettimeofday(&now, (struct timezone *) NULL); + timeval_diff(&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; - - if (isVerbose) printf("INFO: Sending ICMP packet to %s.\n", p->name); - - (void)gettimeofday((struct timeval *)&outpack[8], - (struct timezone *)NULL); - - cc = DEFDATALEN + 8; /* skips ICMP portion */ - - /* compute ICMP checksum here */ - icp->icmp_cksum = in_cksum((u_short *)icp, cc); - - i = sendto(p->socket, (char *)outpack, cc, 0, (const struct sockaddr *)(&p->dest), - sizeof(struct sockaddr)); - - (void)gettimeofday(&p->last_ping_sent, - (struct timezone *)NULL); - - if(i<0 || i!=cc) - { + icp->icmp_id = getpid() & 0xFFFF; + + if (verbose) printf("INFO: Sending ICMP packet to %s.\n", p->name); + + gettimeofday((struct timeval *) &outpack[8], (struct timezone *) NULL); + + int cc = DEFAULTDATALEN + 8; /* skips ICMP portion */ + + icp->icmp_cksum = checksum((uint16_t *) outpack); + + 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; - + p = p->next; } - - (void)signal(SIGALRM, pinger); /* restore handler */ - alarm(send_delay); + + signal(SIGALRM, pinger); /* restore handler */ + alarm(TIMER_RESOLUTION); } -static void get_response(void) +static void +read_icmp_data(struct monitor_host * p) { - fd_set rfds; - int retval; - monitor_host_t *p; - int maxd=-1; - - 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; - } + int cc, iphdrlen, delay; + socklen_t fromlen; + struct sockaddr_in from; + struct ip * ip; + struct icmp * icmp; + struct timeval tv; + unsigned char buf[MAXPACKETSIZE]; - retval = select(maxd+1, &rfds, NULL, NULL, NULL); - if(retval<0) - { - /* we get her in case we are interrupted by signal. - it's ok. */ - } - else - { - if(retval>0) - { - p=hosts[0]; - while(p) - { - if(p->socket!=-1 && FD_ISSET(p->socket, &rfds)) - { - /* Read data */ - read_icmp_data(p); - } - p=p->next; - } - } else { - /* TODO: How to handle this error? */ - } - } - } -} + gettimeofday(&tv, (struct timezone *) NULL); -static void read_icmp_data(monitor_host_t *p) -{ - socklen_t fromlen ; - struct sockaddr_in from ; - int cc ; - struct ip *ip ; - struct icmp *icmp ; - int iphdrlen ; - int delay ; - struct timeval tv ; - unsigned char buf[MAXPACKET]; /* read buffer */ - - (void)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; + icmp = (struct icmp *) (buf + iphdrlen); - /* 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]); - 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(!fork()) - { - system(p->upcmd); - exit(0); - } else - { + + 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 (!fork()) { + system(p->up_cmd); + exit(EXIT_SUCCESS); + } else { wait(NULL); } } @@ -381,154 +225,225 @@ static void read_icmp_data(monitor_host_t *p) } } -static void read_hosts(const char *cfg_file_name) +static void +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(monitor_host_t *) * cfg->nelements); - for (i=0; inelements; 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); + } + 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; + 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] = malloc(sizeof(monitor_host_t)); - 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; - } else { - fprintf(stderr, "ERROR: Illegal value %s in record %n for startup condition.\n", cfg->dict[i]->value[4], n); - 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); - - n++; - } + } } +} - freecfg(cfg); +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); + } - if (n <= 0) { - fprintf(stderr, "ERROR: No hosts defined in cfg file, exiting.\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); } + + 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++] = ':'; + + 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) +static int +get_host_addr(const char * name) { - static int res; - struct hostent *he; - - if((res=inet_addr(name))<0) - { - he=gethostbyname(name); - if(!he) - return -1; - memcpy( &res , he->h_addr , he->h_length ); - } + static int res; + struct hostent * host_ent; + + if ((res = inet_addr(name)) < 0) { + host_ent = gethostbyname(name); + if (!host_ent) return -1; + memcpy(&res, host_ent->h_addr, host_ent->h_length); + } return(res); } -static void init_hosts(void) +static int +gcd(int x, int y) { - monitor_host_t *p=hosts[0]; - struct protoent *proto; - int ok=0; + int remainder = x % y; + if (remainder == 0) return y; + return gcd(y, remainder); +} + +static void +init_hosts(void) +{ + struct monitor_host * p = hosts; + struct protoent * proto; + int ok = 0; if ((proto = getprotobyname("icmp")) == NULL) { 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) - { + + while (p) { + bzero(&p->dest, sizeof(p->dest)); + p->dest.sin_family = AF_INET; + 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 - { - if((p->socket=socket(AF_INET,SOCK_RAW,proto->p_proto))<0) - { + } else { + if ((p->socket = socket(AF_INET,SOCK_RAW,proto->p_proto)) < 0) { 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); + } else { + //if (ok == 0) send_delay = p->ping_interval; + //else send_delay = gcd(send_delay, p->ping_interval); ok++; } } - p=p->next; + p = p->next; } - if(!ok) - { + if (!ok) { fprintf(stderr, "ERROR: No hosts left to process.\n"); exit(EXIT_FAILURE); } } -/* - * tvsub -- - * Subtract 2 timeval structs: out = out - in. Out is assumed to - * be >= 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; - } - out->tv_sec -= in->tv_sec; + 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]); } -static int gcd(int x, int y) +void +parse_params(int argc, char ** argv) { - int remainder = x % y; - if (remainder == 0) return y; - return gcd(y, remainder); + 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); + } +} + +int +main(int argc, char ** argv) +{ + parse_params(argc, argv); + + init_hosts(); + + signal(SIGALRM, pinger); + alarm(TIMER_RESOLUTION); + + get_response(); + + exit(EXIT_SUCCESS); }