From c9b16ece585295b83d84cc148d30071d49b87b2e Mon Sep 17 00:00:00 2001 From: Aaron Taylor Date: Sat, 21 Sep 2019 02:34:05 -0700 Subject: [PATCH] Reordered functions to eliminate declarations. Combined up,down in host struct into hostup bool. Eliminated trailing whitespace. --- icmpmonitor.c | 308 +++++++++++++++++++++++--------------------------- 1 file changed, 143 insertions(+), 165 deletions(-) diff --git a/icmpmonitor.c b/icmpmonitor.c index d222d61..04aa91c 100644 --- a/icmpmonitor.c +++ b/icmpmonitor.c @@ -1,6 +1,6 @@ /* * Monitor hosts using ICMP "echo" and notify when down. - * + * * © 2019 Aaron Taylor * © 1999 Vadim Zaliva * © 1989 The Regents of the University of California & Mike Muuss @@ -9,6 +9,7 @@ #include #include +#include #include #include #include @@ -40,28 +41,15 @@ struct monitor_host { 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 hostup; struct sockaddr_in dest; unsigned int sentpackets; unsigned int recvdpackets; - + /* 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; @@ -69,50 +57,6 @@ 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); -} - /* * Checksum routine for Internet Protocol family headers */ @@ -123,7 +67,7 @@ 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 +77,13 @@ 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 +91,21 @@ in_cksum(unsigned short * addr, int len) return(answer); } +/* + * Subtracts two timeval structs. + * Ensure out >= in. + * Modifies out = out - in. + */ +static void +tvsub(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, @@ -166,16 +125,14 @@ pinger(int ignore) 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); + 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 (!fork()) { system(p->downcmd); exit(EXIT_SUCCESS); @@ -184,10 +141,10 @@ pinger(int ignore) } } } - + gettimeofday(&now, (struct timezone *) NULL); tvsub(&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; @@ -197,18 +154,18 @@ pinger(int ignore) icp->icmp_id = ident; 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 */ - + /* 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); } @@ -217,46 +174,11 @@ pinger(int ignore) } 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) { @@ -265,40 +187,39 @@ 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++; 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 (!p->hostup) { + if (isVerbose) printf("INFO: Host %s started responding. Executing UP command.\n", p->name); + p->hostup = true; if (!fork()) { system(p->upcmd); exit(EXIT_SUCCESS); @@ -311,17 +232,52 @@ read_icmp_data(struct monitor_host * p) } } +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_hosts(const char * cfg_file_name) { 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++) { @@ -332,29 +288,22 @@ read_hosts(const char * cfg_file_name) fprintf(stderr, "ERROR: Too many fields in record %d of cfg file. Got %d.\n", n, cfg->dict[i]->nvalues+1); exit(EXIT_FAILURE); } - + 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; + hosts[n]->hostup = true; } else if (strcmp(cfg->dict[i]->value[4], "up") == 0) { - hosts[n]->down = 0; - hosts[n]->up = 1; + hosts[n]->hostup = true; } else if (strcmp(cfg->dict[i]->value[4], "down") == 0) { - hosts[n]->down = 1; - hosts[n]->up = 0; + hosts[n]->hostup = false; } 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; + /* 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); exit(EXIT_FAILURE); @@ -368,7 +317,7 @@ read_hosts(const char * cfg_file_name) gettimeofday(&(hosts[n]->last_ping_received), (struct timezone *)NULL); n++; - } + } } freecfg(cfg); @@ -384,15 +333,23 @@ gethostaddr(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); - } + } 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) { @@ -404,7 +361,7 @@ 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; @@ -430,25 +387,46 @@ 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) +int +main(int argc, char ** argv) { - if ((out->tv_usec -= in->tv_usec) < 0) { - --out->tv_sec; - out->tv_usec += 1000000; + 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); + } } - out->tv_sec -= in->tv_sec; -} -static int -gcd(int x, int y) -{ - int remainder = x % y; - if (remainder == 0) return y; - return gcd(y, remainder); + 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); } -- 2.20.1