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arp-scan.c
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/*
* arp-scan is Copyright (C) 2005-2022 Roy Hills
*
* This file is part of arp-scan.
*
* arp-scan is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* arp-scan is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with arp-scan. If not, see <http://www.gnu.org/licenses/>.
*
* arp-scan -- Send ARP requests to network hosts and display responses
*
* Author: Roy Hills
* Date: 13 October 2005
*
* Usage:
* arp-scan [options] [host...]
*
* Description:
*
* arp-scan sends the specified ARP packet to the specified hosts
* and displays any responses received.
*
* The ARP protocol is defined in RFC 826 Ethernet Address Resolution Protocol
*
*/
#include "arp-scan.h"
/* Global variables */
static host_entry *helist = NULL; /* Array of host entries */
static host_entry **helistptr; /* Array of pointers to host entries */
static host_entry **cursor; /* Pointer to current host entry ptr */
static unsigned num_hosts = 0; /* Number of entries in the list */
static unsigned responders = 0; /* Number of hosts which responded */
static unsigned live_count; /* Number of entries awaiting reply */
static int verbose = 0; /* Verbose level */
static char *filename; /* Target list file name */
static int filename_flag = 0; /* Set if using target list file */
static int random_flag = 0; /* Randomise the list */
static int numeric_flag = 0; /* IP addresses only */
static unsigned interval = 0; /* Desired interval between packets */
static unsigned bandwidth = DEFAULT_BANDWIDTH; /* Bandwidth in bits per sec */
static unsigned retry = DEFAULT_RETRY; /* Number of retries */
static unsigned timeout = DEFAULT_TIMEOUT; /* Per-host timeout */
static float backoff_factor = DEFAULT_BACKOFF_FACTOR; /* Backoff factor */
static int snaplen = SNAPLEN; /* Pcap snap length */
static char *if_name = NULL; /* Interface name, e.g. "eth0" */
static int quiet_flag = 0; /* Don't decode the packet */
static int ignore_dups = 0; /* Don't display duplicate packets */
static uint32_t arp_spa; /* Source IP address */
static int arp_spa_flag = 0; /* Source IP address specified */
static int arp_spa_is_tpa = 0; /* Source IP is dest IP */
static unsigned char arp_sha[ETH_ALEN]; /* Source Ethernet MAC Address */
static int arp_sha_flag = 0; /* Source MAC address specified */
static char *ouifilename = NULL; /* OUI filename */
static char *macfilename = NULL; /* MAC filename */
static char *pcap_savefile = NULL; /* pcap savefile filename */
static int arp_op = DEFAULT_ARP_OP; /* ARP Operation code */
static int arp_hrd = DEFAULT_ARP_HRD; /* ARP hardware type */
static int arp_pro = DEFAULT_ARP_PRO; /* ARP protocol */
static int arp_hln = DEFAULT_ARP_HLN; /* Hardware address length */
static int arp_pln = DEFAULT_ARP_PLN; /* Protocol address length */
static int eth_pro = DEFAULT_ETH_PRO; /* Ethernet protocol type */
static unsigned char arp_tha[6] = {0, 0, 0, 0, 0, 0};
static unsigned char target_mac[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
static unsigned char source_mac[6];
static int source_mac_flag = 0;
static unsigned char *padding = NULL;
static size_t padding_len = 0;
static int localnet_flag = 0; /* Scan local network */
static int llc_flag = 0; /* Use 802.2 LLC with SNAP */
static int ieee_8021q_vlan = -1; /* Use 802.1Q VLAN tagging if >= 0 */
static int pkt_write_file_flag = 0; /* Write packet to file flag */
static int pkt_read_file_flag = 0; /* Read packet from file flag */
static char *pkt_filename = NULL; /* Read/Write packet to file filename */
static int write_pkt_to_file = 0; /* Write packet to file for debugging */
static int rtt_flag = 0; /* Display round-trip time */
static pcap_dumper_t *pcap_dump_handle = NULL; /* pcap savefile handle */
static int plain_flag = 0; /* Only show host information */
static int resolve_flag = 0; /* Resolve IP addresses to hostnames */
unsigned int random_seed = 0;
static unsigned retry_send = DEFAULT_RETRY_SEND; /* Number of send packet retries */
static unsigned retry_send_interval = DEFAULT_RETRY_SEND_INTERVAL; /* Interval in seconds between send packet retries */
static unsigned int host_limit = 0; /* Exit after n responders if nonzero */
static format_element *format = NULL; /* Output format linked list */
int
main(int argc, char *argv[]) {
struct timeval now;
struct timeval diff; /* Difference between two timevals */
int select_timeout; /* Select timeout */
uint64_t loop_timediff; /* Time since last packet sent in us */
uint64_t host_timediff; /* Time since last pkt sent to this host (us) */
struct timeval last_packet_time; /* Time last packet was sent */
int req_interval; /* Requested per-packet interval */
int cum_err = 0; /* Cumulative timing error */
struct timeval start_time; /* Program start time */
struct timeval end_time; /* Program end time */
struct timeval elapsed_time; /* Elapsed time as timeval */
double elapsed_seconds; /* Elapsed time in seconds */
int reset_cum_err;
int pass_no = 0;
int first_timeout = 1;
unsigned i;
char errbuf[PCAP_ERRBUF_SIZE];
struct bpf_program filter;
char *filter_string;
bpf_u_int32 netmask;
bpf_u_int32 localnet;
int datalink;
int ret_status = 0;
int pcap_fd; /* Pcap file descriptor */
unsigned char interface_mac[ETH_ALEN];
pcap_t *pcap_handle; /* pcap handle */
struct in_addr interface_ip_addr;
/*
* Limit process capabilities to the minimum necessary to run this program.
*
* If we have POSIX.1e capability support, this removes all capabilities
* from the effective set and reduces the capabilities in the permitted
* set to the minimum needed.
*
* If we do not have capability support, then drop any SUID root privs
* by setting the effective user id to the real uid.
*/
limit_capabilities();
/*
* Process options.
*/
process_options(argc, argv);
/*
* If we're not reading from a file, and --localnet was not specified, then
* die if no hosts were given as command line arguments.
*/
if (!filename_flag && !localnet_flag)
if ((argc - optind) < 1)
err_msg("ERROR: No target hosts on command line and neither --file or "
"--localnet options given");
/*
* Get program start time for statistics displayed on completion.
*/
Gettimeofday(&start_time);
/*
* Open the network device for reading with pcap, or the pcap file if we
* have specified --readpktfromfile. If we are writing packets to a binary
* file, then set pcap_handle to NULL as we don't need to read packets in
* this case.
*/
if (pkt_read_file_flag) {
if (!(pcap_handle = pcap_open_offline(pkt_filename, errbuf)))
err_msg("pcap_open_offline: %s", errbuf);
} else if (!pkt_write_file_flag) {
/*
* enable CAP_NET_RAW in the effective set if we have POSIX.1e capability
* support. If we don't have capability support then restore SUID root
* privs by setting the effective user id to the saved euid.
*/
set_capability(ENABLE);
/*
* Determine network interface to use. If the interface was specified
* with the --interface option then use that, otherwise use
* my_lookupdev() to pick a suitable interface.
*
*/
if (!if_name) {
if (!(if_name = my_lookupdev(errbuf))) {
err_msg("my_lookupdev: %s", errbuf);
}
}
if (!(pcap_handle = pcap_create(if_name, errbuf)))
err_msg("pcap_create: %s", errbuf);
if ((pcap_set_snaplen(pcap_handle, snaplen)) < 0)
err_msg("pcap_set_snaplen: %s", pcap_geterr(pcap_handle));
if ((pcap_set_promisc(pcap_handle, PROMISC)) < 0)
err_msg("pcap_set_promisc: %s", pcap_geterr(pcap_handle));
if ((pcap_set_immediate_mode(pcap_handle, 1)) < 0)
err_msg("pcap_set_immediate_mode: %s", pcap_geterr(pcap_handle));
if ((pcap_set_timeout(pcap_handle, TO_MS)) < 0) /* Is this still needed? */
err_msg("pcap_set_timeout: %s", pcap_geterr(pcap_handle));
ret_status = pcap_activate(pcap_handle);
if (ret_status < 0) { /* Error from pcap_activate() */
char *cp;
cp = pcap_geterr(pcap_handle);
if (ret_status == PCAP_ERROR)
err_msg("pcap_activate: %s", cp);
else if ((ret_status == PCAP_ERROR_NO_SUCH_DEVICE ||
ret_status == PCAP_ERROR_PERM_DENIED) && *cp != '\0')
err_msg("pcap_activate: %s: %s\n(%s)", if_name,
pcap_statustostr(ret_status), cp);
else
err_msg("pcap_activate: %s: %s", if_name,
pcap_statustostr(ret_status));
} else if (ret_status > 0) { /* Warning from pcap_activate() */
char *cp;
cp = pcap_geterr(pcap_handle);
if (ret_status == PCAP_WARNING)
warn_msg("pcap_activate: %s", cp);
else if (ret_status == PCAP_WARNING_PROMISC_NOTSUP && *cp != '\0')
warn_msg("pcap_activate: %s: %s\n(%s)", if_name,
pcap_statustostr(ret_status), cp);
else
warn_msg("pcap_activate: %s: %s", if_name,
pcap_statustostr(ret_status));
}
/*
* Obtain the MAC address for the selected interface, and use this
* as the default value for the source hardware addresses in the frame
* header and ARP packet if the user has not specified their values.
*/
get_hardware_address(if_name, interface_mac);
/*
* Disable CAP_NET_RAW in the effective set if we have POSIX.1e capability
* support. If we don't have capability support then drop SUID root
* privs by setting the effective user id to the real uid.
*/
set_capability(DISABLE);
/*
* Permanently remove all capabilities or SUID root privilege as we
* don't need any special privileges after this point.
*
* We disable all capabilities in both the effective and permitted sets
* if we have POSIX.1e capability support, otherwise we permanently drop
* SUID root privs by setting the user ID to the real user ID.
*/
drop_capabilities();
/*
* Die with an error if we can't get the MAC address, as this
* indicates that the interface doesn't have a MAC address, so is
* probably not a compatible interface type.
*/
if (interface_mac[0]==0 && interface_mac[1]==0 &&
interface_mac[2]==0 && interface_mac[3]==0 &&
interface_mac[4]==0 && interface_mac[5]==0) {
err_msg("ERROR: Could not obtain MAC address for interface %s",
if_name);
}
if (source_mac_flag == 0)
memcpy(source_mac, interface_mac, ETH_ALEN);
if (arp_sha_flag == 0)
memcpy(arp_sha, interface_mac, ETH_ALEN);
/*
* Obtain the interface IP address, and use that as the default value
* if the user has not manually specified the ARP source address.
*
* Give a warning and use 0.0.0.0 if the interface has no IP address.
*/
ret_status = get_source_ip(if_name, &interface_ip_addr);
if (arp_spa_flag == 0) {
if (ret_status == -1) {
warn_msg("WARNING: Could not obtain IP address for interface %s. "
"Using 0.0.0.0 for", if_name);
warn_msg("the source address, which may not be what you want.");
warn_msg("Either configure %s with an IP address, or manually "
"specify the address", if_name);
warn_msg("with the --arpspa option.");
}
memcpy(&arp_spa, &(interface_ip_addr.s_addr), sizeof(arp_spa));
}
} else {
pcap_handle = NULL;
}
/*
* If we are reading data with pcap, get and display the datalink details
*/
if (pcap_handle) {
if ((datalink = pcap_datalink(pcap_handle)) < 0)
err_msg("pcap_datalink: %s", pcap_geterr(pcap_handle));
if (!plain_flag) {
if (!pkt_read_file_flag) {
printf("Interface: %s, type: %s, "
"MAC: %.2x:%.2x:%.2x:%.2x:%.2x:%.2x, IPv4: %s\n",
if_name, pcap_datalink_val_to_name(datalink),
interface_mac[0], interface_mac[1], interface_mac[2],
interface_mac[3], interface_mac[4], interface_mac[5],
(interface_ip_addr.s_addr==0) ? "(none)" : my_ntoa(interface_ip_addr));
} else {
printf("Interface: pcap file\n");
}
}
if (datalink != DLT_EN10MB) {
warn_msg("WARNING: Unsupported datalink type");
}
}
/*
* If we are reading from a network device, then get the associated file
* descriptor and configure it, determine the interface IP network and
* netmask, and install a pcap filter to receive only ARP responses.
* If we are reading from a pcap file, or writing to a binary file, just
* set the file descriptor to -1 to indicate that it is not associated
* with a network device.
*/
if (!pkt_read_file_flag && !pkt_write_file_flag) {
if ((pcap_fd = pcap_get_selectable_fd(pcap_handle)) < 0)
err_msg("pcap_fileno: %s", pcap_geterr(pcap_handle));
if ((pcap_setnonblock(pcap_handle, 1, errbuf)) < 0)
err_msg("pcap_setnonblock: %s", errbuf);
if (pcap_lookupnet(if_name, &localnet, &netmask, errbuf) < 0) {
memset(&localnet, '\0', sizeof(localnet));
memset(&netmask, '\0', sizeof(netmask));
if (localnet_flag) {
warn_msg("ERROR: Could not obtain interface IP address and netmask");
err_msg("ERROR: pcap_lookupnet: %s", errbuf);
}
}
/*
* The pcap filter string selects packets addressed to the ARP source
* address that are Ethernet-II ARP packets, 802.3 LLC/SNAP ARP packets,
* 802.1Q tagged ARP packets or 802.1Q tagged 802.3 LLC/SNAP ARP packets.
*/
filter_string=make_message("ether dst %.2x:%.2x:%.2x:%.2x:%.2x:%.2x and "
"(arp or (ether[14:4]=0xaaaa0300 and "
"ether[20:2]=0x0806) or (ether[12:2]=0x8100 "
"and ether[16:2]=0x0806) or "
"(ether[12:2]=0x8100 and "
"ether[18:4]=0xaaaa0300 and "
"ether[24:2]=0x0806))",
arp_sha[0], arp_sha[1],
arp_sha[2], arp_sha[3],
arp_sha[4], arp_sha[5]);
if (verbose > 1)
warn_msg("DEBUG: pcap filter string: \"%s\"", filter_string);
if ((pcap_compile(pcap_handle, &filter, filter_string, OPTIMISE,
netmask)) < 0)
err_msg("pcap_compile: %s", pcap_geterr(pcap_handle));
free(filter_string);
if ((pcap_setfilter(pcap_handle, &filter)) < 0)
err_msg("pcap_setfilter: %s", pcap_geterr(pcap_handle));
} else { /* Reading packets from file */
pcap_fd = -1;
}
/*
* Open pcap savefile is the --pcapsavefile (-W) option was specified
*/
if (pcap_savefile) {
if (!(pcap_dump_handle = pcap_dump_open(pcap_handle, pcap_savefile))) {
err_msg("pcap_dump_open: %s", pcap_geterr(pcap_handle));
}
}
/*
* Check that the combination of specified options and arguments is
* valid.
*/
if (interval && bandwidth != DEFAULT_BANDWIDTH)
err_msg("ERROR: You cannot specify both --bandwidth and --interval.");
if (localnet_flag) {
if ((argc - optind) > 0)
err_msg("ERROR: You can not specify targets with the --localnet option");
if (filename_flag)
err_msg("ERROR: You can not specify both --file and --localnet options");
}
/*
* Create MAC/Vendor hash table if quiet is not in effect.
*/
if (!quiet_flag) {
char *fn;
int count;
if ((hcreate(HASH_TABLE_SIZE)) == 0)
err_sys("hcreate");
fn = get_mac_vendor_filename(ouifilename, PKGDATADIR, OUIFILENAME);
count = add_mac_vendor(fn);
if (verbose > 1 && count > 0)
warn_msg("DEBUG: Loaded %d IEEE OUI/Vendor entries from %s.",
count, fn);
free(fn);
fn = get_mac_vendor_filename(macfilename, PKGSYSCONFDIR, MACFILENAME);
count = add_mac_vendor(fn);
if (verbose > 1 && count > 0)
warn_msg("DEBUG: Loaded %d MAC/Vendor entries from %s.",
count, fn);
free(fn);
}
/*
* Populate the list from the specified file if --file was specified, or
* from the interface address and mask if --localnet was specified, or
* otherwise from the remaining command line arguments.
*/
if (filename_flag) { /* Populate list from file */
FILE *fp;
char line[MAXLINE];
char *cp;
if ((strcmp(filename, "-")) == 0) { /* Filename "-" means stdin */
fp = stdin;
} else {
if ((fp = fopen(filename, "r")) == NULL) {
err_sys("Cannot open %s", filename);
}
}
while (fgets(line, MAXLINE, fp)) {
for (cp = line; !isspace((unsigned char)*cp) && *cp != '\0'; cp++)
;
*cp = '\0';
add_host_pattern(line, timeout);
}
if (fp != stdin) {
fclose(fp);
}
} else if (localnet_flag) { /* Populate list from i/f addr & mask */
struct in_addr if_network;
struct in_addr if_netmask;
char *c_network;
char *c_netmask;
const char *cp;
char localnet_descr[32];
if_network.s_addr = localnet;
if_netmask.s_addr = netmask;
cp = my_ntoa(if_network);
c_network = make_message("%s", cp);
cp = my_ntoa(if_netmask);
c_netmask = make_message("%s", cp);
snprintf(localnet_descr, 32, "%s:%s", c_network, c_netmask);
free(c_network);
free(c_netmask);
if (verbose) {
warn_msg("Using %s for localnet", localnet_descr);
}
add_host_pattern(localnet_descr, timeout);
} else { /* Populate list from command line arguments */
argv = &argv[optind];
while (*argv) {
add_host_pattern(*argv, timeout);
argv++;
}
}
/*
* Check that we have at least one entry in the list.
*/
if (!num_hosts)
err_msg("ERROR: No hosts to process.");
/*
* If --writepkttofile was specified, open the specified output file.
*/
if (pkt_write_file_flag) {
write_pkt_to_file = open(pkt_filename, O_WRONLY|O_CREAT|O_TRUNC, 0666);
if (write_pkt_to_file == -1)
err_sys("open %s", pkt_filename);
}
/*
* Create and initialise array of pointers to host entries.
*/
helistptr = Malloc(num_hosts * sizeof(host_entry *));
for (i=0; i<num_hosts; i++)
helistptr[i] = &helist[i];
/*
* Randomise the list if required. Uses Knuth's shuffle algorithm.
*/
if (random_flag) {
int r;
host_entry *temp;
/*
* Seed random number generator.
* If the random seed has been specified (is non-zero), then use that.
* Otherwise, seed the RNG with an unpredictable value.
*/
if (!random_seed) {
struct timeval tv;
Gettimeofday(&tv);
random_seed = tv.tv_usec ^ getpid(); /* Unpredictable value */
}
init_genrand(random_seed);
for (i=num_hosts-1; i>0; i--) {
r = (int)(genrand_real2() * i); /* 0<=r<i */
temp = helistptr[i];
helistptr[i] = helistptr[r];
helistptr[r] = temp;
}
}
/*
* Set current host pointer (cursor) to start of list, zero
* last packet sent time, and set last receive time to now.
*/
live_count = num_hosts;
cursor = helistptr;
last_packet_time.tv_sec = 0;
last_packet_time.tv_usec = 0;
/*
* Calculate the required interval to achieve the required outgoing
* bandwidth unless the interval was manually specified with --interval.
*/
if (!interval) {
size_t packet_out_len;
packet_out_len = send_packet(NULL, NULL, NULL); /* Get packet data size */
if (packet_out_len < MINIMUM_FRAME_SIZE)
packet_out_len = MINIMUM_FRAME_SIZE; /* Adjust to minimum size */
packet_out_len += PACKET_OVERHEAD; /* Add layer 2 overhead */
interval = ((uint64_t)packet_out_len * 8 * 1000000) / bandwidth;
if (verbose > 1) {
warn_msg("DEBUG: pkt len=%zu bytes, bandwidth=%u bps, interval=%u us",
packet_out_len, bandwidth, interval);
}
}
/*
* Display initial message.
*/
if (!plain_flag) {
printf("Starting %s with %u hosts (https://github.com/royhills/arp-scan)\n",
PACKAGE_STRING, num_hosts);
}
/*
* Display the lists if verbose setting is 3 or more.
*/
if (verbose > 2)
dump_list();
/*
* Main loop: send packets to all hosts in order until a response
* has been received or the host has exhausted its retry limit.
*
* The loop exits when all hosts have either responded or timed out;
* or if the number of responders reaches host_limit when host_limit is
* non zero.
*/
reset_cum_err = 1;
req_interval = interval;
while (live_count && !(host_limit != 0 && responders >= host_limit)) {
/*
* Obtain current time and calculate deltas since last packet and
* last packet to this host.
*/
Gettimeofday(&now);
/*
* If the last packet was sent more than interval microseconds ago, we
* can potentially send a packet to the current host.
*/
timeval_diff(&now, &last_packet_time, &diff);
loop_timediff = (uint64_t)1000000*diff.tv_sec + diff.tv_usec;
if (loop_timediff >= (unsigned)req_interval) {
/*
* If the last packet to this host was sent more than the current
* timeout for this host us ago, then we can potentially send a packet
* to it.
*/
timeval_diff(&now, &((*cursor)->last_send_time), &diff);
host_timediff = (uint64_t)1000000*diff.tv_sec + diff.tv_usec;
if (host_timediff >= (*cursor)->timeout) {
if (reset_cum_err) {
cum_err = 0;
req_interval = interval;
reset_cum_err = 0;
} else {
cum_err += loop_timediff - interval;
if (req_interval >= cum_err) {
req_interval = req_interval - cum_err;
} else {
req_interval = 0;
}
}
select_timeout = req_interval;
/*
* If we've exceeded our retry limit, this host has timed out so
* remove it from the list. Otherwise increase the timeout by the
* backoff factor if this is not the first packet sent to this host
* and send a packet.
*/
if (verbose && (*cursor)->num_sent > pass_no) {
warn_msg("---\tPass %d complete", pass_no+1);
pass_no = (*cursor)->num_sent;
}
if ((*cursor)->num_sent >= retry) {
if (verbose > 1)
warn_msg("---\tRemoving host %s - Timeout",
my_ntoa((*cursor)->addr));
remove_host(cursor); /* Automatically calls advance_cursor() */
if (first_timeout) {
timeval_diff(&now, &((*cursor)->last_send_time), &diff);
host_timediff = (uint64_t)1000000*diff.tv_sec +
diff.tv_usec;
while (host_timediff >= (*cursor)->timeout && live_count) {
if ((*cursor)->live) {
if (verbose > 1)
warn_msg("---\tRemoving host %s - Catch-Up Timeout",
my_ntoa((*cursor)->addr));
remove_host(cursor);
} else {
advance_cursor();
}
timeval_diff(&now, &((*cursor)->last_send_time), &diff);
host_timediff = (uint64_t)1000000*diff.tv_sec +
diff.tv_usec;
}
first_timeout = 0;
}
Gettimeofday(&last_packet_time);
} else { /* Retry limit not reached for this host */
if ((*cursor)->num_sent)
(*cursor)->timeout *= backoff_factor;
send_packet(pcap_handle, *cursor, &last_packet_time);
advance_cursor();
}
} else { /* We can't send a packet to this host yet */
/*
* There is no point calling advance_cursor() here because if
* host n is not ready to send host n+1 will not be ready either.
*/
select_timeout = (*cursor)->timeout - host_timediff;
reset_cum_err = 1; /* Zero cumulative error */
} /* End If */
} else { /* We can't send a packet yet */
select_timeout = req_interval - loop_timediff;
} /* End If */
recvfrom_wto(pcap_fd, select_timeout, pcap_handle);
} /* End While */
if (!plain_flag) {
printf("\n"); /* Ensure we have a blank line */
}
clean_up(pcap_handle);
if (write_pkt_to_file)
close(write_pkt_to_file);
Gettimeofday(&end_time);
timeval_diff(&end_time, &start_time, &elapsed_time);
elapsed_seconds = (elapsed_time.tv_sec*1000 +
elapsed_time.tv_usec/1000) / 1000.0;
if (!plain_flag) {
printf("Ending %s: %u hosts scanned in %.3f seconds (%.2f hosts/sec). %u "
"responded\n",
PACKAGE_STRING, num_hosts, elapsed_seconds,
num_hosts/elapsed_seconds, responders);
}
/*
* exit with status 1 if host_limit has been set with the --limit option and
* the number of responding hosts is less than this limit. Otherwise exit
* with status 0.
*/
return (host_limit == 0 || responders >= host_limit) ? 0 : 1;
}
/*
* display_packet -- Check and display received packet
*
* Inputs:
*
* he The host entry corresponding to the received packet
* arpei ARP packet structure
* extra_data Extra data after ARP packet (padding)
* extra_data_len Length of extra data
* framing Framing type (e.g. Ethernet II, LLC)
* vlan_id 802.1Q VLAN identifier, or -1 if not 802.1Q
* frame_hdr The Ethernet frame header
* pcap_header The PCAP header struct
*
* Returns:
*
* None.
*
* This checks the received packet and displays details of what
* was received in the format: <IP-Address><TAB><Details>.
*/
void
display_packet(host_entry *he, arp_ether_ipv4 *arpei,
const unsigned char *extra_data, size_t extra_data_len,
int framing, int vlan_id, ether_hdr *frame_hdr,
const struct pcap_pkthdr *pcap_header) {
typedef struct {
const char *name;
char *value;
} field;
static field fields[NUMFIELDS] = {
{"IP",NULL}, {"Name",NULL}, {"MAC",NULL}, {"HdrMAC",NULL},
{"Vendor",NULL}, {"Padding",NULL}, {"Framing",NULL}, {"VLAN",NULL},
{"Proto",NULL}, {"DUP",NULL}, {"RTT",NULL}
};
static const id_name_map fields_map[] = {
{0, "IP"}, {1, "Name"}, {2, "MAC"},
{3, "HdrMAC"}, {4, "Vendor"}, {5, "Padding"},
{6, "Framing"}, {7, "VLAN"}, {8, "Proto"},
{9, "DUP"}, {10, "RTT"}, {-1, NULL} /* -1 marks end of list */
};
char *msg;
char *cp;
char *ga_err_msg;
int nonzero = 0;
unsigned i;
/*
* Assign output fields based on response packet and options.
*/
/*
* IP field, always present.
*/
fields[0].value = make_message("%s", my_ntoa(he->addr));
/*
* Name field, present if --resolve option given.
*/
if (resolve_flag) {
cp = get_host_name(he->addr, &ga_err_msg);
if (cp) {
fields[1].value = make_message("%s", cp);
} else {
warn_msg("WARNING: getnameinfo() failed for \"%s\": %s",
my_ntoa(he->addr), ga_err_msg);
}
}
/*
* MAC field, always present.
*/
fields[2].value = make_message("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
arpei->ar_sha[0], arpei->ar_sha[1],
arpei->ar_sha[2], arpei->ar_sha[3],
arpei->ar_sha[4], arpei->ar_sha[5]);
/*
* HdrMAC field, present if source MAC in the ARP packet is different
* to source MAC in the Ethernet frame header.
*/
if ((memcmp(arpei->ar_sha, frame_hdr->src_addr, ETH_ALEN)) != 0) {
fields[3].value = make_message("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
frame_hdr->src_addr[0], frame_hdr->src_addr[1],
frame_hdr->src_addr[2], frame_hdr->src_addr[3],
frame_hdr->src_addr[4], frame_hdr->src_addr[5]);
}
/*
* Vendor field, present if --quiet option not given
*/
if (!quiet_flag) {
/*
* Find vendor in hash table.
*
* We start with more specific matches (against larger parts of the
* hardware address), and work towards less specific matches until
* we find a match or exhaust all possible matches.
*/
char oui_string[13]; /* Space for full hw addr plus NULL */
const char *vendor = NULL;
int oui_end = 12;
ENTRY hash_query;
ENTRY *hash_result;
snprintf(oui_string, 13, "%.2X%.2X%.2X%.2X%.2X%.2X",
arpei->ar_sha[0], arpei->ar_sha[1], arpei->ar_sha[2],
arpei->ar_sha[3], arpei->ar_sha[4], arpei->ar_sha[5]);
while (vendor == NULL && oui_end > 1) {
oui_string[oui_end] = '\0'; /* Truncate oui string */
hash_query.key = oui_string;
hash_result = hsearch(hash_query, FIND);
if (hash_result) {
vendor = hash_result->data;
} else {
vendor = NULL;
}
oui_end--;
}
if (vendor)
fields[4].value = make_message("%s", vendor);
else
/* Check the second-least-significant bit of first octet */
if (arpei->ar_sha[0] & (1<<1))
fields[4].value = make_message("%s", "(Unknown: locally administered)");
else
fields[4].value = make_message("%s", "(Unknown)");
/*
* Padding field, present if --quiet option not given and frame padding
* is non zero
*/
/*
* Check that any data after the ARP packet is zero.
* If it is non-zero, and verbose is selected, then set the Padding
* field to the hex representation of the padding.
*/
if (extra_data_len > 0) {
const unsigned char *ucp = extra_data;
for (i=0; i<extra_data_len; i++) {
if (ucp[i] != '\0') {
nonzero = 1;
break;
}
}
}
if (nonzero) {
fields[5].value = hexstring(extra_data, extra_data_len);
}
/*
* Framing field, present if the framing type is 802.2 LLC/SNAP
*/
if (framing == FRAMING_LLC_SNAP) {
fields[6].value = make_message("802.2 LLC/SNAP");
}
/*
* VLAN field, present if the packet uses 802.1Q VLAN tagging.
*/
if (vlan_id != -1) {
fields[7].value = make_message("%d", vlan_id);
}
/*
* Proto field, present if the ARP protocol type is not IP (0x0800)
* This can occur with trailer encapsulation ARP replies on 4.2BSD VAX
*/
if (ntohs(arpei->ar_pro) != 0x0800) {
fields[8].value = make_message("0x%04x", ntohs(arpei->ar_pro));
}
/*
* DUP field, present if this is not the first response from this host.
*/
if (he->num_recv > 1) {
fields[9].value = make_message("%u", he->num_recv);
}
/*
* RTT field, present if the --rtt option is given
*/
if (rtt_flag) {
struct timeval rtt;
struct timeval pcap_timestamp;
unsigned long rtt_us; /* round-trip time in microseconds */
/*
* We can't pass a pointer to pcap_header->ts directly to timeval_diff
* because it may not have the same size as a struct timeval.
* E.g. OpenBSD 5.1 on amd64.
*/
pcap_timestamp.tv_sec = pcap_header->ts.tv_sec;
pcap_timestamp.tv_usec = pcap_header->ts.tv_usec;
timeval_diff(&pcap_timestamp, &(he->last_send_time), &rtt);
rtt_us = rtt.tv_sec * 1000000 + rtt.tv_usec;
fields[10].value=make_message("%lu.%03lu", rtt_us/1000, rtt_us%1000);
}
} /* End if (!quiet_flag) */
/*
* Output fields.
*/
if (!format) { /* If --format option not given */
/*
* Output IP field or Name field depending on whether --resolve option
* was given.
*/
if (resolve_flag) {
msg = make_message("%s", fields[1].value);
} else {
msg = make_message("%s", fields[0].value);
}
/*
* Output MAC field
*/
cp = msg;
msg = make_message("%s\t%s", cp, fields[2].value);
free(cp);
/*
* Output HdrMAC field if present
*/
if (fields[3].value) {
cp = msg;
msg = make_message("%s (%s)", cp, fields[3].value);
free(cp);
}
/*
* Output Vendor field if present.
*/
if (fields[4].value) {
cp = msg;
msg = make_message("%s\t%s", cp, fields[4].value);
free(cp);
}
/*
* Output Padding field if present and --verbose is given
*/
if (fields[5].value && verbose) {
cp = msg;
msg = make_message("%s\tPadding=%s", cp, fields[5].value);
free(cp);
}
/*
* Output Framing field if present.
*/
if (fields[6].value) {
cp = msg;
if (framing == FRAMING_LLC_SNAP) {
msg = make_message("%s (%s)", cp, fields[6].value);
}
free(cp);
}
/*
* Output VLAN ID if the VLAN field is present.
*/
if (fields[7].value) {
cp = msg;
msg = make_message("%s (802.1Q VLAN=%s)", cp, fields[7].value);
free(cp);
}
/*
* Output Proto field if present.
*/
if (fields[8].value) {
cp = msg;
msg = make_message("%s (ARP Proto=%s)", cp, fields[8].value);
free(cp);
}
/*
* Output DUP field if present.
*/
if (fields[9].value) {
cp = msg;
msg = make_message("%s (DUP: %s)", cp, fields[9].value);
free(cp);
}
/*
* Output RTT field if present.
*/
if (fields[10].value) {
cp = msg;
msg = make_message("%s\tRTT=%s ms", cp, fields[10].value);
free(cp);
}
} else { /* --format option given */
format_element *fmt;
int idx;
msg = dupstr(""); /* Set msg to empty string */
for (fmt=format; fmt; fmt=fmt->next) {
if (fmt->type == FORMAT_FIELD) {
if ((idx=name_to_id(fmt->data, fields_map)) != -1 &&
fields[idx].value) {
cp = msg;
msg = make_message("%s%*s", cp, fmt->width, fields[idx].value);
free(cp);
} else { /* Field name not found in map */
warn_msg("WARNING: Field ${%s} unknown or not available",
fmt->data);
}
} else if (fmt->type == FORMAT_STRING) {
cp = msg;
msg = make_message("%s%s", cp, fmt->data);
free(cp);
}
}
}
/*
* Display the message on stdout.
*/
printf("%s\n", msg);
free(msg);
for (i=0; i<NUMFIELDS; i++)
if (fields[i].value) {
free(fields[i].value);
fields[i].value = NULL;
}
}
/*
* send_packet -- Construct and send a packet to the specified host
*
* Inputs:
*
* pcap_handle Pcap handle
* he Host entry to send to. If NULL, then no packet is sent
* last_packet_time Time when last packet was sent
*
* Returns:
*
* The size of the packet that was sent.
*
* This constructs an appropriate packet and sends it to the host
* identified by "he" using the socket "s". It also updates the
* "last_send_time" field for the host entry.
*
* If we are using the undocumented --writepkttofile option, then we
* write the packet to the write_pkt_to_file file descriptor instead of
* transmitting it on the network.
*
* If we are using the undocumented --readpktfromfile option, then we
* don't send anything.
*/
int
send_packet(pcap_t *pcap_handle, host_entry *he,
struct timeval *last_packet_time) {
unsigned char buf[MAX_FRAME];
size_t buflen;
ether_hdr frame_hdr;
arp_ether_ipv4 arpei;
int nsent = 0;
unsigned i;
struct timeval to;
int n;
/*
* Construct Ethernet frame header
*/
memcpy(frame_hdr.dest_addr, target_mac, ETH_ALEN);
memcpy(frame_hdr.src_addr, source_mac, ETH_ALEN);