/***************************************************************************
* This thread spews packets as fast as it can
*
* THIS IS WHERE ALL THE EXCITEMENT HAPPENS!!!!
* 90% of CPU cycles are in the function.
*
***************************************************************************/
static void
transmit_thread(void *v) /*aka. scanning_thread() */
{
struct ThreadPair *parms = (struct ThreadPair *)v;
uint64_t i;
uint64_t start;
uint64_t end;
const struct Masscan *masscan = parms->masscan;
unsigned retries = masscan->retries;
unsigned rate = (unsigned)masscan->max_rate;
unsigned r = retries + 1;
uint64_t range;
struct BlackRock blackrock;
uint64_t count_ips = rangelist_count(&masscan->targets);
struct Throttler *throttler = parms->throttler;
struct TemplateSet pkt_template = templ_copy(parms->tmplset);
unsigned *picker = parms->picker;
struct Adapter *adapter = parms->adapter;
uint64_t packets_sent = 0;
unsigned increment = (masscan->shard.of-1) + masscan->nic_count;
unsigned src_ip;
unsigned src_ip_mask;
unsigned src_port;
unsigned src_port_mask;
get_sources(masscan, parms->nic_index,
&src_ip, &src_ip_mask,
&src_port, &src_port_mask);
LOG(1, "xmit: starting transmit thread #%u\n", parms->nic_index);
/* Create the shuffler/randomizer. This creates the 'range' variable,
* which is simply the number of IP addresses times the number of
* ports */
range = rangelist_count(&masscan->targets)
* rangelist_count(&masscan->ports);
blackrock_init(&blackrock, range, masscan->seed);
/* Calculate the 'start' and 'end' of a scan. One reason to do this is
* to support --shard, so that multiple machines can co-operate on
* the same scan. Another reason to do this is so that we can bleed
* a little bit past the end when we have --retries. Yet another
* thing to do here is deal with multiple network adapters, which
* is essentially the same logic as shards. */
start = masscan->resume.index + (masscan->shard.one-1) + parms->nic_index;
end = range;
if (masscan->resume.count && end > start + masscan->resume.count)
end = start + masscan->resume.count;
end += retries * rate;
/* "THROTTLER" rate-limits how fast we transmit, set with the
* --max-rate parameter */
throttler_start(throttler, masscan->max_rate/masscan->nic_count);
/* -----------------
* the main loop
* -----------------*/
LOG(3, "xmit: starting main loop: [%llu..%llu]\n", start, end);
for (i=start; i<end; ) {
uint64_t batch_size;
/*
* Do a batch of many packets at a time. That because per-packet
* throttling is expensive at 10-million pps, so we reduce the
* per-packet cost by doing batches. At slower rates, the batch
* size will always be one. (--max-rate)
*/
batch_size = throttler_next_batch(throttler, packets_sent);
/*
* Transmit packets from other thread, when doing --banners. This
* takes priority over sending SYN packets. If there is so much
* activity grabbing banners that we cannot transmit more SYN packets,
* then "batch_size" will get decremented to zero, and we won't be
* able to transmit SYN packets.
*/
flush_packets(adapter, parms->packet_buffers, parms->transmit_queue,
&packets_sent, &batch_size);
/*
* Transmit a bunch of packets. At any rate slower than 100,000
* packets/second, the 'batch_size' is likely to be 1
*/
while (batch_size && i < end) {
uint64_t xXx;
unsigned ip_them;
unsigned port_them;
unsigned ip_me;
unsigned port_me;
uint64_t cookie;
/*
* RANDOMIZE THE TARGET:
* This is kinda a tricky bit that picks a random IP and port
* number in order to scan. We monotonically increment the
* index 'i' from [0..range]. We then shuffle (randomly transmog)
* that index into some other, but unique/1-to-1, number in the
* same range. That way we visit all targets, but in a random
* order. Then, once we've shuffled the index, we "pick" the
* the IP address and port that the index refers to.
*/
xXx = (i + (r--) * rate);
while (xXx >= range)
xXx -= range;
xXx = blackrock_shuffle(&blackrock, xXx);
ip_them = rangelist_pick2(&masscan->targets, xXx % count_ips, picker);
port_them = rangelist_pick(&masscan->ports, xXx / count_ips);
/*
* SYN-COOKIE LOGIC
*/
ip_me = src_ip + (i & src_ip_mask);
port_me = src_port + (xXx & src_port_mask);
cookie = syn_cookie(ip_them, port_them, ip_me, port_me);
/*
* SEND THE PROBE
* This is sorta the entire point of the program, but little
* exciting happens here. The thing to note that this may
* be a "raw" transmit that bypasses the kernel, meaning
* we can call this function millions of times a second.
*/
rawsock_send_probe(
adapter,
ip_them, port_them,
ip_me, port_me,
(unsigned)cookie,
!batch_size, /* flush queue on last packet in batch */
&pkt_template
);
batch_size--;
packets_sent++;
foo_count++; /* TODO: debug thing, will be removed*/
/*
* SEQUENTIALLY INCREMENT THROUGH THE RANGE
* Yea, I know this is a puny 'i++' here, but it's a core feature
* of the system that is linearly increments through the range,
* but produces from that a shuffled sequence of targets (as
* described above). Because we are linearly incrementing this
* number, we can do lots of creative stuff, like doing clever
* retransmits and sharding.
*/
if (r == 0) {
i += increment; /* <------ increment by 1 normally, more with shards/nics */
r = retries + 1;
}
} /* end of batch */
/* If the user pressed <ctrl-c>, then we need to exit. but, in case
* the user wants to --resume the scan later, we save the current
* state in a file */
if (control_c_pressed) {
break;
}
/* save our current location for resuming, if the user pressed
* <ctrl-c> to exit early */
parms->my_index = i;
}
/*
* We are done transmitting. However, response packets will take several
* seconds to arrive. Therefore, sit in short loop waiting for those
* packets to arrive. Pressing <ctrl-c> a second time will exit this
* prematurely.
*/
while (!control_c_pressed_again) {
unsigned k;
uint64_t batch_size;
for (k=0; k<1000; k++) {
/*
* Only send a few packets at a time, throttled according to the max
* --max-rate set by the user
*/
batch_size = throttler_next_batch(throttler, packets_sent);
/* Transmit packets from the receive thread */
flush_packets( adapter,
parms->packet_buffers,
parms->transmit_queue,
&packets_sent,
&batch_size);
pixie_usleep(1000);
}
}
/* Thread is about to exit */
parms->done_transmitting = 1;
LOG(1, "xmit: stopping transmit thread #%u\n", parms->nic_index);
}
/***************************************************************************
*
* Asynchronous receive thread
*
* The transmit and receive threads run independently of each other. There
* is no record what was transmitted. Instead, the transmit thread sets a
* "SYN-cookie" in transmitted packets, which the receive thread will then
* use to match up requests with responses.
***************************************************************************/
static void
receive_thread(void *v)
{
struct ThreadPair *parms = (struct ThreadPair *)v;
const struct Masscan *masscan = parms->masscan;
struct Output *out;
struct DedupTable *dedup;
struct PcapFile *pcapfile = NULL;
struct TCP_ConnectionTable *tcpcon = 0;
LOG(1, "recv: start receive thread #%u\n", parms->nic_index);
/* Lock this thread to a CPU. Transmit threads are on even CPUs,
* receive threads on odd CPUs */
if (pixie_cpu_get_count() > 1) {
unsigned cpu_count = pixie_cpu_get_count();
unsigned cpu = parms->nic_index * 2 + 1;
while (cpu >= cpu_count) {
cpu -= cpu_count;
cpu++;
}
pixie_cpu_set_affinity(cpu);
}
/*
* If configured, open a --pcap file for saving raw packets. This is
* so that we can debug scans, but also so that we can look at the
* strange things people send us. Note that we don't record transmitted
* packets, just the packets we've received.
*/
/*if (masscan->pcap_filename[0])
pcapfile = pcapfile_openwrite(masscan->pcap_filename, 1);*/
/*
* Open output. This is where results are reported when saving
* the --output-format to the --output-filename
*/
out = output_create(masscan);
/*
* Create deduplication table. This is so when somebody sends us
* multiple responses, we only record the first one.
*/
dedup = dedup_create();
/*
* Create a TCP connection table for interacting with live
* connections when doing --banners
*/
if (masscan->is_banners) {
tcpcon = tcpcon_create_table(
(size_t)((masscan->max_rate/5) / masscan->nic_count),
parms->transmit_queue,
parms->packet_buffers,
&parms->tmplset->pkts[Proto_TCP],
output_report_banner,
out,
masscan->tcb.timeout
);
if (masscan->http_user_agent_length)
tcpcon_set_parameter( tcpcon,
"http-user-agent",
masscan->http_user_agent_length,
masscan->http_user_agent);
}
/*
* In "offline" mode, we don't have any receive threads, so simply
* wait until transmitter thread is done then go to the end
*/
if (masscan->is_offline) {
while (!control_c_pressed_again)
pixie_usleep(10000);
parms->done_receiving = 1;
goto end;
}
/*
* Receive packets. This is where we catch any responses and print
* them to the terminal.
*/
LOG(1, "begin receive thread\n");
while (!control_c_pressed_again) {
int status;
unsigned length;
unsigned secs;
unsigned usecs;
const unsigned char *px;
int err;
unsigned x;
struct PreprocessedInfo parsed;
unsigned ip_me;
unsigned port_me;
unsigned ip_them;
unsigned port_them;
unsigned seqno_me;
unsigned seqno_them;
unsigned cookie;
/*
* RECIEVE
*
* This is the boring part of actually receiving a packet
*/
err = rawsock_recv_packet(
parms->adapter,
&length,
&secs,
&usecs,
&px);
if (err != 0)
continue;
/*
* Do any TCP event timeouts based on the current timestamp from
* the packet. For example, if the connection has been open for
* around 10 seconds, we'll close the connection. (--banners)
*/
if (tcpcon) {
tcpcon_timeouts(tcpcon, secs, usecs);
}
if (length > 1514)
continue;
/*
* "Preprocess" the response packet. This means to go through and
* figure out where the TCP/IP headers are and the locations of
* some fields, like IP address and port numbers.
*/
x = preprocess_frame(px, length, 1, &parsed);
if (!x)
continue; /* corrupt packet */
ip_me = parsed.ip_dst[0]<<24 | parsed.ip_dst[1]<<16
| parsed.ip_dst[2]<< 8 | parsed.ip_dst[3]<<0;
ip_them = parsed.ip_src[0]<<24 | parsed.ip_src[1]<<16
| parsed.ip_src[2]<< 8 | parsed.ip_src[3]<<0;
port_me = parsed.port_dst;
port_them = parsed.port_src;
seqno_them = TCP_SEQNO(px, parsed.transport_offset);
seqno_me = TCP_ACKNO(px, parsed.transport_offset);
cookie = syn_cookie(ip_them, port_them, ip_me, port_me) & 0xFFFFFFFF;
/* verify: my IP address */
if (!is_my_ip(&parms->src, ip_me))
continue;
/*
* Handle non-TCP protocols
*/
switch (parsed.found) {
case FOUND_ARP:
LOGip(2, ip_them, 0, "-> ARP [%u] \n", px[parsed.found_offset]);
switch (px[parsed.found_offset + 6]<<8 | px[parsed.found_offset+7]) {
case 1: /* request */
/* This function will transmit a "reply" to somebody's ARP request
* for our IP address (as part of our user-mode TCP/IP).
* Since we completely bypass the TCP/IP stack, we have to handle ARPs
* ourself, or the router will lose track of us.*/
arp_response( ip_me,
parms->adapter_mac,
px, length,
parms->packet_buffers,
parms->transmit_queue);
break;
case 2: /* response */
/* This is for "arp scan" mode, where we are ARPing targets rather
* than port scanning them */
/* If we aren't doing an ARP scan, then ignore ARP responses */
if (!masscan->is_arp)
break;
/* If this response isn't in our range, then ignore it */
if (!rangelist_is_contains(&masscan->targets, ip_them))
break;
/* Ignore duplicates */
if (dedup_is_duplicate(dedup, ip_them, 0))
continue;
/* ...everything good, so now report this response */
handle_arp(out, px, length, &parsed);
break;
}
continue;
case FOUND_UDP:
case FOUND_DNS:
if (!is_nic_port(masscan, port_me))
continue;
if (parms->masscan->nmap.packet_trace)
packet_trace(stdout, px, length, 0);
handle_udp(out, px, length, &parsed);
continue;
case FOUND_ICMP:
handle_icmp(out, px, length, &parsed);
continue;
case FOUND_TCP:
/* fall down to below */
break;
default:
continue;
}
/* verify: my port number */
if (!is_my_port(&parms->src, port_me))
continue;
if (parms->masscan->nmap.packet_trace)
packet_trace(stdout, px, length, 0);
/* Save raw packet in --pcap file */
if (pcapfile) {
pcapfile_writeframe(
pcapfile,
px,
length,
length,
secs,
usecs);
}
{
char buf[64];
LOGip(5, ip_them, port_them, "-> TCP ackno=0x%08x flags=0x%02x(%s)\n",
seqno_me,
TCP_FLAGS(px, parsed.transport_offset),
reason_string(TCP_FLAGS(px, parsed.transport_offset), buf, sizeof(buf)));
}
/* If recording --banners, create a new "TCP Control Block (TCB)" */
if (tcpcon) {
struct TCP_Control_Block *tcb;
/* does a TCB already exist for this connection? */
tcb = tcpcon_lookup_tcb(tcpcon,
ip_me, ip_them,
port_me, port_them);
if (TCP_IS_SYNACK(px, parsed.transport_offset)) {
if (cookie != seqno_me - 1) {
LOG(2, "%u.%u.%u.%u - bad cookie: ackno=0x%08x expected=0x%08x\n",
(ip_them>>24)&0xff, (ip_them>>16)&0xff, (ip_them>>8)&0xff, (ip_them>>0)&0xff,
seqno_me-1, cookie);
continue;
}
if (tcb == NULL) {
tcb = tcpcon_create_tcb(tcpcon,
ip_me, ip_them,
port_me, port_them,
seqno_me, seqno_them+1);
}
tcpcon_handle(tcpcon, tcb, TCP_WHAT_SYNACK,
0, 0, secs, usecs, seqno_them+1);
} else if (tcb) {
/* If this is an ACK, then handle that first */
if (TCP_IS_ACK(px, parsed.transport_offset)) {
tcpcon_handle(tcpcon, tcb, TCP_WHAT_ACK,
0, seqno_me, secs, usecs, seqno_them);
}
/* If this contains payload, handle that */
if (parsed.app_length) {
tcpcon_handle(tcpcon, tcb, TCP_WHAT_DATA,
px + parsed.app_offset, parsed.app_length,
secs, usecs, seqno_them);
}
/* If this is a FIN, handle that. Note that ACK +
* payload + FIN can come together */
if (TCP_IS_FIN(px, parsed.transport_offset)
&& !TCP_IS_RST(px, parsed.transport_offset)) {
tcpcon_handle(tcpcon, tcb, TCP_WHAT_FIN,
0, 0, secs, usecs, seqno_them);
}
/* If this is a RST, then we'll be closing the connection */
if (TCP_IS_RST(px, parsed.transport_offset)) {
tcpcon_handle(tcpcon, tcb, TCP_WHAT_RST,
0, 0, secs, usecs, seqno_them);
}
} else if (TCP_IS_FIN(px, parsed.transport_offset)) {
/*
* NO TCB!
* This happens when we've sent a FIN, deleted our connection,
* but the other side didn't get the packet.
*/
if (!TCP_IS_RST(px, parsed.transport_offset))
tcpcon_send_FIN(
tcpcon,
ip_me, ip_them,
port_me, port_them,
seqno_them, seqno_me);
}
}
/***************************************************************************
* This is where we handle all incoming ICMP packets. Some of these packets
* will be due to scans we are doing, like pings (echoes). Some will
* be inadvertent, such as "destination unreachable" messages.
***************************************************************************/
void
handle_icmp(struct Output *out, time_t timestamp,
const unsigned char *px, unsigned length,
struct PreprocessedInfo *parsed)
{
unsigned type = parsed->port_src;
unsigned code = parsed->port_dst;
unsigned seqno_me;
unsigned ip_me;
unsigned ip_them;
unsigned cookie;
ip_me = parsed->ip_dst[0]<<24 | parsed->ip_dst[1]<<16
| parsed->ip_dst[2]<< 8 | parsed->ip_dst[3]<<0;
ip_them = parsed->ip_src[0]<<24 | parsed->ip_src[1]<<16
| parsed->ip_src[2]<< 8 | parsed->ip_src[3]<<0;
seqno_me = px[parsed->transport_offset+4]<<24
| px[parsed->transport_offset+5]<<16
| px[parsed->transport_offset+6]<<8
| px[parsed->transport_offset+7]<<0;
switch (type) {
case 0: /* ICMP echo reply */
cookie = (unsigned)syn_cookie(ip_them, Templ_ICMP_echo, ip_me, 0);
if ((cookie & 0xFFFFFFFF) != seqno_me)
return; /* not my response */
//if (syn_hash(ip_them, Templ_ICMP_echo) != seqno_me)
// return; /* not my response */
/*
* Report "open" or "existence" of host
*/
output_report_status(
out,
timestamp,
PortStatus_Open,
ip_them,
1, /* ip proto */
0,
0,
0);
break;
case 3: /* destination unreachable */
switch (code) {
case 0: /* net unreachable */
/* We get these a lot while port scanning, often a flood coming
* back from broken/misconfigured networks */
break;
case 1: /* host unreachable */
/* This means the router doesn't exist */
break;
case 2: /* protocol unreachable */
/* The host exists, but it doesn't support SCTP */
break;
case 3: /* port unreachable */
if (length - parsed->transport_offset > 8) {
unsigned ip_me2, ip_them2, port_me2, port_them2;
unsigned ip_proto;
int err;
err = parse_port_unreachable(
px + parsed->transport_offset + 8,
length - parsed->transport_offset + 8,
&ip_me2, &ip_them2, &port_me2, &port_them2,
&ip_proto);
if (err)
return;
if (!matches_me(out, ip_me2, port_me2))
return;
switch (ip_proto) {
case 6:
output_report_status(
out,
timestamp,
PortStatus_Closed,
ip_them2,
ip_proto,
port_them2,
0,
px[parsed->ip_offset + 8]);
break;
case 17:
output_report_status(
out,
timestamp,
PortStatus_Closed,
ip_them2,
ip_proto,
port_them2,
0,
px[parsed->ip_offset + 8]);
break;
case 132:
output_report_status(
out,
timestamp,
PortStatus_Closed,
ip_them2,
ip_proto,
port_them2,
0,
px[parsed->ip_offset + 8]);
break;
}
}
}
break;
default:
;
}
}
