pscan: add -c, -b: report closed, blocked ports

2 files changed, 34 insertions, 16 deletions

diff --git a/include/usage.h b/include/usage.h
index aa1b8b6da..7918b24d8 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3019,10 +3019,12 @@
        " 2990 andersen andersen R ps\n"
 
 #define pscan_trivial_usage \
-       "[-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
+       "[-cb] [-p MIN_PORT] [-P MAX_PORT] [-t TIMEOUT] [-T MIN_RTT] HOST"
 #define pscan_full_usage \
        "Scan a host, print all open ports\n" \
      "\nOptions:" \
+     "\n        -c      Show closed ports too" \
+     "\n        -c      Show blocked ports too" \
      "\n        -p      Scan from this port (default 1)" \
      "\n        -P      Scan up to this port (default 1024)" \
      "\n        -t      Timeout (default 5000 ms)" \
diff --git a/networking/pscan.c b/networking/pscan.c
index 022d21254..b332d7133 100644
--- a/networking/pscan.c
+++ b/networking/pscan.c
@@ -42,8 +42,10 @@ int pscan_main(int argc ATTRIBUTE_UNUSED, char **argv)
          * Rule of thumb: with min_rtt of N msec, scanning 1000 ports
          * will take N seconds at absolute minimum */
         const char *opt_min_rtt = "5";          /* -T: default min rtt in msec */
+        const char *result_str;
         len_and_sockaddr *lsap;
         int s;
+        unsigned opt;
         unsigned port, max_port, nports;
         unsigned closed_ports = 0;
         unsigned open_ports = 0;
@@ -51,16 +53,18 @@ int pscan_main(int argc ATTRIBUTE_UNUSED, char **argv)
         unsigned timeout;
         unsigned min_rtt;
         unsigned rtt_4;
-        unsigned start;
+        unsigned start, diff;
 
         opt_complementary = "=1"; /* exactly one non-option */
-        getopt32(argv, "p:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
+        opt = getopt32(argv, "cbp:P:t:T:", &opt_min_port, &opt_max_port, &opt_timeout, &opt_min_rtt);
         argv += optind;
         max_port = xatou_range(opt_max_port, 1, 65535);
         port = xatou_range(opt_min_port, 1, max_port);
         nports = max_port - port + 1;
-        rtt_4 = timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
         min_rtt = xatou_range(opt_min_rtt, 1, INT_MAX/1000 / 4) * 1000;
+        timeout = xatou_range(opt_timeout, 1, INT_MAX/1000 / 4) * 1000;
+        /* Initial rtt is BIG: */
+        rtt_4 = timeout;
 
         DMSG("min_rtt %u timeout %u", min_rtt, timeout);
 
@@ -74,11 +78,12 @@ int pscan_main(int argc ATTRIBUTE_UNUSED, char **argv)
                 /* The SOCK_STREAM socket type is implemented on the TCP/IP protocol. */
                 set_nport(lsap, htons(port));
                 s = xsocket(lsap->u.sa.sa_family, SOCK_STREAM, 0);
-
                 /* We need unblocking socket so we don't need to wait for ETIMEOUT. */
                 /* Nonblocking connect typically "fails" with errno == EINPROGRESS */
                 ndelay_on(s);
+
                 DMSG("connect to port %u", port);
+                result_str = NULL;
                 start = MONOTONIC_US();
                 if (connect(s, &lsap->u.sa, lsap->len) == 0) {
                         /* Unlikely, for me even localhost fails :) */
@@ -92,35 +97,46 @@ int pscan_main(int argc ATTRIBUTE_UNUSED, char **argv)
                         bb_perror_nomsg_and_die();
                 }
 
+                diff = 0;
                 while (1) {
                         if (errno == ECONNREFUSED) {
-                                DMSG("port %u: ECONNREFUSED", port);
+                                if (opt & 1) /* -c: show closed too */
+                                        result_str = "closed";
                                 closed_ports++;
                                 break;
                         }
-                        DERR("port %u errno %d @%u", port, errno, MONOTONIC_US() - start);
-                        if ((MONOTONIC_US() - start) > rtt_4)
+                        DERR("port %u errno %d @%u", port, errno, diff);
+
+                        if (diff > rtt_4) {
+                                if (opt & 2) /* -b: show blocked too */
+                                        result_str = "blocked";
                                 break;
+                        }
                         /* Can sleep (much) longer than specified delay.
                          * We check rtt BEFORE we usleep, otherwise
-                         * on localhost we'll do zero writes done (!)
+                         * on localhost we'll have no writes done (!)
                          * before we exceed (rather small) rtt */
                         usleep(rtt_4/8);
-                        DMSG("write to port %u @%u", port, MONOTONIC_US() - start);
-                        if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
  open:
+                        diff = MONOTONIC_US() - start;
+                        DMSG("write to port %u @%u", port, diff - start);
+                        if (write(s, " ", 1) >= 0) { /* We were able to write to the socket */
                                 open_ports++;
-                                printf("%5u\ttcp\topen\t%s\n", port, port_name(port));
+                                result_str = "open";
                                 break;
                         }
                 }
-                DMSG("out of loop @%u", MONOTONIC_US() - start);
+                DMSG("out of loop @%u", diff);
+                if (result_str)
+                        printf("%5u" "\t" "tcp" "\t" "%s" "\t" "%s" "\n",
+                                        port, result_str, port_name(port));
 
                 /* Estimate new rtt - we don't want to wait entire timeout
                  * for each port. *4 allows for rise in net delay.
-                 * We increase rtt quickly (*4), decrease slowly (4/8 == 1/2)
+                 * We increase rtt quickly (rtt_4*4), decrease slowly
+                 * (diff is at least rtt_4/8, *4 == rtt_4/2)
                  * because we don't want to accidentally miss ports. */
-                rtt_4 = (MONOTONIC_US() - start) * 4;
+                rtt_4 = diff * 4;
                 if (rtt_4 < min_rtt)
                         rtt_4 = min_rtt;
                 if (rtt_4 > timeout)
@@ -130,7 +146,7 @@ int pscan_main(int argc ATTRIBUTE_UNUSED, char **argv)
         }
         if (ENABLE_FEATURE_CLEAN_UP) free(lsap);
 
-        printf("%d closed, %d open, %d timed out ports\n",
+        printf("%d closed, %d open, %d timed out (or blocked) ports\n",
                                         closed_ports,
                                         open_ports,
                                         nports - (closed_ports + open_ports));