nc_bloaty: support -ll and -lk. Closes 2245

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/nc_bloaty.c b/networking/nc_bloaty.c
index 62a0251..00ba6f1 100644 (file)
--- a/networking/nc_bloaty.c
+++ b/networking/nc_bloaty.c
@@ -63,6 +63,12 @@
 //usage:       "       -e PROG Run PROG after connect (must be last)"
 //usage:       IF_NC_SERVER(
 //usage:     "\n       -l      Listen mode, for inbound connects"
+//usage:     "\n       -lk     With -e, provides persistent server"
+/* -ll does the same as -lk, but its our extension, while -k is BSD'd,
+ * presumably more widely known. Therefore we advertise it, not -ll.
+ * I would like to drop -ll support, but our "small" nc supports it,
+ * and Rob uses it.
+ */
 //usage:       )
 //usage:     "\n       -p PORT Local port"
 //usage:     "\n       -s ADDR Local address"
@@ -166,18 +172,14 @@ enum {
        OPT_v = (1 << 4),
        OPT_w = (1 << 5),
        OPT_l = (1 << 6) * ENABLE_NC_SERVER,
-       OPT_i = (1 << (6+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
-       OPT_o = (1 << (7+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
-       OPT_z = (1 << (8+ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
+       OPT_k = (1 << 7) * ENABLE_NC_SERVER,
+       OPT_i = (1 << (7+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
+       OPT_o = (1 << (8+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
+       OPT_z = (1 << (9+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
 };
 
 #define o_nflag   (option_mask32 & OPT_n)
 #define o_udpmode (option_mask32 & OPT_u)
-#if ENABLE_NC_SERVER
-#define o_listen  (option_mask32 & OPT_l)
-#else
-#define o_listen  0
-#endif
 #if ENABLE_NC_EXTRA
 #define o_ofile   (option_mask32 & OPT_o)
 #define o_zero    (option_mask32 & OPT_z)
@@ -298,7 +300,7 @@ static int connect_w_timeout(int fd)
  incoming and returns an open connection *from* someplace.  If we were
  given host/port args, any connections from elsewhere are rejected.  This
  in conjunction with local-address binding should limit things nicely... */
-static void dolisten(void)
+static void dolisten(int is_persistent, char **proggie)
 {
        int rr;
 
@@ -371,6 +373,7 @@ create new one, and bind() it. TODO */
                        xconnect(netfd, &remend.u.sa, ouraddr->len);
        } else {
                /* TCP */
+ another:
                arm(o_wait); /* wrap this in a timer, too; 0 = forever */
                if (setjmp(jbuf) == 0) {
  again:
@@ -405,6 +408,19 @@ create new one, and bind() it. TODO */
                        unarm();
                } else
                        bb_error_msg_and_die("timeout");
+
+               if (is_persistent && proggie) {
+                       /* -l -k -e PROG */
+                       signal(SIGCHLD, SIG_IGN); /* no zombies please */
+                       if (xvfork() != 0) {
+                               /* parent: go back and accept more connections */
+                               close(rr);
+                               goto another;
+                       }
+                       /* child */
+                       signal(SIGCHLD, SIG_DFL);
+               }
+
                xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
                /* find out what address the connection was *to* on our end, in case we're
                 doing a listen-on-any on a multihomed machine.  This allows one to
@@ -454,6 +470,9 @@ create new one, and bind() it. TODO */
                if (!o_nflag)
                        free(remhostname);
        }
+
+       if (proggie)
+               doexec(proggie);
 }
 
 /* udptest:
@@ -730,6 +749,7 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
        char *themdotted = themdotted; /* for compiler */
        char **proggie;
        int x;
+       unsigned cnt_l = 0;
        unsigned o_lport = 0;
 
        INIT_G();
@@ -760,7 +780,7 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
                if (proggie[0][0] == '-') {
                        char *optpos = *proggie + 1;
                        /* Skip all valid opts w/o params */
-                       optpos = optpos + strspn(optpos, "nuv"IF_NC_SERVER("l")IF_NC_EXTRA("z"));
+                       optpos = optpos + strspn(optpos, "nuv"IF_NC_SERVER("lk")IF_NC_EXTRA("z"));
                        if (*optpos == 'e' && !optpos[1]) {
                                *optpos = '\0';
                                proggie++;
@@ -774,17 +794,21 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
  e_found:
 
        // -g -G -t -r deleted, unimplemented -a deleted too
-       opt_complementary = "?2:vv:w+"; /* max 2 params; -v is a counter; -w N */
-       getopt32(argv, "np:s:uvw:" IF_NC_SERVER("l")
+       opt_complementary = "?2:vv:ll:w+"; /* max 2 params; -v and -l are counters; -w N */
+       getopt32(argv, "np:s:uvw:" IF_NC_SERVER("lk")
                        IF_NC_EXTRA("i:o:z"),
                        &str_p, &str_s, &o_wait
-                       IF_NC_EXTRA(, &str_i, &str_o), &o_verbose);
+                       IF_NC_EXTRA(, &str_i, &str_o), &o_verbose IF_NC_SERVER(, &cnt_l));
        argv += optind;
 #if ENABLE_NC_EXTRA
        if (option_mask32 & OPT_i) /* line-interval time */
                o_interval = xatou_range(str_i, 1, 0xffff);
 #endif
+#if ENABLE_NC_SERVER
        //if (option_mask32 & OPT_l) /* listen mode */
+       if (option_mask32 & OPT_k) /* persistent server mode */
+               cnt_l = 2;
+#endif
        //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
        //if (option_mask32 & OPT_o) /* hexdump log */
        if (option_mask32 & OPT_p) { /* local source port */
@@ -833,7 +857,7 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
        if (o_udpmode)
                socket_want_pktinfo(netfd);
        if (!ENABLE_FEATURE_UNIX_LOCAL
-        || o_listen
+        || cnt_l != 0 /* listen */
         || ouraddr->u.sa.sa_family != AF_UNIX
        ) {
                xbind(netfd, &ouraddr->u.sa, ouraddr->len);
@@ -862,11 +886,9 @@ int nc_main(int argc UNUSED_PARAM, char **argv)
                xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
 #endif
 
-       if (o_listen) {
-               dolisten();
+       if (cnt_l != 0) {
+               dolisten((cnt_l - 1), proggie);
                /* dolisten does its own connect reporting */
-               if (proggie) /* -e given? */
-                       doexec(proggie);
                x = readwrite(); /* it even works with UDP! */
        } else {
                /* Outbound connects.  Now we're more picky about args... */