tcpsvd,udpsvd: make them NOMMU-capable

inetd: make udp nowait work

function                                             old     new   delta
inetd_main                                          1797    2036    +239
tcpudpsvd_main                                      1839    1973    +134
xsetenv_plain                                          -      39     +39
xsetenv_proto                                         23      40     +17
bump_nofile                                          169     170      +1
sig_term_handler                                      72      69      -3
sig_child_handler                                    239     233      -6
connection_status                                     37      31      -6
parse_one_line                                      1102    1092     -10
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/4 up/down: 430/-25)           Total: 405 bytes
   text    data     bss     dec     hex filename
 798437     661    7428  806526   c4e7e busybox_old
 798734     661    7428  806823   c4fa7 busybox_unstripped

3 files changed, 198 insertions, 140 deletions

diff --git a/TODO_config_nommu b/TODO_config_nommu
index b0221bbc3..8bf7b215c 100644
--- a/TODO_config_nommu
+++ b/TODO_config_nommu
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.10.0.svn
-# Thu Mar  6 20:18:05 2008
+# Sat Mar  8 01:11:42 2008
 #
 CONFIG_HAVE_DOT_CONFIG=y
 
@@ -844,5 +844,5 @@ CONFIG_LPQ=y
 #
 # ipsvd utilities
 #
-# CONFIG_TCPSVD is not set
-# CONFIG_UDPSVD is not set
+CONFIG_TCPSVD=y
+CONFIG_UDPSVD=y
diff --git a/ipsvd/tcpudp.c b/ipsvd/tcpudp.c
index 5362af5fd..2e8dffa0f 100644
--- a/ipsvd/tcpudp.c
+++ b/ipsvd/tcpudp.c
@@ -13,12 +13,12 @@
  *
  * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused.
  *
- * Output of verbose mode matches original (modulo bugs and
- * unimplemented stuff). Unnatural splitting of IP and PORT
- * is retained (personally I prefer one-value "IP:PORT" notation -
- * it is a natural string representation of struct sockaddr_XX).
+ * Busybox version exports TCPLOCALADDR instead of
+ * TCPLOCALIP + TCPLOCALPORT pair. ADDR more closely matches reality
+ * (which is "struct sockaddr_XXX". Port is not a separate entity,
+ * it's just a part of (AF_INET[6]) sockaddr!).
  *
- * TCPORIGDST{IP,PORT} is busybox-specific addition
+ * TCPORIGDSTADDR is Busybox-specific addition.
  *
  * udp server is hacked up by reusing TCP code. It has the following
  * limitation inherent in Unix DGRAM sockets implementation:
@@ -46,6 +46,8 @@ struct globals {
         unsigned cur_per_host;
         unsigned cnum;
         unsigned cmax;
+        char **env_cur;
+        char *env_var[1]; /* actually bigger */
 };
 #define G (*(struct globals*)&bb_common_bufsiz1)
 #define verbose      (G.verbose     )
@@ -53,21 +55,46 @@ struct globals {
 #define cur_per_host (G.cur_per_host)
 #define cnum         (G.cnum        )
 #define cmax         (G.cmax        )
+#define env_cur      (G.env_cur     )
+#define env_var      (G.env_var     )
 #define INIT_G() \
         do { \
                 cmax = 30; \
+                env_cur = &env_var[0]; \
         } while (0)
 
 
+/* We have to be careful about leaking memory in repeated setenv's */
+static void xsetenv_plain(const char *n, const char *v)
+{
+        char *var = xasprintf("%s=%s", n, v);
+        *env_cur++ = var;
+        putenv(var);
+}
+
 static void xsetenv_proto(const char *proto, const char *n, const char *v)
 {
-        putenv(xasprintf("%s%s=%s", proto, n, v));
+        char *var = xasprintf("%s%s=%s", proto, n, v);
+        *env_cur++ = var;
+        putenv(var);
+}
+
+static void undo_xsetenv(void)
+{
+        char **pp = env_cur = &env_var[0];
+        while (*pp) {
+                char *var = *pp;
+                *strchrnul(var, '=') = '\0';
+                unsetenv(var);
+                free(var);
+                *pp++ = NULL;
+        }
 }
 
 static void sig_term_handler(int sig)
 {
         if (verbose)
-                printf("%s: info: sigterm received, exit\n", applet_name);
+                bb_error_msg("got signal %u, exit", sig);
         kill_myself_with_sig(sig);
 }
 
@@ -85,7 +112,7 @@ static void print_waitstat(unsigned pid, int wstat)
                 cause = "signal";
                 e = WTERMSIG(wstat);
         }
-        printf("%s: info: end %d %s %d\n", applet_name, pid, cause, e);
+        bb_error_msg("end %d %s %d", pid, cause, e);
 }
 
 /* Must match getopt32 in main! */
@@ -113,7 +140,7 @@ static void connection_status(void)
 {
         /* "only 1 client max" desn't need this */
         if (cmax > 1)
-                printf("%s: info: status %u/%u\n", applet_name, cnum, cmax);
+                bb_error_msg("status %u/%u", cnum, cmax);
 }
 
 static void sig_child_handler(int sig)
@@ -145,13 +172,11 @@ int tcpudpsvd_main(int argc, char **argv)
 #ifndef SSLSVD
         struct bb_uidgid_t ugid;
 #endif
-        bool need_hostnames, need_remote_ip, tcp;
+        bool tcp;
         uint16_t local_port;
-        char *local_hostname = NULL;
-        char *remote_hostname = (char*)""; /* "" used if no -h */
-        char *local_addr = local_addr; /* gcc */
-        char *remote_addr = remote_addr; /* gcc */
-        char *remote_ip = remote_addr; /* gcc */
+        char *preset_local_hostname = NULL;
+        char *remote_hostname = remote_hostname; /* for compiler */
+        char *remote_addr = remote_addr; /* for compiler */
         len_and_sockaddr *lsa;
         len_and_sockaddr local, remote;
         socklen_t sa_len;
@@ -168,12 +193,12 @@ int tcpudpsvd_main(int argc, char **argv)
         opt_complementary = "-3:i--i:ph:vv";
 #ifdef SSLSVD
         getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
-                &str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
+                &str_c, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
                 &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose
         );
 #else
         getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
-                &str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
+                &str_c, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
                 &str_b, &str_t, &verbose
         );
 #endif
@@ -210,26 +235,21 @@ int tcpudpsvd_main(int argc, char **argv)
         if (!tcp)
                 max_per_host = 0;
 
-        /* stdout is used for logging, don't buffer */
-        setlinebuf(stdout);
         bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
 
-        need_hostnames = verbose || !(option_mask32 & OPT_E);
-        need_remote_ip = max_per_host || need_hostnames;
-
 #ifdef SSLSVD
         sslser = user;
         client = 0;
         if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
                 xfunc_exitcode = 100;
-                bb_error_msg_and_die("fatal: -U ssluser must be set when running as root");
+                bb_error_msg_and_die("-U ssluser must be set when running as root");
         }
         if (option_mask32 & OPT_u)
                 if (!uidgid_get(&sslugid, ssluser, 1)) {
                         if (errno) {
                                 bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser);
                         }
-                        bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser);
+                        bb_error_msg_and_die("unknown user/group '%s'", ssluser);
                 }
         if (!cert) cert = "./cert.pem";
         if (!key) key = cert;
@@ -246,7 +266,7 @@ int tcpudpsvd_main(int argc, char **argv)
 
         sig_block(SIGCHLD);
         signal(SIGCHLD, sig_child_handler);
-        signal(SIGTERM, sig_term_handler);
+        bb_signals(BB_SIGS_FATAL, sig_term_handler);
         signal(SIGPIPE, SIG_IGN);
 
         if (max_per_host)
@@ -254,6 +274,8 @@ int tcpudpsvd_main(int argc, char **argv)
 
         local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
         lsa = xhost2sockaddr(argv[0], local_port);
+        argv += 2;
+
         sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
         setsockopt_reuseaddr(sock);
         sa_len = lsa->len; /* I presume sockaddr len stays the same */
@@ -274,14 +296,13 @@ int tcpudpsvd_main(int argc, char **argv)
 
         if (verbose) {
                 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
-                printf("%s: info: listening on %s", applet_name, addr);
+                bb_error_msg("listening on %s, starting", addr);
                 free(addr);
 #ifndef SSLSVD
                 if (option_mask32 & OPT_u)
                         printf(", uid %u, gid %u",
                                 (unsigned)ugid.uid, (unsigned)ugid.gid);
 #endif
-                puts(", starting");
         }
 
         /* Main accept() loop */
@@ -297,14 +318,15 @@ int tcpudpsvd_main(int argc, char **argv)
         close(0);
  again2:
         sig_unblock(SIGCHLD);
+        local.len = remote.len = sa_len;
         if (tcp) {
-                remote.len = sa_len;
                 conn = accept(sock, &remote.u.sa, &remote.len);
         } else {
                 /* In case recv_from_to won't be able to recover local addr.
                  * Also sets port - recv_from_to is unable to do it. */
                 local = *lsa;
-                conn = recv_from_to(sock, NULL, 0, MSG_PEEK, &remote.u.sa, &local.u.sa, sa_len);
+                conn = recv_from_to(sock, NULL, 0, MSG_DONTWAIT | MSG_PEEK,
+                                &remote.u.sa, &local.u.sa, sa_len);
         }
         sig_block(SIGCHLD);
         if (conn < 0) {
@@ -317,19 +339,19 @@ int tcpudpsvd_main(int argc, char **argv)
         if (max_per_host) {
                 /* Drop connection immediately if cur_per_host > max_per_host
                  * (minimizing load under SYN flood) */
-                remote_ip = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
-                cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp);
+                remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
+                cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
                 if (cur_per_host > max_per_host) {
                         /* ipsvd_perhost_add detected that max is exceeded
                          * (and did not store ip in connection table) */
-                        free(remote_ip);
+                        free(remote_addr);
                         if (msg_per_host) {
                                 /* don't block or test for errors */
-                                ndelay_on(0);
-                                write(0, msg_per_host, len_per_host);
+                                send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
                         }
                         goto again1;
                 }
+                /* NB: remote_addr is not leaked, it is stored in conn table */
         }
 
         if (!tcp) {
@@ -372,19 +394,21 @@ int tcpudpsvd_main(int argc, char **argv)
 #endif
         }
 
-        pid = fork();
+        pid = vfork();
         if (pid == -1) {
-                bb_perror_msg("fork");
+                bb_perror_msg("vfork");
                 goto again;
         }
 
         if (pid != 0) {
-                /* parent */
+                /* Parent */
                 cnum++;
                 if (verbose)
                         connection_status();
                 if (hccp)
                         hccp->pid = pid;
+                /* clean up changes done by vforked child */
+                undo_xsetenv();
                 goto again;
         }
 
@@ -394,78 +418,93 @@ int tcpudpsvd_main(int argc, char **argv)
         if (tcp)
                 close(sock);
 
-        if (need_remote_ip)
-                remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
-
-        if (need_hostnames) {
-                if (option_mask32 & OPT_h) {
-                        remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
-                        if (!remote_hostname) {
-                                bb_error_msg("warning: cannot look up hostname for %s", remote_addr);
-                                remote_hostname = (char*)"";
+        { /* vfork alert! every xmalloc in this block should be freed! */
+                char *local_hostname = local_hostname; /* for compiler */
+                char *local_addr = NULL;
+                char *free_me0 = NULL;
+                char *free_me1 = NULL;
+                char *free_me2 = NULL;
+
+                if (verbose || !(option_mask32 & OPT_E)) {
+                        if (!max_per_host) /* remote_addr is not yet known */
+                                free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
+                        if (option_mask32 & OPT_h) {
+                                free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
+                                if (!remote_hostname) {
+                                        bb_error_msg("cannot look up hostname for %s", remote_addr);
+                                        remote_hostname = remote_addr;
+                                }
+                        }
+                        /* Find out local IP peer connected to.
+                         * Errors ignored (I'm not paranoid enough to imagine kernel
+                         * which doesn't know local IP). */
+                        if (tcp)
+                                getsockname(0, &local.u.sa, &local.len);
+                        /* else: for UDP it is done earlier by parent */
+                        local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
+                        if (option_mask32 & OPT_h) {
+                                local_hostname = preset_local_hostname;
+                                if (!local_hostname) {
+                                        free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
+                                        if (!local_hostname)
+                                                bb_error_msg_and_die("cannot look up hostname for %s", local_addr);
+                                }
+                                /* else: local_hostname is not NULL, but is NOT malloced! */
                         }
                 }
-                /* Find out local IP peer connected to.
-                 * Errors ignored (I'm not paranoid enough to imagine kernel
-                 * which doesn't know local IP). */
-                if (tcp) {
-                        local.len = sa_len;
-                        getsockname(0, &local.u.sa, &local.len);
-                }
-                local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
-                if (!local_hostname) {
-                        local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
-                        if (!local_hostname)
-                                bb_error_msg_and_die("warning: cannot look up hostname for %s"+9, local_addr);
+                if (verbose) {
+                        pid = getpid();
+                        if (max_per_host) {
+                                bb_error_msg("concurrency %s %u/%u",
+                                        remote_addr,
+                                        cur_per_host, max_per_host);
+                        }
+                        bb_error_msg((option_mask32 & OPT_h)
+                                ? "start %u %s-%s (%s-%s)"
+                                : "start %u %s-%s",
+                                pid,
+                                local_addr, remote_addr,
+                                local_hostname, remote_hostname);
                 }
-        }
 
-        if (verbose) {
-                pid = getpid();
-                printf("%s: info: pid %u from %s\n", applet_name, pid, remote_addr);
-                if (max_per_host)
-                        printf("%s: info: concurrency %u %s %u/%u\n",
-                                applet_name, pid, remote_ip, cur_per_host, max_per_host);
-                printf("%s: info: start %u %s:%s :%s:%s\n",
-                        applet_name, pid,
-                        local_hostname, local_addr,
-                        remote_hostname, remote_addr);
-        }
-
-        if (!(option_mask32 & OPT_E)) {
-                /* setup ucspi env */
-                const char *proto = tcp ? "TCP" : "UDP";
-
-                /* Extract "original" destination addr:port
-                 * from Linux firewall. Useful when you redirect
-                 * an outbond connection to local handler, and it needs
-                 * to know where it originally tried to connect */
-                if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &lsa->u.sa, &lsa->len) == 0) {
-                        char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
-                        xsetenv("TCPORIGDSTADDR", addr);
-                        free(addr);
-                }
-                xsetenv("PROTO", proto);
-                xsetenv_proto(proto, "LOCALADDR", local_addr);
-                xsetenv_proto(proto, "LOCALHOST", local_hostname);
-                xsetenv_proto(proto, "REMOTEADDR", remote_addr);
-                if (option_mask32 & OPT_h) {
-                        xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
+                if (!(option_mask32 & OPT_E)) {
+                        /* setup ucspi env */
+                        const char *proto = tcp ? "TCP" : "UDP";
+
+                        /* Extract "original" destination addr:port
+                         * from Linux firewall. Useful when you redirect
+                         * an outbond connection to local handler, and it needs
+                         * to know where it originally tried to connect */
+                        if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
+                                char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
+                                xsetenv_plain("TCPORIGDSTADDR", addr);
+                                free(addr);
+                        }
+                        xsetenv_plain("PROTO", proto);
+                        xsetenv_proto(proto, "LOCALADDR", local_addr);
+                        xsetenv_proto(proto, "REMOTEADDR", remote_addr);
+                        if (option_mask32 & OPT_h) {
+                                xsetenv_proto(proto, "LOCALHOST", local_hostname);
+                                xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
+                        }
+                        //compat? xsetenv_proto(proto, "REMOTEINFO", "");
+                        /* additional */
+                        if (cur_per_host > 0) /* can not be true for udp */
+                                xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
                 }
-                xsetenv_proto(proto, "REMOTEINFO", "");
-                /* additional */
-                if (cur_per_host > 0) /* can not be true for udp */
-                        xsetenv("TCPCONCURRENCY", utoa(cur_per_host));
+                free(local_addr);
+                free(free_me0);
+                free(free_me1);
+                free(free_me2);
         }
 
-        dup2(0, 1);
+        xdup2(0, 1);
 
         signal(SIGTERM, SIG_DFL);
         signal(SIGPIPE, SIG_DFL);
         signal(SIGCHLD, SIG_DFL);
         sig_unblock(SIGCHLD);
 
-        argv += 2;
 #ifdef SSLSVD
         strcpy(id, utoa(pid));
         ssl_io(0, argv);
diff --git a/networking/inetd.c b/networking/inetd.c
index 0620188d6..41824dbc8 100644
--- a/networking/inetd.c
+++ b/networking/inetd.c
@@ -130,8 +130,13 @@
  * tening service socket, and must accept at least one connection request
  * before exiting.  Such a server would normally accept and process incoming
  * connection requests until a timeout.
- *
- * In short: "stream" can be "wait" or "nowait"; "dgram" must be "wait".
+ */
+
+/* Despite of above doc saying that dgram services must use "wait",
+ * "udp nowait" servers are implemented in busyboxed inetd.
+ * IPv6 addresses are also implemented. However, they may look ugly -
+ * ":::service..." means "address '::' (IPv6 wildcard addr)":"service"...
+ * You have to put "tcp6"/"udp6" in protocol field to select IPv6.
  */
 
 /* Here's the scoop concerning the user[:group] feature:
@@ -832,9 +837,6 @@ static NOINLINE servtab_t *parse_one_line(void)
         if (sep->se_socktype == SOCK_DGRAM) {
                 if (sep->se_proto_no == IPPROTO_TCP)
                         goto parse_err;
-                /* "udp nowait" is a small fork bomb :) */
-                if (!sep->se_wait)
-                        goto parse_err;
         }
 
         /* check if the hostname specifier is a comma separated list
@@ -1195,7 +1197,7 @@ int inetd_main(int argc, char **argv)
 
         for (;;) {
                 int ready_fd_cnt;
-                int ctrl, accepted_fd;
+                int ctrl, accepted_fd, new_udp_fd;
                 fd_set readable;
 
                 if (maxsock < 0)
@@ -1220,12 +1222,43 @@ int inetd_main(int argc, char **argv)
                         ready_fd_cnt--;
                         ctrl = sep->se_fd;
                         accepted_fd = -1;
-                        if (!sep->se_wait && sep->se_socktype == SOCK_STREAM) {
-                                ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
-                                if (ctrl < 0) {
-                                        if (errno != EINTR)
-                                                bb_perror_msg("accept (for %s)", sep->se_service);
-                                        continue;
+                        new_udp_fd = -1;
+                        if (!sep->se_wait) {
+                                if (sep->se_socktype == SOCK_STREAM) {
+                                        ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
+                                        if (ctrl < 0) {
+                                                if (errno != EINTR)
+                                                        bb_perror_msg("accept (for %s)", sep->se_service);
+                                                continue;
+                                        }
+                                }
+                                /* "nowait" udp */
+                                if (sep->se_socktype == SOCK_DGRAM
+                                 && sep->se_family != AF_UNIX
+                                ) {
+/* How udp "nowait" works:
+ * child peeks at (received and buffered by kernel) UDP packet,
+ * performs connect() on the socket so that it is linked only
+ * to this peer. But this also affects parent, because descriptors
+ * are shared after fork() a-la dup(). When parent performs
+ * select(), it will see this descriptor connected to the peer (!)
+ * and still readable, will act on it and mess things up
+ * (can create many copies of same child, etc).
+ * Parent must create and use new socket instead. */
+                                        new_udp_fd = socket(sep->se_family, SOCK_DGRAM, 0);
+                                        if (new_udp_fd < 0) { /* error: eat packet, forget about it */
+ udp_err:
+                                                recv(sep->se_fd, line, LINE_SIZE, MSG_DONTWAIT);
+                                                continue;
+                                        }
+                                        setsockopt_reuseaddr(new_udp_fd);
+                                        /* TODO: better do bind after vfork in parent,
+                                         * so that we don't have two wildcard bound sockets
+                                         * even for a brief moment? */
+                                        if (bind(new_udp_fd, &sep->se_lsa->u.sa, sep->se_lsa->len) < 0) {
+                                                close(new_udp_fd);
+                                                goto udp_err;
+                                        }
                                 }
                         }
 
@@ -1283,10 +1316,15 @@ int inetd_main(int argc, char **argv)
 
                         if (pid > 0) { /* parent */
                                 if (sep->se_wait) {
+                                        /* tcp wait: we passed listening socket to child,
+                                         * will wait for child to terminate */
                                         sep->se_wait = pid;
                                         remove_fd_from_set(sep->se_fd);
-                                        /* we passed listening socket to child,
-                                         * will wait for child to terminate */
+                                }
+                                if (new_udp_fd >= 0) {
+                                        /* udp nowait: child connected the socket,
+                                         * we created and will use new, unconnected one */
+                                        xmove_fd(new_udp_fd, sep->se_fd);
                                 }
                                 restore_sigmask(&omask);
                                 maybe_close(accepted_fd);
@@ -1313,39 +1351,20 @@ int inetd_main(int argc, char **argv)
 #endif
                         /* child */
                         setsid();
-#if 0
-/* This does not work.
- * Actually, it _almost_ works. The idea behind it is: child
- * can peek at (already received and buffered by kernel) UDP packet,
- * and perform connect() on the socket so that it is linked only
- * to this peer. But this also affects parent, because descriptors
- * are shared after fork() a-la dup(). When parent returns to
- * select(), it will see this descriptor attached to the peer (!)
- * and likely still readable, will act on it and mess things up
- * (can create many copies of same child, etc).
- * If child will create new socket instead, then bind() and
- * connect() it to peer's address, descriptor aliasing problem
- * is solved, but first packet cannot be "transferred" to the new
- * socket. It is not a problem if child can account for this,
- * but our child will exec - and exec'ed program does not know
- * about this "lost packet" problem! Pity... */
-                        /* "nowait" udp[6]. Hmmm... */
-                        if (!sep->se_wait
-                         && sep->se_socktype == SOCK_DGRAM
-                         && sep->se_family != AF_UNIX
-                        ) {
+                        /* "nowait" udp */
+                        if (new_udp_fd >= 0) {
                                 len_and_sockaddr *lsa = xzalloc_lsa(sep->se_family);
                                 /* peek at the packet and remember peer addr */
                                 int r = recvfrom(ctrl, NULL, 0, MSG_PEEK|MSG_DONTWAIT,
                                         &lsa->u.sa, &lsa->len);
-                                if (r >= 0)
-                                        /* make this socket "connected" to peer addr:
-                                         * only packets from this peer will be recv'ed,
-                                         * and bare write()/send() will work on it */
-                                        connect(ctrl, &lsa->u.sa, lsa->len);
+                                if (r < 0)
+                                        goto do_exit1;
+                                /* make this socket "connected" to peer addr:
+                                 * only packets from this peer will be recv'ed,
+                                 * and bare write()/send() will work on it */
+                                connect(ctrl, &lsa->u.sa, lsa->len);
                                 free(lsa);
                         }
-#endif
                         /* prepare env and exec program */
                         pwd = getpwnam(sep->se_user);
                         if (pwd == NULL) {