tcpsvd: new applet

It's a GPL-ed 'clone' of Dan Bernstein's tcpserver.
Author: Gerrit Pape <pape@smarden.org>
http://smarden.sunsite.dk/ipsvd/
size tcpsvd.o
   text    data     bss     dec     hex filename
   2571       4      16    2591     a1f tcpsvd.o

5 files changed, 601 insertions, 0 deletions

diff --git a/ipsvd/Config.in b/ipsvd/Config.in
new file mode 100644
index 0000000..fb2931d
--- /dev/null
+++ b/ipsvd/Config.in
@@ -0,0 +1,14 @@
+#
+# For a description of the syntax of this configuration file,
+# see scripts/kbuild/config-language.txt.
+#
+
+menu "ipsvd utilities"
+
+config TCPSVD
+	bool "tcpsvd"
+	default n
+	help
+	  tcpsvd listens on a port and runs a program for each new connection
+
+endmenu
diff --git a/ipsvd/Kbuild b/ipsvd/Kbuild
new file mode 100644
index 0000000..8050921
--- /dev/null
+++ b/ipsvd/Kbuild
@@ -0,0 +1,8 @@
+# Makefile for busybox
+#
+# Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
+#
+# Licensed under the GPL v2, see the file LICENSE in this tarball.
+
+lib-y:=
+lib-$(CONFIG_TCPSVD) += tcpsvd.o ipsvd_perhost.o
diff --git a/ipsvd/ipsvd_perhost.c b/ipsvd/ipsvd_perhost.c
new file mode 100644
index 0000000..c6f7de3
--- /dev/null
+++ b/ipsvd/ipsvd_perhost.c
@@ -0,0 +1,55 @@
+#include "busybox.h"
+#include "ipsvd_perhost.h"
+
+static struct hcc *cc;
+static unsigned cclen;
+
+/* to be optimized */
+
+void ipsvd_perhost_init(unsigned c)
+{
+//	free(cc);
+	cc = xzalloc(c * sizeof(*cc));
+	cclen = c;
+}
+
+unsigned ipsvd_perhost_add(const char *ip, unsigned maxconn, struct hcc **hccpp)
+{
+	unsigned i;
+	unsigned conn = 1;
+	int p = -1;
+
+	for (i = 0; i < cclen; ++i) {
+		if (cc[i].ip[0] == 0) {
+			if (p == -1) p = i;
+    			continue;
+		}
+		if (strncmp(cc[i].ip, ip, sizeof(cc[i].ip)) == 0) {
+			conn++;
+			continue;
+		}
+	}
+	if (p == -1) return 0;
+	if (conn <= maxconn) {
+		strcpy(cc[p].ip, ip);
+		*hccpp = &cc[p];
+	}
+	return conn;
+}
+
+void ipsvd_perhost_remove(int pid)
+{
+	unsigned i;
+	for (i = 0; i < cclen; ++i) {
+		if (cc[i].pid == pid) {
+			cc[i].ip[0] = 0;
+			cc[i].pid = 0;
+			return;
+		}
+	}
+}
+
+//void ipsvd_perhost_free(void)
+//{
+//	free(cc);
+//}
diff --git a/ipsvd/ipsvd_perhost.h b/ipsvd/ipsvd_perhost.h
new file mode 100644
index 0000000..05c939d
--- /dev/null
+++ b/ipsvd/ipsvd_perhost.h
@@ -0,0 +1,10 @@
+struct hcc {
+        char ip[32 - sizeof(int)];
+        int pid;
+};
+
+void ipsvd_perhost_init(unsigned);
+unsigned ipsvd_perhost_add(const char *ip, unsigned maxconn, struct hcc **hccpp);
+void ipsvd_perhost_remove(int pid);
+//unsigned ipsvd_perhost_setpid(int pid);
+//void ipsvd_perhost_free(void);
diff --git a/ipsvd/tcpsvd.c b/ipsvd/tcpsvd.c
new file mode 100644
index 0000000..9a0a348
--- /dev/null
+++ b/ipsvd/tcpsvd.c
@@ -0,0 +1,514 @@
+/*
+# /usr/bin/tcpsvd -v 0 1234 true
+tcpsvd: info: pid 24916 from 127.0.0.1
+tcpsvd: info: start 24916 localhost:127.0.0.1 ::127.0.0.1:47905
+tcpsvd: info: pid 24918 from 127.0.0.1
+tcpsvd: info: start 24918 localhost:127.0.0.1 ::127.0.0.1:47906
+# ./busybox tcpsvd -v 0 1234 true
+tcpsvd: info: pid 24924 from 127.0.0.1
+tcpsvd: info: start 24924 localhost:1234:127.0.0.1:1234 ::127.0.0.1:47908
+tcpsvd: info: pid 24926 from 127.0.0.1
+tcpsvd: info: start 24926 localhost:1234:127.0.0.1:1234 ::127.0.0.1:47909
+*/
+
+#include "busybox.h"
+#include "ipsvd_perhost.h"
+
+#ifdef SSLSVD
+#include "matrixSsl.h"
+#include "ssl_io.h"
+#endif
+
+
+static unsigned max_per_host; /* originally in ipsvd_check.c */
+static unsigned cur_per_host;
+static unsigned verbose;
+static unsigned cnum;
+static unsigned cmax = 30;
+
+/* Must match getopt32 in main! */
+enum {
+	OPT_c = (1 << 0),
+	OPT_C = (1 << 1),
+	OPT_i = (1 << 2),
+	OPT_x = (1 << 3),
+	OPT_u = (1 << 4),
+	OPT_l = (1 << 5),
+	OPT_E = (1 << 6),
+	OPT_b = (1 << 7),
+	OPT_h = (1 << 8),
+	OPT_p = (1 << 9),
+	OPT_t = (1 << 10),
+	OPT_v = (1 << 11),
+	OPT_V = (1 << 12),
+	OPT_U = (1 << 13),
+	OPT_slash = (1 << 14),
+	OPT_Z = (1 << 15),
+	OPT_K = (1 << 16),
+};
+
+static void connection_status(void)
+{
+	printf("%s: info: status %u/%u\n", applet_name, cnum, cmax);
+}
+
+static void sig_term_handler(int sig)
+{
+	if (verbose)
+		printf("%s: info: sigterm received, exit\n", applet_name);
+	exit(0);
+}
+
+static void sig_child_handler(int sig)
+{
+	int wstat;
+	int pid;
+
+	while ((pid = wait_nohang(&wstat)) > 0) {
+		if (max_per_host)
+			ipsvd_perhost_remove(pid);
+		if (cnum)
+			cnum--;
+		if (verbose) {
+			/* Little bloated, but tries to give accurate info
+			 * how child exited. Makes easier to spot segfaulting
+			 * children etc... */
+			unsigned e = 0;
+			const char *cause = "?exit";
+			if (WIFEXITED(wstat)) {
+				cause++;
+				e = WEXITSTATUS(wstat);
+			} else if (WIFSIGNALED(wstat)) {
+				cause = "signal";
+				e = WTERMSIG(wstat);
+			}
+			printf("%s: info: end %d %s %d\n",
+					applet_name, pid, cause, e);
+		}
+	}
+	if (verbose)
+		connection_status();
+}
+
+int tcpsvd_main(int argc, char **argv);
+int tcpsvd_main(int argc, char **argv)
+{
+	char *str_c, *str_C, *str_b, *str_t;
+	char *user;
+	struct hcc *hccp;
+	const char *instructs;
+	char *msg_per_host = NULL;
+	unsigned len_per_host = len_per_host; /* gcc */
+	int need_addresses;
+	int pid;
+	int sock;
+	int conn;
+	unsigned backlog = 20;
+	union {
+		struct sockaddr sa;
+		struct sockaddr_in sin;
+		USE_FEATURE_IPV6(struct sockaddr_in6 sin6;)
+	} sock_adr;
+	socklen_t sockadr_size;
+	uint16_t local_port = local_port;
+	uint16_t remote_port;
+	unsigned port;
+	char *local_hostname = NULL;
+	char *remote_hostname = (char*)""; /* "" used if no -h */
+	char *local_ip = local_ip;
+	char *remote_ip = NULL;
+	//unsigned iscdb = 0;		/* = option_mask32 & OPT_x (TODO) */
+	//unsigned long timeout = 0;
+#ifndef SSLSVD
+	struct bb_uidgid_t ugid;
+#endif
+
+	/* 3+ args, -i at most once, -p implies -h, -v is counter */
+	opt_complementary = "-3:?:i--i:ph:vv";
+#ifdef SSLSVD
+	getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
+		&str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
+		&str_b, &str_t, &ssluser, &root, &cert, &key, &verbose
+	);
+#else
+	getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:v",
+		&str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
+		&str_b, &str_t, &verbose
+	);
+#endif
+	if (option_mask32 & OPT_c)
+		cmax = xatou_range(str_c, 1, INT_MAX);
+	if (option_mask32 & OPT_C) { /* -C n[:message] */
+		max_per_host = bb_strtou(str_C, &str_C, 10);
+		if (str_C[0]) {
+			if (str_C[0] != ':')
+				bb_show_usage();
+			msg_per_host = str_C + 1;
+			len_per_host = strlen(msg_per_host);
+		}
+	}
+	if (max_per_host > cmax)
+		max_per_host = cmax;
+	if (option_mask32 & OPT_u) {
+		if (!get_uidgid(&ugid, user, 1))
+			bb_error_msg_and_die("unknown user/group: %s", user);
+	}
+	if (option_mask32 & OPT_b)
+		backlog = xatou(str_b);
+//	if (option_mask32 & OPT_t) timeout = xatou(str_t);
+#ifdef SSLSVD
+	if (option_mask32 & OPT_U) ssluser = (char*)optarg; break;
+	if (option_mask32 & OPT_slash) root = (char*)optarg; break;
+	if (option_mask32 & OPT_Z) cert = (char*)optarg; break;
+	if (option_mask32 & OPT_K) key = (char*)optarg; break;
+#endif
+	argv += optind;
+	if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
+		argv[0] = (char*)"0.0.0.0";
+
+	need_addresses = verbose || !(option_mask32 & OPT_E);
+
+#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");
+	}
+	if (option_mask32 & OPT_u)
+		if (!uidgid_get(&sslugid, ssluser, 1)) {
+			if (errno) {
+				xfunc_exitcode = 100;
+				bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser);
+			}
+			xfunc_exitcode = 111;
+			bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser);
+		}
+	if (!cert) cert = "./cert.pem";
+	if (!key) key = cert;
+	if (matrixSslOpen() < 0)
+		fatal("cannot initialize ssl");
+	if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
+		if (client)
+			fatal("cannot read cert, key, or ca file");
+		fatal("cannot read cert or key file");
+	}
+	if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
+		fatal("cannot create ssl session");
+#endif
+
+	sig_block(SIGCHLD);
+	signal(SIGCHLD, sig_child_handler);
+	signal(SIGTERM, sig_term_handler);
+	signal(SIGPIPE, SIG_IGN);
+
+	if (max_per_host)
+		ipsvd_perhost_init(cmax);
+
+	port = bb_lookup_port(argv[1], "tcp", 0);
+	sock = create_and_bind_stream_or_die(argv[0], port);
+	xlisten(sock, backlog);
+	/* ndelay_off(sock); - it is the default I think? */
+
+#ifndef SSLSVD
+	if (option_mask32 & OPT_u) {
+		/* drop permissions */
+		xsetgid(ugid.gid);
+		xsetuid(ugid.uid);
+	}
+#endif
+	bb_sanitize_stdio(); /* fd# 1,2 must be opened */
+	close(0);
+
+	if (verbose) {
+		/* we do it only for ":port" cosmetics... oh well */
+		len_and_sockaddr *lsa = xhost2sockaddr(argv[0], port);
+		char *addr = xmalloc_sockaddr2dotted(&lsa->sa, lsa->len);
+
+		printf("%s: info: listening on %s", applet_name, addr);
+		free(addr);
+#ifndef SSLSVD
+		if (option_mask32 & OPT_u)
+			printf(", uid %u, gid %u",
+				(unsigned)ugid.uid, (unsigned)ugid.uid);
+#endif
+		puts(", starting");
+	}
+
+	/* The rest is a main accept() loop */
+
+ again:
+	hccp = NULL;
+
+	while (cnum >= cmax)
+		sig_pause(); /* wait for any signal (expecting SIGCHLD) */
+
+	sockadr_size = sizeof(sock_adr);
+	sig_unblock(SIGCHLD);
+	conn = accept(sock, &sock_adr.sa, &sockadr_size);
+	sig_block(SIGCHLD);
+	if (conn == -1) {
+		if (errno != EINTR)
+			bb_perror_msg("accept");
+		goto again;
+	}
+
+	if (max_per_host) {
+		/* we drop connection immediately if cur_per_host > max_per_host
+		 * (minimizing load under SYN flood) */
+		free(remote_ip);
+		remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size);
+		cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp);
+		if (cur_per_host > max_per_host) {
+			/* ipsvd_perhost_add detected that max is exceeded
+			 * (and did not store us in connection table) */
+			if (msg_per_host) {
+				ndelay_on(conn);
+				/* don't test for errors */
+				write(conn, msg_per_host, len_per_host);
+			}
+			close(conn);
+			goto again;
+		}
+	}
+
+	cnum++;
+	if (verbose)
+		connection_status();
+
+	pid = fork();
+	if (pid == -1) {
+		bb_perror_msg("fork");
+		close(conn);
+		goto again;
+	}
+	if (pid != 0) {
+		/* parent */
+		close(conn);
+		if (hccp)
+			hccp->pid = pid;
+		goto again;
+	}
+
+	/* Child: prepare env, log, and exec prog */
+
+	close(sock);
+
+	if (!max_per_host)
+		remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sizeof(sock_adr));
+	/* else it is already done */
+	
+	remote_port = get_nport(&sock_adr.sa);
+	remote_port = ntohs(remote_port);
+	
+	if (verbose) {
+		pid = getpid();
+		printf("%s: info: pid %d from %s\n", applet_name, pid, remote_ip);
+	}
+	
+	if (need_addresses && (option_mask32 & OPT_h)) {
+		remote_hostname = xmalloc_sockaddr2host(&sock_adr.sa, sizeof(sock_adr));
+		if (!remote_hostname) {
+			bb_error_msg("warning: cannot look up hostname for %s", remote_ip);
+			remote_hostname = (char*)"";
+		}
+	}
+	
+	sockadr_size = sizeof(sock_adr);
+	/* Errors ignored (I'm not paranoid enough to imagine kernel
+	 * which doesn't know local ip) */
+	getsockname(conn, &sock_adr.sa, &sockadr_size);
+
+	if (need_addresses) {
+		local_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size);
+		local_port = get_nport(&sock_adr.sa);
+		local_port = ntohs(local_port);
+		if (!local_hostname) {
+			local_hostname = xmalloc_sockaddr2host_noport(&sock_adr.sa, sockadr_size);
+			if (!local_hostname)
+				bb_error_msg_and_die("cannot look up local hostname for %s", local_ip);
+		}
+	}
+	
+	if (!(option_mask32 & OPT_E)) {
+		/* setup ucspi env */
+		xsetenv("PROTO", "TCP");
+		xsetenv("TCPLOCALIP", local_ip);
+		xsetenv("TCPLOCALPORT", utoa(local_port));
+		xsetenv("TCPLOCALHOST", local_hostname);
+		xsetenv("TCPREMOTEIP", remote_ip);
+		xsetenv("TCPREMOTEPORT", utoa(remote_port));
+		if (option_mask32 & OPT_h) {
+			xsetenv("TCPREMOTEHOST", remote_hostname);
+		}
+		xsetenv("TCPREMOTEINFO", "");
+		/* additional */
+		if (cur_per_host > 0)
+			xsetenv("TCPCONCURRENCY", utoa(cur_per_host));
+	}
+	
+#if 0
+	if (instructs) {
+		ac = ipsvd_check(iscdb, &inst, &match, (char*)instructs,
+							remote_ip, remote_hostname, timeout);
+		if (ac == -1) drop2("cannot check inst", remote_ip);
+		if (ac == IPSVD_ERR) drop2("cannot read", (char*)instructs);
+	} else
+		ac = IPSVD_DEFAULT;
+#endif
+	
+	if (max_per_host && verbose)
+		printf("%s: info: concurrency %u %s %u/%u\n",
+			applet_name, pid, remote_ip, cur_per_host, max_per_host);
+	
+	if (verbose) {
+		printf("%s: info: start %u %s:%s :%s:%s:%u\n",
+			applet_name, pid,
+			local_hostname, local_ip,
+			remote_hostname, remote_ip, (unsigned)remote_port);
+#if 0
+		switch(ac) {
+		case IPSVD_DENY:
+			printf("deny "); break;
+		case IPSVD_DEFAULT:
+		case IPSVD_INSTRUCT:
+			printf("start "); break;
+		case IPSVD_EXEC:
+			printf("exec "); break;
+		}
+		...
+		if (instructs) {
+			printf(" ");
+			if (iscdb) {
+				printf((char*)instructs);
+				printf("/");
+			}
+			outfix(match.s);
+			if(inst.s && inst.len && (verbose > 1)) {
+				printf(": ");
+				printf(&inst);
+			}
+		}
+		printf("\n");
+#endif
+	}
+
+#if 0
+	if (ac == IPSVD_DENY) {
+		close(conn);
+		_exit(100);
+	}
+	if (ac == IPSVD_EXEC) {
+		args[0] = "/bin/sh";
+		args[1] = "-c";
+		args[2] = inst.s;
+		args[3] = 0;
+		run = args;
+	} else
+		run = argv + 2; /* below: we use argv+2 (was using run) */
+#endif
+
+	xmove_fd(conn, 0);
+	dup2(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);
+#else
+	BB_EXECVP(argv[0], argv);
+#endif
+	bb_perror_msg_and_die("exec '%s'", argv[0]);
+}
+
+/*
+tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name] [-i dir|-x cdb] [ -t sec] host port prog
+
+tcpsvd creates a TCP/IP socket, binds it to the address host:port,
+and listens on the socket for incoming connections.
+
+On each incoming connection, tcpsvd conditionally runs a program,
+with standard input reading from the socket, and standard output
+writing to the socket, to handle this connection. tcpsvd keeps
+listening on the socket for new connections, and can handle
+multiple connections simultaneously.
+
+tcpsvd optionally checks for special instructions depending
+on the IP address or hostname of the client that initiated
+the connection, see ipsvd-instruct(5).
+
+host
+    host either is a hostname, or a dotted-decimal IP address,
+    or 0. If host is 0, tcpsvd accepts connections to any local
+    IP address.
+port
+    tcpsvd accepts connections to host:port. port may be a name
+    from /etc/services or a number.
+prog
+    prog consists of one or more arguments. For each connection,
+    tcpsvd normally runs prog, with file descriptor 0 reading from
+    the network, and file descriptor 1 writing to the network.
+    By default it also sets up TCP-related environment variables,
+    see tcp-environ(5) 
+-i dir
+    read instructions for handling new connections from the instructions
+    directory dir. See ipsvd-instruct(5) for details. 
+-x cdb
+    read instructions for handling new connections from the constant database
+    cdb. The constant database normally is created from an instructions
+    directory by running ipsvd-cdb(8). 
+-t sec
+    timeout. This option only takes effect if the -i option is given.
+    While checking the instructions directory, check the time of last access
+    of the file that matches the clients address or hostname if any, discard
+    and remove the file if it wasn't accessed within the last sec seconds;
+    tcpsvd does not discard or remove a file if the user's write permission
+    is not set, for those files the timeout is disabled. Default is 0,
+    which means that the timeout is disabled. 
+-l name
+    local hostname. Do not look up the local hostname in DNS, but use name
+    as hostname. This option must be set if tcpsvd listens on port 53
+    to avoid loops. 
+-u user[:group]
+    drop permissions. Switch user ID to user's UID, and group ID to user's
+    primary GID after creating and binding to the socket. If user is followed
+    by a colon and a group name, the group ID is switched to the GID of group
+    instead. All supplementary groups are removed. 
+-c n
+    concurrency. Handle up to n connections simultaneously. Default is 30.
+    If there are n connections active, tcpsvd defers acceptance of a new
+    connection until an active connection is closed. 
+-C n[:msg]
+    per host concurrency. Allow only up to n connections from the same IP
+    address simultaneously. If there are n active connections from one IP	
+    address, new incoming connections from this IP address are closed
+    immediately. If n is followed by :msg, the message msg is written	
+    to the client if possible, before closing the connection. By default
+    msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
+
+    For each accepted connection, the current per host concurrency is
+    available through the environment variable TCPCONCURRENCY. n and msg
+    can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
+    By default tcpsvd doesn't keep track of connections. 
+-h
+    Look up the client's hostname in DNS. 
+-p
+    paranoid. After looking up the client's hostname in DNS, look up the IP
+    addresses in DNS for that hostname, and forget about the hostname
+    if none of the addresses match the client's IP address. You should
+    set this option if you use hostname based instructions. The -p option
+    implies the -h option. 
+-b n
+    backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
+    is silently limited. Default is 20. 
+-E
+    no special environment. Do not set up TCP-related environment variables. 
+-v
+    verbose. Print verbose messsages to standard output. 
+-vv
+    more verbose. Print more verbose messages to standard output. 
+*/