separate TLS code into a library, use in in wget

A new applet, ssl_client, is the TLS debug thing now.
It doubles as wget's NOMMU helper.
In MMU mode, wget still forks, but then directly calls TLS code,
without execing.

This can also be applied to sendmail/popmail (SMTPS / SMTP+starttls support)
and nc --ssl (ncat, nmap's nc clone, has such option).

function                                             old     new   delta
tls_handshake                                          -    1691   +1691
tls_run_copy_loop                                      -     443    +443
ssl_client_main                                        -     128    +128
packed_usage                                       30978   31007     +29
wget_main                                           2508    2535     +27
applet_names                                        2553    2560      +7
...
xwrite_encrypted                                     360     342     -18
tls_main                                            2127       -   -2127
------------------------------------------------------------------------------
(add/remove: 4/1 grow/shrink: 13/8 up/down: 2351/-2195)       Total: 156 bytes

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

1 files changed, 54 insertions, 48 deletions

diff --git a/networking/wget.c b/networking/wget.c
index 58ead4c96..a448acdae 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -47,18 +47,26 @@
 //config:	  FEATURE_WGET_LONG_OPTIONS is also enabled, the --timeout option
 //config:	  will work in addition to -T.
 //config:
+//config:config FEATURE_WGET_HTTPS
+//config:	bool "Support HTTPS using internal TLS code"
+//config:	default y
+//config:	depends on WGET
+//config:	select TLS
+//config:	help
+//config:	  wget will use internal TLS code to connect to https:// URLs.
+//config:	  Note:
+//config:	  On NOMMU machines, ssl_helper applet should be available
+//config:	  in the $PATH for this to work. Make sure to select that applet.
+//config:
 //config:config FEATURE_WGET_OPENSSL
 //config:	bool "Try to connect to HTTPS using openssl"
 //config:	default y
 //config:	depends on WGET
 //config:	help
-//config:	  Choose how wget establishes SSL connection for https:// URLs.
-//config:
-//config:	  Busybox itself contains no SSL code. wget will spawn
-//config:	  a helper program to talk over HTTPS.
+//config:	  Try to use openssl to handle HTTPS.
 //config:
 //config:	  OpenSSL has a simple SSL client for debug purposes.
-//config:	  If you select "openssl" helper, wget will effectively run:
+//config:	  If you select this option, wget will effectively run:
 //config:	  "openssl s_client -quiet -connect hostname:443
 //config:	  -servername hostname 2>/dev/null" and pipe its data
 //config:	  through it. -servername is not used if hostname is numeric.
@@ -71,24 +79,9 @@
 //config:	  openssl is also a big binary, often dynamically linked
 //config:	  against ~15 libraries.
 //config:
-//config:config FEATURE_WGET_SSL_HELPER
-//config:	bool "Try to connect to HTTPS using ssl_helper"
-//config:	default y
-//config:	depends on WGET
-//config:	help
-//config:	  Choose how wget establishes SSL connection for https:// URLs.
-//config:
-//config:	  Busybox itself contains no SSL code. wget will spawn
-//config:	  a helper program to talk over HTTPS.
-//config:
-//config:	  ssl_helper is a tool which can be built statically
-//config:	  from busybox sources against a small embedded SSL library.
-//config:	  Please see networking/ssl_helper/README.
-//config:	  It does not require double host resolution and emits
-//config:	  error messages to stderr.
-//config:
-//config:	  Precompiled static binary may be available at
-//config:	  http://busybox.net/downloads/binaries/
+//config:	  If openssl can't be executed, internal TLS code will be used
+//config:	  (if you enabled it); if openssl can be executed but fails later,
+//config:	  wget can't detect this, and download will fail.
 
 //applet:IF_WGET(APPLET(wget, BB_DIR_USR_BIN, BB_SUID_DROP))
 
@@ -137,7 +130,7 @@
 #endif
 
 
-#define SSL_SUPPORTED (ENABLE_FEATURE_WGET_OPENSSL || ENABLE_FEATURE_WGET_SSL_HELPER)
+#define SSL_SUPPORTED (ENABLE_FEATURE_WGET_OPENSSL || ENABLE_FEATURE_WGET_HTTPS)
 
 struct host_info {
 	char *allocated;
@@ -657,7 +650,7 @@ static int spawn_https_helper_openssl(const char *host, unsigned port)
 	char *servername;
 	int sp[2];
 	int pid;
-	IF_FEATURE_WGET_SSL_HELPER(volatile int child_failed = 0;)
+	IF_FEATURE_WGET_HTTPS(volatile int child_failed = 0;)
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) != 0)
 		/* Kernel can have AF_UNIX support disabled */
@@ -702,7 +695,7 @@ static int spawn_https_helper_openssl(const char *host, unsigned port)
 
 		BB_EXECVP(argv[0], argv);
 		xmove_fd(3, 2);
-# if ENABLE_FEATURE_WGET_SSL_HELPER
+# if ENABLE_FEATURE_WGET_HTTPS
 		child_failed = 1;
 		xfunc_die();
 # else
@@ -715,7 +708,7 @@ static int spawn_https_helper_openssl(const char *host, unsigned port)
 	free(servername);
 	free(allocated);
 	close(sp[1]);
-# if ENABLE_FEATURE_WGET_SSL_HELPER
+# if ENABLE_FEATURE_WGET_HTTPS
 	if (child_failed) {
 		close(sp[0]);
 		return -1;
@@ -725,38 +718,51 @@ static int spawn_https_helper_openssl(const char *host, unsigned port)
 }
 #endif
 
-/* See networking/ssl_helper/README how to build one */
-#if ENABLE_FEATURE_WGET_SSL_HELPER
-static void spawn_https_helper_small(int network_fd)
+#if ENABLE_FEATURE_WGET_HTTPS
+static void spawn_ssl_client(const char *host, int network_fd)
 {
 	int sp[2];
 	int pid;
+	char *servername, *p;
+
+	servername = xstrdup(host);
+	p = strrchr(servername, ':');
+	if (p) *p = '\0';
 
 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) != 0)
 		/* Kernel can have AF_UNIX support disabled */
 		bb_perror_msg_and_die("socketpair");
 
+	fflush_all();
 	pid = BB_MMU ? xfork() : xvfork();
 	if (pid == 0) {
 		/* Child */
-		char *argv[3];
-
 		close(sp[0]);
 		xmove_fd(sp[1], 0);
 		xdup2(0, 1);
-		xmove_fd(network_fd, 3);
-		/*
-		 * A simple ssl/tls helper
-		 */
-		argv[0] = (char*)"ssl_helper";
-		argv[1] = (char*)"-d3";
-		argv[2] = NULL;
-		BB_EXECVP(argv[0], argv);
-		bb_perror_msg_and_die("can't execute '%s'", argv[0]);
+		if (BB_MMU) {
+			tls_state_t *tls = new_tls_state();
+			tls->ifd = tls->ofd = network_fd;
+			tls_handshake(tls, servername);
+			tls_run_copy_loop(tls);
+			exit(0);
+		} else {
+			char *argv[5];
+			xmove_fd(network_fd, 3);
+			argv[0] = (char*)"ssl_client";
+			argv[1] = (char*)"-s3";
+			//TODO: if (!is_ip_address(servername))...
+			argv[2] = (char*)"-n";
+			argv[3] = servername;
+			argv[4] = NULL;
+			BB_EXECVP(argv[0], argv);
+			bb_perror_msg_and_die("can't execute '%s'", argv[0]);
+		}
 		/* notreached */
 	}
 
 	/* Parent */
+	free(servername);
 	close(sp[1]);
 	xmove_fd(sp[0], network_fd);
 }
@@ -1005,16 +1011,16 @@ static void download_one_url(const char *url)
 
 		/* Open socket to http(s) server */
 #if ENABLE_FEATURE_WGET_OPENSSL
-		/* openssl (and maybe ssl_helper) support is configured */
+		/* openssl (and maybe internal TLS) support is configured */
 		if (target.protocol == P_HTTPS) {
 			/* openssl-based helper
 			 * Inconvenient API since we can't give it an open fd
 			 */
 			int fd = spawn_https_helper_openssl(server.host, server.port);
-# if ENABLE_FEATURE_WGET_SSL_HELPER
-			if (fd < 0) { /* no openssl? try ssl_helper */
+# if ENABLE_FEATURE_WGET_HTTPS
+			if (fd < 0) { /* no openssl? try internal */
 				sfp = open_socket(lsa);
-				spawn_https_helper_small(fileno(sfp));
+				spawn_ssl_client(server.host, fileno(sfp));
 				goto socket_opened;
 			}
 # else
@@ -1027,11 +1033,11 @@ static void download_one_url(const char *url)
 		}
 		sfp = open_socket(lsa);
  socket_opened:
-#elif ENABLE_FEATURE_WGET_SSL_HELPER
-		/* Only ssl_helper support is configured */
+#elif ENABLE_FEATURE_WGET_HTTPS
+		/* Only internal TLS support is configured */
 		sfp = open_socket(lsa);
 		if (target.protocol == P_HTTPS)
-			spawn_https_helper_small(fileno(sfp));
+			spawn_ssl_client(server.host, fileno(sfp));
 #else
 		/* ssl (https) support is not configured */
 		sfp = open_socket(lsa);