Another demo.

8 files changed, 1783 insertions, 0 deletions

diff --git a/demos/easy_tls/Makefile b/demos/easy_tls/Makefile
new file mode 100644
index 0000000000..0d407eda22
--- /dev/null
+++ b/demos/easy_tls/Makefile
@@ -0,0 +1,123 @@
+# Makefile for easy-tls example application (rudimentary client and server)
+# $Id: Makefile,v 1.1 2001/09/17 19:06:56 bodo Exp $
+
+SOLARIS_CFLAGS=-Wall -pedantic -g -O2
+SOLARIS_LIBS=-lxnet
+
+LINUX_CFLAGS=-Wall -pedantic -g -O2
+LINUX_LIBS=
+
+
+auto-all:
+	case `uname -s` in \
+	SunOS) echo Using SunOS configuration; \
+	  make SYSCFLAGS="$(SOLARIS_CFLAGS)" SYSLIBS="$(SOLARIS_LIBS)" all;; \
+	Linux) echo Using Linux configuration; \
+	  make SYSCFLAGS="$(LINUX_CFLAGS)" SYSLIBS="$(LINUX_LIBS)" all;; \
+	*) echo "unknown system"; exit 1;; \
+	esac
+
+all: test TAGS
+
+# For adapting this Makefile to a different system, only the following
+# definitions should need customizing:
+
+OPENSSLDIR=$(HOME)/openssl/openssl
+CC=gcc
+
+SYSCFLAGS=whatever
+SYSLIBS=whatever
+
+
+#############################################################################
+#
+# SSLeay/OpenSSL imports
+#
+# OPENSSLDIR (set above) can be either the directory where OpenSSL is
+# installed or the directory where it was compiled.
+
+# We rely on having a new OpenSSL release where include files
+# have names like <openssl/ssl.h> (not just <ssl.h>).
+OPENSSLINCLUDES=-I$(OPENSSLDIR)/include
+
+# libcrypto.a and libssl.a are directly in $(OPENSSLDIR) if this is
+# the compile directory, or in $(OPENSSLDIR)/lib if we use an installed
+# library.  With the following definition, we can handle either case.
+OPENSSLLIBS=-L$(OPENSSLDIR) -L$(OPENSSLDIR)/lib -lssl -lcrypto
+
+
+#############################################################################
+#
+# Stuff for handling the source files
+#
+
+SOURCES=easy-tls.c test.c
+HEADERS=easy-tls.h test.h
+DOCSandEXAMPLESetc=Makefile cert.pem cacerts.pem
+EVERYTHING=$(SOURCES) $(HEADERS) $(DOCSandEXAMPLESetc)
+
+ls: ls-l
+ls-l:
+	ls -l $(EVERYTHING)
+# For RCS:
+tag:
+	-rcs -n_`date +%y%m%d`: $(EVERYTHING)
+	rcs -nMYTAG $(EVERYTHING)
+	rcs -nMYTAG: $(EVERYTHING)
+diff:
+	-rcsdiff -rMYTAG -u $(EVERYTHING)
+today:
+	-rcsdiff -r_`date +%y%m%d` -u $(EVERYTHING)
+ident:
+	for a in $(EVERYTHING); do ident $$a; done
+
+# Distribution .tar:
+easy-tls.tar.gz: $(EVERYTHING)
+	tar cvf - $(EVERYTHING) | \
+	gzip -9 > easy-tls.tar.gz
+
+# Working .tar:
+tls.tgz: $(EVERYTHING)
+	tar cfv - `find . -type f -a ! -name '*.tgz' -a ! -name '*.tar.gz'` | \
+	gzip -9 > tls.tgz
+
+# For emacs:
+etags: TAGS
+TAGS: $(SOURCES) $(HEADERS)
+	-etags $(SOURCES) $(HEADERS)
+
+
+#############################################################################
+#
+# Compilation
+#
+# The following definitions are system dependent (and hence defined
+# at the beginning of this Makefile, where they are more easily found):
+
+### CC=gcc
+### SYSCFLAGS=-Wall -pedantic -g -O2
+### SYSLIBS=-lxnet
+
+EXTRACFLAGS=-DTLS_APP=\"test.h\"
+# EXTRACFLAGS=-DTLS_APP=\"test.h\" -DDEBUG_TLS
+
+#
+# The rest shouldn't need to be touched.
+#
+LDFLAGS=$(SYSLIBS) $(OPENSSLLIBS)
+INCLUDES=$(OPENSSLINCLUDES)
+CFLAGS=$(SYSCFLAGS) $(EXTRACFLAGS) $(INCLUDES)
+
+OBJS=easy-tls.o test.o
+
+clean:
+	@rm -f test
+	@rm -f TAGS
+	@rm -f *.o
+	@rm -f core
+
+test: $(OBJS)
+	$(CC) $(OBJS) $(LDFLAGS) -o test
+
+test.o: $(HEADERS)
+easy-tls.o: $(HEADERS)
diff --git a/demos/easy_tls/README b/demos/easy_tls/README
new file mode 100644
index 0000000000..bf5eeca4e6
--- /dev/null
+++ b/demos/easy_tls/README
@@ -0,0 +1,64 @@
+easy_tls - generic SSL/TLS proxy
+========
+
+(... and example for non-blocking SSL/TLS I/O multiplexing.)
+
+
+  easy_tls.c, easy_tls.h:
+
+     Small generic SSL/TLS proxy library: With a few function calls,
+     an application socket will be replaced by a pipe handled by a
+     separate SSL/TLS proxy process.  This allows easily adding
+     SSL/TLS support to many programs not originally designed for it.
+
+     [Actually easy_tls.c is not a proper library: Customization
+     requires defining preprocessor macros while compiling it.
+     This is quite confusing, so I'll probably change it.]
+
+     These files may be used under the OpenSSL license.
+
+
+
+  test.c, test.h, Makefile, cert.pem, cacerts.pem:
+
+     Rudimentary example program using the easy_tls library, and
+     example key and certificates for it.  Usage examples:
+
+       $ ./test 8443     # create server listening at port 8443
+       $ ./test 127.0.0.1 8443  # create client, connect to port 8443
+                                # at IP address 127.0.0.1
+
+     'test' will not automatically do SSL/TLS, or even read or write
+     data -- it must be told to do so on input lines starting
+     with a command letter.  'W' means write a line, 'R' means
+     read a line, 'C' means close the connection, 'T' means
+     start an SSL/TLS proxy.  E.g. (user input tagged with '*'):
+
+     * R
+       <<< 220 mail.example.net
+     * WSTARTTLS
+       >>> STARTTLS
+     * R
+       <<< 220 Ready to start TLS
+     * T
+       test_process_init(fd = 3, client_p = 1, apparg = (nil))
+       +++ `E:self signed certificate in certificate chain'
+       +++ `<... certificate info ...>'
+     * WHELO localhost
+       >>> HELO localhost
+       R
+       <<< 250 mail.example.net
+
+     You can even do SSL/TLS over SSL/TLS over SSL/TLS ... by using
+     'T' multiple times.  I have no idea why you would want to though.
+
+
+This code is rather old.  When I find time I will look if it still
+compiles, and update code comments.  The least you will have to do to
+use the sample program 'test' is change the Makefile.
+
+As noted above, easy_tls.c will be changed to become a library one
+day, which means that future revisions will not be fully compatible to
+the current version.
+
+Bodo Möller <bodo@openssl.org>
diff --git a/demos/easy_tls/cacerts.pem b/demos/easy_tls/cacerts.pem
new file mode 100644
index 0000000000..acc70baf19
--- /dev/null
+++ b/demos/easy_tls/cacerts.pem
@@ -0,0 +1,18 @@
+$Id: cacerts.pem,v 1.1 2001/09/17 19:06:57 bodo Exp $
+
+issuer= /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test PCA (1024 bit)
+subject=/C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit)
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/demos/easy_tls/cert.pem b/demos/easy_tls/cert.pem
new file mode 100644
index 0000000000..364fe10d5b
--- /dev/null
+++ b/demos/easy_tls/cert.pem
@@ -0,0 +1,31 @@
+$Id: cert.pem,v 1.1 2001/09/17 19:06:57 bodo Exp $
+
+Example certificate and key.
+
+-----BEGIN CERTIFICATE-----
+MIIB1jCCAT8CAQEwDQYJKoZIhvcNAQEEBQAwRTELMAkGA1UEBhMCQVUxEzARBgNV
+BAgTClNvbWUtU3RhdGUxITAfBgNVBAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0
+ZDAeFw05OTA1MDEwMTI2MzVaFw05OTA1MzEwMTI2MzVaMCIxCzAJBgNVBAYTAkRF
+MRMwEQYDVQQDEwpUZXN0c2VydmVyMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB
+gQD6I3oDKiexwwlkzjar69AIFnVUaG85LtCege2R+CtIDlkQYw68/8MbT3ou0pdF
+AcL9IGiYY3Y0SHM9PqF00RO1MCtNpqTnF3ScLpbmggGjKilmWYn2ai7emdjMjXVL
+tzWW2xGgIGATWQN32KgfJng4jXi1UjEiyLhkw0Zf1I/ggwIDAQABMA0GCSqGSIb3
+DQEBBAUAA4GBAMgM+sbAk8DfjSfa+Rf2gcGXmbrvZAzKzC+5RU3kaq/NyxIXAGco
+9dZjozzWfN/xuGup5boFk+KrP+xdgsaqGHsyzlgEoqz4ekqLjQeVbnoj339hVFU9
+MhPi6JULPxjXKumjfX2LLNkikW5puz8Df3UiX0EiaJvd7EwP8J75tiUT
+-----END CERTIFICATE-----
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----
diff --git a/demos/easy_tls/easy-tls.c b/demos/easy_tls/easy-tls.c
new file mode 100644
index 0000000000..88d7a8a1ec
--- /dev/null
+++ b/demos/easy_tls/easy-tls.c
@@ -0,0 +1,1235 @@
+/* -*- Mode: C; c-file-style: "bsd" -*- */
+/*
+ * easy-tls.c -- generic TLS proxy.
+ * $Id: easy-tls.c,v 1.1 2001/09/17 19:06:57 bodo Exp $
+ */
+/*
+ (c) Copyright 1999 Bodo Moeller.  All rights reserved.
+
+ This is free software; you can redistributed and/or modify it
+ unter the terms of either
+   -  the GNU General Public License as published by the
+      Free Software Foundation, version 1, or (at your option)
+      any later version,
+ or
+   -  the following license:
+*/
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that each of the following
+ * conditions is met:
+ *
+ * 1. Redistributions qualify as "freeware" or "Open Source Software" under
+ *    one of the following terms:
+ * 
+ *    (a) Redistributions are made at no charge beyond the reasonable cost of
+ *        materials and delivery.
+ * 
+ *    (b) Redistributions are accompanied by a copy of the Source Code
+ *        or by an irrevocable offer to provide a copy of the Source Code
+ *        for up to three years at the cost of materials and delivery.
+ *        Such redistributions must allow further use, modification, and
+ *        redistribution of the Source Code under substantially the same
+ *        terms as this license.
+ *
+ * 2. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 3. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 4. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by Bodo Moeller."
+ *    (If available, substitute umlauted o for oe.)
+ *
+ * 5. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by Bodo Moeller."
+ *
+ * THIS SOFTWARE IS PROVIDED BY BODO MOELLER ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL BODO MOELLER OR
+ * HIS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * Attribution for OpenSSL library:
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ * This product includes software developed by the OpenSSL Project
+ * for use in the OpenSSL Toolkit. (http://www.openssl.org/)
+ */
+
+static char const rcsid[] =
+"$Id: easy-tls.c,v 1.1 2001/09/17 19:06:57 bodo Exp $";
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/utsname.h>
+#include <unistd.h>
+
+#include <openssl/crypto.h>
+#include <openssl/dh.h>
+#include <openssl/dsa.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/opensslv.h>
+#include <openssl/pem.h>
+#include <openssl/rand.h>
+#ifndef NO_RSA
+ #include <openssl/rsa.h>
+#endif
+#include <openssl/ssl.h>
+#include <openssl/x509.h>
+#include <openssl/x509_vfy.h>
+
+#if OPENSSL_VERSION_NUMBER < 0x00904000L /* 0.9.4-dev */
+# error "This program needs OpenSSL 0.9.4 or later."
+#endif
+
+#include "easy-tls.h" /* include after <openssl/ssl.h> if both are needed */
+
+#if TLS_INFO_SIZE > PIPE_BUF
+# if PIPE_BUF < 512
+#  error "PIPE_BUF < 512" /* non-POSIX */
+# endif
+# error "TLS_INFO_SIZE > PIPE_BUF"
+#endif
+
+/*****************************************************************************/
+
+#ifdef TLS_APP
+# include TLS_APP
+#endif
+
+/* Applications can define:
+ *   TLS_APP_PROCESS_INIT -- void ...(int fd, int client_p, void *apparg)
+ *   TLS_CUMULATE_ERRORS 
+ *   TLS_ERROR_BUFSIZ
+ *   TLS_APP_ERRFLUSH -- void ...(int child_p, char *, size_t, void *apparg)
+ */
+
+#ifndef TLS_APP_PROCESS_INIT
+# define TLS_APP_PROCESS_INIT(fd, client_p, apparg) ((void) 0)
+#endif
+
+#ifndef TLS_ERROR_BUFSIZ
+# define TLS_ERROR_BUFSIZ (10*160)
+#endif
+#if TLS_ERROR_BUFSIZ < 2 /* {'\n',0} */
+# error "TLS_ERROR_BUFSIZE is too small."
+#endif
+
+#ifndef TLS_APP_ERRFLUSH
+# define TLS_APP_ERRFLUSH tls_app_errflush
+static void
+tls_app_errflush(int child_p, char *errbuf, size_t num, void *apparg)
+{
+    fputs(errbuf, stderr);
+}
+#endif
+
+/*****************************************************************************/
+
+#ifdef DEBUG_TLS
+# define DEBUG_MSG(x) fprintf(stderr,"  %s\n",x)
+# define DEBUG_MSG2(x,y) fprintf(stderr, "  %s: %d\n",x,y)
+static int tls_loop_count = 0;
+static int tls_select_count = 0;
+#else
+# define DEBUG_MSG(x) (void)0
+# define DEBUG_MSG2(x,y) (void)0
+#endif
+
+static void tls_rand_seed_uniquely(void);
+static void tls_proxy(int clear_fd, int tls_fd, int info_fd, SSL_CTX *ctx, int client_p);
+static int tls_socket_nonblocking(int fd);
+
+static int tls_child_p = 0;
+static void *tls_child_apparg;
+
+
+struct tls_start_proxy_args
+tls_start_proxy_defaultargs(void)
+{
+    struct tls_start_proxy_args ret;
+
+    ret.fd = -1;
+    ret.client_p = -1;
+    ret.ctx = NULL;
+    ret.pid = NULL;
+    ret.infofd = NULL;
+    
+    return ret;
+}
+
+/* Slice in TLS proxy process at fd.
+ * Return value:
+ *   0    ok  (*pid is set to child's PID if pid != NULL),
+ *   < 0  look at errno
+ *   > 0  other error
+ *   (return value encodes place of error)
+ *
+ */
+int
+tls_start_proxy(struct tls_start_proxy_args a, void *apparg)
+{
+    int fds[2] = {-1, -1};
+    int infofds[2] = {-1, -1};
+    int r, getfd, getfl;
+    int ret;
+
+    DEBUG_MSG2("tls_start_proxy fd", a.fd);
+    DEBUG_MSG2("tls_start_proxy client_p", a.client_p);
+
+    if (a.fd == -1 || a.client_p == -1 || a.ctx == NULL)
+	return 1;
+
+    if (a.pid != NULL) {
+	*a.pid = 0;
+    }
+    if (a.infofd != NULL) {
+	*a.infofd = -1;
+    }
+
+    r = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+    if (r == -1)
+	return -1;
+    if (a.fd >= FD_SETSIZE || fds[0] >= FD_SETSIZE) {
+	ret = 2;
+	goto err;
+    }
+    if (a.infofd != NULL) {
+	r = pipe(infofds);
+	if (r == -1) {
+	    ret = -3;
+	    goto err;
+	}
+    }
+
+    r = fork();
+    if (r == -1) {
+	ret = -4;
+	goto err;
+    }
+    if (r == 0) {
+	DEBUG_MSG("fork");
+	tls_child_p = 1;
+	tls_child_apparg = apparg;
+	close(fds[1]);
+	if (infofds[0] != -1)
+	    close(infofds[0]);
+	TLS_APP_PROCESS_INIT(a.fd, a.client_p, apparg);
+	DEBUG_MSG("TLS_APP_PROCESS_INIT");
+	tls_proxy(fds[0], a.fd, infofds[1], a.ctx, a.client_p);
+	exit(0);
+    }
+    if (a.pid != NULL)
+	*a.pid = r;
+    if (infofds[1] != -1) {
+	close(infofds[1]);
+	infofds[1] = -1;
+    }
+    /* install fds[1] in place of fd: */
+    close(fds[0]);
+    fds[0] = -1;
+    getfd = fcntl(a.fd, F_GETFD);
+    getfl = fcntl(a.fd, F_GETFL);
+    r = dup2(fds[1], a.fd);
+    close(fds[1]);
+    fds[1] = -1;
+    if (r == -1) {
+	ret = -5;
+	goto err;
+    }
+    if (getfd != 1)
+	fcntl(a.fd, F_SETFD, getfd);
+    if (getfl & O_NONBLOCK)
+	(void)tls_socket_nonblocking(a.fd);
+    if (a.infofd != NULL)
+	*a.infofd = infofds[0];
+    return 0;
+    
+  err:
+    if (fds[0] != -1)
+	close(fds[0]);
+    if (fds[1] != -1)
+	close(fds[1]);
+    if (infofds[0] != -1)
+	close(infofds[0]);
+    if (infofds[1] != -1)
+	close(infofds[1]);
+    return ret;
+}
+
+/*****************************************************************************/
+
+static char errbuf[TLS_ERROR_BUFSIZ];
+static size_t errbuf_i = 0;
+
+static void
+tls_errflush(void *apparg)
+{
+    if (errbuf_i == 0)
+	return;
+    
+    assert(errbuf_i < sizeof errbuf);
+    assert(errbuf[errbuf_i] == 0);
+    if (errbuf_i == sizeof errbuf - 1) {
+	/* make sure we have a newline, even if string has been truncated */
+	errbuf[errbuf_i - 1] = '\n';
+    }
+
+    /* TLS_APP_ERRFLUSH may modify the string as needed,
+     * e.g. substitute other characters for \n for convenience */
+    TLS_APP_ERRFLUSH(tls_child_p, errbuf, errbuf_i, apparg);
+
+    errbuf_i = 0;
+}
+
+static void
+tls_errprintf(int flush, void *apparg, const char *fmt, ...)
+{
+    va_list args;
+    int r;
+    
+    if (errbuf_i < sizeof errbuf - 1) {
+	size_t n;
+
+	va_start(args, fmt);
+	n = (sizeof errbuf) - errbuf_i;
+	r = vsnprintf(errbuf + errbuf_i, n, fmt, args);
+	if (r >= n)
+	    r = n - 1;
+	if (r >= 0) {
+	    errbuf_i += r;
+	} else {
+	    errbuf_i = sizeof errbuf - 1;
+	    errbuf[errbuf_i] = '\0';
+	}
+	assert(errbuf_i < sizeof errbuf);
+	assert(errbuf[errbuf_i] == 0);
+    }
+#ifndef TLS_CUMULATE_ERRORS
+    tls_errflush(apparg);
+#else
+    if (flush)
+	tls_errflush(apparg);
+#endif
+}
+
+/* app_prefix.. are for additional information provided by caller.
+ * If OpenSSL error queue is empty, print default_text ("???" if NULL).
+ */
+static char *
+tls_openssl_errors(const char *app_prefix_1, const char *app_prefix_2, const char *default_text, void *apparg)
+{
+    static char reasons[255];
+    size_t reasons_i;
+    unsigned long err;
+    const char *file;
+    int line;
+    const char *data;
+    int flags;
+    char *errstring;
+    int printed_something = 0;
+    
+    reasons_i = 0;
+
+    assert(app_prefix_1 != NULL);
+    assert(app_prefix_2 != NULL);
+
+    if (default_text == NULL)
+	default_text = "???";
+    
+    while ((err = ERR_get_error_line_data(&file,&line,&data,&flags)) != 0) {
+	if (reasons_i < sizeof reasons) {
+	    size_t n;
+	    int r;
+
+	    n = (sizeof reasons) - reasons_i;
+	    r = snprintf(reasons + reasons_i, n, "%s%s", (reasons_i > 0 ? ", " : ""), ERR_reason_error_string(err));
+	    if (r >= n)
+		r = n - 1;
+	    if (r >= 0) {
+		reasons_i += r;
+	    } else {
+		reasons_i = sizeof reasons;
+	    }
+	    assert(reasons_i <= sizeof reasons);
+	}
+	
+	errstring = ERR_error_string(err, NULL);
+	assert(errstring != NULL);
+	tls_errprintf(0, apparg, "OpenSSL error%s%s: %s:%s:%d:%s\n", app_prefix_1, app_prefix_2, errstring, file, line, (flags & ERR_TXT_STRING) ? data : "");
+	printed_something = 1;
+    }
+
+    if (!printed_something) {
+	assert(reasons_i == 0);
+	snprintf(reasons, sizeof reasons, "%s", default_text);
+	tls_errprintf(0, apparg, "OpenSSL error%s%s: %s\n", app_prefix_1, app_prefix_2, default_text);
+    }
+
+#ifdef TLS_CUMULATE_ERRORS    
+    tls_errflush(apparg);
+#endif
+    assert(errbuf_i == 0);
+
+    return reasons;
+}
+
+/*****************************************************************************/
+
+static int tls_init_done = 0;
+
+static int
+tls_init(void *apparg)
+{
+    if (tls_init_done)
+	return 0;
+    
+    SSL_load_error_strings();
+    if (!SSL_library_init() /* aka SSLeay_add_ssl_algorithms() */ ) {
+	tls_errprintf(1, apparg, "SSL_library_init failed.\n");
+	return -1;
+    }
+    tls_init_done = 1;
+    tls_rand_seed();
+    return 0;
+}
+
+/*****************************************************************************/
+
+static void
+tls_rand_seed_uniquely(void)
+{
+    struct {
+	pid_t pid;
+	time_t time;
+	void *stack;
+    } data;
+
+    data.pid = getpid();
+    data.time = time(NULL);
+    data.stack = (void *)&data;
+
+    RAND_seed((const void *)&data, sizeof data);
+}
+
+void
+tls_rand_seed(void)
+{
+    struct {
+	struct utsname uname;
+	int uname_1;
+	int uname_2;
+	uid_t uid;
+	uid_t euid;
+	gid_t gid;
+	gid_t egid;
+    } data;
+    
+    data.uname_1 = uname(&data.uname);
+    data.uname_2 = errno; /* Let's hope that uname fails randomly :-) */
+
+    data.uid = getuid();
+    data.euid = geteuid();
+    data.gid = getgid();
+    data.egid = getegid();
+    
+    RAND_seed((const void *)&data, sizeof data);
+    tls_rand_seed_uniquely();
+}
+
+static int tls_rand_seeded_p = 0;
+
+#define my_MIN_SEED_BYTES 256 /* struct stat can be larger than 128 */
+int
+tls_rand_seed_from_file(const char *filename, size_t n, void *apparg)
+{
+    /* Seed OpenSSL's random number generator from file.
+       Try to read n bytes if n > 0, whole file if n == 0. */
+
+    int r;
+
+    if (tls_init(apparg) == -1)
+	return -1;
+    tls_rand_seed();
+
+    r = RAND_load_file(filename, (n > 0 && n < LONG_MAX) ? (long)n : LONG_MAX);
+    /* r is the number of bytes filled into the random number generator,
+     * which are taken from "stat(filename, ...)" in addition to the
+     * file contents.
+     */
+    assert(1 < my_MIN_SEED_BYTES);
+    /* We need to detect at least those cases when the file does not exist
+     * at all.  With current versions of OpenSSL, this should do it: */
+    if (n == 0)
+	n = my_MIN_SEED_BYTES;
+    if (r < n) {
+	tls_errprintf(1, apparg, "rand_seed_from_file: could not read %d bytes from %s.\n", n, filename);
+	return -1;
+    } else {
+	tls_rand_seeded_p = 1;
+	return 0;
+    }
+}
+
+void
+tls_rand_seed_from_memory(const void *buf, size_t n)
+{
+    size_t i = 0;
+    
+    while (i < n) {
+	size_t rest = n - i;
+	int chunk = rest < INT_MAX ? (int)rest : INT_MAX;
+	RAND_seed((const char *)buf + i, chunk);
+	i += chunk;
+    }
+    tls_rand_seeded_p = 1;
+}
+
+
+/*****************************************************************************/
+
+struct tls_x509_name_string {
+    char str[100];
+};
+
+static void
+tls_get_x509_subject_name_oneline(X509 *cert, struct tls_x509_name_string *namestring)
+{
+    X509_NAME *name;
+
+    if (cert == NULL) {
+	namestring->str[0] = '\0';
+	return;
+    }
+    
+    name = X509_get_subject_name(cert); /* does not increment any reference counter */
+
+    assert(sizeof namestring->str >= 4); /* "?" or "...", plus 0 */
+    
+    if (name == NULL) {
+	namestring->str[0] = '?';
+	namestring->str[1] = 0;
+    } else {
+	size_t len;
+
+	X509_NAME_oneline(name, namestring->str, sizeof namestring->str);
+	len = strlen(namestring->str);
+	assert(namestring->str[len] == 0);
+	assert(len < sizeof namestring->str);
+
+	if (len+1 == sizeof namestring->str) {
+	    /* (Probably something was cut off.)
+	     * Does not really work -- X509_NAME_oneline truncates after
+	     * name components, we cannot tell from the result whether
+	     * anything is missing. */
+
+	    assert(namestring->str[len] == 0);
+	    namestring->str[--len] = '.';
+	    namestring->str[--len] = '.';
+	    namestring->str[--len] = '.';
+	}
+    }
+}
+
+/*****************************************************************************/
+
+/* to hinder OpenSSL from asking for passphrases */
+static int
+no_passphrase_callback(char *buf, int num, int w, void *arg)
+{
+    return -1;
+}
+
+static int
+verify_dont_fail_cb(X509_STORE_CTX *c)
+{
+    int i;
+    
+    i = X509_verify_cert(c); /* sets c->error */
+#if OPENSSL_VERSION_NUMBER >= 0x00905000L /* don't allow unverified
+					   * certificates -- they could
+					   * survive session reuse, but
+					   * OpenSSL < 0.9.5-dev does not
+					   * preserve their verify_result */
+    if (i == 0)
+	return 1;
+    else
+#endif
+	return i;
+}
+
+static DH *tls_dhe1024 = NULL; /* generating these takes a while, so do it just once */
+
+void
+tls_set_dhe1024(int i, void *apparg)
+{
+    DSA *dsaparams;
+    DH *dhparams;
+    const char *seed[] = { ";-)  :-(  :-)  :-(  ",
+			   ";-)  :-(  :-)  :-(  ",
+			   "Random String no. 12",
+			   ";-)  :-(  :-)  :-(  ",
+			   "hackers have even mo", /* from jargon file */
+    };
+    unsigned char seedbuf[20];
+    
+    tls_init(apparg);
+    if (i >= 0) {
+	i %= sizeof seed / sizeof seed[0];
+	assert(strlen(seed[i]) == 20);
+	memcpy(seedbuf, seed[i], 20);
+	dsaparams = DSA_generate_parameters(1024, seedbuf, 20, NULL, NULL, 0, NULL);
+    } else {
+	/* random parameters (may take a while) */
+	dsaparams = DSA_generate_parameters(1024, NULL, 0, NULL, NULL, 0, NULL);
+    }
+    
+    if (dsaparams == NULL) {
+	tls_openssl_errors("", "", NULL, apparg);
+	return;
+    }
+    dhparams = DSA_dup_DH(dsaparams);
+    DSA_free(dsaparams);
+    if (dhparams == NULL) {
+	tls_openssl_errors("", "", NULL, apparg);
+	return;
+    }
+    if (tls_dhe1024 != NULL)
+	DH_free(tls_dhe1024);
+    tls_dhe1024 = dhparams;
+}
+
+struct tls_create_ctx_args
+tls_create_ctx_defaultargs(void)
+{
+	struct tls_create_ctx_args ret;
+
+	ret.client_p = 0;
+	ret.certificate_file = NULL;
+	ret.key_file = NULL;
+	ret.ca_file = NULL;
+	ret.verify_depth = -1;
+	ret.fail_unless_verified = 0;
+	ret.export_p = 0;
+
+	return ret;
+}
+
+SSL_CTX *
+tls_create_ctx(struct tls_create_ctx_args a, void *apparg)
+{
+    int r;
+    static long context_num = 0;
+    SSL_CTX *ret;
+    const char *err_pref_1 = "", *err_pref_2 = "";
+    
+    if (tls_init(apparg) == -1)
+	return NULL;
+
+    ret = SSL_CTX_new((a.client_p? SSLv23_client_method:SSLv23_server_method)());
+
+    if (ret == NULL)
+	goto err;
+
+    SSL_CTX_set_default_passwd_cb(ret, no_passphrase_callback);
+    SSL_CTX_set_mode(ret, SSL_MODE_ENABLE_PARTIAL_WRITE);
+    
+    if ((a.certificate_file != NULL) || (a.key_file != NULL)) {
+	if (a.key_file == NULL) {
+	    tls_errprintf(1, apparg, "Need a key file.\n");
+	    goto err_return;
+	}
+	if (a.certificate_file == NULL) {
+	    tls_errprintf(1, apparg, "Need a certificate chain file.\n");
+	    goto err_return;
+	}
+	
+	if (!SSL_CTX_use_PrivateKey_file(ret, a.key_file, SSL_FILETYPE_PEM))
+	    goto err;
+	if (!tls_rand_seeded_p) {
+	    /* particularly paranoid people may not like this --
+	     * so provide your own random seeding before calling this */
+	    if (tls_rand_seed_from_file(a.key_file, 0, apparg) == -1)
+		goto err_return;
+	}
+	if (!SSL_CTX_use_certificate_chain_file(ret, a.certificate_file))
+	    goto err;
+	if (!SSL_CTX_check_private_key(ret)) {
+	    tls_errprintf(1, apparg, "Private key \"%s\" does not match certificate \"%s\".\n", a.key_file, a.certificate_file);
+	    goto err_peek;
+	}
+    }
+    
+    if ((a.ca_file != NULL) || (a.verify_depth > 0)) {
+	context_num++;
+	r = SSL_CTX_set_session_id_context(ret, (const void *)&context_num, (unsigned int)sizeof context_num);
+	if (!r)
+	    goto err;
+	
+	SSL_CTX_set_verify(ret, SSL_VERIFY_PEER | (a.fail_unless_verified ? SSL_VERIFY_FAIL_IF_NO_PEER_CERT : 0), 0);
+	if (!a.fail_unless_verified)
+	    SSL_CTX_set_cert_verify_callback(ret, verify_dont_fail_cb, NULL);
+	    
+	if (a.verify_depth > 0)
+	    SSL_CTX_set_verify_depth(ret, a.verify_depth);
+	
+	if (a.ca_file != NULL) {
+	    r = SSL_CTX_load_verify_locations(ret, a.ca_file, NULL /* no CA-directory */); /* does not report failure if file does not exist ... */
+	    if (!r) {
+		err_pref_1 = " while processing certificate file ";
+		err_pref_2 = a.ca_file;
+		goto err;
+	    }
+	    
+	    if (!a.client_p) {
+		/* SSL_load_client_CA_file is a misnomer, it just creates a list of CNs. */
+		SSL_CTX_set_client_CA_list(ret, SSL_load_client_CA_file(a.ca_file));
+		/* SSL_CTX_set_client_CA_list does not have a return value;
+		 * it does not really need one, but make sure
+		 * (we really test if SSL_load_client_CA_file worked) */
+		if (SSL_CTX_get_client_CA_list(ret) == NULL) {
+		    tls_errprintf(1, apparg, "Could not set client CA list from \"%s\".\n", a.ca_file);
+		    goto err_peek;
+		}
+	    }
+	}
+    }
+    
+    if (!a.client_p) {
+	if (tls_dhe1024 == NULL) {
+	    int i;
+
+	    RAND_bytes((unsigned char *) &i, sizeof i);
+	    /* make sure that i is non-negative -- pick one of the provided
+	     * seeds */
+	    if (i < 0)
+		i = -i;
+	    if (i < 0)
+		i = 0;
+	    tls_set_dhe1024(i, apparg);
+	    if (tls_dhe1024 == NULL)
+		goto err_return;
+	}
+	
+	if (!SSL_CTX_set_tmp_dh(ret, tls_dhe1024))
+	    goto err;
+
+	/* avoid small subgroup attacks: */
+	SSL_CTX_set_options(ret, SSL_OP_SINGLE_DH_USE);
+    }
+	
+#ifndef NO_RSA
+    if (!a.client_p && a.export_p) {
+	RSA *tmpkey;
+
+	tmpkey = RSA_generate_key(512, RSA_F4, 0, NULL);
+	if (tmpkey == NULL)
+	    goto err;
+	if (!SSL_CTX_set_tmp_rsa(ret, tmpkey)) {
+	    RSA_free(tmpkey);
+	    goto err;
+	}
+	RSA_free(tmpkey); /* SSL_CTX_set_tmp_rsa uses a duplicate. */
+    }
+#endif
+	
+    return ret;
+    
+ err_peek:
+    if (!ERR_peek_error())
+	goto err_return;
+ err:
+    tls_openssl_errors(err_pref_1, err_pref_2, NULL, apparg);
+ err_return:
+    if (ret != NULL)
+	SSL_CTX_free(ret);
+    return NULL;
+}
+
+
+/*****************************************************************************/
+
+static int
+tls_socket_nonblocking(int fd)
+{
+    int v, r;
+
+    v = fcntl(fd, F_GETFL, 0);
+    if (v == -1) {
+	if (errno == EINVAL)
+	    return 0; /* already shut down -- ignore */
+	return -1;
+    }
+    r = fcntl(fd, F_SETFL,