1 files changed, 142 insertions, 0 deletions
diff --git a/src/tls/tls_prng_exch.c b/src/tls/tls_prng_exch.c
new file mode 100644
index 0000000..31523a3
--- /dev/null
+++ b/src/tls/tls_prng_exch.c
@@ -0,0 +1,142 @@
+/*++
+/* NAME
+/*	tls_prng_exch 3
+/* SUMMARY
+/*	maintain PRNG exchange file
+/* SYNOPSIS
+/*	#include <tls_prng_src.h>
+/*
+/*	TLS_PRNG_SRC *tls_prng_exch_open(name, timeout)
+/*	const char *name;
+/*	int	timeout;
+/*
+/*	void	tls_prng_exch_update(fh, length)
+/*	TLS_PRNG_SRC *fh;
+/*	size_t length;
+/*
+/*	void	tls_prng_exch_close(fh)
+/*	TLS_PRNG_SRC *fh;
+/* DESCRIPTION
+/*	tls_prng_exch_open() opens the specified PRNG exchange file
+/*	and returns a handle that should be used with all subsequent
+/*	access.
+/*
+/*	tls_prng_exch_update() reads the requested number of bytes
+/*	from the PRNG exchange file, updates the OpenSSL PRNG, and
+/*	writes the requested number of bytes to the exchange file.
+/*	The file is locked for exclusive access.
+/*
+/*	tls_prng_exch_close() closes the specified PRNG exchange
+/*	file and releases memory that was allocated for the handle.
+/*
+/*	Arguments:
+/* .IP name
+/*	The name of the PRNG exchange file.
+/* .IP length
+/*	The number of bytes to read from/write to the entropy file.
+/* .IP timeout
+/*	Time limit on individual I/O operations.
+/* DIAGNOSTICS
+/*	All errors are fatal.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <limits.h>
+
+/* OpenSSL library. */
+
+#ifdef USE_TLS
+#include <openssl/rand.h>		/* For the PRNG */
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <iostuff.h>
+#include <myflock.h>
+
+/* TLS library. */
+
+#include <tls_prng.h>
+
+/* Application specific. */
+
+#define TLS_PRNG_EXCH_SIZE	1024	/* XXX Why not configurable? */
+
+/* tls_prng_exch_open - open PRNG exchange file */
+
+TLS_PRNG_SRC *tls_prng_exch_open(const char *name)
+{
+    const char *myname = "tls_prng_exch_open";
+    TLS_PRNG_SRC *eh;
+    int     fd;
+
+    if ((fd = open(name, O_RDWR | O_CREAT, 0600)) < 0)
+	msg_fatal("%s: cannot open PRNG exchange file %s: %m", myname, name);
+    eh = (TLS_PRNG_SRC *) mymalloc(sizeof(*eh));
+    eh->fd = fd;
+    eh->name = mystrdup(name);
+    eh->timeout = 0;
+    if (msg_verbose)
+	msg_info("%s: opened PRNG exchange file %s", myname, name);
+    return (eh);
+}
+
+/* tls_prng_exch_update - update PRNG exchange file */
+
+void    tls_prng_exch_update(TLS_PRNG_SRC *eh)
+{
+    unsigned char buffer[TLS_PRNG_EXCH_SIZE];
+    ssize_t count;
+
+    /*
+     * Update the PRNG exchange file. Since other processes may have added
+     * entropy, we use a read-stir-write cycle.
+     */
+    if (myflock(eh->fd, INTERNAL_LOCK, MYFLOCK_OP_EXCLUSIVE) != 0)
+	msg_fatal("cannot lock PRNG exchange file %s: %m", eh->name);
+    if (lseek(eh->fd, 0, SEEK_SET) < 0)
+	msg_fatal("cannot seek PRNG exchange file %s: %m", eh->name);
+    if ((count = read(eh->fd, buffer, sizeof(buffer))) < 0)
+	msg_fatal("cannot read PRNG exchange file %s: %m", eh->name);
+
+    if (count > 0)
+	RAND_seed(buffer, count);
+    RAND_bytes(buffer, sizeof(buffer));
+
+    if (lseek(eh->fd, 0, SEEK_SET) < 0)
+	msg_fatal("cannot seek PRNG exchange file %s: %m", eh->name);
+    if (write(eh->fd, buffer, sizeof(buffer)) != sizeof(buffer))
+	msg_fatal("cannot write PRNG exchange file %s: %m", eh->name);
+    if (myflock(eh->fd, INTERNAL_LOCK, MYFLOCK_OP_NONE) != 0)
+	msg_fatal("cannot unlock PRNG exchange file %s: %m", eh->name);
+}
+
+/* tls_prng_exch_close - close PRNG exchange file */
+
+void    tls_prng_exch_close(TLS_PRNG_SRC *eh)
+{
+    const char *myname = "tls_prng_exch_close";
+
+    if (close(eh->fd) < 0)
+	msg_fatal("close PRNG exchange file %s: %m", eh->name);
+    if (msg_verbose)
+	msg_info("%s: closed PRNG exchange file %s", myname, eh->name);
+    myfree(eh->name);
+    myfree((void *) eh);
+}
+
+#endif