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/*++
/* 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
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