240 lines
6.4 KiB
C
240 lines
6.4 KiB
C
/*
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* Copyright (c) 2001 Damien Miller. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/socket.h>
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#ifdef HAVE_SYS_UN_H
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# include <sys/un.h>
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#endif
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <errno.h>
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#include <signal.h>
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#include <string.h>
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#include <unistd.h>
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#include <stddef.h> /* for offsetof */
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#include <openssl/rand.h>
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#include <openssl/crypto.h>
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#include <openssl/err.h>
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#include "ssh.h"
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#include "misc.h"
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#include "xmalloc.h"
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#include "atomicio.h"
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#include "pathnames.h"
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#include "log.h"
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#include "buffer.h"
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/*
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* Portable OpenSSH PRNG seeding:
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* If OpenSSL has not "internally seeded" itself (e.g. pulled data from
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* /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from
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* PRNGd.
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*/
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#ifndef OPENSSL_PRNG_ONLY
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#define RANDOM_SEED_SIZE 48
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/*
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* Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
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* listening either on 'tcp_port', or via Unix domain socket at *
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* 'socket_path'.
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* Either a non-zero tcp_port or a non-null socket_path must be
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* supplied.
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* Returns 0 on success, -1 on error
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*/
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int
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get_random_bytes_prngd(unsigned char *buf, int len,
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unsigned short tcp_port, char *socket_path)
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{
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int fd, addr_len, rval, errors;
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u_char msg[2];
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struct sockaddr_storage addr;
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struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
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struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
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mysig_t old_sigpipe;
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/* Sanity checks */
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if (socket_path == NULL && tcp_port == 0)
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fatal("You must specify a port or a socket");
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if (socket_path != NULL &&
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strlen(socket_path) >= sizeof(addr_un->sun_path))
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fatal("Random pool path is too long");
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if (len <= 0 || len > 255)
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fatal("Too many bytes (%d) to read from PRNGD", len);
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memset(&addr, '\0', sizeof(addr));
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if (tcp_port != 0) {
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addr_in->sin_family = AF_INET;
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addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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addr_in->sin_port = htons(tcp_port);
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addr_len = sizeof(*addr_in);
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} else {
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addr_un->sun_family = AF_UNIX;
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strlcpy(addr_un->sun_path, socket_path,
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sizeof(addr_un->sun_path));
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addr_len = offsetof(struct sockaddr_un, sun_path) +
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strlen(socket_path) + 1;
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}
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old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
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errors = 0;
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rval = -1;
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reopen:
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fd = socket(addr.ss_family, SOCK_STREAM, 0);
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if (fd == -1) {
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error("Couldn't create socket: %s", strerror(errno));
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goto done;
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}
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if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
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if (tcp_port != 0) {
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error("Couldn't connect to PRNGD port %d: %s",
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tcp_port, strerror(errno));
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} else {
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error("Couldn't connect to PRNGD socket \"%s\": %s",
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addr_un->sun_path, strerror(errno));
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}
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goto done;
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}
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/* Send blocking read request to PRNGD */
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msg[0] = 0x02;
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msg[1] = len;
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if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
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if (errno == EPIPE && errors < 10) {
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close(fd);
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errors++;
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goto reopen;
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}
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error("Couldn't write to PRNGD socket: %s",
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strerror(errno));
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goto done;
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}
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if (atomicio(read, fd, buf, len) != (size_t)len) {
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if (errno == EPIPE && errors < 10) {
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close(fd);
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errors++;
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goto reopen;
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}
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error("Couldn't read from PRNGD socket: %s",
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strerror(errno));
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goto done;
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}
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rval = 0;
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done:
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mysignal(SIGPIPE, old_sigpipe);
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if (fd != -1)
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close(fd);
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return rval;
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}
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static int
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seed_from_prngd(unsigned char *buf, size_t bytes)
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{
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#ifdef PRNGD_PORT
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debug("trying egd/prngd port %d", PRNGD_PORT);
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if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
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return 0;
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#endif
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#ifdef PRNGD_SOCKET
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debug("trying egd/prngd socket %s", PRNGD_SOCKET);
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if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
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return 0;
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#endif
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return -1;
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}
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void
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rexec_send_rng_seed(Buffer *m)
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{
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u_char buf[RANDOM_SEED_SIZE];
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if (RAND_bytes(buf, sizeof(buf)) <= 0) {
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error("Couldn't obtain random bytes (error %ld)",
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ERR_get_error());
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buffer_put_string(m, "", 0);
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} else
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buffer_put_string(m, buf, sizeof(buf));
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}
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void
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rexec_recv_rng_seed(Buffer *m)
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{
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u_char *buf;
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u_int len;
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buf = buffer_get_string_ret(m, &len);
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if (buf != NULL) {
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debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
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RAND_add(buf, len, len);
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}
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}
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#endif /* OPENSSL_PRNG_ONLY */
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void
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seed_rng(void)
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{
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#ifndef OPENSSL_PRNG_ONLY
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unsigned char buf[RANDOM_SEED_SIZE];
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#endif
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/*
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* OpenSSL version numbers: MNNFFPPS: major minor fix patch status
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* We match major, minor, fix and status (not patch) for <1.0.0.
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* After that, we acceptable compatible fix versions (so we
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* allow 1.0.1 to work with 1.0.0). Going backwards is only allowed
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* within a patch series.
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*/
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u_long version_mask = SSLeay() >= 0x1000000f ? ~0xffff0L : ~0xff0L;
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if (((SSLeay() ^ OPENSSL_VERSION_NUMBER) & version_mask) ||
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(SSLeay() >> 12) < (OPENSSL_VERSION_NUMBER >> 12))
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fatal("OpenSSL version mismatch. Built against %lx, you "
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"have %lx", (u_long)OPENSSL_VERSION_NUMBER, SSLeay());
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#ifndef OPENSSL_PRNG_ONLY
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if (RAND_status() == 1) {
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debug3("RNG is ready, skipping seeding");
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return;
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}
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if (seed_from_prngd(buf, sizeof(buf)) == -1)
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fatal("Could not obtain seed from PRNGd");
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RAND_add(buf, sizeof(buf), sizeof(buf));
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memset(buf, '\0', sizeof(buf));
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#endif /* OPENSSL_PRNG_ONLY */
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if (RAND_status() != 1)
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fatal("PRNG is not seeded");
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}
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