/*
 * Copyright (c) 2001 Damien Miller.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 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 THE AUTHOR 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.
 */

#include "includes.h"

#include <sys/types.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_UN_H
# include <sys/un.h>
#endif

#include <netinet/in.h>
#include <arpa/inet.h>

#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stddef.h> /* for offsetof */

#include "atomicio.h"
#include "misc.h"
#include "log.h"

#if defined(PRNGD_PORT) || defined(PRNGD_SOCKET)
/*
 * EGD/PRNGD interface.
 *
 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
 * listening either on 'tcp_port', or via Unix domain socket at *
 * 'socket_path'.
 * Either a non-zero tcp_port or a non-null socket_path must be
 * supplied.
 * Returns 0 on success, -1 on error
 */
static int
get_random_bytes_prngd(unsigned char *buf, int len,
    unsigned short tcp_port, char *socket_path)
{
        int fd, addr_len, rval, errors;
        u_char msg[2];
        struct sockaddr_storage addr;
        struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
        struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
        sshsig_t old_sigpipe;

        /* Sanity checks */
        if (socket_path == NULL && tcp_port == 0)
                fatal("You must specify a port or a socket");
        if (socket_path != NULL &&
            strlen(socket_path) >= sizeof(addr_un->sun_path))
                fatal("Random pool path is too long");
        if (len <= 0 || len > 255)
                fatal("Too many bytes (%d) to read from PRNGD", len);

        memset(&addr, '\0', sizeof(addr));

        if (tcp_port != 0) {
                addr_in->sin_family = AF_INET;
                addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
                addr_in->sin_port = htons(tcp_port);
                addr_len = sizeof(*addr_in);
        } else {
                addr_un->sun_family = AF_UNIX;
                strlcpy(addr_un->sun_path, socket_path,
                    sizeof(addr_un->sun_path));
                addr_len = offsetof(struct sockaddr_un, sun_path) +
                    strlen(socket_path) + 1;
        }

        old_sigpipe = ssh_signal(SIGPIPE, SIG_IGN);

        errors = 0;
        rval = -1;
reopen:
        fd = socket(addr.ss_family, SOCK_STREAM, 0);
        if (fd == -1) {
                error("Couldn't create socket: %s", strerror(errno));
                goto done;
        }

        if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
                if (tcp_port != 0) {
                        error("Couldn't connect to PRNGD port %d: %s",
                            tcp_port, strerror(errno));
                } else {
                        error("Couldn't connect to PRNGD socket \"%s\": %s",
                            addr_un->sun_path, strerror(errno));
                }
                goto done;
        }

        /* Send blocking read request to PRNGD */
        msg[0] = 0x02;
        msg[1] = len;

        if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
                if (errno == EPIPE && errors < 10) {
                        close(fd);
                        errors++;
                        goto reopen;
                }
                error("Couldn't write to PRNGD socket: %s",
                    strerror(errno));
                goto done;
        }

        if (atomicio(read, fd, buf, len) != (size_t)len) {
                if (errno == EPIPE && errors < 10) {
                        close(fd);
                        errors++;
                        goto reopen;
                }
                error("Couldn't read from PRNGD socket: %s",
                    strerror(errno));
                goto done;
        }

        rval = 0;
done:
        ssh_signal(SIGPIPE, old_sigpipe);
        if (fd != -1)
                close(fd);
        return rval;
}
#endif /* PRNGD_PORT || PRNGD_SOCKET */

int
seed_from_prngd(unsigned char *buf, size_t bytes)
{
#ifdef PRNGD_PORT
        debug("trying egd/prngd port %d", PRNGD_PORT);
        if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
                return 0;
#endif
#ifdef PRNGD_SOCKET
        debug("trying egd/prngd socket %s", PRNGD_SOCKET);
        if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
                return 0;
#endif
        return -1;
}