[paraslash.git] / client_common.c

/*
 * Copyright (C) 1997-2010 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file client_common.c Common functions of para_client and para_audiod. */

#include <regex.h>
#include <sys/types.h>
#include <dirent.h>
#include <openssl/rc4.h>

#include "para.h"
#include "error.h"
#include "list.h"
#include "sched.h"
#include "client.cmdline.h"
#include "crypt.h"
#include "rc4.h"
#include "net.h"
#include "fd.h"
#include "string.h"
#include "client.cmdline.h"
#include "client.h"
#include "hash.h"
#include "buffer_tree.h"

/** The size of the receiving buffer. */
#define CLIENT_BUFSIZE 4000

/**
 * Close the connection to para_server and free all resources.
 *
 * \param ct Pointer to the client data.
 *
 * \sa client_open.
 */
void client_close(struct client_task *ct)
{
        if (!ct)
                return;
        if (ct->rc4c.fd >= 0)
                close(ct->rc4c.fd);
        free(ct->user);
        free(ct->config_file);
        free(ct->key_file);
        client_cmdline_parser_free(&ct->conf);
        free(ct);
}

/**
 * The preselect hook for server commands.
 *
 * \param s Pointer to the scheduler.
 * \param t Pointer to the task struct for this command.
 *
 * The task pointer must contain a pointer to the initialized client data
 * structure as it is returned by client_open().
 *
 * This function checks the state of the connection and adds the file descriptor
 * of the connection to the read or write fd set of \a s accordingly.
 *
 * \sa register_task() client_open(), struct sched, struct task.
 */
static void client_pre_select(struct sched *s, struct task *t)
{
        int ret;
        struct client_task *ct = container_of(t, struct client_task, task);
        struct btr_node *btrn = ct->btrn;

        if (ct->rc4c.fd < 0)
                return;
        switch (ct->status) {
        case CL_CONNECTED:
        case CL_SENT_AUTH:
        case CL_SENT_CH_RESPONSE:
        case CL_SENT_COMMAND:
                para_fd_set(ct->rc4c.fd, &s->rfds, &s->max_fileno);
                return;

        case CL_RECEIVED_WELCOME:
        case CL_RECEIVED_PROCEED:
                para_fd_set(ct->rc4c.fd, &s->wfds, &s->max_fileno);
                return;

        case CL_RECEIVING:
                ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
                if (ret != 0) {
                        if (ret < 0)
                                sched_min_delay(s);
                        else
                                para_fd_set(ct->rc4c.fd, &s->rfds,
                                        &s->max_fileno);
                }
                return;
        case CL_SENDING:
                ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
                if (ret != 0) {
                        if (ret < 0)
                                sched_min_delay(s);
                        else
                                para_fd_set(ct->rc4c.fd, &s->wfds,
                                        &s->max_fileno);
                }
                return;
        }
}

static int client_recv_buffer(struct client_task *ct, fd_set *rfds,
                char *buf, size_t sz, size_t *n)
{
        int ret;

        if (ct->status < CL_SENT_CH_RESPONSE)
                return read_nonblock(ct->rc4c.fd, buf, sz, rfds, n);

        *n = 0;
        ret = rc4_recv_buffer(&ct->rc4c, buf, sz);
        /*
         * rc4_recv_buffer is used with blocking fds elsewhere, so it
         * does not use the nonblock-API. Therefore we need to
         * check for EOF and EAGAIN.
         */
        if (ret == 0)
                return -E_SERVER_EOF;
        if (ret == -ERRNO_TO_PARA_ERROR(EAGAIN))
                return 0;
        if (ret < 0)
                return ret;
        *n = ret;
        return 0;
}

/**
 * The post select hook for client commands.
 *
 * \param s Pointer to the scheduler.
 * \param t Pointer to the task struct for this command.
 *
 * Depending on the current state of the connection and the status of the read
 * and write fd sets of \a s, this function performs the necessary steps to
 * authenticate the connection, to send the command given by \a t->private_data
 * and to receive para_server's output, if any.
 *
 * \sa struct sched, struct task.
 */
static void client_post_select(struct sched *s, struct task *t)
{
        struct client_task *ct = container_of(t, struct client_task, task);
        struct btr_node *btrn = ct->btrn;
        int ret = 0;
        size_t n;
        char buf[CLIENT_BUFSIZE];

        t->error = 0;
        if (ct->rc4c.fd < 0)
                return;
        switch (ct->status) {
        case CL_CONNECTED: /* receive welcome message */
                ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
                if (ret < 0 || n == 0)
                        goto out;
                ct->status = CL_RECEIVED_WELCOME;
                return;
        case CL_RECEIVED_WELCOME: /* send auth command */
                sprintf(buf, AUTH_REQUEST_MSG "%s", ct->user);
                PARA_INFO_LOG("--> %s\n", buf);
                if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
                        return;
                ret = send_buffer(ct->rc4c.fd, buf);
                if (ret < 0)
                        goto err;
                ct->status = CL_SENT_AUTH;
                return;
        case CL_SENT_AUTH:
                /*
                 * Receive challenge and rc4 keys, decrypt the challenge and
                 * send back the hash of the decrypted challenge.
                 */
                {
                /* decrypted challenge/rc4 buffer */
                unsigned char crypt_buf[1024];
                /* the SHA1 of the decrypted challenge */
                unsigned char challenge_sha1[HASH_SIZE];

                ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
                if (ret < 0 || n == 0)
                        goto out;
                PARA_INFO_LOG("<-- [challenge] (%zu bytes)\n", n);
                ret = para_decrypt_buffer(ct->key_file, crypt_buf,
                        (unsigned char *)buf, n);
                if (ret < 0)
                        goto err;
                sha1_hash((char *)crypt_buf, CHALLENGE_SIZE, challenge_sha1);
                RC4_set_key(&ct->rc4c.send_key, RC4_KEY_LEN,
                        crypt_buf + CHALLENGE_SIZE);
                RC4_set_key(&ct->rc4c.recv_key, RC4_KEY_LEN,
                        crypt_buf + CHALLENGE_SIZE + RC4_KEY_LEN);
                hash_to_asc(challenge_sha1, buf);
                PARA_INFO_LOG("--> %s\n", buf);
                ret = send_bin_buffer(ct->rc4c.fd, (char *)challenge_sha1,
                        HASH_SIZE);
                if (ret < 0)
                        goto err;
                ct->status = CL_SENT_CH_RESPONSE;
                return;
                }
        case CL_SENT_CH_RESPONSE: /* read server response */
                {
                ret = client_recv_buffer(ct, &s->rfds, buf, sizeof(buf), &n);
                if (ret < 0 || n == 0)
                        goto out;
                /* check if server has sent "Proceed" message */
                ret = -E_CLIENT_AUTH;
                if (n < PROCEED_MSG_LEN)
                        goto out;
                if (!strstr(buf, PROCEED_MSG))
                        goto out;
                ct->status = CL_RECEIVED_PROCEED;
                return;
                }
        case CL_RECEIVED_PROCEED: /* concat args and send command */
                {
                int i;
                char *command = NULL;
                if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
                        return;
                for (i = 0; i < ct->conf.inputs_num; i++) {
                        char *tmp = command;
                        command = make_message("%s\n%s", command?
                                command : "", ct->conf.inputs[i]);
                        free(tmp);
                }
                command = para_strcat(command, EOC_MSG "\n");
                PARA_DEBUG_LOG("--> %s\n", command);
                ret = rc4_send_buffer(&ct->rc4c, command);
                free(command);
                if (ret < 0)
                        goto err;
                ct->status = CL_SENT_COMMAND;
                return;
                }
        case CL_SENT_COMMAND:
                {
                char *buf2;
                /* can not use "buf" here because we need a malloced buffer */
                buf2 = para_malloc(CLIENT_BUFSIZE);
                ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
                if (n > 0) {
                        if (strstr(buf2, AWAITING_DATA_MSG)) {
                                free(buf2);
                                ct->status = CL_SENDING;
                                return;
                        }
                        ct->status = CL_RECEIVING;
                        btr_add_output(buf2, n, btrn);
                } else
                        free(buf2);
                goto out;
                }
        case CL_SENDING:
                {
                char *buf2;
                size_t sz;
                ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
                if (ret < 0)
                        goto err;
                if (ret == 0)
                        return;
                if (!FD_ISSET(ct->rc4c.fd, &s->wfds))
                        return;
                sz = btr_next_buffer(btrn, &buf2);
                ret = rc4_send_bin_buffer(&ct->rc4c, buf2, sz);
                if (ret < 0)
                        goto err;
                btr_consume(btrn, sz);
                return;
                }
        case CL_RECEIVING:
                {
                char *buf2;
                ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
                if (ret < 0)
                        goto err;
                if (ret == 0)
                        return;
                /*
                 * The FD_ISSET() is not strictly necessary, but is allows us
                 * to skip the malloc below if there is nothing to read anyway.
                 */
                if (!FD_ISSET(ct->rc4c.fd, &s->rfds))
                        return;
                buf2 = para_malloc(CLIENT_BUFSIZE);
                ret = client_recv_buffer(ct, &s->rfds, buf2, CLIENT_BUFSIZE, &n);
                if (n > 0) {
                        buf2 = para_realloc(buf2, n);
                        btr_add_output(buf2, n, btrn);
                } else
                        free(buf2);
                goto out;
                }
        }
err:
out:
        t->error = ret;
        if (ret < 0) {
                if (ret != -E_SERVER_EOF && ret != -E_BTR_EOF)
                        PARA_ERROR_LOG("%s\n", para_strerror(-t->error));
                btr_remove_node(btrn);
        }
}

/* connect to para_server and register the client task */
static int client_connect(struct client_task *ct)
{
        int ret;

        ct->rc4c.fd = -1;
        ret = para_connect_simple(IPPROTO_TCP, ct->conf.hostname_arg,
                                               ct->conf.server_port_arg);
        if (ret < 0)
                return ret;
        ct->rc4c.fd = ret;
        ct->status = CL_CONNECTED;
        ret = mark_fd_nonblocking(ct->rc4c.fd);
        if (ret < 0)
                goto err_out;
        ct->task.pre_select = client_pre_select;
        ct->task.post_select = client_post_select;
        sprintf(ct->task.status, "client");
        register_task(&ct->task);
        return 1;
err_out:
        close(ct->rc4c.fd);
        ct->rc4c.fd = -1;
        return ret;
}

/**
 * Open connection to para_server.
 *
 * \param argc Usual argument count.
 * \param argv Usual argument vector.
 * \param ct_ptr Points to dynamically allocated and initialized client task
 * struct upon successful return.
 * \param loglevel If not \p NULL, the number of the loglevel is stored here.
 * \param parent Add the new buffer tree node as a child of this node.
 * \param child Add the new buffer tree node as a parent of this node.
 *
 * Check the command line options given by \a argc and argv, set default values
 * for user name and rsa key file, read further option from the config file.
 * Finally, establish a connection to para_server.
 *
 * \return Standard.
 */
int client_open(int argc, char *argv[], struct client_task **ct_ptr,
                int *loglevel, struct btr_node *parent, struct btr_node *child)
{
        char *home = para_homedir();
        int ret;
        struct client_task *ct = para_calloc(sizeof(struct client_task));

        ct->btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.name = "client", .parent = parent, .child = child));
        *ct_ptr = ct;
        ct->rc4c.fd = -1;
        ret = -E_CLIENT_SYNTAX;
        if (client_cmdline_parser(argc, argv, &ct->conf))
                goto out;
        HANDLE_VERSION_FLAG("client", ct->conf);
        ret = -E_CLIENT_SYNTAX;
        if (!ct->conf.inputs_num)
                goto out;

        ct->config_file = ct->conf.config_file_given?
                para_strdup(ct->conf.config_file_arg) :
                make_message("%s/.paraslash/client.conf", home);
        ret = file_exists(ct->config_file);
        if (!ret && ct->conf.config_file_given) {
                ret = -E_NO_CONFIG;
                goto out;
        }
        if (ret) {
                struct client_cmdline_parser_params params = {
                        .override = 0,
                        .initialize = 0,
                        .check_required = 0,
                        .check_ambiguity = 0,
                        .print_errors = 0
                };
                ret = -E_BAD_CONFIG;
                if (client_cmdline_parser_config_file(ct->config_file,
                        &ct->conf, &params))
                        goto out;
        }
        ct->user = ct->conf.user_given?
                para_strdup(ct->conf.user_arg) : para_logname();

        ct->key_file = ct->conf.key_file_given?
                para_strdup(ct->conf.key_file_arg) :
                make_message("%s/.paraslash/key.%s", home, ct->user);

        if (loglevel)
                *loglevel = get_loglevel_by_name(ct->conf.loglevel_arg);
        PARA_INFO_LOG("loglevel: %s\n", ct->conf.loglevel_arg);
        PARA_INFO_LOG("config_file: %s\n", ct->config_file);
        PARA_INFO_LOG("key_file: %s\n", ct->key_file);
        PARA_NOTICE_LOG("connecting %s:%d\n", ct->conf.hostname_arg,
                ct->conf.server_port_arg);
        ret = client_connect(ct);
out:
        free(home);
        if (ret < 0) {
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                btr_remove_node(ct->btrn);
                btr_free_node(ct->btrn);
                client_close(ct);
                *ct_ptr = NULL;
        }
        return ret;
}