[paraslash.git] / send_common.c

/*
 * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file send_common.c Functions used by more than one paraslash sender. */

#include <dirent.h>
#include "para.h"
#include "error.h"
#include "string.h"
#include "fd.h"
#include "net.h"
#include "list.h"
#include "afh.h"
#include "afs.h"
#include "server.h"
#include "acl.h"
#include "send.h"
#include "close_on_fork.h"
#include "chunk_queue.h"
#include "vss.h"

/** Clients will be kicked if there are more than that many bytes pending. */
#define MAX_CQ_BYTES 40000

/**
 * Open a passive socket of given layer4 type.
 *
 * Set the resulting file descriptor to nonblocking mode and add it to the list
 * of fds that are being closed in the child process when the server calls
 * fork().
 *
 * \param l4type The transport-layer protocol.
 * \param port The port number.
 *
 * \return The listening fd on success, negative on errors.
 */
static int open_sender(unsigned l4type, int port)
{
        int fd, ret = para_listen(AF_UNSPEC, l4type, port);

        if (ret < 0)
                return ret;
        fd = ret;
        ret = mark_fd_nonblocking(fd);
        if (ret < 0) {
                close(fd);
                return ret;
        }
        add_close_on_fork_list(fd);
        return fd;
}

/**
 * Shut down a client connected to a paraslash sender.
 *
 * \param sc The client to shut down.
 * \param ss The sender whose clients are to be shut down.
 *
 * Close the file descriptor given by \a sc, remove it from the close-on-fork
 * list, destroy the chunk queue of this client, delete the client from the
 * list of connected clients and free the sender_client struct.
 */
void shutdown_client(struct sender_client *sc, struct sender_status *ss)
{
        PARA_INFO_LOG("shutting down %s on fd %d\n", sc->name, sc->fd);
        free(sc->name);
        close(sc->fd);
        del_close_on_fork_list(sc->fd);
        cq_destroy(sc->cq);
        list_del(&sc->node);
        free(sc->private_data);
        free(sc);
        ss->num_clients--;
}

void shutdown_clients(struct sender_status *ss)
{
        struct sender_client *sc, *tmp;
        list_for_each_entry_safe(sc, tmp, &ss->client_list, node)
                shutdown_client(sc, ss);
}

/**
 * Write a buffer to a non-blocking file descriptor.
 *
 * \param fd The file descriptor.
 * \param buf the buffer to write.
 * \param len the number of bytes of \a buf.
 * \param max_bytes_per_write Do not write more than that many bytes at once.
 *
 * If \a max_bytes_per_write is non-zero, do not send more than that many bytes
 * per write().
 *
 * EAGAIN is not considered an error condition.  For example CCID3 has a
 * sending wait queue which fills up and is emptied asynchronously. The EAGAIN
 * case means that there is currently no space in the wait queue, but this can
 * change at any moment.
 *
 * \return Negative on errors, number of bytes written else.
 */
static int write_nonblock(int fd, const char *buf, size_t len,
                size_t max_bytes_per_write)
{
        size_t written = 0;
        int ret = 0;

        while (written < len) {
                size_t num = len - written;

                if (max_bytes_per_write && max_bytes_per_write < num)
                        num = max_bytes_per_write;
                ret = write(fd, buf + written, num);
                if (ret < 0 && errno == EAGAIN)
                        return written;
                if (ret < 0)
                        return -ERRNO_TO_PARA_ERROR(errno);
                written += ret;
        }
        return written;
}

static int queue_chunk_or_shutdown(struct sender_client *sc,
                struct sender_status *ss, const char *buf, size_t num_bytes)
{
        int ret = cq_enqueue(sc->cq, buf, num_bytes);
        if (ret < 0)
                shutdown_client(sc, ss);
        return ret;
}

/* return: negative on errors, zero if not everything was sent, one otherwise */
static int send_queued_chunks(struct sender_client *sc,
                size_t max_bytes_per_write)
{
        struct queued_chunk *qc;
        while ((qc = cq_peek(sc->cq))) {
                const char *buf;
                size_t len;
                int ret;
                cq_get(qc, &buf, &len);
                ret = write_nonblock(sc->fd, buf, len, max_bytes_per_write);
                if (ret < 0)
                        return ret;
                cq_update(sc->cq, ret);
                if (ret != len)
                        return 0;
                cq_dequeue(sc->cq);
        }
        return 1;
}

/**
 * Send one chunk of audio data to a connected client.
 *
 * \param sc The client.
 * \param ss The sender.
 * \param max_bytes_per_write Split writes to chunks of at most that many bytes.
 * \param current_chunk The number of the chunk to write.
 * \param buf The data to write.
 * \param len The number of bytes of \a buf.
 *
 * On errors, the client is shut down. If only a part of the buffer could be
 * written, the remainder is put into the chunk queue for that client.
 */
void send_chunk(struct sender_client *sc, struct sender_status *ss,
                size_t max_bytes_per_write, long unsigned current_chunk,
                const char *buf, size_t len)
{
        int ret;

        if (!sc->header_sent && current_chunk) {
                size_t header_len;
                char *header_buf;

                vss_get_header(&header_buf, &header_len);
                if (header_buf && header_len > 0) {
                        ret = queue_chunk_or_shutdown(sc, ss, header_buf, header_len);
                        if (ret < 0)
                                goto out;
                }
                sc->header_sent = 1;
        }
        ret = send_queued_chunks(sc, max_bytes_per_write);
        if (ret < 0) {
                shutdown_client(sc, ss);
                goto out;
        }
        if (!len)
                goto out;
        if (!ret) { /* still data left in the queue */
                ret = queue_chunk_or_shutdown(sc, ss, buf, len);
                goto out;
        }
        ret = write_nonblock(sc->fd, buf, len, max_bytes_per_write);
        if (ret < 0) {
                shutdown_client(sc, ss);
                goto out;
        }
        if (ret != len)
                ret = queue_chunk_or_shutdown(sc, ss, buf + ret, len - ret);
out:
        if (ret < 0)
                PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
}

/**
 * Initialize a struct sender status.
 *
 * \param ss The struct to initialize.
 * \param access_arg The array of access arguments given at the command line.
 * \param num_access_args The number of elements in \a access_arg.
 * \param port The tcp or dccp port to listen on.
 * \param max_clients The maximal number of simultaneous connections.
 * \param default_deny Whether a blacklist should be used for access control.
 */
void init_sender_status(struct sender_status *ss, char **access_arg,
        int num_access_args, int port, int max_clients, int default_deny)
{
        ss->listen_fd = -1;
        INIT_LIST_HEAD(&ss->client_list);
        ss->port = port;
        acl_init(&ss->acl, access_arg, num_access_args);
        ss->num_clients = 0;
        ss->max_clients = max_clients;
        ss->default_deny = default_deny;
}

/**
 * Return a string containing the current status of a sender.
 *
 * \param ss The sender.
 * \param name Used for printing the header line.
 *
 * \return The string printed in the "si" command.
 */
char *get_sender_info(struct sender_status *ss, char *name)
{
        char *clnts = NULL, *ret;
        struct sender_client *sc, *tmp_sc;

        char *acl_contents = acl_get_contents(&ss->acl);
        list_for_each_entry_safe(sc, tmp_sc, &ss->client_list, node) {
                char *tmp = make_message("%s%s ", clnts? clnts : "", sc->name);
                free(clnts);
                clnts = tmp;
        }
        ret = make_message(
                "%s sender:\n"
                "\tstatus: %s\n"
                "\tport: %d\n"
                "\tnumber of connected clients: %d\n"
                "\tmaximal number of clients: %d%s\n"
                "\tconnected clients: %s\n"
                "\taccess %s list: %s\n",
                name,
                (ss->listen_fd >= 0)? "on" : "off",
                ss->port,
                ss->num_clients,
                ss->max_clients,
                ss->max_clients > 0? "" : " (unlimited)",
                clnts? clnts : "(none)",
                ss->default_deny? "allow" : "deny",
                acl_contents? acl_contents : "(empty)"
        );
        free(acl_contents);
        free(clnts);
        return ret;
}

/**
 * Allow connections from the given range of IP addresses.
 *
 * \param scd Contains the IP and the netmask.
 * \param ss The sender.
 *
 * \sa generic_com_deny().
 */
void generic_com_allow(struct sender_command_data *scd,
                struct sender_status *ss)
{
        acl_allow(scd->addr, scd->netmask, &ss->acl, ss->default_deny);
}

/**
 * Deny connections from the given range of IP addresses.
 *
 * \param scd see \ref generic_com_allow().
 * \param ss see \ref generic_com_allow().
 *
 * \sa generic_com_allow().
 */
void generic_com_deny(struct sender_command_data *scd,
                struct sender_status *ss)
{
        acl_deny(scd->addr, scd->netmask, &ss->acl, ss->default_deny);
}

/**
 * Activate a paraslash sender.
 *
 * \param ss The sender to activate.
 * \param protocol The symbolic name of the transport-layer protocol.
 *
 * \return Standard.
 */
int generic_com_on(struct sender_status *ss, unsigned protocol)
{
        int ret;

        if (ss->listen_fd >= 0)
                return 1;
        ret = open_sender(protocol, ss->port);
        if (ret < 0)
                return ret;
        ss->listen_fd = ret;
        return 1;
}

/**
 * Deactivate a paraslash sender.
 *
 * Shutdown all connected clients and stop listening on the TCP/DCCP socket.
 *
 * \param ss The sender to deactivate.
 *
 * \sa \ref del_close_on_fork_list(), shutdown_clients().
 */
void generic_com_off(struct sender_status *ss)
{
        if (ss->listen_fd < 0)
                return;
        PARA_NOTICE_LOG("closing port %d\n", ss->port);
        close(ss->listen_fd);
        del_close_on_fork_list(ss->listen_fd);
        shutdown_clients(ss);
        ss->listen_fd = -1;
}

/**
 * Accept a connection on the socket this server is listening on.
 *
 * \param ss The sender whose listening fd is ready for reading.
 *
 * This must be called only if the socket fd of \a ss is ready for reading.  It
 * calls para_accept() to accept the connection and performs the following
 * actions on the resulting file descriptor \a fd:
 *
 *      - Checks whether the maximal number of connections are exceeded.
 *      - Sets \a fd to nonblocking mode.
 *      - Checks the acl of the sender to find out whether connections
 *        are allowed from the IP of the connecting peer.
 *      - Increases the number of connections for this sender.
 *      - Creates and initializes a new chunk queue for queuing network
 *        packets that can not be sent immediately.
 *      - Allocates a new struct sender_client and fills in its \a fd, \a cq
 *        and \a name members.
 *      - Adds \a fd to the list of connected clients for this sender.
 *      - Adds \a fd to the list of file descriptors that should be closed
 *        in the child process when the server calls fork().
 *
 * \return A pointer to the allocated sender_client structure on success, \p
 * NULL on errors.
 *
 * \sa \ref para_accept(), \ref mark_fd_nonblocking(), \ref acl_check_access(),
 * \ref cq_new(), \ref add_close_on_fork_list().
 */
struct sender_client *accept_sender_client(struct sender_status *ss)
{
        struct sender_client *sc;
        int fd, ret = para_accept(ss->listen_fd, NULL, 0);
        if (ret < 0) {
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                return NULL;
        }
        fd = ret;
        ret = -E_MAX_CLIENTS;
        if (ss->max_clients > 0 && ss->num_clients >= ss->max_clients)
                goto err_out;
        ret = mark_fd_nonblocking(fd);
        if (ret < 0)
                goto err_out;
        ret = acl_check_access(fd, &ss->acl, ss->default_deny);
        if (ret < 0)
                goto err_out;
        ss->num_clients++;
        sc = para_calloc(sizeof(*sc));
        sc->fd = fd;
        sc->name = make_message("%s", remote_name(fd));
        sc->cq = cq_new(MAX_CQ_BYTES);
        para_list_add(&sc->node, &ss->client_list);
        add_close_on_fork_list(fd);
        PARA_INFO_LOG("accepted client #%d: %s (fd %d)\n", ss->num_clients,
                sc->name, fd);
        return sc;
err_out:
        PARA_WARNING_LOG("%s\n", para_strerror(-ret));
        close(fd);
        return NULL;
}

/**
 * Get the generic help text.
 *
 * \return A dynamically allocated string containing the help text for
 * a paraslash sender.
 */
char *generic_sender_help(void)
{
        return make_message(
                "usage: {on|off}\n"
                "usage: {allow|deny} IP mask\n"
                "example: allow 127.0.0.1 32\n"
        );
}