[paraslash.git] / send_common.c

/* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */

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

#include <netinet/in.h>
#include <sys/socket.h>
#include <regex.h>
#include <osl.h>
#include <arpa/inet.h>
#include <sys/un.h>
#include <netdb.h>
#include <lopsub.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 "sched.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_simple(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.
 *
 * \sa \ref shutdown_clients().
 */
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);
        if (!process_is_command_handler()) {
                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--;
}

/**
 * Shut down all clients connected to a paraslash sender.
 *
 * \param ss The sender whose clients are to be shut down.
 *
 * This just loops over all connected clients and calls shutdown_client()
 * for each client.
 */
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);
}

/**
 * Try to empty the chunk queue for this fd.
 *
 * \param fd The file descriptor.
 * \param cq The list of queued chunks.
 *
 * \return Negative on errors, zero if not everything was sent, one otherwise.
 */
int send_queued_chunks(int fd, struct chunk_queue *cq)
{
        struct queued_chunk *qc;
        while ((qc = cq_peek(cq))) {
                const char *buf;
                size_t len;
                int ret;

                cq_get(qc, &buf, &len);
                ret = xwrite(fd, buf, len);
                if (ret < 0)
                        return ret;
                cq_update(cq, ret);
                if (ret != len)
                        return 0;
                cq_dequeue(cq);
        }
        return 1;
}

/**
 * Initialize a struct sender status.
 *
 * \param ss The struct to initialize.
 * \param acl_opt_result Contains array of --{http|dccp}-access arguments.
 * \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,
                const struct lls_opt_result *acl_opt_result, int port,
                int max_clients, int default_deny)
{
        int i;

        ss->listen_fd = -1;
        INIT_LIST_HEAD(&ss->client_list);
        ss->port = port;

        /* Initialize an access control list */
        INIT_LIST_HEAD(&ss->acl);
        for (i = 0; i < lls_opt_given(acl_opt_result); i++) {
                const char *arg = lls_string_val(i, acl_opt_result);
                char addr[16];
                int mask;
                if (!parse_cidr(arg, addr, sizeof(addr), &mask))
                        PARA_WARNING_LOG("ACL syntax error: %s, ignoring\n",
                                arg);
                else
                        acl_add_entry(&ss->acl, addr, mask);
        }
        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 *generic_sender_status(struct sender_status *ss, const 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(
                "status: %s\n"
                "port: %s\n"
                "number of connected clients: %d\n"
                "maximal number of clients: %d%s\n"
                "connected clients: %s\n"
                "access %s list: %s\n",
                (ss->listen_fd >= 0)? "on" : "off",
                stringify_port(ss->port, strcmp(name, "http") ? "dccp" : "tcp"),
                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 \ref generic_com_deny().
 */
void generic_com_allow(struct sender_command_data *scd,
                struct sender_status *ss)
{
        acl_allow(scd->host, scd->netmask, &ss->acl, ss->default_deny);
}

/**
 * Empty the access control list of a sender.
 *
 * \param acl The access control list of the sender.
 *
 * This is called from the ->shutdown methods of the http and the dccp sender.
 */
void generic_acl_deplete(struct list_head *acl)
{
        /*
         * Since default_deny is false, the ACL is considered a blacklist. A
         * netmask of zero matches any IP address, so this call empties the ACL.
         */
        acl_allow("0.0.0.0", 0 /* netmask */, acl, 0 /* 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 \ref generic_com_allow().
 */
void generic_com_deny(struct sender_command_data *scd,
                struct sender_status *ss)
{
        acl_deny(scd->host, 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(), \ref 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.
 * \param rfds Passed to para_accept(),
 *
 * 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, fd_set *rfds)
{
        struct sender_client *sc;
        int fd, ret;

        if (ss->listen_fd < 0)
                return NULL;
        ret = para_accept(ss->listen_fd, rfds, NULL, 0, &fd);
        if (ret < 0)
                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
        if (ret <= 0)
                return NULL;
        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 = para_strdup(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[/netmask]\n"
                "       where mask defaults to 32\n"
                "example: allow 192.168.0.1/24\n"
        );
}

static int parse_fec_parms(const char *arg, struct sender_command_data *scd)
{
        int32_t val;
        char *a = para_strdup(arg),
             *b = strchr(a, ':'),
             *c = strrchr(a, ':');
        int ret = -E_COMMAND_SYNTAX;

        if (!b || !c)
                goto out;
        *b = *c = '\0';

        ret = para_atoi32(a, &val);
        if (ret < 0)
                goto out;

        /* optional max_slice_bytes (0 means "use MTU") */
        if (b == c) {
                scd->max_slice_bytes = 0;
        } else {
                if (val < 0 || val > 65535)
                        goto fec_einval;
                scd->max_slice_bytes = val;

                ret = para_atoi32(b + 1, &val);
                if (ret < 0)
                        goto out;
        }

        /* k = data_slices_per_group */
        if (val < 0 || val > 255)
                goto fec_einval;
        scd->data_slices_per_group = val;

        /* n = slices_per_group */
        ret = para_atoi32(c + 1, &val);
        if (ret < 0)
                goto out;
        if (val < 0 || val < scd->data_slices_per_group)
                goto fec_einval;
        scd->slices_per_group = val;
        ret = 0;
out:
        free(a);
        return ret;
fec_einval:
        ret = -ERRNO_TO_PARA_ERROR(EINVAL);
        goto out;
}

/**
 * Parse a FEC URL string.
 *
 * \param arg the URL string to parse.
 * \param scd The structure containing host, port and the FEC parameters.
 *
 * \return Standard.
 *
 * A FEC URL consists of an ordinary URL string according to RFC 3986,
 * optionally followed by a slash and the three FEC parameters slice_size,
 * data_slices_per_group and slices_per_group. The three FEC parameters are
 * separated by colons.
 *
 * \sa \ref parse_url().
 */
int parse_fec_url(const char *arg, struct sender_command_data *scd)
{
        char *a = para_strdup(arg), *p = strchr(a, '/');
        int ret = 0;

        /* default fec parameters */
        scd->max_slice_bytes       = 0;
        scd->data_slices_per_group = 14;
        scd->slices_per_group      = 16;

        if (p) {
                *p = '\0';
                ret = parse_fec_parms(p + 1, scd);
                if (ret < 0)
                        goto out;
        }
        if (!parse_url(a, scd->host, sizeof(scd->host), &scd->port))
                ret = -ERRNO_TO_PARA_ERROR(EINVAL);
out:
        free(a);
        return ret;
}