pptp_ctrl.c

pptp第二层隧道模块

    /* fill in the phone number if it was specified */
    if (phonenr) {
        strncpy(packet.phone_num, phonenr, sizeof(packet.phone_num));
        packet.phone_len = strlen(phonenr);
        if( packet.phone_len > sizeof(packet.phone_num))
            packet.phone_len = sizeof(packet.phone_num);
        packet.phone_len = hton16 (packet.phone_len);
    }
    if (pptp_send_ctrl_packet(conn, &packet, sizeof(packet))) {
        pptp_reset_timer();
        call->state.pns = PNS_WAIT_REPLY;
        /* and add it to the call vector */
        vector_insert(conn->call, i, call);
        return call;
    } else { /* oops, unsuccessful. Deallocate. */
        free(call);
        return NULL;
    }
}

/*** pptp_call_close **********************************************************/
void pptp_call_close(PPTP_CONN * conn, PPTP_CALL * call)
{
    struct pptp_call_clear_rqst rqst = {
        PPTP_HEADER_CTRL(PPTP_CALL_CLEAR_RQST), 0, 0
    };
    assert(conn && conn->call); assert(call);
    assert(vector_contains(conn->call, call->call_id));
    /* haven't thought about PAC yet */
    assert(call->call_type == PPTP_CALL_PNS);
    assert(call->state.pns != PNS_IDLE);
    rqst.call_id = hton16(call->call_id);
    /* don't check state against WAIT_DISCONNECT... allow multiple disconnect
     * requests to be made.
     */
    pptp_send_ctrl_packet(conn, &rqst, sizeof(rqst));
    pptp_reset_timer();
    call->state.pns = PNS_WAIT_DISCONNECT;
    /* call structure will be freed when we have confirmation of disconnect. */
}

/*** hard close ***************************************************************/
void pptp_call_destroy(PPTP_CONN *conn, PPTP_CALL *call)
{
    assert(conn && conn->call); assert(call);
    assert(vector_contains(conn->call, call->call_id));
    /* notify */
    if (call->callback != NULL) call->callback(conn, call, CALL_CLOSE_DONE);
    /* deallocate */
    vector_remove(conn->call, call->call_id);
    free(call);
}

/*** this is a soft close *****************************************************/
void pptp_conn_close(PPTP_CONN * conn, u_int8_t close_reason)
{
    struct pptp_stop_ctrl_conn rqst = {
        PPTP_HEADER_CTRL(PPTP_STOP_CTRL_CONN_RQST), 
        hton8(close_reason), 0, 0
    };
    int i;
    assert(conn && conn->call);
    /* avoid repeated close attempts */
    if (conn->conn_state == CONN_IDLE || conn->conn_state == CONN_WAIT_STOP_REPLY) 
        return;
    /* close open calls, if any */
    for (i = 0; i < vector_size(conn->call); i++)
        pptp_call_close(conn, vector_get_Nth(conn->call, i));
    /* now close connection */
    log("Closing PPTP connection");
    pptp_send_ctrl_packet(conn, &rqst, sizeof(rqst));
    pptp_reset_timer(); /* wait 60 seconds for reply */
    conn->conn_state = CONN_WAIT_STOP_REPLY;
    return;
}

/*** this is a hard close *****************************************************/
void pptp_conn_destroy(PPTP_CONN * conn)
{
    int i;
    assert(conn != NULL); assert(conn->call != NULL);
    /* destroy all open calls */
    for (i = 0; i < vector_size(conn->call); i++)
        pptp_call_destroy(conn, vector_get_Nth(conn->call, i));
    /* notify */
    if (conn->callback != NULL) conn->callback(conn, CONN_CLOSE_DONE);
    sigpipe_close();
    close(conn->inet_sock);
    /* deallocate */
    vector_destroy(conn->call);
    free(conn);
}

/*** Deal with messages, in a non-blocking manner 
 * Add file descriptors used by pptp to fd_set.
 */
void pptp_fd_set(PPTP_CONN * conn, fd_set * read_set, fd_set * write_set,
                 int * max_fd)
{
    assert(conn && conn->call);
    /* Add fd to write_set if there are outstanding writes. */
    if (conn->write_size > 0)
        FD_SET(conn->inet_sock, write_set);
    /* Always add fd to read_set. (always want something to read) */
    FD_SET(conn->inet_sock, read_set);
    if (*max_fd < conn->inet_sock) *max_fd = conn->inet_sock;
    /* Add signal pipe file descriptor to set */
    int sig_fd = sigpipe_fd();
    FD_SET(sig_fd, read_set);
    if (*max_fd < sig_fd) *max_fd = sig_fd;
}

/*** handle any pptp file descriptors set in fd_set, and clear them ***********/
int pptp_dispatch(PPTP_CONN * conn, fd_set * read_set, fd_set * write_set)
{
    int r = 0;
    assert(conn && conn->call);
    /* Check for signals */
    if (FD_ISSET(sigpipe_fd(), read_set)) {
        if (sigpipe_read() == SIGALRM) pptp_handle_timer();
	FD_CLR(sigpipe_fd(), read_set);
    }
    /* Check write_set could be set. */
    if (FD_ISSET(conn->inet_sock, write_set)) {
        FD_CLR(conn->inet_sock, write_set);
        if (conn->write_size > 0)
            r = pptp_write_some(conn);/* write as much as we can without blocking */
    }
    /* Check read_set */
    if (r >= 0 && FD_ISSET(conn->inet_sock, read_set)) {
        void *buffer; size_t size;
        FD_CLR(conn->inet_sock, read_set);
        r = pptp_read_some(conn); /* read as much as we can without blocking */
	if (r < 0)
	    return r;
        /* make packets of the buffer, while we can. */
        while (r >= 0 && pptp_make_packet(conn, &buffer, &size)) {
            r = pptp_dispatch_packet(conn, buffer, size);
            free(buffer);
        }
    }
    /* That's all, folks.  Simple, eh? */
    return r;
}

/*** Non-blocking write *******************************************************/
int pptp_write_some(PPTP_CONN * conn) {
    ssize_t retval;
    assert(conn && conn->call);
    retval = write(conn->inet_sock, conn->write_buffer, conn->write_size);
    if (retval < 0) { /* error. */
        if (errno == EAGAIN || errno == EINTR) { 
            return 0;
        } else { /* a real error */
            log("write error: %s", strerror(errno));
	    return -1;
        }
    }
    assert(retval <= conn->write_size);
    conn->write_size -= retval;
    memmove(conn->write_buffer, conn->write_buffer + retval, conn->write_size);
    ctrlp_rep(conn->write_buffer, retval, 0);
    return 0;
}

/*** Non-blocking read ********************************************************/
int pptp_read_some(PPTP_CONN * conn)
{
    ssize_t retval;
    assert(conn && conn->call);
    if (conn->read_size == conn->read_alloc) { /* need to alloc more memory */
        char *new_buffer = realloc(conn->read_buffer, 
                sizeof(*(conn->read_buffer)) * conn->read_alloc * 2);
        if (new_buffer == NULL) {
            log("Out of memory"); return -1;
        }
        conn->read_alloc *= 2;
        conn->read_buffer = new_buffer;
    }
    retval = read(conn->inet_sock, conn->read_buffer + conn->read_size,
            conn->read_alloc  - conn->read_size);
    if (retval == 0) {
        log("read returned zero, peer has closed");
        return -1;
    }
    if (retval < 0) {
        if (errno == EINTR || errno == EAGAIN)
	    return 0;
        else { /* a real error */
            log("read error: %s", strerror(errno));
            return -1;
        }
    }
    conn->read_size += retval;
    assert(conn->read_size <= conn->read_alloc);
    return 0;
}

/*** Packet formation *********************************************************/
int pptp_make_packet(PPTP_CONN * conn, void **buf, size_t *size)
{
    struct pptp_header *header;
    size_t bad_bytes = 0;
    assert(conn && conn->call); assert(buf != NULL); assert(size != NULL);
    /* Give up unless there are at least sizeof(pptp_header) bytes */
    while ((conn->read_size-bad_bytes) >= sizeof(struct pptp_header)) {
        /* Throw out bytes until we have a valid header. */
        header = (struct pptp_header *) (conn->read_buffer + bad_bytes);
        if (ntoh32(header->magic) != PPTP_MAGIC) goto throwitout;
        if (ntoh16(header->reserved0) != 0)
            log("reserved0 field is not zero! (0x%x) Cisco feature? \n",
                    ntoh16(header->reserved0));
        if (ntoh16(header->length) < sizeof(struct pptp_header)) goto throwitout;
        if (ntoh16(header->length) > PPTP_CTRL_SIZE_MAX) goto throwitout;
        /* well.  I guess it's good. Let's see if we've got it all. */
        if (ntoh16(header->length) > (conn->read_size-bad_bytes))
            /* nope.  Let's wait until we've got it, then. */
            goto flushbadbytes;
        /* One last check: */
        if ((ntoh16(header->pptp_type) == PPTP_MESSAGE_CONTROL) &&
                (ntoh16(header->length) !=
                         PPTP_CTRL_SIZE(ntoh16(header->ctrl_type))))
            goto throwitout;
        /* well, I guess we've got it. */
        *size = ntoh16(header->length);
        *buf = malloc(*size);
        if (*buf == NULL) { log("Out of memory."); return 0; /* ack! */ }
        memcpy(*buf, conn->read_buffer + bad_bytes, *size);
        /* Delete this packet from the read_buffer. */
        conn->read_size -= (bad_bytes + *size);
        memmove(conn->read_buffer, conn->read_buffer + bad_bytes + *size, 
                conn->read_size);
        if (bad_bytes > 0) 
            log("%lu bad bytes thrown away.", (unsigned long) bad_bytes);
        return 1;
throwitout:
        bad_bytes++;
    }
flushbadbytes:
    /* no more packets.  Let's get rid of those bad bytes */
    conn->read_size -= bad_bytes;
    memmove(conn->read_buffer, conn->read_buffer + bad_bytes, conn->read_size);
    if (bad_bytes > 0) 
        log("%lu bad bytes thrown away.", (unsigned long) bad_bytes);
    return 0;
}

/*** pptp_send_ctrl_packet ****************************************************/
int pptp_send_ctrl_packet(PPTP_CONN * conn, void * buffer, size_t size)
{
    assert(conn && conn->call); assert(buffer);
    if( conn->write_size > 0) pptp_write_some( conn);
    if( conn->write_size == 0) {
        ssize_t retval;
        retval = write(conn->inet_sock, buffer, size);
        if (retval < 0) { /* error. */
            if (errno == EAGAIN || errno == EINTR) { 
                /* ignore */;
                retval = 0;
            } else { /* a real error */
                log("write error: %s", strerror(errno));
                pptp_conn_destroy(conn); /* shut down fast. */
                return 0;
            }
        }
        ctrlp_rep( buffer, retval, 0);
        size -= retval;
        if( size <= 0) return 1;
    }
    /* Shove anything not written into the write buffer */
    if (conn->write_size + size > conn->write_alloc) { /* need more memory */
        char *new_buffer = realloc(conn->write_buffer, 
                sizeof(*(conn->write_buffer)) * conn->write_alloc * 2);
        if (new_buffer == NULL) {
            log("Out of memory"); return 0;
        }
        conn->write_alloc *= 2;
        conn->write_buffer = new_buffer;
    }
    memcpy(conn->write_buffer + conn->write_size, buffer, size);
    conn->write_size += size;
    ctrlp_rep( buffer,size,1);
    return 1;
}

/*** Packet Dispatch **********************************************************/
int pptp_dispatch_packet(PPTP_CONN * conn, void * buffer, size_t size)
{
    int r = 0;
    struct pptp_header *header = (struct pptp_header *)buffer;
    assert(conn && conn->call); assert(buffer);
    assert(ntoh32(header->magic) == PPTP_MAGIC);
    assert(ntoh16(header->length) == size);
    switch (ntoh16(header->pptp_type)) {
        case PPTP_MESSAGE_CONTROL:
            r = ctrlp_disp(conn, buffer, size);
            break;
        case PPTP_MESSAGE_MANAGE:
            /* MANAGEMENT messages aren't even part of the spec right now. */
            log("PPTP management message received, but not understood.");
            break;
        default:
            log("Unknown PPTP control message type received: %u", 
                    (unsigned int) ntoh16(header->pptp_type));
            break;
    }
    return r;
}

/*** log echo request/replies *************************************************/
static void logecho( int type)
{
    /* hack to stop flooding the log files (the most interesting part is right
     * after the connection built-up) */
    if( nlogecho > 0) {
        log( "Echo Re%s received.", type == PPTP_ECHO_RQST ? "quest" :"ply");
        if( --nlogecho == 0)
            log("no more Echo Reply/Request packets will be reported.");
    }
}

/*** pptp_dispatch_ctrl_packet ************************************************/
int ctrlp_disp(PPTP_CONN * conn, void * buffer, size_t size)
{
    struct pptp_header *header = (struct pptp_header *)buffer;
    u_int8_t close_reason = PPTP_STOP_NONE;
    assert(conn && conn->call); assert(buffer);
    assert(ntoh32(header->magic) == PPTP_MAGIC);
    assert(ntoh16(header->length) == size);
    assert(ntoh16(header->pptp_type) == PPTP_MESSAGE_CONTROL);
    if (size < PPTP_CTRL_SIZE(ntoh16(header->ctrl_type))) {
        log("Invalid packet received [type: %d; length: %d].",
                (int) ntoh16(header->ctrl_type), (int) size);
        return 0;
    }
    switch (ntoh16(header->ctrl_type)) {
        /* ----------- STANDARD Start-Session MESSAGES ------------ */
        case PPTP_START_CTRL_CONN_RQST:
        {
            struct pptp_start_ctrl_conn *packet = 
                (struct pptp_start_ctrl_conn *) buffer;
            struct pptp_start_ctrl_conn reply = {
                PPTP_HEADER_CTRL(PPTP_START_CTRL_CONN_RPLY),
                hton16(PPTP_VERSION), 0, 0,
                hton32(PPTP_FRAME_CAP), hton32(PPTP_BEARER_CAP),
                hton16(PPTP_MAX_CHANNELS), hton16(PPTP_FIRMWARE_VERSION),
                PPTP_HOSTNAME, PPTP_VENDOR };
            int idx, rc;
            log("Received Start Control Connection Request");
            /* fix this packet, if necessary */
            idx = get_quirk_index();
            if (idx != -1 && pptp_fixups[idx].start_ctrl_conn) {
                if ((rc = pptp_fixups[idx].start_ctrl_conn(&reply)))
                    warn("calling the start_ctrl_conn hook failed (%d)", rc);
            }
            if (conn->conn_state == CONN_IDLE) {
                if (ntoh16(packet->version) < PPTP_VERSION) {
                    /* Can't support this (earlier) PPTP_VERSION */
                    reply.version = packet->version;
                    /* protocol version not supported */