lib/dns/tcpmsg.c

	tcpmsg.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
 * Copyright (C) 1999-2001, 2004-2007, 2015, 2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id: tcpmsg.c,v 1.31 2007/06/19 23:47:16 tbox Exp $ */

/*! \file */

#include <config.h>

#include <isc/mem.h>
#include <isc/print.h>
#include <isc/task.h>
#include <isc/util.h>

#include <dns/events.h>
#include <dns/result.h>
#include <dns/tcpmsg.h>

#ifdef TCPMSG_DEBUG
#include <stdio.h>      /* Required for printf. */
#define XDEBUG(x) printf x
#else
#define XDEBUG(x)
#endif

#define TCPMSG_MAGIC        ISC_MAGIC('T', 'C', 'P', 'm')
#define VALID_TCPMSG(foo)   ISC_MAGIC_VALID(foo, TCPMSG_MAGIC)

static void recv_length(isc_task_t *, isc_event_t *);
static void recv_message(isc_task_t *, isc_event_t *);


static void
recv_length(isc_task_t *task, isc_event_t *ev_in) {
    isc_socketevent_t *ev = (isc_socketevent_t *)ev_in;
    isc_event_t *dev;
    dns_tcpmsg_t *tcpmsg = ev_in->ev_arg;
    isc_region_t region;
    isc_result_t result;

    INSIST(VALID_TCPMSG(tcpmsg));

    dev = &tcpmsg->event;
    tcpmsg->address = ev->address;

    if (ev->result != ISC_R_SUCCESS) {
        tcpmsg->result = ev->result;
        goto send_and_free;
    }

    /*
     * Success.
     */
    tcpmsg->size = ntohs(tcpmsg->size);
    if (tcpmsg->size == 0) {
        tcpmsg->result = ISC_R_UNEXPECTEDEND;
        goto send_and_free;
    }
    if (tcpmsg->size > tcpmsg->maxsize) {
        tcpmsg->result = ISC_R_RANGE;
        goto send_and_free;
    }

    region.base = isc_mem_get(tcpmsg->mctx, tcpmsg->size);
    region.length = tcpmsg->size;
    if (region.base == NULL) {
        tcpmsg->result = ISC_R_NOMEMORY;
        goto send_and_free;
    }
    XDEBUG(("Allocated %d bytes\n", tcpmsg->size));

    isc_buffer_init(&tcpmsg->buffer, region.base, region.length);
    result = isc_socket_recv(tcpmsg->sock, &region, 0,
                 task, recv_message, tcpmsg);
    if (result != ISC_R_SUCCESS) {
        tcpmsg->result = result;
        goto send_and_free;
    }

    isc_event_free(&ev_in);
    return;

 send_and_free:
    isc_task_send(tcpmsg->task, &dev);
    tcpmsg->task = NULL;
    isc_event_free(&ev_in);
    return;
}

static void
recv_message(isc_task_t *task, isc_event_t *ev_in) {
    isc_socketevent_t *ev = (isc_socketevent_t *)ev_in;
    isc_event_t *dev;
    dns_tcpmsg_t *tcpmsg = ev_in->ev_arg;

    (void)task;

    INSIST(VALID_TCPMSG(tcpmsg));

    dev = &tcpmsg->event;
    tcpmsg->address = ev->address;

    if (ev->result != ISC_R_SUCCESS) {
        tcpmsg->result = ev->result;
        goto send_and_free;
    }

    tcpmsg->result = ISC_R_SUCCESS;
    isc_buffer_add(&tcpmsg->buffer, ev->n);

    XDEBUG(("Received %d bytes (of %d)\n", ev->n, tcpmsg->size));

 send_and_free:
    isc_task_send(tcpmsg->task, &dev);
    tcpmsg->task = NULL;
    isc_event_free(&ev_in);
}

void
dns_tcpmsg_init(isc_mem_t *mctx, isc_socket_t *sock, dns_tcpmsg_t *tcpmsg) {
    REQUIRE(mctx != NULL);
    REQUIRE(sock != NULL);
    REQUIRE(tcpmsg != NULL);

    tcpmsg->magic = TCPMSG_MAGIC;
    tcpmsg->size = 0;
    tcpmsg->buffer.base = NULL;
    tcpmsg->buffer.length = 0;
    tcpmsg->maxsize = 65535;        /* Largest message possible. */
    tcpmsg->mctx = mctx;
    tcpmsg->sock = sock;
    tcpmsg->task = NULL;            /* None yet. */
    tcpmsg->result = ISC_R_UNEXPECTED;  /* None yet. */
    /*
     * Should probably initialize the event here, but it can wait.
     */
}


void
dns_tcpmsg_setmaxsize(dns_tcpmsg_t *tcpmsg, unsigned int maxsize) {
    REQUIRE(VALID_TCPMSG(tcpmsg));
    REQUIRE(maxsize < 65536);

    tcpmsg->maxsize = maxsize;
}


isc_result_t
dns_tcpmsg_readmessage(dns_tcpmsg_t *tcpmsg,
               isc_task_t *task, isc_taskaction_t action, void *arg)
{
    isc_result_t result;
    isc_region_t region;

    REQUIRE(VALID_TCPMSG(tcpmsg));
    REQUIRE(task != NULL);
    REQUIRE(tcpmsg->task == NULL);  /* not currently in use */

    if (tcpmsg->buffer.base != NULL) {
        isc_mem_put(tcpmsg->mctx, tcpmsg->buffer.base,
                tcpmsg->buffer.length);
        tcpmsg->buffer.base = NULL;
        tcpmsg->buffer.length = 0;
    }

    tcpmsg->task = task;
    tcpmsg->action = action;
    tcpmsg->arg = arg;
    tcpmsg->result = ISC_R_UNEXPECTED;  /* unknown right now */

    ISC_EVENT_INIT(&tcpmsg->event, sizeof(isc_event_t), 0, 0,
               DNS_EVENT_TCPMSG, action, arg, tcpmsg,
               NULL, NULL);

    region.base = (unsigned char *)&tcpmsg->size;
    region.length = 2;  /* isc_uint16_t */
    result = isc_socket_recv(tcpmsg->sock, &region, 0,
                 tcpmsg->task, recv_length, tcpmsg);

    if (result != ISC_R_SUCCESS)
        tcpmsg->task = NULL;

    return (result);
}

void
dns_tcpmsg_cancelread(dns_tcpmsg_t *tcpmsg) {
    REQUIRE(VALID_TCPMSG(tcpmsg));

    isc_socket_cancel(tcpmsg->sock, NULL, ISC_SOCKCANCEL_RECV);
}

void
dns_tcpmsg_keepbuffer(dns_tcpmsg_t *tcpmsg, isc_buffer_t *buffer) {
    REQUIRE(VALID_TCPMSG(tcpmsg));
    REQUIRE(buffer != NULL);

    *buffer = tcpmsg->buffer;
    tcpmsg->buffer.base = NULL;
    tcpmsg->buffer.length = 0;
}

#if 0
void
dns_tcpmsg_freebuffer(dns_tcpmsg_t *tcpmsg) {
    REQUIRE(VALID_TCPMSG(tcpmsg));

    if (tcpmsg->buffer.base == NULL)
        return;

    isc_mem_put(tcpmsg->mctx, tcpmsg->buffer.base, tcpmsg->buffer.length);
    tcpmsg->buffer.base = NULL;
    tcpmsg->buffer.length = 0;
}
#endif

void
dns_tcpmsg_invalidate(dns_tcpmsg_t *tcpmsg) {
    REQUIRE(VALID_TCPMSG(tcpmsg));

    tcpmsg->magic = 0;

    if (tcpmsg->buffer.base != NULL) {
        isc_mem_put(tcpmsg->mctx, tcpmsg->buffer.base,
                tcpmsg->buffer.length);
        tcpmsg->buffer.base = NULL;
        tcpmsg->buffer.length = 0;
    }
}