tcpmsg.c

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/*
 * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

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

/*! \file */

#include <config.h>

#include <isc/mem.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;
        }
}

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