lib/isc/buffer.c

/*
 * Copyright (C) 1998-2002, 2004-2008, 2012, 2014-2017  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/.
 */

/*! \file */

#include <config.h>

#include <isc/buffer.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/region.h>
#include <isc/string.h>
#include <isc/util.h>

void
isc__buffer_init(isc_buffer_t *b, void *base, unsigned int length) {
    /*
     * Make 'b' refer to the 'length'-byte region starting at 'base'.
     * XXXDCL see the comment in buffer.h about base being const.
     */

    REQUIRE(b != NULL);

    ISC__BUFFER_INIT(b, base, length);
}

void
isc__buffer_initnull(isc_buffer_t *b) {
    /*
     * Initialize a new buffer which has no backing store.  This can
     * later be grown as needed and swapped in place.
     */

    ISC__BUFFER_INIT(b, NULL, 0);
}

void
isc_buffer_reinit(isc_buffer_t *b, void *base, unsigned int length) {
    /*
     * Re-initialize the buffer enough to reconfigure the base of the
     * buffer.  We will swap in the new buffer, after copying any
     * data we contain into the new buffer and adjusting all of our
     * internal pointers.
     *
     * The buffer must not be smaller than the length of the original
     * buffer.
     */
    REQUIRE(b->length <= length);
    REQUIRE(base != NULL);
    REQUIRE(!b->autore);

    (void)memmove(base, b->base, b->length);
    b->base = base;
    b->length = length;
}

void
isc__buffer_invalidate(isc_buffer_t *b) {
    /*
     * Make 'b' an invalid buffer.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(!ISC_LINK_LINKED(b, link));
    REQUIRE(b->mctx == NULL);

    ISC__BUFFER_INVALIDATE(b);
}

void
isc_buffer_setautorealloc(isc_buffer_t *b, isc_boolean_t enable) {
    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->mctx != NULL);
    b->autore = enable;
}

void
isc__buffer_region(isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_REGION(b, r);
}

void
isc__buffer_usedregion(const isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the used region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_USEDREGION(b, r);
}

void
isc__buffer_availableregion(isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the available region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_AVAILABLEREGION(b, r);
}

void
isc__buffer_add(isc_buffer_t *b, unsigned int n) {
    /*
     * Increase the 'used' region of 'b' by 'n' bytes.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used + n <= b->length);

    ISC__BUFFER_ADD(b, n);
}

void
isc__buffer_subtract(isc_buffer_t *b, unsigned int n) {
    /*
     * Decrease the 'used' region of 'b' by 'n' bytes.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used >= n);

    ISC__BUFFER_SUBTRACT(b, n);
}

void
isc__buffer_clear(isc_buffer_t *b) {
    /*
     * Make the used region empty.
     */

    REQUIRE(ISC_BUFFER_VALID(b));

    ISC__BUFFER_CLEAR(b);
}

void
isc__buffer_consumedregion(isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the consumed region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_CONSUMEDREGION(b, r);
}

void
isc__buffer_remainingregion(isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the remaining region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_REMAININGREGION(b, r);
}

void
isc__buffer_activeregion(isc_buffer_t *b, isc_region_t *r) {
    /*
     * Make 'r' refer to the active region of 'b'.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    ISC__BUFFER_ACTIVEREGION(b, r);
}

void
isc__buffer_setactive(isc_buffer_t *b, unsigned int n) {
    /*
     * Sets the end of the active region 'n' bytes after current.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->current + n <= b->used);

    ISC__BUFFER_SETACTIVE(b, n);
}

void
isc__buffer_first(isc_buffer_t *b) {
    /*
     * Make the consumed region empty.
     */

    REQUIRE(ISC_BUFFER_VALID(b));

    ISC__BUFFER_FIRST(b);
}

void
isc__buffer_forward(isc_buffer_t *b, unsigned int n) {
    /*
     * Increase the 'consumed' region of 'b' by 'n' bytes.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->current + n <= b->used);

    ISC__BUFFER_FORWARD(b, n);
}

void
isc__buffer_back(isc_buffer_t *b, unsigned int n) {
    /*
     * Decrease the 'consumed' region of 'b' by 'n' bytes.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(n <= b->current);

    ISC__BUFFER_BACK(b, n);
}

void
isc_buffer_compact(isc_buffer_t *b) {
    unsigned int length;
    void *src;

    /*
     * Compact the used region by moving the remaining region so it occurs
     * at the start of the buffer.  The used region is shrunk by the size
     * of the consumed region, and the consumed region is then made empty.
     */

    REQUIRE(ISC_BUFFER_VALID(b));

    src = isc_buffer_current(b);
    length = isc_buffer_remaininglength(b);
    (void)memmove(b->base, src, (size_t)length);

    if (b->active > b->current)
        b->active -= b->current;
    else
        b->active = 0;
    b->current = 0;
    b->used = length;
}

isc_uint8_t
isc_buffer_getuint8(isc_buffer_t *b) {
    unsigned char *cp;
    isc_uint8_t result;

    /*
     * Read an unsigned 8-bit integer from 'b' and return it.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used - b->current >= 1);

    cp = isc_buffer_current(b);
    b->current += 1;
    result = ((isc_uint8_t)(cp[0]));

    return (result);
}

void
isc__buffer_putuint8(isc_buffer_t *b, isc_uint8_t val) {
    isc_result_t result;
    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, 1);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= 1);

    ISC__BUFFER_PUTUINT8(b, val);
}

isc_uint16_t
isc_buffer_getuint16(isc_buffer_t *b) {
    unsigned char *cp;
    isc_uint16_t result;

    /*
     * Read an unsigned 16-bit integer in network byte order from 'b',
     * convert it to host byte order, and return it.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used - b->current >= 2);

    cp = isc_buffer_current(b);
    b->current += 2;
    result = ((unsigned int)(cp[0])) << 8;
    result |= ((unsigned int)(cp[1]));

    return (result);
}

void
isc__buffer_putuint16(isc_buffer_t *b, isc_uint16_t val) {
    isc_result_t result;
    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, 2);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= 2);

    ISC__BUFFER_PUTUINT16(b, val);
}

void
isc__buffer_putuint24(isc_buffer_t *b, isc_uint32_t val) {
    isc_result_t result;
    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, 3);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= 3);

    ISC__BUFFER_PUTUINT24(b, val);
}

isc_uint32_t
isc_buffer_getuint32(isc_buffer_t *b) {
    unsigned char *cp;
    isc_uint32_t result;

    /*
     * Read an unsigned 32-bit integer in network byte order from 'b',
     * convert it to host byte order, and return it.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used - b->current >= 4);

    cp = isc_buffer_current(b);
    b->current += 4;
    result = ((unsigned int)(cp[0])) << 24;
    result |= ((unsigned int)(cp[1])) << 16;
    result |= ((unsigned int)(cp[2])) << 8;
    result |= ((unsigned int)(cp[3]));

    return (result);
}

void
isc__buffer_putuint32(isc_buffer_t *b, isc_uint32_t val) {
    isc_result_t result;
    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, 4);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= 4);

    ISC__BUFFER_PUTUINT32(b, val);
}

isc_uint64_t
isc_buffer_getuint48(isc_buffer_t *b) {
    unsigned char *cp;
    isc_uint64_t result;

    /*
     * Read an unsigned 48-bit integer in network byte order from 'b',
     * convert it to host byte order, and return it.
     */

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(b->used - b->current >= 6);

    cp = isc_buffer_current(b);
    b->current += 6;
    result = ((isc_int64_t)(cp[0])) << 40;
    result |= ((isc_int64_t)(cp[1])) << 32;
    result |= ((isc_int64_t)(cp[2])) << 24;
    result |= ((isc_int64_t)(cp[3])) << 16;
    result |= ((isc_int64_t)(cp[4])) << 8;
    result |= ((isc_int64_t)(cp[5]));

    return (result);
}

void
isc__buffer_putuint48(isc_buffer_t *b, isc_uint64_t val) {
    isc_result_t result;
    isc_uint16_t valhi;
    isc_uint32_t vallo;

    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, 6);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= 6);

    valhi = (isc_uint16_t)(val >> 32);
    vallo = (isc_uint32_t)(val & 0xFFFFFFFF);
    ISC__BUFFER_PUTUINT16(b, valhi);
    ISC__BUFFER_PUTUINT32(b, vallo);
}

void
isc__buffer_putmem(isc_buffer_t *b, const unsigned char *base,
           unsigned int length)
{
    isc_result_t result;
    REQUIRE(ISC_BUFFER_VALID(b));
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, length);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= length);

    ISC__BUFFER_PUTMEM(b, base, length);
}

void
isc__buffer_putstr(isc_buffer_t *b, const char *source) {
    unsigned int l;
    unsigned char *cp;
    isc_result_t result;

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(source != NULL);

    /*
     * Do not use ISC__BUFFER_PUTSTR(), so strlen is only done once.
     */
    l = strlen(source);
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, l);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= l);

    cp = isc_buffer_used(b);
    memmove(cp, source, l);
    b->used += l;
}

void
isc_buffer_putdecint(isc_buffer_t *b, isc_int64_t v) {
    unsigned int l=0;
    unsigned char *cp;
    char buf[21];
    isc_result_t result;

    REQUIRE(ISC_BUFFER_VALID(b));

    /* xxxwpk do it more low-level way ? */
    l = snprintf(buf, 21, "%" ISC_PRINT_QUADFORMAT "d", v);
    RUNTIME_CHECK(l <= 21);
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, l);
        REQUIRE(result == ISC_R_SUCCESS);
    }
    REQUIRE(isc_buffer_availablelength(b) >= l);

    cp = isc_buffer_used(b);
    memmove(cp, buf, l);
    b->used += l;
}

isc_result_t
isc_buffer_dup(isc_mem_t *mctx, isc_buffer_t **dstp, const isc_buffer_t *src) {
    isc_buffer_t *dst = NULL;
    isc_region_t region;
    isc_result_t result;

    REQUIRE(dstp != NULL && *dstp == NULL);
    REQUIRE(ISC_BUFFER_VALID(src));

    isc_buffer_usedregion(src, &region);

    result = isc_buffer_allocate(mctx, &dst, region.length);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_buffer_copyregion(dst, &region);
    RUNTIME_CHECK(result == ISC_R_SUCCESS); /* NOSPACE is impossible */
    *dstp = dst;
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_copyregion(isc_buffer_t *b, const isc_region_t *r) {
    unsigned char *base;
    unsigned int available;
    isc_result_t result;

    REQUIRE(ISC_BUFFER_VALID(b));
    REQUIRE(r != NULL);

    /*
     * XXXDCL
     */
    base = isc_buffer_used(b);
    available = isc_buffer_availablelength(b);
    if (ISC_UNLIKELY(b->autore)) {
        result = isc_buffer_reserve(&b, r->length);
        if (result != ISC_R_SUCCESS)
            return (result);
    }
    if (r->length > available)
        return (ISC_R_NOSPACE);
    memmove(base, r->base, r->length);
    b->used += r->length;

    return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_allocate(isc_mem_t *mctx, isc_buffer_t **dynbuffer,
            unsigned int length)
{
    isc_buffer_t *dbuf;
    unsigned char * bdata;
    REQUIRE(dynbuffer != NULL);
    REQUIRE(*dynbuffer == NULL);

    dbuf = isc_mem_get(mctx, sizeof(isc_buffer_t));
    if (dbuf == NULL)
        return (ISC_R_NOMEMORY);

    bdata = isc_mem_get(mctx, length);
    if (bdata == NULL) {
        isc_mem_put(mctx, dbuf, sizeof(isc_buffer_t));
        return (ISC_R_NOMEMORY);
    }

    isc_buffer_init(dbuf, bdata, length);
    dbuf->mctx = mctx;

    ENSURE(ISC_BUFFER_VALID(dbuf));

    *dynbuffer = dbuf;

    return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_reallocate(isc_buffer_t **dynbuffer, unsigned int length) {
    unsigned char *bdata;

    REQUIRE(dynbuffer != NULL);
    REQUIRE(ISC_BUFFER_VALID(*dynbuffer));
    REQUIRE((*dynbuffer)->mctx != NULL);

    if ((*dynbuffer)->length > length)
        return (ISC_R_NOSPACE);

    /*
     * XXXMUKS: This is far more expensive than plain realloc() as
     * it doesn't remap pages, but does ordinary copy. So is
     * isc_mem_reallocate(), which has additional issues.
     */
    bdata = isc_mem_get((*dynbuffer)->mctx, length);
    if (bdata == NULL)
        return (ISC_R_NOMEMORY);

    memmove(bdata, (*dynbuffer)->base, (*dynbuffer)->length);
    isc_mem_put((*dynbuffer)->mctx, (*dynbuffer)->base,
            (*dynbuffer)->length);

    (*dynbuffer)->base = bdata;
    (*dynbuffer)->length = length;

    return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_reserve(isc_buffer_t **dynbuffer, unsigned int size) {
    isc_uint64_t len;

    REQUIRE(dynbuffer != NULL);
    REQUIRE(ISC_BUFFER_VALID(*dynbuffer));

    len = (*dynbuffer)->length;
    if ((len - (*dynbuffer)->used) >= size)
        return (ISC_R_SUCCESS);

    if ((*dynbuffer)->mctx == NULL)
        return (ISC_R_NOSPACE);

    /* Round to nearest buffer size increment */
    len = size + (*dynbuffer)->used;
    len = (len + ISC_BUFFER_INCR - 1 - ((len - 1) % ISC_BUFFER_INCR));

    /* Cap at UINT_MAX */
    if (len > UINT_MAX) {
        len = UINT_MAX;
    }

    if ((len - (*dynbuffer)->used) < size)
        return (ISC_R_NOMEMORY);

    return (isc_buffer_reallocate(dynbuffer, (unsigned int) len));
}

void
isc_buffer_free(isc_buffer_t **dynbuffer) {
    isc_buffer_t *dbuf;
    isc_mem_t *mctx;

    REQUIRE(dynbuffer != NULL);
    REQUIRE(ISC_BUFFER_VALID(*dynbuffer));
    REQUIRE((*dynbuffer)->mctx != NULL);

    dbuf = *dynbuffer;
    *dynbuffer = NULL;  /* destroy external reference */
    mctx = dbuf->mctx;
    dbuf->mctx = NULL;

    isc_mem_put(mctx, dbuf->base, dbuf->length);
    isc_buffer_invalidate(dbuf);
    isc_mem_put(mctx, dbuf, sizeof(isc_buffer_t));
}