/*

 * Copyright 1998-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <openssl/objects.h>

#include "internal/e_os.h"

#include "internal/comp.h"

#include <openssl/err.h>

#include "crypto/cryptlib.h"

#include "internal/bio.h"

#include "internal/thread_once.h"

#include "comp_local.h"

COMP_METHOD *COMP_zlib(void);

#ifdef OPENSSL_NO_ZLIB

#undef ZLIB_SHARED

#else

#include <zlib.h>

static int zlib_stateful_init(COMP_CTX *ctx);

static void zlib_stateful_finish(COMP_CTX *ctx);

static ossl_ssize_t zlib_stateful_compress_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen);

static ossl_ssize_t zlib_stateful_expand_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen);

/* memory allocations functions for zlib initialisation */

static void *zlib_zalloc(void *opaque, unsigned int no, unsigned int size)

{

    void *p;

    p = OPENSSL_calloc(no, size);

    return p;

}

static void zlib_zfree(void *opaque, void *address)

{

    OPENSSL_free(address);

}

static COMP_METHOD zlib_stateful_method = {

    NID_zlib_compression,

    LN_zlib_compression,

    zlib_stateful_init,

    zlib_stateful_finish,

    zlib_stateful_compress_block,

    zlib_stateful_expand_block

};

/*

 * When OpenSSL is built on Windows, we do not want to require that

 * the ZLIB.DLL be available in order for the OpenSSL DLLs to

 * work.  Therefore, all ZLIB routines are loaded at run time

 * and we do not link to a .LIB file when ZLIB_SHARED is set.

 */

#ifdef ZLIB_SHARED

#include "internal/dso.h"

/* Function pointers */

typedef int (*compress_ft)(Bytef *dest, uLongf *destLen,

    const Bytef *source, uLong sourceLen);

typedef int (*uncompress_ft)(Bytef *dest, uLongf *destLen,

    const Bytef *source, uLong sourceLen);

typedef int (*inflateEnd_ft)(z_streamp strm);

typedef int (*inflate_ft)(z_streamp strm, int flush);

typedef int (*inflateInit__ft)(z_streamp strm,

    const char *version, int stream_size);

typedef int (*deflateEnd_ft)(z_streamp strm);

typedef int (*deflate_ft)(z_streamp strm, int flush);

typedef int (*deflateInit__ft)(z_streamp strm, int level,

    const char *version, int stream_size);

typedef const char *(*zError__ft)(int err);

static compress_ft p_compress = NULL;

static uncompress_ft p_uncompress = NULL;

static inflateEnd_ft p_inflateEnd = NULL;

static inflate_ft p_inflate = NULL;

static inflateInit__ft p_inflateInit_ = NULL;

static deflateEnd_ft p_deflateEnd = NULL;

static deflate_ft p_deflate = NULL;

static deflateInit__ft p_deflateInit_ = NULL;

static zError__ft p_zError = NULL;

static DSO *zlib_dso = NULL;

#define compress p_compress

#define uncompress p_uncompress

#define inflateEnd p_inflateEnd

#define inflate p_inflate

#define inflateInit_ p_inflateInit_

#define deflateEnd p_deflateEnd

#define deflate p_deflate

#define deflateInit_ p_deflateInit_

#define zError p_zError

#endif /* ZLIB_SHARED */

struct zlib_state {

    z_stream istream;

    z_stream ostream;

};

static int zlib_stateful_init(COMP_CTX *ctx)

{

    int err;

    struct zlib_state *state = OPENSSL_zalloc(sizeof(*state));

    if (state == NULL)

        goto err;

    state->istream.zalloc = zlib_zalloc;

    state->istream.zfree = zlib_zfree;

    state->istream.opaque = Z_NULL;

    state->istream.next_in = Z_NULL;

    state->istream.next_out = Z_NULL;

    err = inflateInit_(&state->istream, ZLIB_VERSION, sizeof(z_stream));

    if (err != Z_OK)

        goto err;

    state->ostream.zalloc = zlib_zalloc;

    state->ostream.zfree = zlib_zfree;

    state->ostream.opaque = Z_NULL;

    state->ostream.next_in = Z_NULL;

    state->ostream.next_out = Z_NULL;

    err = deflateInit_(&state->ostream, Z_DEFAULT_COMPRESSION,

        ZLIB_VERSION, sizeof(z_stream));

    if (err != Z_OK)

        goto err;

    ctx->data = state;

    return 1;

err:

    OPENSSL_free(state);

    return 0;

}

static void zlib_stateful_finish(COMP_CTX *ctx)

{

    struct zlib_state *state = ctx->data;

    inflateEnd(&state->istream);

    deflateEnd(&state->ostream);

    OPENSSL_free(state);

}

static ossl_ssize_t zlib_stateful_compress_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen)

{

    int err = Z_OK;

    struct zlib_state *state = ctx->data;

    if (state == NULL)

        return -1;

    state->ostream.next_in = in;

    state->ostream.avail_in = ilen;

    state->ostream.next_out = out;

    state->ostream.avail_out = olen;

    if (ilen > 0)

        err = deflate(&state->ostream, Z_SYNC_FLUSH);

    if (err != Z_OK)

        return -1;

    if (state->ostream.avail_out > olen)

        return -1;

    return (ossl_ssize_t)(olen - state->ostream.avail_out);

}

static ossl_ssize_t zlib_stateful_expand_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen)

{

    int err = Z_OK;

    struct zlib_state *state = ctx->data;

    if (state == NULL)

        return 0;

    state->istream.next_in = in;

    state->istream.avail_in = ilen;

    state->istream.next_out = out;

    state->istream.avail_out = olen;

    if (ilen > 0)

        err = inflate(&state->istream, Z_SYNC_FLUSH);

    if (err != Z_OK)

        return -1;

    if (state->istream.avail_out > olen)

        return -1;

    return (ossl_ssize_t)(olen - state->istream.avail_out);

}

/* ONESHOT COMPRESSION/DECOMPRESSION */

static int zlib_oneshot_init(COMP_CTX *ctx)

{

    return 1;

}

static void zlib_oneshot_finish(COMP_CTX *ctx)

{

}

static ossl_ssize_t zlib_oneshot_compress_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen)

{

    uLongf out_size;

    if (ilen == 0)

        return 0;

    /* zlib's uLongf defined as unsigned long FAR */

    if (olen > ULONG_MAX)

        return -1;

    out_size = (uLongf)olen;

    if (compress(out, &out_size, in, ilen) != Z_OK)

        return -1;

    if (out_size > OSSL_SSIZE_MAX)

        return -1;

    return (ossl_ssize_t)out_size;

}

static ossl_ssize_t zlib_oneshot_expand_block(COMP_CTX *ctx, unsigned char *out,

    size_t olen, unsigned char *in,

    size_t ilen)

{

    uLongf out_size;

    if (ilen == 0)

        return 0;

    /* zlib's uLongf defined as unsigned long FAR */

    if (olen > ULONG_MAX)

        return -1;

    out_size = (uLongf)olen;

    if (uncompress(out, &out_size, in, ilen) != Z_OK)

        return -1;

    if (out_size > OSSL_SSIZE_MAX)

        return -1;

    return (ossl_ssize_t)out_size;

}

static COMP_METHOD zlib_oneshot_method = {

    NID_zlib_compression,

    LN_zlib_compression,

    zlib_oneshot_init,

    zlib_oneshot_finish,

    zlib_oneshot_compress_block,

    zlib_oneshot_expand_block

};

static CRYPTO_ONCE zlib_once = CRYPTO_ONCE_STATIC_INIT;

DEFINE_RUN_ONCE_STATIC(ossl_comp_zlib_init)

{

#ifdef ZLIB_SHARED

    /* LIBZ may be externally defined, and we should respect that value */

#ifndef LIBZ

#if defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_WIN32)

#define LIBZ "ZLIB1"

#elif defined(OPENSSL_SYS_VMS)

#define LIBZ "LIBZ"

#else

#define LIBZ "z"

#endif

#endif

    zlib_dso = DSO_load(NULL, LIBZ, NULL, 0);

    if (zlib_dso != NULL) {

        p_compress = (compress_ft)DSO_bind_func(zlib_dso, "compress");

        p_uncompress = (uncompress_ft)DSO_bind_func(zlib_dso, "uncompress");

        p_inflateEnd = (inflateEnd_ft)DSO_bind_func(zlib_dso, "inflateEnd");

        p_inflate = (inflate_ft)DSO_bind_func(zlib_dso, "inflate");

        p_inflateInit_ = (inflateInit__ft)DSO_bind_func(zlib_dso, "inflateInit_");

        p_deflateEnd = (deflateEnd_ft)DSO_bind_func(zlib_dso, "deflateEnd");

        p_deflate = (deflate_ft)DSO_bind_func(zlib_dso, "deflate");

        p_deflateInit_ = (deflateInit__ft)DSO_bind_func(zlib_dso, "deflateInit_");

        p_zError = (zError__ft)DSO_bind_func(zlib_dso, "zError");

    }

    if (p_compress == NULL || p_uncompress == NULL || p_inflateEnd == NULL

        || p_inflate == NULL || p_inflateInit_ == NULL

        || p_deflateEnd == NULL || p_deflate == NULL

        || p_deflateInit_ == NULL || p_zError == NULL) {

        ossl_comp_zlib_cleanup();

        return 0;

    }

#endif

    return 1;

}

#endif

COMP_METHOD *COMP_zlib(void)

{

    COMP_METHOD *meth = NULL;

#ifndef OPENSSL_NO_ZLIB

    if (RUN_ONCE(&zlib_once, ossl_comp_zlib_init))

        meth = &zlib_stateful_method;

#endif

    return meth;

}

COMP_METHOD *COMP_zlib_oneshot(void)

{

    COMP_METHOD *meth = NULL;

#ifndef OPENSSL_NO_ZLIB

    if (RUN_ONCE(&zlib_once, ossl_comp_zlib_init))

        meth = &zlib_oneshot_method;

#endif

    return meth;

}

/* Also called from OPENSSL_cleanup() */

void ossl_comp_zlib_cleanup(void)

{

#ifdef ZLIB_SHARED

    DSO_free(zlib_dso);

    zlib_dso = NULL;

#endif

}

#ifndef OPENSSL_NO_ZLIB

/* Zlib based compression/decompression filter BIO */

typedef struct {

    unsigned char *ibuf; /* Input buffer */

    int ibufsize; /* Buffer size */

    z_stream zin; /* Input decompress context */

    unsigned char *obuf; /* Output buffer */

    int obufsize; /* Output buffer size */

    unsigned char *optr; /* Position in output buffer */

    int ocount; /* Amount of data in output buffer */

    int odone; /* deflate EOF */

    int comp_level; /* Compression level to use */

    z_stream zout; /* Output compression context */

} BIO_ZLIB_CTX;

#define ZLIB_DEFAULT_BUFSIZE 1024

static int bio_zlib_new(BIO *bi);

static int bio_zlib_free(BIO *bi);

static int bio_zlib_read(BIO *b, char *out, int outl);

static int bio_zlib_write(BIO *b, const char *in, int inl);

static long bio_zlib_ctrl(BIO *b, int cmd, long num, void *ptr);

static long bio_zlib_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp);

static const BIO_METHOD bio_meth_zlib = {

    BIO_TYPE_COMP,

    "zlib",

    bwrite_conv,

    bio_zlib_write,

    bread_conv,

    bio_zlib_read,

    NULL, /* bio_zlib_puts, */

    NULL, /* bio_zlib_gets, */

    bio_zlib_ctrl,

    bio_zlib_new,

    bio_zlib_free,

    bio_zlib_callback_ctrl

};

#endif

const BIO_METHOD *BIO_f_zlib(void)

{

#ifndef OPENSSL_NO_ZLIB

    if (RUN_ONCE(&zlib_once, ossl_comp_zlib_init))

        return &bio_meth_zlib;

#endif

    return NULL;

}

#ifndef OPENSSL_NO_ZLIB

static int bio_zlib_new(BIO *bi)

{

    BIO_ZLIB_CTX *ctx;

#ifdef ZLIB_SHARED

    if (!RUN_ONCE(&zlib_once, ossl_comp_zlib_init)) {

        ERR_raise(ERR_LIB_COMP, COMP_R_ZLIB_NOT_SUPPORTED);

        return 0;

    }

#endif

    ctx = OPENSSL_zalloc(sizeof(*ctx));

    if (ctx == NULL)

        return 0;

    ctx->ibufsize = ZLIB_DEFAULT_BUFSIZE;

    ctx->obufsize = ZLIB_DEFAULT_BUFSIZE;

    ctx->zin.zalloc = Z_NULL;

    ctx->zin.zfree = Z_NULL;

    ctx->zout.zalloc = Z_NULL;

    ctx->zout.zfree = Z_NULL;

    ctx->comp_level = Z_DEFAULT_COMPRESSION;

    BIO_set_init(bi, 1);

    BIO_set_data(bi, ctx);

    return 1;

}

static int bio_zlib_free(BIO *bi)

{

    BIO_ZLIB_CTX *ctx;

    if (!bi)

        return 0;

    ctx = BIO_get_data(bi);

    if (ctx->ibuf) {

        /* Destroy decompress context */

        inflateEnd(&ctx->zin);

        OPENSSL_free(ctx->ibuf);

    }

    if (ctx->obuf) {

        /* Destroy compress context */

        deflateEnd(&ctx->zout);

        OPENSSL_free(ctx->obuf);

    }

    OPENSSL_free(ctx);

    BIO_set_data(bi, NULL);

    BIO_set_init(bi, 0);

    return 1;

}

static int bio_zlib_read(BIO *b, char *out, int outl)

{

    BIO_ZLIB_CTX *ctx;

    int ret;

    z_stream *zin;

    BIO *next = BIO_next(b);

    if (!out || !outl)

        return 0;

    ctx = BIO_get_data(b);

    zin = &ctx->zin;

    BIO_clear_retry_flags(b);

    if (!ctx->ibuf) {

        ctx->ibuf = OPENSSL_malloc(ctx->ibufsize);

        if (ctx->ibuf == NULL)

            return 0;

        if ((ret = inflateInit(zin)) != Z_OK) {

            ERR_raise_data(ERR_LIB_COMP, COMP_R_ZLIB_INFLATE_ERROR,

                "zlib error: %s", zError(ret));

            return 0;

        }

        zin->next_in = ctx->ibuf;

        zin->avail_in = 0;

    }

    /* Copy output data directly to supplied buffer */

    zin->next_out = (unsigned char *)out;

    zin->avail_out = (unsigned int)outl;

    for (;;) {

        /* Decompress while data available */

        while (zin->avail_in) {

            ret = inflate(zin, 0);

            if ((ret != Z_OK) && (ret != Z_STREAM_END)) {

                ERR_raise_data(ERR_LIB_COMP, COMP_R_ZLIB_INFLATE_ERROR,

                    "zlib error: %s", zError(ret));

                return 0;

            }

            /* If EOF or we've read everything then return */

            if ((ret == Z_STREAM_END) || !zin->avail_out)

                return outl - zin->avail_out;

        }

        /*

         * No data in input buffer try to read some in, if an error then

         * return the total data read.

         */

        ret = BIO_read(next, ctx->ibuf, ctx->ibufsize);

        if (ret <= 0) {

            /* Total data read */

            int tot = outl - zin->avail_out;

            BIO_copy_next_retry(b);

            if (ret < 0)

                return (tot > 0) ? tot : ret;

            return tot;

        }

        zin->avail_in = ret;

        zin->next_in = ctx->ibuf;

    }

}

static int bio_zlib_write(BIO *b, const char *in, int inl)

{

    BIO_ZLIB_CTX *ctx;

    int ret;

    z_stream *zout;

    BIO *next = BIO_next(b);

    if (!in || !inl)

        return 0;

    ctx = BIO_get_data(b);

    if (ctx->odone)

        return 0;

    zout = &ctx->zout;

    BIO_clear_retry_flags(b);

    if (!ctx->obuf) {

        ctx->obuf = OPENSSL_malloc(ctx->obufsize);

        /* Need error here */

        if (ctx->obuf == NULL)

            return 0;

        ctx->optr = ctx->obuf;

        ctx->ocount = 0;

        if ((ret = deflateInit(zout, ctx->comp_level)) != Z_OK) {

            ERR_raise_data(ERR_LIB_COMP, COMP_R_ZLIB_DEFLATE_ERROR,

                "zlib error: %s", zError(ret));

            return 0;

        }

        zout->next_out = ctx->obuf;

        zout->avail_out = ctx->obufsize;

    }

    /* Obtain input data directly from supplied buffer */

    zout->next_in = (void *)in;

    zout->avail_in = inl;

    for (;;) {

        /* If data in output buffer write it first */

        while (ctx->ocount) {

            ret = BIO_write(next, ctx->optr, ctx->ocount);

            if (ret <= 0) {

                /* Total data written */

                int tot = inl - zout->avail_in;

                BIO_copy_next_retry(b);

                if (ret < 0)

                    return (tot > 0) ? tot : ret;

                return tot;

            }

            ctx->optr += ret;

            ctx->ocount -= ret;

        }

        /* Have we consumed all supplied data? */

        if (!zout->avail_in)

            return inl;

        /* Compress some more */

        /* Reset buffer */

        ctx->optr = ctx->obuf;

        zout->next_out = ctx->obuf;

        zout->avail_out = ctx->obufsize;

        /* Compress some more */

        ret = deflate(zout, 0);

        if (ret != Z_OK) {

            ERR_raise_data(ERR_LIB_COMP, COMP_R_ZLIB_DEFLATE_ERROR,

                "zlib error: %s", zError(ret));

            return 0;

        }

        ctx->ocount = ctx->obufsize - zout->avail_out;

    }

}

static int bio_zlib_flush(BIO *b)

{

    BIO_ZLIB_CTX *ctx;

    int ret;

    z_stream *zout;

    BIO *next = BIO_next(b);

    ctx = BIO_get_data(b);

    /* If no data written or already flush show success */

    if (!ctx->obuf || (ctx->odone && !ctx->ocount))

        return 1;

    zout = &ctx->zout;

    BIO_clear_retry_flags(b);

    /* No more input data */

    zout->next_in = NULL;

    zout->avail_in = 0;

    for (;;) {

        /* If data in output buffer write it first */

        while (ctx->ocount) {

            ret = BIO_write(next, ctx->optr, ctx->ocount);

            if (ret <= 0) {

                BIO_copy_next_retry(b);

                return ret;

            }

            ctx->optr += ret;

            ctx->ocount -= ret;

        }

        if (ctx->odone)

            return 1;

        /* Compress some more */

        /* Reset buffer */

        ctx->optr = ctx->obuf;

        zout->next_out = ctx->obuf;

        zout->avail_out = ctx->obufsize;

        /* Compress some more */

        ret = deflate(zout, Z_FINISH);

        if (ret == Z_STREAM_END)

            ctx->odone = 1;

        else if (ret != Z_OK) {

            ERR_raise_data(ERR_LIB_COMP, COMP_R_ZLIB_DEFLATE_ERROR,

                "zlib error: %s", zError(ret));

            return 0;

        }

        ctx->ocount = ctx->obufsize - zout->avail_out;

    }

}

static long bio_zlib_ctrl(BIO *b, int cmd, long num, void *ptr)

{

    BIO_ZLIB_CTX *ctx;

    int ret, *ip;

    int ibs, obs;

    BIO *next = BIO_next(b);

    if (next == NULL)

        return 0;

    ctx = BIO_get_data(b);

    switch (cmd) {

    case BIO_CTRL_RESET:

        ctx->ocount = 0;

        ctx->odone = 0;

        ret = 1;

        break;

    case BIO_CTRL_FLUSH:

        ret = bio_zlib_flush(b);

        if (ret > 0) {

            ret = BIO_flush(next);

            BIO_copy_next_retry(b);

        }

        break;

    case BIO_C_SET_BUFF_SIZE:

        ibs = -1;

        obs = -1;

        if (ptr != NULL) {

            ip = ptr;

            if (*ip == 0)

                ibs = (int)num;

            else

                obs = (int)num;

        } else {

            ibs = (int)num;

            obs = ibs;

        }

        if (ibs != -1) {

            OPENSSL_free(ctx->ibuf);

            ctx->ibuf = NULL;

            ctx->ibufsize = ibs;

        }

        if (obs != -1) {

            OPENSSL_free(ctx->obuf);

            ctx->obuf = NULL;

            ctx->obufsize = obs;

        }

        ret = 1;

        break;

    case BIO_C_DO_STATE_MACHINE:

        BIO_clear_retry_flags(b);

        ret = BIO_ctrl(next, cmd, num, ptr);

        BIO_copy_next_retry(b);

        break;

    case BIO_CTRL_WPENDING:

        if (ctx->obuf == NULL)

            return 0;

        if (ctx->odone) {

            ret = ctx->ocount;

        } else {

            ret = ctx->ocount;

            if (ret == 0)

                /* Unknown amount pending but we are not finished */

                ret = 1;

        }

        if (ret == 0)

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_PENDING:

        ret = ctx->zin.avail_in;

        if (ret == 0)

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    default:

        ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    }

    return ret;

}

static long bio_zlib_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)

{

    BIO *next = BIO_next(b);

    if (next == NULL)

        return 0;

    return BIO_callback_ctrl(next, cmd, fp);

}

#endif