Rename OSSL_SERIALIZER / OSSL_DESERIALIZER to OSSL_ENCODE / OSSL_DECODE

Fixes #12455

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12660)

11 files changed, 2625 insertions, 0 deletions

diff --git a/crypto/encode_decode/build.info b/crypto/encode_decode/build.info
new file mode 100644
index 0000000000..4686c4a19d
--- /dev/null
+++ b/crypto/encode_decode/build.info
@@ -0,0 +1,8 @@
+SOURCE[../../libcrypto]=endecode_pass.c
+
+SOURCE[../../libcrypto]=encoder_meth.c encoder_lib.c encoder_pkey.c
+SOURCE[../../libcrypto]=decoder_meth.c decoder_lib.c \
+        decoder_pkey.c
+
+SOURCE[../../libcrypto]=encoder_err.c
+SOURCE[../../libcrypto]=decoder_err.c
diff --git a/crypto/encode_decode/decoder_err.c b/crypto/encode_decode/decoder_err.c
new file mode 100644
index 0000000000..984f7abeb9
--- /dev/null
+++ b/crypto/encode_decode/decoder_err.c
@@ -0,0 +1,31 @@
+/*
+ * Generated by util/mkerr.pl DO NOT EDIT
+ * Copyright 1995-2020 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 <openssl/err.h>
+#include <openssl/decodererr.h>
+
+#ifndef OPENSSL_NO_ERR
+
+static const ERR_STRING_DATA OSSL_DECODER_str_reasons[] = {
+    {ERR_PACK(ERR_LIB_OSSL_DECODER, 0, OSSL_DECODER_R_MISSING_GET_PARAMS),
+     "missing get params"},
+    {0, NULL}
+};
+
+#endif
+
+int ERR_load_OSSL_DECODER_strings(void)
+{
+#ifndef OPENSSL_NO_ERR
+    if (ERR_reason_error_string(OSSL_DECODER_str_reasons[0].error) == NULL)
+        ERR_load_strings_const(OSSL_DECODER_str_reasons);
+#endif
+    return 1;
+}
diff --git a/crypto/encode_decode/decoder_lib.c b/crypto/encode_decode/decoder_lib.c
new file mode 100644
index 0000000000..21b4703084
--- /dev/null
+++ b/crypto/encode_decode/decoder_lib.c
@@ -0,0 +1,483 @@
+/*
+ * Copyright 2020 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 <openssl/core_names.h>
+#include <openssl/bio.h>
+#include <openssl/params.h>
+#include <openssl/provider.h>
+#include "encoder_local.h"
+#include "e_os.h"
+
+struct decoder_process_data_st {
+    OSSL_DECODER_CTX *ctx;
+
+    /* Current BIO */
+    BIO *bio;
+
+    /* Index of the current decoder instance to be processed */
+    size_t current_deser_inst_index;
+};
+
+static int decoder_process(const OSSL_PARAM params[], void *arg);
+
+int OSSL_DECODER_from_bio(OSSL_DECODER_CTX *ctx, BIO *in)
+{
+    struct decoder_process_data_st data;
+    int ok = 0;
+
+    memset(&data, 0, sizeof(data));
+    data.ctx = ctx;
+    data.bio = in;
+
+    ok = decoder_process(NULL, &data);
+
+    /* Clear any internally cached passphrase */
+    if (!ctx->flag_user_passphrase) {
+        OSSL_DECODER_CTX_set_passphrase(ctx, NULL, 0);
+        ctx->flag_user_passphrase = 0;
+    }
+    return ok;
+}
+
+#ifndef OPENSSL_NO_STDIO
+static BIO *bio_from_file(FILE *fp)
+{
+    BIO *b;
+
+    if ((b = BIO_new(BIO_s_file())) == NULL) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_BIO_LIB);
+        return NULL;
+    }
+    BIO_set_fp(b, fp, BIO_NOCLOSE);
+    return b;
+}
+
+int OSSL_DECODER_from_fp(OSSL_DECODER_CTX *ctx, FILE *fp)
+{
+    BIO *b = bio_from_file(fp);
+    int ret = 0;
+
+    if (b != NULL)
+        ret = OSSL_DECODER_from_bio(ctx, b);
+
+    BIO_free(b);
+    return ret;
+}
+#endif
+
+int OSSL_DECODER_CTX_set_input_type(OSSL_DECODER_CTX *ctx,
+                                    const char *input_type)
+{
+    if (!ossl_assert(ctx != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    /*
+     * NULL is a valid starting input type, and means that the caller leaves
+     * it to code to discover what the starting input type is.
+     */
+    ctx->start_input_type = input_type;
+    return 1;
+}
+
+int OSSL_DECODER_CTX_add_decoder(OSSL_DECODER_CTX *ctx, OSSL_DECODER *decoder)
+{
+    OSSL_DECODER_INSTANCE *decoder_inst = NULL;
+    const OSSL_PROVIDER *prov = NULL;
+    OSSL_PARAM params[2];
+    void *provctx = NULL;
+
+    if (!ossl_assert(ctx != NULL) || !ossl_assert(decoder != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    if (decoder->get_params == NULL) {
+        ERR_raise(ERR_LIB_OSSL_DECODER,
+                  OSSL_DECODER_R_MISSING_GET_PARAMS);
+        return 0;
+    }
+
+    if (ctx->decoder_insts == NULL
+        && (ctx->decoder_insts =
+            sk_OSSL_DECODER_INSTANCE_new_null()) == NULL) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+    if ((decoder_inst = OPENSSL_zalloc(sizeof(*decoder_inst))) == NULL) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+    if (!OSSL_DECODER_up_ref(decoder)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+    decoder_inst->decoder = decoder;
+
+    prov = OSSL_DECODER_provider(decoder_inst->decoder);
+    provctx = OSSL_PROVIDER_get0_provider_ctx(prov);
+
+    /* Cache the input type for this encoder */
+    params[0] =
+        OSSL_PARAM_construct_utf8_ptr(OSSL_DECODER_PARAM_INPUT_TYPE,
+                                      (char **)&decoder_inst->input_type, 0);
+    params[1] = OSSL_PARAM_construct_end();
+
+    if (!decoder_inst->decoder->get_params(params)
+        || !OSSL_PARAM_modified(&params[0]))
+        goto err;
+
+    if ((decoder_inst->deserctx = decoder_inst->decoder->newctx(provctx))
+        == NULL)
+        goto err;
+
+    if (sk_OSSL_DECODER_INSTANCE_push(ctx->decoder_insts, decoder_inst) <= 0)
+        goto err;
+
+    return 1;
+ err:
+    if (decoder_inst != NULL) {
+        if (decoder_inst->decoder != NULL)
+            decoder_inst->decoder->freectx(decoder_inst->deserctx);
+        OSSL_DECODER_free(decoder_inst->decoder);
+        OPENSSL_free(decoder_inst);
+    }
+    return 0;
+}
+
+int OSSL_DECODER_CTX_add_extra(OSSL_DECODER_CTX *ctx,
+                               OPENSSL_CTX *libctx, const char *propq)
+{
+    /*
+     * This function goes through existing decoder methods in
+     * |ctx->decoder_insts|, and tries to fetch new decoders that produce
+     * what the existing ones want as input, and push those newly fetched
+     * decoders on top of the same stack.
+     * Then it does the same again, but looping over the newly fetched
+     * decoders, until there are no more encoders to be fetched, or
+     * when we have done this 10 times.
+     *
+     * we do this with sliding windows on the stack by keeping track of indexes
+     * and of the end.
+     *
+     * +----------------+
+     * |   DER to RSA   | <--- w_prev_start
+     * +----------------+
+     * |   DER to DSA   |
+     * +----------------+
+     * |   DER to DH    |
+     * +----------------+
+     * |   PEM to DER   | <--- w_prev_end, w_new_start
+     * +----------------+
+     *                    <--- w_new_end
+     */
+    size_t w_prev_start, w_prev_end; /* "previous" decoders */
+    size_t w_new_start, w_new_end;   /* "new" decoders */
+    size_t count = 0; /* Calculates how many were added in each iteration */
+    size_t depth = 0; /* Counts the number of iterations */
+
+    if (!ossl_assert(ctx != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    /*
+     * If there is no stack of OSSL_DECODER_INSTANCE, we have nothing
+     * more to add.  That's fine.
+     */
+    if (ctx->decoder_insts == NULL)
+        return 1;
+
+    w_prev_start = 0;
+    w_prev_end = sk_OSSL_DECODER_INSTANCE_num(ctx->decoder_insts);
+    do {
+        size_t i;
+
+        w_new_start = w_new_end = w_prev_end;
+
+        for (i = w_prev_start; i < w_prev_end; i++) {
+            OSSL_DECODER_INSTANCE *decoder_inst =
+                sk_OSSL_DECODER_INSTANCE_value(ctx->decoder_insts, i);
+            const char *name = decoder_inst->input_type;
+            OSSL_DECODER *decoder = NULL;
+
+            /*
+             * If the caller has specified what the initial input should be,
+             * and the decoder implementation we're looking at has that
+             * input type, there's no point adding on more implementations
+             * on top of this one, so we don't.
+             */
+            if (ctx->start_input_type != NULL
+                && strcasecmp(ctx->start_input_type,
+                              decoder_inst->input_type) != 0)
+                continue;
+
+            ERR_set_mark();
+            decoder = OSSL_DECODER_fetch(libctx, name, propq);
+            ERR_pop_to_mark();
+
+            if (decoder != NULL) {
+                size_t j;
+
+                /*
+                 * Check that we don't already have this decoder in our
+                 * stack We only need to check among the newly added ones.
+                 */
+                for (j = w_new_start; j < w_new_end; j++) {
+                    OSSL_DECODER_INSTANCE *check_inst =
+                        sk_OSSL_DECODER_INSTANCE_value(ctx->decoder_insts, j);
+
+                    if (decoder == check_inst->decoder) {
+                        /* We found it, so drop the new fetch */
+                        OSSL_DECODER_free(decoder);
+                        decoder = NULL;
+                        break;
+                    }
+                }
+            }
+
+            if (decoder == NULL)
+                continue;
+
+            /*
+             * Apart from keeping w_new_end up to date, We don't care about
+             * errors here.  If it doesn't collect, then it doesn't...
+             */
+            if (OSSL_DECODER_CTX_add_decoder(ctx, decoder)) /* ref++ */
+                w_new_end++;
+            OSSL_DECODER_free(decoder); /* ref-- */
+        }
+        /* How many were added in this iteration */
+        count = w_new_end - w_new_start;
+
+        /* Slide the "previous decoder" windows */
+        w_prev_start = w_new_start;
+        w_prev_end = w_new_end;
+
+        depth++;
+    } while (count != 0 && depth <= 10);
+
+    return 1;
+}
+
+int OSSL_DECODER_CTX_num_decoders(OSSL_DECODER_CTX *ctx)
+{
+    if (ctx == NULL || ctx->decoder_insts == NULL)
+        return 0;
+    return sk_OSSL_DECODER_INSTANCE_num(ctx->decoder_insts);
+}
+
+int OSSL_DECODER_CTX_set_construct(OSSL_DECODER_CTX *ctx,
+                                   OSSL_DECODER_CONSTRUCT *construct)
+{
+    if (!ossl_assert(ctx != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ctx->construct = construct;
+    return 1;
+}
+
+int OSSL_DECODER_CTX_set_construct_data(OSSL_DECODER_CTX *ctx,
+                                        void *construct_data)
+{
+    if (!ossl_assert(ctx != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ctx->construct_data = construct_data;
+    return 1;
+}
+
+int OSSL_DECODER_CTX_set_cleanup(OSSL_DECODER_CTX *ctx,
+                                 OSSL_DECODER_CLEANUP *cleanup)
+{
+    if (!ossl_assert(ctx != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+    ctx->cleanup = cleanup;
+    return 1;
+}
+
+OSSL_DECODER_CONSTRUCT *
+OSSL_DECODER_CTX_get_construct(OSSL_DECODER_CTX *ctx)
+{
+    if (ctx == NULL)
+        return NULL;
+    return ctx->construct;
+}
+
+void *OSSL_DECODER_CTX_get_construct_data(OSSL_DECODER_CTX *ctx)
+{
+    if (ctx == NULL)
+        return NULL;
+    return ctx->construct_data;
+}
+
+OSSL_DECODER_CLEANUP *
+OSSL_DECODER_CTX_get_cleanup(OSSL_DECODER_CTX *ctx)
+{
+    if (ctx == NULL)
+        return NULL;
+    return ctx->cleanup;
+}
+
+int OSSL_DECODER_export(OSSL_DECODER_INSTANCE *decoder_inst,
+                        void *reference, size_t reference_sz,
+                        OSSL_CALLBACK *export_cb, void *export_cbarg)
+{
+    if (!(ossl_assert(decoder_inst != NULL)
+          && ossl_assert(reference != NULL)
+          && ossl_assert(export_cb != NULL)
+          && ossl_assert(export_cbarg != NULL))) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    return decoder_inst->decoder->export_object(decoder_inst->deserctx,
+                                                reference, reference_sz,
+                                                export_cb, export_cbarg);
+}
+
+OSSL_DECODER *OSSL_DECODER_INSTANCE_decoder(OSSL_DECODER_INSTANCE *decoder_inst)
+{
+    if (decoder_inst == NULL)
+        return NULL;
+    return decoder_inst->decoder;
+}
+
+void *OSSL_DECODER_INSTANCE_decoder_ctx(OSSL_DECODER_INSTANCE *decoder_inst)
+{
+    if (decoder_inst == NULL)
+        return NULL;
+    return decoder_inst->deserctx;
+}
+
+static int decoder_process(const OSSL_PARAM params[], void *arg)
+{
+    struct decoder_process_data_st *data = arg;
+    OSSL_DECODER_CTX *ctx = data->ctx;
+    OSSL_DECODER_INSTANCE *decoder_inst = NULL;
+    OSSL_DECODER *decoder = NULL;
+    BIO *bio = data->bio;
+    long loc;
+    size_t i;
+    int ok = 0;
+    /* For recursions */
+    struct decoder_process_data_st new_data;
+
+    memset(&new_data, 0, sizeof(new_data));
+    new_data.ctx = data->ctx;
+
+    if (params == NULL) {
+        /* First iteration, where we prepare for what is to come */
+
+        data->current_deser_inst_index =
+            OSSL_DECODER_CTX_num_decoders(ctx);
+
+        bio = data->bio;
+    } else {
+        const OSSL_PARAM *p;
+
+        decoder_inst =
+            sk_OSSL_DECODER_INSTANCE_value(ctx->decoder_insts,
+                                           data->current_deser_inst_index);
+        decoder = OSSL_DECODER_INSTANCE_decoder(decoder_inst);
+
+        if (ctx->construct != NULL
+            && ctx->construct(decoder_inst, params, ctx->construct_data)) {
+            ok = 1;
+            goto end;
+        }
+
+        /* The constructor didn't return success */
+
+        /*
+         * so we try to use the object we got and feed it to any next
+         * decoder that will take it.  Object references are not
+         * allowed for this.
+         * If this data isn't present, decoding has failed.
+         */
+
+        p = OSSL_PARAM_locate_const(params, OSSL_DECODER_PARAM_DATA);
+        if (p == NULL || p->data_type != OSSL_PARAM_OCTET_STRING)
+            goto end;
+        new_data.bio = BIO_new_mem_buf(p->data, (int)p->data_size);
+        if (new_data.bio == NULL)
+            goto end;
+        bio = new_data.bio;
+    }
+
+    /*
+     * If we have no more decoders to look through at this point,
+     * we failed
+     */
+    if (data->current_deser_inst_index == 0)
+        goto end;
+
+    if ((loc = BIO_tell(bio)) < 0) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_BIO_LIB);
+        goto end;
+    }
+
+    for (i = data->current_deser_inst_index; i-- > 0;) {
+        OSSL_DECODER_INSTANCE *new_deser_inst =
+            sk_OSSL_DECODER_INSTANCE_value(ctx->decoder_insts, i);
+        OSSL_DECODER *new_deser =
+            OSSL_DECODER_INSTANCE_decoder(new_deser_inst);
+
+        /*
+         * If |decoder| is NULL, it means we've just started, and the caller
+         * may have specified what it expects the initial input to be.  If
+         * that's the case, we do this extra check.
+         */
+        if (decoder == NULL && ctx->start_input_type != NULL
+            && strcasecmp(ctx->start_input_type,
+                          new_deser_inst->input_type) != 0)
+            continue;
+
+        /*
+         * If we have a previous decoder, we check that the input type
+         * of the next to be used matches the type of this previous one.
+         * decoder_inst->input_type is a cache of the parameter "input-type"
+         * value for that decoder.
+         */
+        if (decoder != NULL
+            && !OSSL_DECODER_is_a(decoder, new_deser_inst->input_type))
+            continue;
+
+        /*
+         * Checking the return value of BIO_reset() or BIO_seek() is unsafe.
+         * Furthermore, BIO_reset() is unsafe to use if the source BIO happens
+         * to be a BIO_s_mem(), because the earlier BIO_tell() gives us zero
+         * no matter where we are in the underlying buffer we're reading from.
+         *
+         * So, we simply do a BIO_seek(), and use BIO_tell() that we're back
+         * at the same position.  This is a best effort attempt, but BIO_seek()
+         * and BIO_tell() should come as a pair...
+         */
+        (void)BIO_seek(bio, loc);
+        if (BIO_tell(bio) != loc)
+            goto end;
+
+        /* Recurse */
+        new_data.current_deser_inst_index = i;
+        ok = new_deser->decode(new_deser_inst->deserctx, (OSSL_CORE_BIO *)bio,
+                               decoder_process, &new_data,
+                               ctx->passphrase_cb, new_data.ctx);
+        if (ok)
+            break;
+    }
+
+ end:
+    BIO_free(new_data.bio);
+    return ok;
+}
diff --git a/crypto/encode_decode/decoder_meth.c b/crypto/encode_decode/decoder_meth.c
new file mode 100644
index 0000000000..2259c6348a
--- /dev/null
+++ b/crypto/encode_decode/decoder_meth.c
@@ -0,0 +1,552 @@
+/*
+ * Copyright 2020 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 <openssl/core.h>
+#include <openssl/core_dispatch.h>
+#include <openssl/decoder.h>
+#include <openssl/ui.h>
+#include "internal/core.h"
+#include "internal/namemap.h"
+#include "internal/property.h"
+#include "internal/provider.h"
+#include "crypto/encoder.h"
+#include "encoder_local.h"
+
+static void OSSL_DECODER_INSTANCE_free(OSSL_DECODER_INSTANCE *instance);
+
+/*
+ * Decoder can have multiple names, separated with colons in a name string
+ */
+#define NAME_SEPARATOR ':'
+
+/* Simple method structure constructor and destructor */
+static OSSL_DECODER *ossl_decoder_new(void)
+{
+    OSSL_DECODER *decoder = NULL;
+
+    if ((decoder = OPENSSL_zalloc(sizeof(*decoder))) == NULL
+        || (decoder->base.lock = CRYPTO_THREAD_lock_new()) == NULL) {
+        OSSL_DECODER_free(decoder);
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_MALLOC_FAILURE);
+        return NULL;
+    }
+
+    decoder->base.refcnt = 1;
+
+    return decoder;
+}
+
+int OSSL_DECODER_up_ref(OSSL_DECODER *decoder)
+{
+    int ref = 0;
+
+    CRYPTO_UP_REF(&decoder->base.refcnt, &ref, decoder->base.lock);
+    return 1;
+}
+
+void OSSL_DECODER_free(OSSL_DECODER *decoder)
+{
+    int ref = 0;
+
+    if (decoder == NULL)
+        return;
+
+    CRYPTO_DOWN_REF(&decoder->base.refcnt, &ref, decoder->base.lock);
+    if (ref > 0)
+        return;
+    ossl_provider_free(decoder->base.prov);
+    CRYPTO_THREAD_lock_free(decoder->base.lock);
+    OPENSSL_free(decoder);
+}
+
+/* Permanent decoder method store, constructor and destructor */
+static void decoder_store_free(void *vstore)
+{
+    ossl_method_store_free(vstore);
+}
+
+static void *decoder_store_new(OPENSSL_CTX *ctx)
+{
+    return ossl_method_store_new(ctx);
+}
+
+
+static const OPENSSL_CTX_METHOD decoder_store_method = {
+    decoder_store_new,
+    decoder_store_free,
+};
+
+/* Data to be passed through ossl_method_construct() */
+struct decoder_data_st {
+    OPENSSL_CTX *libctx;
+    OSSL_METHOD_CONSTRUCT_METHOD *mcm;
+    int id;                      /* For get_decoder_from_store() */
+    const char *names;           /* For get_decoder_from_store() */
+    const char *propquery;       /* For get_decoder_from_store() */
+};
+
+/*
+ * Generic routines to fetch / create DECODER methods with
+ * ossl_method_construct()
+ */
+
+/* Temporary decoder method store, constructor and destructor */
+static void *alloc_tmp_decoder_store(OPENSSL_CTX *ctx)
+{
+    return ossl_method_store_new(ctx);
+}
+
+static void dealloc_tmp_decoder_store(void *store)
+{
+    if (store != NULL)
+        ossl_method_store_free(store);
+}
+
+/* Get the permanent decoder store */
+static OSSL_METHOD_STORE *get_decoder_store(OPENSSL_CTX *libctx)
+{
+    return openssl_ctx_get_data(libctx, OPENSSL_CTX_DECODER_STORE_INDEX,
+                                &decoder_store_method);
+}
+
+/* Get decoder methods from a store, or put one in */
+static void *get_decoder_from_store(OPENSSL_CTX *libctx, void *store,
+                                    void *data)
+{
+    struct decoder_data_st *methdata = data;
+    void *method = NULL;
+    int id;
+
+    if ((id = methdata->id) == 0) {
+        OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
+
+        id = ossl_namemap_name2num(namemap, methdata->names);
+    }
+
+    if (store == NULL
+        && (store = get_decoder_store(libctx)) == NULL)
+        return NULL;
+
+    if (!ossl_method_store_fetch(store, id, methdata->propquery, &method))
+        return NULL;
+    return method;
+}
+
+static int put_decoder_in_store(OPENSSL_CTX *libctx, void *store,
+                                void *method, const OSSL_PROVIDER *prov,
+                                int operation_id, const char *names,
+                                const char *propdef, void *unused)
+{
+    OSSL_NAMEMAP *namemap;
+    int id;
+
+    if ((namemap = ossl_namemap_stored(libctx)) == NULL
+        || (id = ossl_namemap_name2num(namemap, names)) == 0)
+        return 0;
+
+    if (store == NULL && (store = get_decoder_store(libctx)) == NULL)
+        return 0;
+
+    return ossl_method_store_add(store, prov, id, propdef, method,
+                                 (int (*)(void *))OSSL_DECODER_up_ref,
+                                 (void (*)(void *))OSSL_DECODER_free);
+}
+
+/* Create and populate a decoder method */
+static void *decoder_from_dispatch(int id, const OSSL_ALGORITHM *algodef,
+                                   OSSL_PROVIDER *prov)
+{
+    OSSL_DECODER *decoder = NULL;
+    const OSSL_DISPATCH *fns = algodef->implementation;
+
+    if ((decoder = ossl_decoder_new()) == NULL)
+        return NULL;
+    decoder->base.id = id;
+    decoder->base.propdef = algodef->property_definition;
+
+    for (; fns->function_id != 0; fns++) {
+        switch (fns->function_id) {
+        case OSSL_FUNC_DECODER_NEWCTX:
+            if (decoder->newctx == NULL)
+                decoder->newctx = OSSL_FUNC_decoder_newctx(fns);
+            break;
+        case OSSL_FUNC_DECODER_FREECTX:
+            if (decoder->freectx == NULL)
+                decoder->freectx = OSSL_FUNC_decoder_freectx(fns);
+            break;
+        case OSSL_FUNC_DECODER_GET_PARAMS:
+            if (decoder->get_params == NULL)
+                decoder->get_params =
+                    OSSL_FUNC_decoder_get_params(fns);
+            break;
+        case OSSL_FUNC_DECODER_GETTABLE_PARAMS:
+            if (decoder->gettable_params == NULL)
+                decoder->gettable_params =
+                    OSSL_FUNC_decoder_gettable_params(fns);
+            break;
+        case OSSL_FUNC_DECODER_SET_CTX_PARAMS:
+            if (decoder->set_ctx_params == NULL)
+                decoder->set_ctx_params =
+                    OSSL_FUNC_decoder_set_ctx_params(fns);
+            break;
+        case OSSL_FUNC_DECODER_SETTABLE_CTX_PARAMS:
+            if (decoder->settable_ctx_params == NULL)
+                decoder->settable_ctx_params =
+                    OSSL_FUNC_decoder_settable_ctx_params(fns);
+            break;
+        case OSSL_FUNC_DECODER_DECODE:
+            if (decoder->decode == NULL)
+                decoder->decode = OSSL_FUNC_decoder_decode(fns);
+            break;
+        case OSSL_FUNC_DECODER_EXPORT_OBJECT:
+            if (decoder->export_object == NULL)
+                decoder->export_object = OSSL_FUNC_decoder_export_object(fns);
+            break;
+        }
+    }
+    /*
+     * Try to check that the method is sensible.
+     * If you have a constructor, you must have a destructor and vice versa.
+     * You must have at least one of the encoding driver functions.
+     */
+    if (!((decoder->newctx == NULL && decoder->freectx == NULL)
+          || (decoder->newctx != NULL && decoder->freectx != NULL))
+        || (decoder->decode == NULL && decoder->export_object == NULL)) {
+        OSSL_DECODER_free(decoder);
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_INVALID_PROVIDER_FUNCTIONS);
+        return NULL;
+    }
+
+    if (prov != NULL && !ossl_provider_up_ref(prov)) {
+        OSSL_DECODER_free(decoder);
+        return NULL;
+    }
+
+    decoder->base.prov = prov;
+    return decoder;
+}
+
+
+/*
+ * The core fetching functionality passes the names of the implementation.
+ * This function is responsible to getting an identity number for them,
+ * then call decoder_from_dispatch() with that identity number.
+ */
+static void *construct_decoder(const OSSL_ALGORITHM *algodef,
+                               OSSL_PROVIDER *prov, void *unused)
+{
+    /*
+     * This function is only called if get_decoder_from_store() returned
+     * NULL, so it's safe to say that of all the spots to create a new
+     * namemap entry, this is it.  Should the name already exist there, we
+     * know that ossl_namemap_add() will return its corresponding number.
+     */
+    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
+    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
+    const char *names = algodef->algorithm_names;
+    int id = ossl_namemap_add_names(namemap, 0, names, NAME_SEPARATOR);
+    void *method = NULL;
+
+    if (id != 0)
+        method = decoder_from_dispatch(id, algodef, prov);
+
+    return method;
+}
+
+/* Intermediary function to avoid ugly casts, used below */
+static void destruct_decoder(void *method, void *data)
+{
+    OSSL_DECODER_free(method);
+}
+
+static int up_ref_decoder(void *method)
+{
+    return OSSL_DECODER_up_ref(method);
+}
+
+static void free_decoder(void *method)
+{
+    OSSL_DECODER_free(method);
+}
+
+/* Fetching support.  Can fetch by numeric identity or by name */
+static OSSL_DECODER *inner_ossl_decoder_fetch(OPENSSL_CTX *libctx, int id,
+                                              const char *name,
+                                              const char *properties)
+{
+    OSSL_METHOD_STORE *store = get_decoder_store(libctx);
+    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
+    void *method = NULL;
+
+    if (store == NULL || namemap == NULL)
+        return NULL;
+
+    /*
+     * If we have been passed neither a name_id or a name, we have an
+     * internal programming error.
+     */
+    if (!ossl_assert(id != 0 || name != NULL))
+        return NULL;
+
+    if (id == 0)
+        id = ossl_namemap_name2num(namemap, name);
+
+    if (id == 0
+        || !ossl_method_store_cache_get(store, id, properties, &method)) {
+        OSSL_METHOD_CONSTRUCT_METHOD mcm = {
+            alloc_tmp_decoder_store,
+            dealloc_tmp_decoder_store,
+            get_decoder_from_store,
+            put_decoder_in_store,
+            construct_decoder,
+            destruct_decoder
+        };
+        struct decoder_data_st mcmdata;
+
+        mcmdata.libctx = libctx;
+        mcmdata.mcm = &mcm;
+        mcmdata.id = id;
+        mcmdata.names = name;
+        mcmdata.propquery = properties;
+        if ((method = ossl_method_construct(libctx, OSSL_OP_DECODER,
+                                            0 /* !force_cache */,
+                                            &mcm, &mcmdata)) != NULL) {
+            /*
+             * If construction did create a method for us, we know that
+             * there is a correct name_id and meth_id, since those have
+             * already been calculated in get_decoder_from_store() and
+             * put_decoder_in_store() above.
+             */
+            if (id == 0)
+                id = ossl_namemap_name2num(namemap, name);
+            ossl_method_store_cache_set(store, id, properties, method,
+                                        up_ref_decoder, free_decoder);
+        }
+    }
+
+    return method;
+}
+
+OSSL_DECODER *OSSL_DECODER_fetch(OPENSSL_CTX *libctx, const char *name,
+                                 const char *properties)
+{
+    return inner_ossl_decoder_fetch(libctx, 0, name, properties);
+}
+
+OSSL_DECODER *ossl_decoder_fetch_by_number(OPENSSL_CTX *libctx, int id,
+                                           const char *properties)
+{
+    return inner_ossl_decoder_fetch(libctx, id, NULL, properties);
+}
+
+/*
+ * Library of basic method functions
+ */
+
+const OSSL_PROVIDER *OSSL_DECODER_provider(const OSSL_DECODER *decoder)
+{
+    if (!ossl_assert(decoder != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    return decoder->base.prov;
+}
+
+const char *OSSL_DECODER_properties(const OSSL_DECODER *decoder)
+{
+    if (!ossl_assert(decoder != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    return decoder->base.propdef;
+}
+
+int OSSL_DECODER_number(const OSSL_DECODER *decoder)
+{
+    if (!ossl_assert(decoder != NULL)) {
+        ERR_raise(ERR_LIB_OSSL_DECODER, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    return decoder->base.id;
+}
+
+int OSSL_DECODER_is_a(const OSSL_DECODER *decoder, const char *name)
+{
+    if (decoder->base.prov != NULL) {
+        OPENSSL_CTX *libctx = ossl_provider_library_context(decoder->base.prov);
+        OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
+
+        return ossl_namemap_name2num(namemap, name) == decoder->base.id;
+    }
+    return 0;
+}
+
+struct decoder_do_all_data_st {
+    void (*user_fn)(void *method, void *arg);
+    void *user_arg;
+};
+
+static void decoder_do_one(OSSL_PROVIDER *provider,
+                           const OSSL_ALGORITHM *algodef,
+                           int no_store, void *vdata)
+{
+    struct decoder_do_all_data_st *data = vdata;
+    OPENSSL_CTX *libctx = ossl_provider_library_context(provider);
+    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);