cjdns/dht/dhtcore/ReplySerializer.c

/* vim: set expandtab ts=4 sw=4: */
/*
 * You may redistribute this program and/or modify it under the terms of
 * the GNU General Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "benc/Dict.h"
#include "benc/String.h"
#include "crypto/AddressCalc.h"
#include "dht/CJDHTConstants.h"
#include "dht/dhtcore/ReplySerializer.h"
#include "dht/dhtcore/VersionList.h"
#include "dht/Address.h"
#include "memory/Allocator.h"
#include "switch/LabelSplicer.h"
#include "util/Identity.h"
#include "util/log/Log.h"
#include "util/Assert.h"

/**
 * For serializing and parsing responses to getPeers and search requests.
 */
struct Address_List* ReplySerializer_parse(struct Address* fromNode,
                                           Dict* result,
                                           struct Log* log,
                                           struct Allocator* alloc)
{
    String* nodes = Dict_getString(result, CJDHTConstants_NODES);

    if (!nodes) { return NULL; }

    if (nodes->len == 0 || nodes->len % Address_SERIALIZED_SIZE != 0) {
        Log_debug(log, "Dropping unrecognized reply");
        return NULL;
    }

    struct VersionList* versions = NULL;
    String* versionsStr = Dict_getString(result, CJDHTConstants_NODE_PROTOCOLS);
    if (versionsStr) {
        versions = VersionList_parse(versionsStr, alloc);
        #ifdef Version_1_COMPAT
            // Version 1 lies about the versions of other nodes, assume they're all v1.
            if (fromNode->protocolVersion < 2) {
                for (int i = 0; i < (int)versions->length; i++) {
                    versions->versions[i] = 1;
                }
            }
        #endif
    }
    if (!versions || versions->length != (nodes->len / Address_SERIALIZED_SIZE)) {
        Log_debug(log, "Reply with missing or invalid versions");
        return NULL;
    }

    struct Address_List* out = Address_List_new(versions->length, alloc);

    uint32_t j = 0;
    for (uint32_t i = 0; nodes && i < nodes->len; i += Address_SERIALIZED_SIZE) {

        struct Address addr = { .path = 0 };
        Address_parse(&addr, (uint8_t*) &nodes->bytes[i]);
        addr.protocolVersion = versions->versions[i / Address_SERIALIZED_SIZE];

        // calculate the ipv6
        Address_getPrefix(&addr);

        // We need to splice the given address on to the end of the
        // address of the node which gave it to us.
        uint64_t path = LabelSplicer_splice(addr.path, fromNode->path);

        if (path == UINT64_MAX) {
            /* common, lots of noise
            uint8_t discovered[60];
            uint8_t fromAddr[60];
            Address_print(discovered, &addr);
            Address_print(fromAddr, fromNode);
            Log_debug(log, "Dropping response [%s] from [%s] because route could not be spliced",
                      discovered, fromAddr);*/
            continue;
        }

        addr.path = path;

        /*#ifdef Log_DEBUG
            uint8_t printedAddr[60];
            Address_print(printedAddr, &addr);
            Log_debug(log, "discovered node [%s]", printedAddr);
        #endif*/

        Address_getPrefix(&addr);
        if (!AddressCalc_validAddress(addr.ip6.bytes)) {
            Log_debug(log, "Was told garbage.\n");
            // This should never happen, badnode.
            continue;
        }

        Bits_memcpyConst(&out->elems[j++], &addr, sizeof(struct Address));
    }
    out->length = j;
    return out;
}