hush3/zcutil/fetch-params.sh

#!/bin/bash
# Copyright 2019 The Hush developers

set -eu

# We do not declare our own location because we can use the params
# from any other installed coins
if [[ "$OSTYPE" == "darwin"* ]]; then
    PARAMS_DIR="$HOME/Library/Application Support/ZcashParams"
else
    PARAMS_DIR="$HOME/.zcash-params"
fi

SAPLING_SPEND_NAME='sapling-spend.params'
SAPLING_OUTPUT_NAME='sapling-output.params'
URL="https://z.cash/downloads"
IPFS="/ipfs/QmZKKx7Xup7LiAtFRhYsE1M7waXcv9ir9eCECyXAFGxhEo"

SHA256CMD="$(command -v sha256sum || echo shasum)"
SHA256ARGS="$(command -v sha256sum >/dev/null || echo '-a 256')"

WGETCMD="$(command -v wget || echo '')"
IPFSCMD="$(command -v ipfs || echo '')"
CURLCMD="$(command -v curl || echo '')"

# fetch methods can be disabled with ZC_DISABLE_SOMETHING=1
ZC_DISABLE_WGET="${ZC_DISABLE_WGET:-}"
ZC_DISABLE_IPFS="${ZC_DISABLE_IPFS:-}"
ZC_DISABLE_CURL="${ZC_DISABLE_CURL:-}"

function fetch_wget {
    if [ -z "$WGETCMD" ] || ! [ -z "$ZC_DISABLE_WGET" ]; then
        return 1
    fi

    local filename="$1"
    local dlname="$2"

    cat <<EOF

Retrieving (wget): $URL/$filename
EOF

    wget \
        --progress=dot:giga \
        --output-document="$dlname" \
        --continue \
        --retry-connrefused --waitretry=3 --timeout=30 \
        "$URL/$filename"
}

function fetch_ipfs {
    if [ -z "$IPFSCMD" ] || ! [ -z "$ZC_DISABLE_IPFS" ]; then
        return 1
    fi

    local filename="$1"
    local dlname="$2"

    cat <<EOF

Retrieving (ipfs): $IPFS/$filename
EOF

    ipfs get --output "$dlname" "$IPFS/$filename"
}

function fetch_curl {
    if [ -z "$CURLCMD" ] || ! [ -z "$ZC_DISABLE_CURL" ]; then
        return 1
    fi

    local filename="$1"
    local dlname="$2"

    cat <<EOF

Retrieving (curl): $URL/$filename
EOF

    curl \
        --output "$dlname" \
        -# -L -C - \
        "$URL/$filename"

}

function fetch_failure {
    cat >&2 <<EOF

Failed to fetch the Zcash zkSNARK parameters!
Try installing one of the following programs and make sure you're online:

 * ipfs
 * wget
 * curl

EOF
    exit 1
}

function fetch_params {
    local filename="$1"
    local output="$2"
    local dlname="${output}.dl"
    local expectedhash="$3"

    if ! [ -f "$output" ]
    then
        for method in wget ipfs curl failure; do
            if "fetch_$method" "$filename" "$dlname"; then
                echo "Download successful!"
                break
            fi
        done

        "$SHA256CMD" $SHA256ARGS -c <<EOF
$expectedhash  $dlname
EOF

        # Check the exit code of the shasum command:
        CHECKSUM_RESULT=$?
        if [ $CHECKSUM_RESULT -eq 0 ]; then
            mv -v "$dlname" "$output"
        else
            echo "Failed to verify parameter checksums!" >&2
            exit 1
        fi
    fi
}

# Use flock to prevent parallel execution.
function lock() {
    local lockfile=/tmp/fetch_params.lock
    if [[ "$OSTYPE" == "darwin"* ]]; then
        if shlock -f ${lockfile} -p $$; then
            return 0
        else
            return 1
        fi
    else
        # create lock file
        eval "exec 200>$lockfile"
        # acquire the lock
        flock -n 200 \
            && return 0 \
            || return 1
    fi
}

function exit_locked_error {
    echo "Only one instance of fetch-params.sh can be run at a time." >&2
    exit 1
}

function main() {

    lock fetch-params.sh \
    || exit_locked_error

    cat <<EOF
Hush - fetch-params.sh

This script will fetch the zkSNARK parameters used in shield
transactions and verify their integrity with sha256sum.

If they already exist locally, it will exit now and do nothing else.
EOF

    # Now create PARAMS_DIR and insert a README if necessary:
    if ! [ -d "$PARAMS_DIR" ]; then
        mkdir -p "$PARAMS_DIR"
        README_PATH="$PARAMS_DIR/README"
        cat >> "$README_PATH" <<EOF
This directory stores common zkSNARK parameters needed for shielded
transactions. Note that it is distinct from the daemon's -datadir argument
because the parameters are large and may be shared across multiple distinct
-datadir's such as when setting up test networks.
EOF

        # This may be the first time the user's run this script, so give
        # them some info, especially about bandwidth usage:
        cat <<EOF
The parameters are currently about 50MB, so plan accordingly
for your bandwidth constraints. If the files are already present and
have the correct sha256sum, no networking is used.

Creating params directory. For details about this directory, see:
$README_PATH

EOF
    fi

    cd "$PARAMS_DIR"

    # Sapling parameters:
    fetch_params "$SAPLING_SPEND_NAME" "$PARAMS_DIR/$SAPLING_SPEND_NAME" "8e48ffd23abb3a5fd9c5589204f32d9c31285a04b78096ba40a79b75677efc13"
    fetch_params "$SAPLING_OUTPUT_NAME" "$PARAMS_DIR/$SAPLING_OUTPUT_NAME" "2f0ebbcbb9bb0bcffe95a397e7eba89c29eb4dde6191c339db88570e3f3fb0e4"

}

main
rm -f /tmp/fetch_params.lock
exit 0