39 lines
1.2 KiB
Nix
39 lines
1.2 KiB
Nix
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{ stdenv, dnsServer }:
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let
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host_resolv_conf = builtins.path {
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name = "host-resolv-conf";
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path = "/etc/resolv.conf";
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};
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in stdenv.mkDerivation {
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name = "resolv-conf";
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buildCommand = ''
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RESOLV_CONF_FILE="$out/resolv.conf"
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mkdir -p $out
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is_host_resolve_conf_valid() {
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if [ ! -f "${host_resolv_conf}" ]; then
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return 1
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fi
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if grep -qE "nameserver\s+127\.0\.0\." "${host_resolv_conf}"; then
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return 1
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else
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return 0
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fi
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}
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if [ -n "${dnsServer}" ] && [ "${dnsServer}" != "none" ]; then
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echo "nameserver ${dnsServer}" > "$RESOLV_CONF_FILE"
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elif is_host_resolve_conf_valid; then
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cp ${host_resolv_conf} $RESOLV_CONF_FILE
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echo "resolv.conf is generated from the host's /etc/resolv.conf"
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else
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echo "Warning: the host's /etc/resolv.conf is not valid for the guest VM (containing lookback addresses)." >&2
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echo "Fall back to Cloudflare's public DNS servers (1.1.1.1)." >&2
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echo "Consider using the DNS_SERVER Makefile variable to specify DNS server explicitly." >&2
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echo "For example: make DNS_SERVER=\"192.168.1.1\"" >&2
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echo "nameserver 1.1.1.1" > "$RESOLV_CONF_FILE"
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fi
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'';
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}
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