Here's my first stab at solving this problem in a backwards-compatible way,
let me know what you think. I've added a --resolv flag to the loader to
enable this behavior.
patch-dhcp.cc:
--- ./core/dhcp.cc~ 2019-01-25 11:18:29.173860626 -0500
+++ ./core/dhcp.cc 2019-01-25 11:17:19.546083373 -0500
@@ -29,6 +29,12 @@
#include <libc/network/__dns.hh>
using namespace boost::asio;
+bool generate_resolv_conf = false;
+
+void enable_resolv_conf()
+{
+ generate_resolv_conf = true;
+}
dhcp::dhcp_worker net_dhcp_worker;
@@ -720,6 +726,31 @@
});
osv::set_dns_config(dm.get_dns_ips(),
std::vector<std::string>());
+
+ // Some linux applications (go, erlang) depend on
/etc/resolv.conf to be
+ // populated with DNS server information in order to function.
The --resolv
+ // option has been added to the kernel loader, which will
enable this
+ // feature.
+ //
+ // TODO: It's possible that the /etc directory does not exist
at this time.
+ // We should ideally check and create it if necessary. What's
the right
+ // way to do that?
+ //
+ // TODO: We are currently ignoring DHCP-provided default domain
+ // names. I'll have to dig further into the code to see if I
can ingest
+ // those.
+ //
+ if( generate_resolv_conf )
+ {
+ FILE *f = fopen("/etc/resolv.conf", "w+");
+ if( f ) {
+ fprintf( f, "## Autoconfigured by DHCP\n" );
+ for( auto &ip : dm.get_dns_ips() )
+ {
+ fprintf( f, "server %s\n",
ip.to_string().c_str() );
+ dhcp_i( "Added DNS server: %s\n",
ip.to_string().c_str() );
+ }
+ fclose( f );
+ dhcp_i( "Generated /etc/resolv.conf" );
+ }
+ }
+
if (dm.get_hostname().size()) {
sethostname(dm.get_hostname().c_str(),
dm.get_hostname().size());
dhcp_i("Set hostname to: %s", dm.get_hostname().c_str());
patch-loader.cc:
--- ./loader.cc~ 2019-01-25 11:10:40.091359718 -0500
+++ ./loader.cc 2019-01-25 11:11:40.243167695 -0500
@@ -144,10 +144,13 @@
bool opt_assign_net = false;
bool opt_maxnic = false;
int maxnic;
+static bool opt_resolv_conf = false;
static int sampler_frequency;
static bool opt_enable_sampler = false;
+void enable_resolv_conf();
+
void parse_options(int loader_argc, char** loader_argv)
{
namespace bpo = boost::program_options;
@@ -182,6 +185,7 @@
("delay", bpo::value<float>()->default_value(0), "delay in seconds
before boot")
("redirect", bpo::value<std::string>(), "redirect stdout and
stderr to file")
("disable_rofs_cache", "disable ROFS memory cache")
+ ("resolv", "generate an /etc/resolv.conf file with DHCP DNS values
(for Linux compatibility)")
;
bpo::variables_map vars;
// don't allow --foo bar (require --foo=bar) so we can find the first
non-option
@@ -234,6 +238,11 @@
enable_verbose();
}
+ if (vars.count("resolv")) {
+ opt_resolv_conf = true;
+ enable_resolv_conf();
+ }
+
if (vars.count("sampler")) {
sampler_frequency = vars["sampler"].as<int>();
opt_enable_sampler = true;
patch-run.py:
--- ./scripts/run.py~ 2019-01-25 11:14:20.858654652 -0500
+++ ./scripts/run.py 2019-01-25 11:14:52.406553829 -0500
@@ -43,6 +43,8 @@
execute = cmdline.read()
if options.verbose:
execute = "--verbose " + execute
+ if options.resolv:
+ execute = "--resolv " + execute
if options.jvm_debug or options.jvm_suspend:
if '-agentlib:jdwp' in execute:
@@ -461,6 +463,8 @@
help="Enable graphics mode.")
parser.add_argument("-V", "--verbose", action="store_true",
help="pass --verbose to OSv, to display more
debugging information on the console")
+ parser.add_argument("--resolv", action="store_true",
+ help="pass --resolv to OSv, to generate an
/etc/resolv.conf file for Linux compatibility")
parser.add_argument("--forward", metavar="RULE", action="append",
default=[],
help="add network forwarding RULE (QEMU syntax)")
parser.add_argument("--dry-run", action="store_true",
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