mahmad/local-etc-hosts-updater
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Add dual version handling, relative path handling

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This commit is contained in:
Muaz Ahmad 2024-05-13 13:07:47 +05:00
parent 6669634565
commit 5b05de3ab3
3 changed files with 68 additions and 25 deletions
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43
src/hosts.zig
View file

@ -61,16 +61,7 @@ fn purge_existing(old_hosts: std.fs.File, tmp_hosts: std.fs.File) !void {
}
}
fn append_new(tmp_hosts: std.fs.File, addr: std.net.Address, local_domain: util.Domain) !void {
const writer = tmp_hosts.writer();
var buff = [_]u8{0x00} ** FILE_LINE_BUFF_SIZE;
// write output
const header_len = hosts_header.*.len;
@memcpy(buff[0..header_len], hosts_header);
try writer.writeAll(buff[0..header_len]);
try writer.writeByte('\n');
fn write_subdomains_map(writer: std.fs.File.Writer, addr: std.net.Address, local_domain: util.Domain) !void {
var subdomains = try get_subdomains();
const domain = try util.getenv("TARGET_DOMAIN");
@ -86,6 +77,24 @@ fn append_new(tmp_hosts: std.fs.File, addr: std.net.Address, local_domain: util.
try std.fmt.format(writer, "{s} {s}.{s}\n", .{ addr_str, subdomain, domain });
}
try std.fmt.format(writer, "{s} {s}\n", .{ addr_str, local_domain.name });
}
fn append_new(tmp_hosts: std.fs.File, ip: util.IP, local_domain: util.Domain) !void {
const writer = tmp_hosts.writer();
var buff = [_]u8{0x00} ** FILE_LINE_BUFF_SIZE;
// write output
const header_len = hosts_header.*.len;
@memcpy(buff[0..header_len], hosts_header);
try writer.writeAll(buff[0..header_len]);
try writer.writeByte('\n');
if (ip.v6) |addr| {
try write_subdomains_map(writer, addr, local_domain);
}
if (ip.v4) |addr| {
try write_subdomains_map(writer, addr, local_domain);
}
// add extra final newline
try writer.writeByte('\n');
@ -97,22 +106,20 @@ fn get_subdomains() !std.mem.SplitIterator(u8, .scalar) {
}
fn create_tmp_hosts(ip: util.IP, domain: util.Domain) !void {
var old_hosts = try std.fs.openFileAbsoluteZ(try util.getenv("OLD_HOSTS_PATH"), .{ .mode = .read_only });
var old_hosts = try std.fs.Dir.openFileZ(util.cwd, try util.getenv("OLD_HOSTS_PATH"), .{ .mode = .read_only });
defer old_hosts.close();
var tmp_hosts = try std.fs.createFileAbsoluteZ(try util.getenv("TMP_HOSTS_PATH"), .{ .truncate = true });
var tmp_hosts = try std.fs.Dir.createFileZ(util.cwd, try util.getenv("TMP_HOSTS_PATH"), .{ .truncate = true });
defer tmp_hosts.close();
try purge_existing(old_hosts, tmp_hosts);
if (ip) |addr| {
try append_new(tmp_hosts, addr, domain);
}
try append_new(tmp_hosts, ip, domain);
}
fn move_tmp_hosts() !void {
var target_hosts = try std.fs.createFileAbsoluteZ(try util.getenv("OLD_HOSTS_PATH"), .{ .lock = .exclusive });
var target_hosts = try std.fs.Dir.createFileZ(util.cwd, try util.getenv("OLD_HOSTS_PATH"), .{ .lock = .exclusive });
defer target_hosts.close();
const target_writer = target_hosts.writer();
var tmp_hosts = try std.fs.openFileAbsoluteZ(try util.getenv("TMP_HOSTS_PATH"), .{});
var tmp_hosts = try std.fs.Dir.openFileZ(util.cwd, try util.getenv("TMP_HOSTS_PATH"), .{});
defer tmp_hosts.close();
const source_reader = tmp_hosts.reader();
@ -122,5 +129,5 @@ fn move_tmp_hosts() !void {
}
};
try std.fs.deleteFileAbsoluteZ(try util.getenv("TMP_HOSTS_PATH"));
try std.fs.Dir.deleteFileZ(util.cwd, try util.getenv("TMP_HOSTS_PATH"));
}

26
src/mdns.zig
View file

@ -2,7 +2,6 @@ const std = @import("std");
const util = @import("util.zig");
const MDNSError = error{
Unimplemented,
SocketInitFail,
UDPConnectFail,
UDPSendFail,
@ -14,10 +13,22 @@ const MDNSError = error{
};
pub fn get_mdns(domain: util.Domain, ip_info: util.IPInfo) !util.IP {
if (ip_info.version != .Both) {
const sock = try send_query(domain, ip_info);
return receive_response(sock, ip_info);
}
const ip_info4 = util.IPInfo{ .version = .IPv4, .interface = ip_info.interface };
var sock = try send_query(domain, ip_info4);
const addr_v4 = try receive_response(sock, ip_info4);
const ip_info6 = util.IPInfo{ .version = .IPv4, .interface = ip_info.interface };
sock = try send_query(domain, ip_info6);
const addr_v6 = try receive_response(sock, ip_info6);
return util.merge_addrs(addr_v4, addr_v6);
}
const socket = c_int;
const MSG_BUFF_SIZE = 200;
@ -25,6 +36,7 @@ fn get_mdns_socket(ip_info: util.IPInfo) !socket {
const sock = std.c.socket(switch (ip_info.version) {
util.IP_VER_ENUM.IPv4 => std.c.AF.INET,
util.IP_VER_ENUM.IPv6 => std.c.AF.INET6,
else => unreachable,
}, std.c.SOCK.DGRAM, std.c.IPPROTO.UDP);
if (sock == -1) {
return MDNSError.SocketInitFail;
@ -59,6 +71,7 @@ fn construct_mdns_query(domain: util.Domain, ip_info: util.IPInfo, buff: []u8) !
[_]u8{ 0x00, switch (ip_info.version) {
util.IP_VER_ENUM.IPv4 => 0x01,
util.IP_VER_ENUM.IPv6 => 0x1c,
else => unreachable,
} } ++ // A or AAAA record
[_]u8{ 0x00, 0x01 } // IN query
;
@ -77,6 +90,7 @@ fn get_target_address(ip_info: util.IPInfo) !std.net.Address {
try std.fmt.format(writer, "ff02::fb%{s}", .{ip_info.interface.?});
break :blk buf[0..writer.context.pos];
},
else => unreachable,
};
return std.net.Address.resolveIp(target_addr, 5353);
}
@ -153,6 +167,7 @@ fn parse_mdns_response(response: []u8, ip_info: util.IPInfo) !util.IP {
if (switch (ip_info.version) {
util.IP_VER_ENUM.IPv4 => ip_len != 4,
util.IP_VER_ENUM.IPv6 => ip_len != 16,
else => unreachable,
}) {
continue;
}
@ -170,5 +185,12 @@ fn parse_mdns_response(response: []u8, ip_info: util.IPInfo) !util.IP {
}
}
}
return addr;
if (addr == null) {
return MDNSError.NoMatchingAddress;
}
return switch (ip_info.version) {
.IPv4 => util.IP{ .v4 = addr },
.IPv6 => util.IP{ .v6 = addr },
else => unreachable,
};
}

20
src/util.zig
View file

@ -7,14 +7,26 @@ const ArgError = error{
InterfaceRequired,
InvalidInterface,
EnvVarNotSet,
InvalidOldHostsPath,
};
pub const IP_VER_ENUM = enum(u3) {
Both = 0,
IPv4 = 4,
IPv6 = 6,
};
pub const IP = ?std.net.Address;
pub const IP = struct {
v4: ?std.net.Address = null,
v6: ?std.net.Address = null,
};
pub fn merge_addrs(v4: IP, v6: IP) IP {
return IP{
.v4 = v4.v4,
.v6 = v6.v6,
};
}
pub const IPInfo = struct {
version: IP_VER_ENUM,
@ -31,10 +43,12 @@ pub fn getenv(key: [*:0]const u8) ![*:0]const u8 {
}
pub fn check_perms() !void {
var f = try std.fs.openFileAbsoluteZ(try getenv("OLD_HOSTS_PATH"), .{ .mode = .write_only });
var f = try std.fs.Dir.openFileZ(cwd, try getenv("OLD_HOSTS_PATH"), .{ .mode = .write_only });
f.close();
}
pub const cwd = std.fs.cwd();
pub fn get_input() !struct {
Domain,
IPInfo,
@ -49,7 +63,7 @@ pub fn get_input() !struct {
const ip_ver = std.meta.intToEnum(IP_VER_ENUM, std.fmt.parseInt(u3, ip_ver_str, 10) catch return ArgError.InvalidAddressVer) catch return ArgError.InvalidAddressVer;
var iface: ?[:0]const u8 = null;
if (ip_ver == IP_VER_ENUM.IPv6) {
if (ip_ver != IP_VER_ENUM.IPv4) {
iface = args.next() orelse return ArgError.InterfaceRequired;
if (std.c.if_nametoindex(iface.?) == 0) {
return ArgError.InvalidInterface;