mirror of
https://codeberg.org/ziglang/zig.git
synced 2025-12-06 13:54:21 +00:00
631 lines
23 KiB
Zig
631 lines
23 KiB
Zig
//! An already-validated host name. A valid host name:
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//! * Has length less than or equal to `max_len`.
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//! * Is valid UTF-8.
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//! * Lacks ASCII characters other than alphanumeric, '-', and '.'.
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const HostName = @This();
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const builtin = @import("builtin");
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const native_os = builtin.os.tag;
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const std = @import("../../std.zig");
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const Io = std.Io;
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const IpAddress = Io.net.IpAddress;
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const Ip6Address = Io.net.Ip6Address;
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const assert = std.debug.assert;
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const Stream = Io.net.Stream;
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/// Externally managed memory. Already checked to be valid.
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bytes: []const u8,
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pub const max_len = 255;
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pub const InitError = error{
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NameTooLong,
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InvalidHostName,
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};
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pub fn init(bytes: []const u8) InitError!HostName {
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if (bytes.len > max_len) return error.NameTooLong;
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if (!std.unicode.utf8ValidateSlice(bytes)) return error.InvalidHostName;
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for (bytes) |byte| {
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if (!std.ascii.isAscii(byte) or byte == '.' or byte == '-' or std.ascii.isAlphanumeric(byte)) {
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continue;
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}
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return error.InvalidHostName;
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}
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return .{ .bytes = bytes };
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}
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/// TODO add a retry field here
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pub const LookupOptions = struct {
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port: u16,
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/// Must have at least length 2.
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addresses_buffer: []IpAddress,
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canonical_name_buffer: *[max_len]u8,
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/// `null` means either.
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family: ?IpAddress.Family = null,
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};
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pub const LookupError = Io.Cancelable || Io.File.OpenError || Io.File.Reader.Error || error{
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UnknownHostName,
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ResolvConfParseFailed,
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// TODO remove from error set; retry a few times then report a different error
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TemporaryNameServerFailure,
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InvalidDnsARecord,
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InvalidDnsAAAARecord,
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NameServerFailure,
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};
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pub const LookupResult = struct {
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/// How many `LookupOptions.addresses_buffer` elements are populated.
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addresses_len: usize,
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canonical_name: HostName,
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pub const empty: LookupResult = .{
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.addresses_len = 0,
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.canonical_name = undefined,
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};
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};
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pub fn lookup(host_name: HostName, io: Io, options: LookupOptions) LookupError!LookupResult {
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const name = host_name.bytes;
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assert(name.len <= max_len);
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assert(options.addresses_buffer.len >= 2);
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if (native_os == .windows) @compileError("TODO");
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if (builtin.link_libc) @compileError("TODO");
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if (native_os == .linux) {
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if (options.family != .ip6) {
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if (IpAddress.parseIp4(name, options.port)) |addr| {
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options.addresses_buffer[0] = addr;
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return .{ .addresses_len = 1, .canonical_name = copyCanon(options.canonical_name_buffer, name) };
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} else |_| {}
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}
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if (options.family != .ip4) {
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if (IpAddress.parseIp6(name, options.port)) |addr| {
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options.addresses_buffer[0] = addr;
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return .{ .addresses_len = 1, .canonical_name = copyCanon(options.canonical_name_buffer, name) };
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} else |_| {}
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}
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{
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const result = try lookupHosts(host_name, io, options);
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if (result.addresses_len > 0) return sortLookupResults(options, result);
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}
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{
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// RFC 6761 Section 6.3.3
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// Name resolution APIs and libraries SHOULD recognize
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// localhost names as special and SHOULD always return the IP
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// loopback address for address queries and negative responses
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// for all other query types.
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// Check for equal to "localhost(.)" or ends in ".localhost(.)"
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const localhost = if (name[name.len - 1] == '.') "localhost." else "localhost";
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if (std.mem.endsWith(u8, name, localhost) and
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(name.len == localhost.len or name[name.len - localhost.len] == '.'))
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{
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var i: usize = 0;
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if (options.family != .ip6) {
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options.addresses_buffer[i] = .{ .ip4 = .localhost(options.port) };
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i += 1;
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}
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if (options.family != .ip4) {
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options.addresses_buffer[i] = .{ .ip6 = .localhost(options.port) };
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i += 1;
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}
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const canon_name = "localhost";
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const canon_name_dest = options.canonical_name_buffer[0..canon_name.len];
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canon_name_dest.* = canon_name.*;
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return sortLookupResults(options, .{
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.addresses_len = i,
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.canonical_name = .{ .bytes = canon_name_dest },
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});
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}
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}
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{
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const result = try lookupDnsSearch(host_name, io, options);
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if (result.addresses_len > 0) return sortLookupResults(options, result);
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}
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return error.UnknownHostName;
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}
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@compileError("unimplemented");
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}
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fn sortLookupResults(options: LookupOptions, result: LookupResult) !LookupResult {
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const addresses = options.addresses_buffer[0..result.addresses_len];
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// No further processing is needed if there are fewer than 2 results or
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// if there are only IPv4 results.
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if (addresses.len < 2) return result;
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const all_ip4 = for (addresses) |a| switch (a) {
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.ip4 => continue,
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.ip6 => break false,
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} else true;
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if (all_ip4) return result;
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// RFC 3484/6724 describes how destination address selection is
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// supposed to work. However, to implement it requires making a bunch
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// of networking syscalls, which is unnecessarily high latency,
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// especially if implemented serially. Furthermore, rules 3, 4, and 7
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// have excessive runtime and code size cost and dubious benefit.
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//
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// Therefore, this logic sorts only using values available without
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// doing any syscalls, relying on the calling code to have a
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// meta-strategy such as attempting connection to multiple results at
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// once and keeping the fastest response while canceling the others.
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const S = struct {
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pub fn lessThan(s: @This(), lhs: IpAddress, rhs: IpAddress) bool {
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return sortKey(s, lhs) < sortKey(s, rhs);
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}
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fn sortKey(s: @This(), a: IpAddress) i32 {
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_ = s;
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var da6: Ip6Address = .{
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.port = 65535,
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.bytes = undefined,
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};
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switch (a) {
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.ip6 => |ip6| {
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da6.bytes = ip6.bytes;
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da6.scope_id = ip6.scope_id;
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},
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.ip4 => |ip4| {
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da6.bytes[0..12].* = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff".*;
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da6.bytes[12..].* = ip4.bytes;
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},
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}
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const da6_scope: i32 = da6.scope();
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const da6_prec: i32 = da6.policy().prec;
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var key: i32 = 0;
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key |= da6_prec << 20;
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key |= (15 - da6_scope) << 16;
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return key;
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}
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};
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std.mem.sort(IpAddress, addresses, @as(S, .{}), S.lessThan);
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return result;
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}
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fn lookupDnsSearch(host_name: HostName, io: Io, options: LookupOptions) !LookupResult {
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const rc = ResolvConf.init(io) catch return error.ResolvConfParseFailed;
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// Count dots, suppress search when >=ndots or name ends in
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// a dot, which is an explicit request for global scope.
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const dots = std.mem.countScalar(u8, host_name.bytes, '.');
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const search_len = if (dots >= rc.ndots or std.mem.endsWith(u8, host_name.bytes, ".")) 0 else rc.search_len;
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const search = rc.search_buffer[0..search_len];
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var canon_name = host_name.bytes;
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// Strip final dot for canon, fail if multiple trailing dots.
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if (std.mem.endsWith(u8, canon_name, ".")) canon_name.len -= 1;
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if (std.mem.endsWith(u8, canon_name, ".")) return error.UnknownHostName;
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// Name with search domain appended is set up in `canon_name`. This
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// both provides the desired default canonical name (if the requested
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// name is not a CNAME record) and serves as a buffer for passing the
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// full requested name to `lookupDns`.
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@memcpy(options.canonical_name_buffer[0..canon_name.len], canon_name);
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options.canonical_name_buffer[canon_name.len] = '.';
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var it = std.mem.tokenizeAny(u8, search, " \t");
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while (it.next()) |token| {
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@memcpy(options.canonical_name_buffer[canon_name.len + 1 ..][0..token.len], token);
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const lookup_canon_name = options.canonical_name_buffer[0 .. canon_name.len + 1 + token.len];
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const result = try lookupDns(io, lookup_canon_name, &rc, options);
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if (result.addresses_len > 0) return sortLookupResults(options, result);
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}
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const lookup_canon_name = options.canonical_name_buffer[0..canon_name.len];
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return lookupDns(io, lookup_canon_name, &rc, options);
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}
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fn lookupDns(io: Io, lookup_canon_name: []const u8, rc: *const ResolvConf, options: LookupOptions) !LookupResult {
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const family_records: [2]struct { af: IpAddress.Family, rr: u8 } = .{
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.{ .af = .ip6, .rr = std.posix.RR.A },
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.{ .af = .ip4, .rr = std.posix.RR.AAAA },
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};
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var query_buffers: [2][280]u8 = undefined;
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var queries_buffer: [2][]const u8 = undefined;
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var answer_buffers: [2][512]u8 = undefined;
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var answers_buffer: [2][]u8 = .{ &answer_buffers[0], &answer_buffers[1] };
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var nq: usize = 0;
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for (family_records) |fr| {
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if (options.family != fr.af) {
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const len = writeResolutionQuery(&query_buffers[nq], 0, lookup_canon_name, 1, fr.rr);
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queries_buffer[nq] = query_buffers[nq][0..len];
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nq += 1;
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}
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}
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const queries = queries_buffer[0..nq];
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const replies = answers_buffer[0..nq];
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try rc.sendMessage(io, queries, replies);
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for (replies) |reply| {
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if (reply.len < 4 or (reply[3] & 15) == 2) return error.TemporaryNameServerFailure;
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if ((reply[3] & 15) == 3) return .empty;
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if ((reply[3] & 15) != 0) return error.UnknownHostName;
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}
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var addresses_len: usize = 0;
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var canonical_name: ?HostName = null;
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for (replies) |reply| {
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var it = DnsResponse.init(reply) catch {
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// TODO accept a diagnostics struct and append warnings
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continue;
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};
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while (it.next() catch {
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// TODO accept a diagnostics struct and append warnings
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continue;
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}) |answer| switch (answer.rr) {
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std.posix.RR.A => {
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if (answer.data.len != 4) return error.InvalidDnsARecord;
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options.addresses_buffer[addresses_len] = .{ .ip4 = .{
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.bytes = answer.data[0..4].*,
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.port = options.port,
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} };
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addresses_len += 1;
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},
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std.posix.RR.AAAA => {
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if (answer.data.len != 16) return error.InvalidDnsAAAARecord;
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options.addresses_buffer[addresses_len] = .{ .ip6 = .{
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.bytes = answer.data[0..16].*,
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.port = options.port,
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} };
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addresses_len += 1;
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},
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std.posix.RR.CNAME => {
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_ = &canonical_name;
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@panic("TODO");
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//var tmp: [256]u8 = undefined;
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//// Returns len of compressed name. strlen to get canon name.
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//_ = try posix.dn_expand(packet, answer.data, &tmp);
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//const canon_name = mem.sliceTo(&tmp, 0);
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//if (isValidHostName(canon_name)) {
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// ctx.canon.items.len = 0;
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// try ctx.canon.appendSlice(gpa, canon_name);
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//}
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},
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else => continue,
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};
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}
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if (addresses_len != 0) return .{
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.addresses_len = addresses_len,
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.canonical_name = canonical_name orelse .{ .bytes = lookup_canon_name },
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};
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return error.NameServerFailure;
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}
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fn lookupHosts(host_name: HostName, io: Io, options: LookupOptions) !LookupResult {
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const file = Io.File.openAbsolute(io, "/etc/hosts", .{}) catch |err| switch (err) {
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error.FileNotFound,
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error.NotDir,
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error.AccessDenied,
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=> return .empty,
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else => |e| return e,
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};
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defer file.close(io);
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var line_buf: [512]u8 = undefined;
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var file_reader = file.reader(io, &line_buf);
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return lookupHostsReader(host_name, options, &file_reader.interface) catch |err| switch (err) {
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error.ReadFailed => return file_reader.err.?,
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};
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}
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fn lookupHostsReader(host_name: HostName, options: LookupOptions, reader: *Io.Reader) error{ReadFailed}!LookupResult {
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var addresses_len: usize = 0;
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var canonical_name: ?HostName = null;
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while (true) {
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const line = reader.takeDelimiterExclusive('\n') catch |err| switch (err) {
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error.StreamTooLong => {
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// Skip lines that are too long.
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_ = reader.discardDelimiterInclusive('\n') catch |e| switch (e) {
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error.EndOfStream => break,
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error.ReadFailed => return error.ReadFailed,
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};
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continue;
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},
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error.ReadFailed => return error.ReadFailed,
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error.EndOfStream => break,
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};
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var split_it = std.mem.splitScalar(u8, line, '#');
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const no_comment_line = split_it.first();
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var line_it = std.mem.tokenizeAny(u8, no_comment_line, " \t");
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const ip_text = line_it.next() orelse continue;
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var first_name_text: ?[]const u8 = null;
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while (line_it.next()) |name_text| {
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if (std.mem.eql(u8, name_text, host_name.bytes)) {
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if (first_name_text == null) first_name_text = name_text;
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break;
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}
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} else continue;
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if (canonical_name == null) {
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if (HostName.init(first_name_text.?)) |name_text| {
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if (name_text.bytes.len <= options.canonical_name_buffer.len) {
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const canonical_name_dest = options.canonical_name_buffer[0..name_text.bytes.len];
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@memcpy(canonical_name_dest, name_text.bytes);
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canonical_name = .{ .bytes = canonical_name_dest };
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}
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} else |_| {}
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}
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if (options.family != .ip6) {
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if (IpAddress.parseIp4(ip_text, options.port)) |addr| {
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options.addresses_buffer[addresses_len] = addr;
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addresses_len += 1;
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if (options.addresses_buffer.len - addresses_len == 0) return .{
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.addresses_len = addresses_len,
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.canonical_name = canonical_name orelse copyCanon(options.canonical_name_buffer, ip_text),
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};
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} else |_| {}
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}
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if (options.family != .ip4) {
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if (IpAddress.parseIp6(ip_text, options.port)) |addr| {
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options.addresses_buffer[addresses_len] = addr;
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addresses_len += 1;
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if (options.addresses_buffer.len - addresses_len == 0) return .{
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.addresses_len = addresses_len,
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.canonical_name = canonical_name orelse copyCanon(options.canonical_name_buffer, ip_text),
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};
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} else |_| {}
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}
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}
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if (canonical_name == null) assert(addresses_len == 0);
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return .{
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.addresses_len = addresses_len,
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.canonical_name = canonical_name orelse undefined,
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};
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}
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fn copyCanon(canonical_name_buffer: *[max_len]u8, name: []const u8) HostName {
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const dest = canonical_name_buffer[0..name.len];
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@memcpy(dest, name);
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return .{ .bytes = dest };
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}
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/// Writes DNS resolution query packet data to `w`; at most 280 bytes.
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fn writeResolutionQuery(q: *[280]u8, op: u4, dname: []const u8, class: u8, ty: u8) usize {
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// This implementation is ported from musl libc.
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// A more idiomatic "ziggy" implementation would be welcome.
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var name = dname;
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if (std.mem.endsWith(u8, name, ".")) name.len -= 1;
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assert(name.len <= 253);
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const n = 17 + name.len + @intFromBool(name.len != 0);
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// Construct query template - ID will be filled later
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@memset(q[0..n], 0);
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q[2] = @as(u8, op) * 8 + 1;
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q[5] = 1;
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@memcpy(q[13..][0..name.len], name);
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var i: usize = 13;
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var j: usize = undefined;
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while (q[i] != 0) : (i = j + 1) {
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j = i;
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while (q[j] != 0 and q[j] != '.') : (j += 1) {}
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// TODO determine the circumstances for this and whether or
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// not this should be an error.
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if (j - i - 1 > 62) unreachable;
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q[i - 1] = @intCast(j - i);
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}
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q[i + 1] = ty;
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q[i + 3] = class;
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std.crypto.random.bytes(q[0..2]);
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return n;
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}
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pub const ExpandDomainNameError = error{InvalidDnsPacket};
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|
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pub fn expandDomainName(
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msg: []const u8,
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comp_dn: []const u8,
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exp_dn: []u8,
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) ExpandDomainNameError!usize {
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// This implementation is ported from musl libc.
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// A more idiomatic "ziggy" implementation would be welcome.
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var p = comp_dn.ptr;
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var len: usize = std.math.maxInt(usize);
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const end = msg.ptr + msg.len;
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if (p == end or exp_dn.len == 0) return error.InvalidDnsPacket;
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var dest = exp_dn.ptr;
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const dend = dest + @min(exp_dn.len, 254);
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// detect reference loop using an iteration counter
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var i: usize = 0;
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while (i < msg.len) : (i += 2) {
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// loop invariants: p<end, dest<dend
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if ((p[0] & 0xc0) != 0) {
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if (p + 1 == end) return error.InvalidDnsPacket;
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const j = @as(usize, p[0] & 0x3f) << 8 | p[1];
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if (len == std.math.maxInt(usize)) len = @intFromPtr(p) + 2 - @intFromPtr(comp_dn.ptr);
|
|
if (j >= msg.len) return error.InvalidDnsPacket;
|
|
p = msg.ptr + j;
|
|
} else if (p[0] != 0) {
|
|
if (dest != exp_dn.ptr) {
|
|
dest[0] = '.';
|
|
dest += 1;
|
|
}
|
|
var j = p[0];
|
|
p += 1;
|
|
if (j >= @intFromPtr(end) - @intFromPtr(p) or j >= @intFromPtr(dend) - @intFromPtr(dest)) {
|
|
return error.InvalidDnsPacket;
|
|
}
|
|
while (j != 0) {
|
|
j -= 1;
|
|
dest[0] = p[0];
|
|
dest += 1;
|
|
p += 1;
|
|
}
|
|
} else {
|
|
dest[0] = 0;
|
|
if (len == std.math.maxInt(usize)) len = @intFromPtr(p) + 1 - @intFromPtr(comp_dn.ptr);
|
|
return len;
|
|
}
|
|
}
|
|
return error.InvalidDnsPacket;
|
|
}
|
|
|
|
pub const DnsResponse = struct {
|
|
bytes: []const u8,
|
|
|
|
pub const Answer = struct {
|
|
rr: u8,
|
|
data: []const u8,
|
|
packet: []const u8,
|
|
};
|
|
|
|
pub const Error = error{InvalidDnsPacket};
|
|
|
|
pub fn init(r: []const u8) Error!DnsResponse {
|
|
if (r.len < 12) return error.InvalidDnsPacket;
|
|
return .{ .bytes = r };
|
|
}
|
|
|
|
pub fn next(dr: *DnsResponse) Error!?Answer {
|
|
_ = dr;
|
|
@panic("TODO");
|
|
}
|
|
};
|
|
|
|
pub const ConnectTcpError = LookupError || IpAddress.ConnectTcpError;
|
|
|
|
pub fn connectTcp(host_name: HostName, io: Io, port: u16) ConnectTcpError!Stream {
|
|
var addresses_buffer: [32]IpAddress = undefined;
|
|
|
|
const results = try lookup(host_name, .{
|
|
.port = port,
|
|
.addresses_buffer = &addresses_buffer,
|
|
.canonical_name_buffer = &.{},
|
|
});
|
|
const addresses = addresses_buffer[0..results.addresses_len];
|
|
|
|
if (addresses.len == 0) return error.UnknownHostName;
|
|
|
|
for (addresses) |addr| {
|
|
return addr.connectTcp(io) catch |err| switch (err) {
|
|
error.ConnectionRefused => continue,
|
|
else => |e| return e,
|
|
};
|
|
}
|
|
return error.ConnectionRefused;
|
|
}
|
|
|
|
pub const ResolvConf = struct {
|
|
attempts: u32,
|
|
ndots: u32,
|
|
timeout: u32,
|
|
nameservers_buffer: [3]IpAddress,
|
|
nameservers_len: usize,
|
|
search_buffer: [max_len]u8,
|
|
search_len: usize,
|
|
|
|
/// Returns `error.StreamTooLong` if a line is longer than 512 bytes.
|
|
fn init(io: Io) !ResolvConf {
|
|
var rc: ResolvConf = .{
|
|
.nameservers_buffer = undefined,
|
|
.nameservers_len = 0,
|
|
.search_buffer = undefined,
|
|
.search_len = 0,
|
|
.ndots = 1,
|
|
.timeout = 5,
|
|
.attempts = 2,
|
|
};
|
|
|
|
const file = Io.File.openAbsolute(io, "/etc/resolv.conf", .{}) catch |err| switch (err) {
|
|
error.FileNotFound,
|
|
error.NotDir,
|
|
error.AccessDenied,
|
|
=> {
|
|
try addNumeric(&rc, "127.0.0.1", 53);
|
|
return rc;
|
|
},
|
|
|
|
else => |e| return e,
|
|
};
|
|
defer file.close(io);
|
|
|
|
var line_buf: [512]u8 = undefined;
|
|
var file_reader = file.reader(io, &line_buf);
|
|
parse(&rc, &file_reader.interface) catch |err| switch (err) {
|
|
error.ReadFailed => return file_reader.err.?,
|
|
else => |e| return e,
|
|
};
|
|
return rc;
|
|
}
|
|
|
|
const Directive = enum { options, nameserver, domain, search };
|
|
const Option = enum { ndots, attempts, timeout };
|
|
|
|
fn parse(rc: *ResolvConf, reader: *Io.Reader) !void {
|
|
while (reader.takeSentinel('\n')) |line_with_comment| {
|
|
const line = line: {
|
|
var split = std.mem.splitScalar(u8, line_with_comment, '#');
|
|
break :line split.first();
|
|
};
|
|
var line_it = std.mem.tokenizeAny(u8, line, " \t");
|
|
|
|
const token = line_it.next() orelse continue;
|
|
switch (std.meta.stringToEnum(Directive, token) orelse continue) {
|
|
.options => while (line_it.next()) |sub_tok| {
|
|
var colon_it = std.mem.splitScalar(u8, sub_tok, ':');
|
|
const name = colon_it.first();
|
|
const value_txt = colon_it.next() orelse continue;
|
|
const value = std.fmt.parseInt(u8, value_txt, 10) catch |err| switch (err) {
|
|
error.Overflow => 255,
|
|
error.InvalidCharacter => continue,
|
|
};
|
|
switch (std.meta.stringToEnum(Option, name) orelse continue) {
|
|
.ndots => rc.ndots = @min(value, 15),
|
|
.attempts => rc.attempts = @min(value, 10),
|
|
.timeout => rc.timeout = @min(value, 60),
|
|
}
|
|
},
|
|
.nameserver => {
|
|
const ip_txt = line_it.next() orelse continue;
|
|
try addNumeric(rc, ip_txt, 53);
|
|
},
|
|
.domain, .search => {
|
|
const rest = line_it.rest();
|
|
@memcpy(rc.search_buffer[0..rest.len], rest);
|
|
rc.search_len = rest.len;
|
|
},
|
|
}
|
|
} else |err| switch (err) {
|
|
error.EndOfStream => if (reader.bufferedLen() != 0) return error.EndOfStream,
|
|
else => |e| return e,
|
|
}
|
|
|
|
if (rc.nameservers_len == 0) {
|
|
try addNumeric(rc, "127.0.0.1", 53);
|
|
}
|
|
}
|
|
|
|
fn addNumeric(rc: *ResolvConf, name: []const u8, port: u16) !void {
|
|
assert(rc.nameservers_len < rc.nameservers_buffer.len);
|
|
rc.nameservers_buffer[rc.nameservers_len] = try .parse(name, port);
|
|
rc.nameservers_len += 1;
|
|
}
|
|
|
|
fn nameservers(rc: *const ResolvConf) []IpAddress {
|
|
return rc.nameservers_buffer[0..rc.nameservers_len];
|
|
}
|
|
|
|
fn sendMessage(
|
|
rc: *const ResolvConf,
|
|
io: Io,
|
|
queries: []const []const u8,
|
|
answers: [][]u8,
|
|
) !void {
|
|
_ = rc;
|
|
_ = io;
|
|
_ = queries;
|
|
_ = answers;
|
|
@panic("TODO");
|
|
}
|
|
};
|