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enable websocket tail-less mode

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This commit is contained in:
Igor Anić 2023-07-13 14:36:10 +02:00
parent 270d34d2d7
commit 53a5be2037
4 changed files with 70 additions and 14 deletions
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1
.gitignore vendored
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@ -1,2 +1,3 @@
zig-cache/
zig-out/
.vscode

8
example/example1.zig
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@ -6,8 +6,6 @@ pub fn main() !void {
defer _ = gpa.deinit();
const allocator = gpa.allocator();
std.debug.print("Pero\n", .{});
const input = "Hello";
var cmp = try zlib.Compressor.init(allocator, .{ .header = .none });
defer cmp.deinit();
@ -44,7 +42,7 @@ test "Hello from example1" {
}
// test with:
// $ zig test --library z -freference-trace example/example1.zig --main-pkg-path . --deps zlib=zlib --mod zlib::src/main.zig
// $ zig test -l z --main-pkg-path . --deps zlib=zlib --mod zlib::src/main.zig example/example1.zig
// build with:
// zig build
// build/run with:
// zig build && zig-out/bin/example1

71
src/main.zig
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@ -129,6 +129,8 @@ pub const CompressorOptions = struct {
none, // raw deflate data with no zlib header or trailer
zlib,
gzip, // to write a simple gzip header and trailer around the compressed data instead of a zlib wrapper
ws, // same as none for header, but also removes 4 octets (that are 0x00 0x00 0xff 0xff) from the tail end.
// ref: https://datatracker.ietf.org/doc/html/rfc7692#section-7.2.1
};
compression_level: c_int = c.Z_DEFAULT_COMPRESSION,
@ -146,7 +148,7 @@ pub const CompressorOptions = struct {
var ws = @as(i6, if (self.window_size < 9) 9 else self.window_size);
return switch (self.header) {
.zlib => ws,
.none => -@as(i6, ws),
.none, .ws => -@as(i6, ws),
.gzip => ws + 16,
};
}
@ -235,6 +237,7 @@ pub const DecompressorOptions = struct {
const HeaderOptions = enum {
none, // raw deflate data with no zlib header or trailer,
zlib_or_gzip,
ws, // websocket compatibile, append deflate tail to the end
};
header: HeaderOptions = .zlib_or_gzip,
@ -243,8 +246,8 @@ pub const DecompressorOptions = struct {
const Self = @This();
pub fn windowSize(self: Self) i5 {
var ws = if (self.window_size < 8) 15 else self.window_size;
return if (self.header == .none) -@as(i5, ws) else ws;
var window_size = if (self.window_size < 8) 15 else self.window_size;
return if (self.header == .none or self.header == .ws) -@as(i5, window_size) else window_size;
}
};
@ -316,6 +319,7 @@ pub fn DecompressorReader(comptime ReaderType: type) type {
pub const Compressor = struct {
allocator: Allocator,
stream: *c.z_stream,
strip_tail: bool = false,
const Self = @This();
@ -330,7 +334,11 @@ pub const Compressor = struct {
opt.memory_level,
opt.strategy,
));
return .{ .allocator = allocator, .stream = stream };
return .{
.allocator = allocator,
.stream = stream,
.strip_tail = opt.header == .ws,
};
}
pub fn deinit(self: *Self) void {
@ -370,15 +378,20 @@ pub const Compressor = struct {
if (flag == c.Z_SYNC_FLUSH) break;
flag = c.Z_SYNC_FLUSH;
}
if (self.strip_tail and len > 4 and tmp[len - 1] == 0xff and tmp[len - 2] == 0xff and tmp[len - 3] == 0x00 and tmp[len - 4] == 0x00)
len -= 4;
return try self.allocator.realloc(tmp, len);
}
};
const chunk_size = 4096;
const deflate_tail = [_]u8{ 0x00, 0x00, 0xff, 0xff };
pub const Decompressor = struct {
allocator: Allocator,
stream: *c.z_stream,
append_tail: bool = false,
const Self = @This();
@ -386,7 +399,11 @@ pub const Decompressor = struct {
var stream = try zStreamInit(allocator);
errdefer zStreamDeinit(allocator, stream);
try checkRC(c.inflateInit2(stream, options.windowSize()));
return .{ .allocator = allocator, .stream = stream };
return .{
.allocator = allocator,
.stream = stream,
.append_tail = options.header == .ws,
};
}
pub fn deinit(self: *Self) void {
@ -404,6 +421,7 @@ pub const Decompressor = struct {
self.stream.next_in = @as([*]u8, @ptrFromInt(@intFromPtr(compressed.ptr)));
self.stream.avail_in = @as(c_uint, @intCast(compressed.len));
var tail_appended = false;
var tmp = try self.allocator.alloc(u8, chunk_size);
var len: usize = 0; // inflated part of the tmp buffer
while (true) {
@ -420,6 +438,13 @@ pub const Decompressor = struct {
tmp = try self.allocator.realloc(tmp, tmp.len * 2); // make more space
continue;
}
if (self.append_tail and !tail_appended) {
self.stream.next_in = @as([*]u8, @ptrFromInt(@intFromPtr(&deflate_tail)));
self.stream.avail_in = @as(c_uint, @intCast(deflate_tail.len));
tail_appended = true;
continue;
}
break;
}
return try self.allocator.realloc(tmp, len);
@ -513,20 +538,48 @@ fn showBuf(buf: []const u8) void {
std.debug.print("\n", .{});
}
test "Hello" {
test "Hello compress/decompress websocket compatibile" {
const allocator = std.testing.allocator;
const input = "Hello";
var cmp = try Compressor.init(allocator, .{ .header = .none });
var cmp = try Compressor.init(allocator, .{ .header = .ws });
defer cmp.deinit();
const compressed = try cmp.compressAllAlloc(input);
defer allocator.free(compressed);
//try std.testing.expectEqualSlices(u8, &[_]u8{ 0xf2, 0x48, 0xcd, 0xc9, 0xc9, 0x07, 0x04, 0x00, 0x00, 0xff, 0xff }, compressed);
try std.testing.expectEqualSlices(u8, &[_]u8{ 0xf2, 0x48, 0xcd, 0xc9, 0xc9, 0x07, 0x08, 0x00 }, compressed);
var dcp = try Decompressor.init(allocator, .{ .header = .none });
var dcp = try Decompressor.init(allocator, .{ .header = .ws });
defer dcp.deinit();
const decompressed = try dcp.decompressAllAlloc(compressed);
defer allocator.free(decompressed);
try std.testing.expectEqualSlices(u8, input, decompressed);
}
// reference: https://datatracker.ietf.org/doc/html/rfc7692#section-7.2.3.2
test "Sharing LZ77 Sliding Window" {
const allocator = std.testing.allocator;
const input = "Hello";
var cmp = try Compressor.init(allocator, .{ .header = .ws });
defer cmp.deinit();
const c1 = try cmp.compressAllAlloc(input);
defer allocator.free(c1);
try std.testing.expectEqualSlices(u8, &[_]u8{ 0xf2, 0x48, 0xcd, 0xc9, 0xc9, 0x07, 0x08, 0x00 }, c1);
// compress second message using same sliding window, should be little shorter
const c2 = try cmp.compressAllAlloc(input);
defer allocator.free(c2);
try std.testing.expectEqualSlices(u8, &[_]u8{ 0xf2, 0x00, 0x11, 0x00, 0x01, 0x00 }, c2);
var dcp = try Decompressor.init(allocator, .{ .header = .ws });
defer dcp.deinit();
const d1 = try dcp.decompressAllAlloc(c1);
defer allocator.free(d1);
try std.testing.expectEqualSlices(u8, input, d1);
const d2 = try dcp.decompressAllAlloc(c1);
defer allocator.free(d2);
try std.testing.expectEqualSlices(u8, input, d2);
}

4
src/readme.md Normal file
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@ -0,0 +1,4 @@
[Compression Extensions for WebSocket](https://datatracker.ietf.org/doc/html/rfc7692)
[zlib 1.2.13 Manual](https://www.zlib.net/manual.html)