Running into TLS1.3 packet chunk size issues with std.http

[SuperAuguste]

Zig Version

0.11.0-dev.2868+1a455b2dd

Steps to Reproduce and Observed Behavior

Make a POST request with a body of size greater than ~16383 - this'll cause a TlsAlert error.

Example:

const std = @import("std");

pub fn main() !void {
    const allocator = std.heap.page_allocator;

    var http_client: std.http.Client = .{ .allocator = allocator };

    var h = std.http.Headers{ .allocator = allocator };
    try h.append("Content-Type", "application/x-protobuf");

    const telemetry_uri = std.Uri.parse("https://telemetry.zigtools.org:4318/v1/traces") catch @panic("Invalid telemetry URI");

    var http_req = try http_client.request(.POST, telemetry_uri, h, .{});

    http_req.transfer_encoding = .chunked;

    var bruh = try allocator.alloc(u8, 17000);
    std.mem.set(u8, bruh, 'a');

    try http_req.start();
    try http_req.writeAll(bruh);
    try http_req.finish();
    try http_req.wait();
}

You'll get the following error:

C:\Programming\Zig\zig-from-the-website\lib\std\crypto\tls\Client.zig:1117:25: 0x7ff7c86d155a in readvAdvanced__anon_11015 (http.exe.obj)
                        return error.TlsAlert;
                        ^
C:\Programming\Zig\zig-from-the-website\lib\std\crypto\tls\Client.zig:898:19: 0x7ff7c86cba26 in readvAtLeast__anon_11014 (http.exe.obj)       
        var amt = try c.readvAdvanced(stream, iovecs[vec_i..]);
                  ^
C:\Programming\Zig\zig-from-the-website\lib\std\crypto\tls\Client.zig:859:5: 0x7ff7c86cb84c in readAtLeast__anon_11012 (http.exe.obj)
    return readvAtLeast(c, stream, &iovecs, len);
    ^
C:\Programming\Zig\zig-from-the-website\lib\std\crypto\tls\Client.zig:864:5: 0x7ff7c86cb7b1 in read__anon_11011 (http.exe.obj)
    return readAtLeast(c, stream, buffer, 1);
    ^
C:\Programming\Zig\zig-from-the-website\lib\std\http\Client.zig:176:31: 0x7ff7c869f6ea in read (http.exe.obj)
            error.TlsAlert => return error.TlsAlert,
                              ^
C:\Programming\Zig\zig-from-the-website\lib\std\http\Client.zig:264:23: 0x7ff7c8668b91 in fill (http.exe.obj)
        const nread = try bconn.conn.read(bconn.buf[0..]);
                      ^
C:\Programming\Zig\zig-from-the-website\lib\std\http\Client.zig:681:17: 0x7ff7c86642ab in wait (http.exe.obj)
                try req.connection.data.buffered.fill();
                ^
C:\Programming\Zig\sandbox\http.zig:27:5: 0x7ff7c8662912 in main (http.exe.obj)
    try http_req.wait();

Expected Behavior

The TLS client should split the request into properly sized chunks for me. @truemedian was mentioning adding in buffering to the std.http parts of the library, maybe that change could improve this too! :)

[andrewrk]

Fixed landed in 9b0da5c.