GET / in the client/web assets handler normalized to an empty fs
path. The empty name is invalid, and file systems wrapped in fs.Sub
reject it with fs.ErrInvalid instead of fs.ErrNotExist. The
index.html fallback only triggers on fs.ErrNotExist, so it never ran
and the request failed with a 500 "internal error". This broke the
corp smoke test that curls http://100.100.100.100/.
Normalize the empty path to index.html before serving. Also make
compserve.ServeFile return fs.ErrNotExist for invalid paths, per its
documented contract, instead of leaking fs.ErrInvalid.
Both layers have regression tests verified to fail without the fix.
Updates tailscale/corp#20099
Updates #12170
Signed-off-by: James Tucker <james@tailscale.com>
Adds tsweb/compserve: content negotiation for precompressed static
variants, with a transcode-to-identity fallback for clients that do not
accept an encoding (including when the raw file is absent), and
CompressWriter, which live-compresses dynamic responses with zstd in its
fastest mode, streamed incrementally with no buffering. Negotiation is
q-value and wildcard aware (gzip;q=0 previously matched gzip).
client/web serves its prebuilt embedded assets through compserve,
replacing brotli with zstd; the embedded FS is wrapped in
tsweb/vcstime for conditional-request mod times. tsweb/compserve/gzip.go
keeps transitional serving of gzip variants from pre-zstd file systems
(such as the currently published web-client-prebuilt module):
passthrough to gzip-accepting clients, transcoded to identity otherwise;
it becomes inert once a zstd-only module is published.
util/zstdframe gains pooled GetDecoder and GetStreamingEncoder
(concurrency=1). util/precompress is now a build-time tool, generating
zstd variants only. cmd/tsconnect and cmd/build-webclient consume the
new precompress/compserve split. tsweb.AcceptsEncoding and
tsweb/tswebutil are removed; negotiation lives in compserve and the
deprecated shim had no callers. go.mod bumps web-client-prebuilt.
Also fixes a transcoding bug where http.ServeContent's size probe via
the promoted zstd.Decoder.WriteTo could report a zero length, serving
empty bodies.
Updates tailscale/corp#20099
Signed-off-by: James Tucker <james@tailscale.com>
James Tucker