rzv-me
commented
9 months ago I have been struggling with a similar problem as @frederichoule had: panic: Header called after Handler finished
The problem is that there is not check in CustomWriter.Header() if the request was cancelled, which is allowed in HTTP2.
I worked on a way to reproduce it, and I have this python script
import threading
import socket
from h2.connection import H2Connection
from h2.events import RequestReceived, StreamReset
from h2.config import H2Configuration
import ssl
from h2.errors import ErrorCodes
def root_function(url='localhost'):
while True:
try:
# Create a TCP connection
sock = socket.create_connection((url, 4433))
print(f"Create a TCP connection")
# Wrap the socket for TLS
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
ctx.set_alpn_protocols(['h2'])
sock = ctx.wrap_socket(sock, server_hostname=url)
print(f"Wrap socket for TLS")
# Make sure we're using HTTP/2
assert sock.selected_alpn_protocol() == 'h2'
# Create HTTP/2 connection
config = H2Configuration(client_side=True)
conn = H2Connection(config=config)
conn.initiate_connection()
sock.sendall(conn.data_to_send())
# # Create a new stream
# stream_id = conn.get_next_available_stream_id()
# conn.send_headers(
# stream_id,
# [(':method', 'GET'), (':authority', url), (':path', '/'), (':scheme', 'https')],
# )
# sock.sendall(conn.data_to_send())
# Read some data
while True:
stream_id = conn.get_next_available_stream_id()
conn.send_headers(
stream_id,
[(':method', 'GET'), (':authority', url), (':path', '/mycachepath'), (':scheme', 'https')],
)
sock.sendall(conn.data_to_send())
#data = sock.recv(65535)
#if not data:
#break
conn.reset_stream(stream_id, error_code=ErrorCodes.CANCEL)
events = conn.receive_data(data)
for event in events:
if isinstance(event, RequestReceived):
# Cancel the stream with error code for CANCEL
conn.reset_stream(event.stream_id, error_code=ErrorCodes.CANCEL)
elif isinstance(event, StreamReset):
print(f"Stream {event.stream_id} cancelled.")
sock.sendall(conn.data_to_send())
except Exception as e:
print(f"An error occurred: {e}")
# Create 50 threads running root_function
threads = []
for i in range(1):
thread = threading.Thread(target=root_function)
thread.start()
threads.append(thread)
print(f"Created thread {i}")
# Keep the main thread alive
for thread in threads:
thread.join()%The caddy file is
{
debug
order cache before reverse_proxy
cache {
log_level debug
}
}
localhost:4433 {
tls internal
encode gzip
reverse_proxy /mycachepath https://[YOURBACKENDHOST] {
header_up Host [YOURBACKENDHOST]
header_up User-Real-IP {remote_host}
header_up User-Real-Proto {scheme}
header_up X-Forwarded-For {remote_host}
header_up X-Forwarded-Port {server_port}
header_up X-Forwarded-Proto {scheme}
header_up X-Forwarded-Host {host}
health_timeout 5s
# header_down -Cache-Control
}
@matchCachePath path /mycachepath
header /mycachepath >Cache-Control "must-revalidate, no-cache, no-store, private"
cache @matchCachePath {
ttl 3s
stale 3s
# log_level debug
mode bypass
key {
disable_body
disable_host
disable_method
}
}
}The git diff for the fix is this:
diff --git a/pkg/middleware/writer.go b/pkg/middleware/writer.go
index a786c8f..c108c98 100644
--- a/pkg/middleware/writer.go
+++ b/pkg/middleware/writer.go
@@ -43,6 +43,10 @@ type CustomWriter struct {
func (r *CustomWriter) Header() http.Header {
r.mutex.Lock()
defer r.mutex.Unlock()
+
+ if (r.Req.Context().Err() != nil) {
+ return http.Header{}
+ }
if r.headersSent {
return http.Header{}
}The problem is that now I get another error
fatal error: concurrent map writes
goroutine 216 [running]:
github.com/caddyserver/caddy/v2.(*Replacer).Set(...)
github.com/caddyserver/caddy/v2@v2.7.6/replacer.go:68
github.com/caddyserver/caddy/v2/modules/caddyhttp.(*HTTPErrorConfig).WithError(0x106887c28, 0x140157a9700, {0x106887c28?, 0x107bdcee0?})
github.com/caddyserver/caddy/v2@v2.7.6/modules/caddyhttp/server.go:656 +0x1a4
github.com/caddyserver/caddy/v2/modules/caddyhttp.(*Server).ServeHTTP(0x140006d2580, {0x10689a450, 0x1400008a8c0}, 0x14015826500)
github.com/caddyserver/caddy/v2@v2.7.6/modules/caddyhttp/server.go:368 +0x1038
net/http.serverHandler.ServeHTTP({0x0?}, {0x10689a450?, 0x1400008a8c0?}, 0x104266a40?)
net/http/server.go:2938 +0xbc
net/http.initALPNRequest.ServeHTTP({{0x1068a0230?, 0x140157a7f80?}, 0x140157d2000?, {0x140004f64b0?}}, {0x10689a450, 0x1400008a8c0}, 0x14015826500)
net/http/server.go:3546 +0x1b4
golang.org/x/net/http2.(*serverConn).runHandler(0x107c5b4c0?, 0x0?, 0x0?, 0x1068789e8?)
golang.org/x/net@v0.19.0/http2/server.go:2368 +0xc0
created by golang.org/x/net/http2.(*serverConn).scheduleHandler in goroutine 232
golang.org/x/net@v0.19.0/http2/server.go:2303 +0x208And it is always in replacer.go:68
Hope this helps you
darkweak
I have a recurring error where the homepage of the website is blank.
When I check the key value in redis, it looks like this:
What strikes to me is the key name, which is
GET-https-www.website.com-/, which all the other keys have{-VARY-}appended to them. If I delete the key, and refresh the website, the new key that appears isGET-https-www.website.com-/{-VARY-}Accept-Encoding:gzip, deflate, br, and now the page isn't blank anymore.What would cause that?