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curl 7.77.0 proxy tunnel CONNECT busy loop waiting for reply #7155

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zloi-user opened this issue May 31, 2021 · 12 comments
Closed

curl 7.77.0 proxy tunnel CONNECT busy loop waiting for reply #7155

zloi-user opened this issue May 31, 2021 · 12 comments

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@zloi-user
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@zloi-user zloi-user commented May 31, 2021

curl loads the cpu, with many threads this is especially noticeable

on version 7.76.1 the problem is not observed

similar problem #5532

@bagder
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@bagder bagder commented May 31, 2021

Please give us a lot more details. What protocol, what components, what platform and most importantly: how can we reproduce. We cannot act on this issue until we get data.

@zloi-user
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@zloi-user zloi-user commented May 31, 2021

curl --proxy 'http://185.169.198.98:3128' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://208.115.109.250:443' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://165.22.81.30:42663' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://157.230.103.189:40151' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://150.136.178.43:80' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://181.3.93.87:10809' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://34.230.61.238:80' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://54.166.131.99:80' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://51.81.82.175:2003' 'https://www.google.com/favicon.ico' -o - >>/dev/null &
curl --proxy 'http://167.172.180.46:39898' 'https://www.google.com/favicon.ico' -o - >>/dev/null &

the problem manifests itself when using HTTP proxy
(Linux Gentoo, kernel 5.10.27 x86_64 AMD)

@jay
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@jay jay commented Jun 7, 2021

We need curl version curl -V. Is there one particular site proxy causing the problem?

@zloi-user
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@zloi-user zloi-user commented Jun 7, 2021

curl -V
curl 7.77.0 (x86_64-pc-linux-gnu) libcurl/7.77.0 OpenSSL/1.1.1k zlib/1.2.11 nghttp2/1.43.0
Release-Date: 2021-05-26
Protocols: dict file ftp ftps http https imap imaps mqtt pop3 pop3s rtsp smb smbs smtp smtps tftp
Features: HSTS HTTP2 HTTPS-proxy IPv6 Largefile libz NTLM SSL TLS-SRP UnixSockets

the problem is not in the site, but when using an http proxy

@jay
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@jay jay commented Jun 7, 2021

Ok. That's what i meant, is there one particular proxy causing the problem? This is going to be hard to debug unless we can isolate it to a single process.

@zloi-user
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@zloi-user zloi-user commented Jun 7, 2021

Ok. That's what i meant, is there one particular proxy causing the problem? This is going to be hard to debug unless we can isolate it to a single process.

curl --proxy 'http://185.169.198.98:3128' 'https://www.google.com/favicon.ico' -o - >>/dev/null

@jay
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@jay jay commented Jul 19, 2021

I can't reproduce this in Windows or Ubuntu.

@zloi-user
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@zloi-user zloi-user commented Jul 19, 2021

I can't reproduce this in Windows or Ubuntu.

this is a public proxy, it does not work now,
if you take others, you will get a load on the cpu

curl --proxy 'http://167.172.110.165:9090' 'https://www.google.com/favicon.ico' -o - >>/dev/null

@jay
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@jay jay commented Jul 19, 2021

curl --proxy 'http://167.172.110.165:9090' 'https://www.google.com/favicon.ico' -o - >>/dev/null

I get connection refused and no load

@zloi-user
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@zloi-user zloi-user commented Jul 19, 2021

I get connection refused and no load

for clarity, run in a loop

while true;do curl --proxy 'http://157.230.103.91:37749' 'https://www.google.com/favicon.ico' -o - >>/dev/null; done

@jay
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@jay jay commented Jul 19, 2021

bisected to 51c0ebc http: deal with partial CONNECT sends. repro done by not sending a reply to CONNECT, eg

socat tcp-listen:8000,reuseaddr,fork -
curl -v --proxy http://localhost:8000 https://foo

curl/lib/http.h

Lines 184 to 188 in 6b951a6

enum {
HTTPSEND_NADA, /* init */
HTTPSEND_REQUEST, /* sending a request */
HTTPSEND_BODY /* sending body */
} sending;

curl/lib/http_proxy.c

Lines 141 to 155 in 6b951a6

/* when we've sent a CONNECT to a proxy, we should rather either wait for the
socket to become readable to be able to get the response headers or if
we're still sending the request, wait for write. */
int Curl_connect_getsock(struct connectdata *conn)
{
struct HTTP *http;
DEBUGASSERT(conn);
DEBUGASSERT(conn->connect_state);
http = &conn->connect_state->http_proxy;
if(http->sending)
return GETSOCK_WRITESOCK(0);
return GETSOCK_READSOCK(0);
}

the commit changed the logic by having multi check if http->sending is !=0 during CONNECT then assume we're still writing and wait for the socket to be writable instead of readable, whereas before it would just check if it was readable. i assume this was necessary to implement partial CONNECT send. however in the CONNECT init phase (TUNNEL_INIT) Curl_buffer_send is called which sends out the actual CONNECT to the server and then sets http->sending to HTTPSEND_BODY immediately afterward. so it just busy loops checking for write when it should actually be checking for read. @bagder

@jay jay changed the title Сurl 7.77 loads the cpu, with many threads this is especially noticeable curl 7.77.0 proxy tunnel CONNECT busy loop waiting for reply Jul 19, 2021
@jay jay removed the needs-info label Jul 19, 2021
@bagder bagder self-assigned this Jul 19, 2021
bagder added a commit that referenced this issue Jul 23, 2021
... so that Curl_connect_getsock() will know how to wait for the socket
to become readable and not writable after the entire CONNECT request has
been issued.

Regression added in 7.77.0

Reported-by: zloi-user on github
Assisted-by: Jay Satiro
Fixes #7155
@bagder bagder closed this in c27a70a Jul 25, 2021
@zloi-user
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@zloi-user zloi-user commented Aug 18, 2021

the problem is not solved, curl still loads the cpu

on version 7.76.1, the problem is not observed, all versions after loading the cpu 100%

while true;do curl --proxy 'http://157.230.103.91:37749' 'https://www.google.com/favicon.ico' -o - >>/dev/null; done

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3 participants