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Windows: no_proxy environment variable ignored when longer than (258) chars #4174

myfonj opened this issue Jul 30, 2019 · 1 comment


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@myfonj myfonj commented Jul 30, 2019

I did this

no_proxy (user) environment variable on my machine is 966 characters long [1] and http_proxy and https_proxy variables set. I've observed that as long as I keep no_proxy length above 258 characters, cURL requests are always passed to proxy on my system.

cURL calls with 258 and 259 characters long `no_proxy` environment variable in my CMD:
C:\apps\cmd>set no_proxy=localhost,127.0.0.*,aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

C:\apps\cmd>curl --location --head http://localhost/
HTTP/1.1 200 OK
Date: Tue, 30 Jul 2019 15:46:25 GMT
Server: Apache/2.4.37 (Win64) PHP/7.3.3
Last-Modified: Thu, 18 Jul 2019 15:02:45 GMT
ETag: "2000-58df5e7002ac0"
X-Clacks-Overhead: GNU Terry Pratchett
Content-Type: text/html;charset=UTF-8

C:\apps\cmd>set no_proxy=localhost,127.0.0.*,aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

C:\apps\cmd>curl --location --head http://localhost/
HTTP/1.1 503 Service Unavailable
Server: squid/(...)

I expected

Both cURL calls had the same outcome.

curl -V

curl 7.65.3 (x86_64-pc-win32) libcurl/7.65.3 OpenSSL/1.1.1c (Schannel) zlib/1.2.11 brotli/1.0.7 WinIDN libssh2/1.9.0 nghttp2/1.39.1
Release-Date: 2019-07-19
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: AsynchDNS HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile MultiSSL NTLM SPNEGO SSL SSPI TLS-SRP brotli libz

Operating system

Windows 10, 10.0.16299, build 1709


System settings GUI for (user) environment variable allows 2047 characters on my system.

[1] don't ask why; just copied what was in the Network settings GUI (inetcpl.cpl) in Exceptions field, replaced semicolons and added it to my CMDer user_profile.cmd script an/or User Environment Variables settings panel as no_proxy entry.

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@bagder bagder commented Jul 30, 2019

Oh... and here's the explanation:

char env[MAX_PATH]; /* MAX_PATH is from windef.h */

We should expand that array quite a bit...

bagder added a commit that referenced this issue Jul 30, 2019
Reported-by: Michal Čaplygin
Fixes #4174
@bagder bagder closed this in b7d1264 Jul 31, 2019
@lock lock bot locked as resolved and limited conversation to collaborators Oct 29, 2019
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