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Debug logs for TLS alerts contain wrong messages #2806

djelinski opened this issue Jul 28, 2018 · 2 comments

Debug logs for TLS alerts contain wrong messages #2806

djelinski opened this issue Jul 28, 2018 · 2 comments


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While examining debug output of #2801, I noticed that the debug output for TLS alerts is garbage. The output currently reads:

TLSv1.2 (IN), TLS alert, Client hello (1):

I expected the following

TLSv1.2 (IN), TLS alert, warning / close notify (1/0)

curl/libcurl version

[curl -V output]
curl 7.60.0 (i386-pc-win32) libcurl/7.60.0 OpenSSL/1.1.0h (WinSSL) zlib/1.2.11 brotli/1.0.4 WinIDN libssh2/1.8.0 nghttp2/1.32.0
Release-Date: 2018-05-16
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 IDN IPv6 Largefile SSPI Kerberos SPNEGO NTLM SSL libz brotli TLS-SRP HTTP2 HTTPS-proxy MultiSSL

operating system

Windows 2008R2

@bagder bagder added the TLS label Jul 28, 2018
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bagder commented Jul 29, 2018

Any suggestion on how to reproduce this?

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Contributor Author

Gist of code used to reproduce:

curl_easy_setopt(curl, CURLOPT_URL, "");
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, DebugCallback);
Sleep(5950); // experimental, server seems to close connection after about this time

Debug function:

int DebugCallback(CURL *handle,curl_infotype type,char *datasize_t size,void *userptr)
if(type >= CURLINFO_DATA_OUT) return 0;
printf("%s",string(data, data+size).c_str());
return 0;

It seems to me that the detailed messages are only valid for TLS handshake, for other message types they don't make sense.

@bagder bagder closed this as completed in aa2ad90 Aug 9, 2018
xquery pushed a commit to xquery/curl that referenced this issue Sep 3, 2018
falconindy pushed a commit to falconindy/curl that referenced this issue Sep 10, 2018
@lock lock bot locked as resolved and limited conversation to collaborators Nov 7, 2018
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