CURLOPT_FOLLOWLOCATION with CURLOPT_CURLU: infinitely following locations

I did this

#include <curl/curl.h>

int main(){
    CURLU* url = curl_url();
    curl_url_set(url, CURLUPART_URL, "https://google.com", 0);

    CURL* get = curl_easy_init();

    curl_easy_setopt(get, CURLOPT_CURLU, url);
    curl_easy_setopt(get, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(get, CURLOPT_VERBOSE, 1L);
    curl_easy_perform(get);

    curl_easy_cleanup(get);
    curl_url_cleanup(url);
}

I expected the following

I expected this would follow to the desired location. Instead curl_easy_perform() is blocking forever, infinitely following the location. Just happens when I set the url with CURLOPT_CURLU, CURLOPT_URL is working as expected. Same error for multiple hosts.

curl/libcurl version

curl 7.71.1 (x86_64-pc-linux-gnu) libcurl/7.71.1 OpenSSL/1.1.1g zlib/1.2.11 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh2/1.9.0 nghttp2/1.41.0
Release-Date: 2020-07-01
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp 
Features: AsynchDNS GSS-API HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP UnixSockets

operating system

Linux 5.7.8-arch1-1

[jay]

I can reproduce this. It probably has something to do with parseurlandfillconn which will set the url handle to the user setting (stored in data->set.uh), even on redirect.

curl/lib/url.c

Lines 1840 to 1848 in 5a1fc8d

	up_free(data); /* cleanup previous leftovers first */
	/* parse the URL */
	if(data->set.uh) {
	uh = data->state.uh = curl_url_dup(data->set.uh);
	}
	else {
	uh = data->state.uh = curl_url();
	}

data->state.uh where the redirect URL handle was stored is freed by up_free and then overwritten. That seems right though but I think something is missing like a data->change.uh to complement data->change.url so uh overwrites data->change.url?

[jay]

Try #5713