When impersonating with libcurl, the built-in user agent used for
impersonation was overriding and useragent the user had set via
CURLOPT_USERAGENT. The fix takes care to specifically handle user agent
set with CURLOPT_USERAGENT and use it instead of the built-in one when
it is supplied.
Let the user disable the built-in list of HTTP headers when using
libcurl-impersonate, either directly or when replacing it at runtime
with LD_PRELOAD. This is intended to give the user more precise control
over the content and order of the HTTP headers.
To support this, the curl_easy_impersonate() now has an added argument
that can be set to 0, in which case the built-in list of HTTP headers
used by libcurl-impersonate will not be automatically sent. Instead,
the user is expected to supply all the headers by themselves using the
standard CURLOPT_HTTPHEADER libcurl option.
When using LD_PRELOAD to inject libcurl-impersonate, one can disable
the built-in headers by setting the CURL_IMPERSONATE_HEADERS
environment variable to "no".
curl_easy_reset() may be used by an application to reset the options on
a curl handle. If an app has the CURL_IMPERSONATE env var defined, then
the impersonation options are automatically set in curl_easy_init() but
will be cleared in a call to curl_easy_reset(). The desired behavior is
for the impersonation options to be retained (as they are "transparent"
to the user), which this commit takes care of.
Note that this only has an effect when libcurl-impersonate is loaded and
the CURL_IMPERSONATE env var is set. Otherwise the regular behavior of
resetting all the handle options is retained.
Test that the unique TLS signature of curl-impersonate is preserved
after a call to curl_easy_reset() when libcurl-impersonate is loaded.
For this purpose change the 'minicurl' testing util to support multiple
URLs and launch it with 2 different URLs when testing the TLS signature.
Add tests to verify that the HTTP headers and HTTP/2 pseudo-headers
generated by curl-impersonate match the expected ones from the browser.
The test uses a local nghttpd HTTP/2 server instance with a self-signed
certificate.
Test that libcurl-impersonate produces the desired TLS signature when
the CURL_IMPERSONATE env var is set. A small C program called "minicurl"
is linked to libcurl, and libcurl-impersonate is loaded at runtime with
LD_PRELOAD.
