145 lines
4.1 KiB
Markdown
145 lines
4.1 KiB
Markdown
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---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: libcurl-env-dbg
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Section: 3
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Source: libcurl
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See-also:
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- libcurl-env (3)
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Protocol:
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- All
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Added-in: n/a
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---
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# NAME
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libcurl-env-dbg - environment variables libcurl DEBUGBUILD understands
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# DESCRIPTION
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This is a set of variables only recognized and used if libcurl was built
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"debug enabled", which should never be true for a library used in production.
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These variables are intended for internal use only, subject to change and have
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many effects on the behavior of libcurl. Refer to the source code to determine
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how exactly they are being used.
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## CURL_ALTSVC_HTTP
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Bypass the AltSvc HTTPS protocol restriction if this variable exists.
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## CURL_DBG_SOCK_RBLOCK
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The percentage of recv() calls that should be answered with a EAGAIN at random.
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For TCP/UNIX sockets.
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## CURL_DBG_SOCK_RMAX
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The maximum data that shall be received from the network in one recv() call.
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For TCP/UNIX sockets. This is applied to every recv.
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Example: **CURL_DBG_SOCK_RMAX=400** means recv buffer size is limited to a
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maximum of 400 bytes.
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## CURL_DBG_SOCK_WBLOCK
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The percentage of send() calls that should be answered with a EAGAIN at random.
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For TCP/UNIX sockets.
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## CURL_DBG_SOCK_WPARTIAL
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The percentage of data that shall be written to the network. For TCP/UNIX
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sockets. This is applied to every send.
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Example: **CURL_DBG_SOCK_WPARTIAL=80** means a send with 1000 bytes would
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only send 800.
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## CURL_DBG_QUIC_WBLOCK
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The percentage of send() calls that should be answered with EAGAIN at random.
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QUIC only.
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## CURL_DEBUG
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Trace logging behavior as an alternative to calling curl_global_trace(3).
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Example: **CURL_DEBUG=http/2** means trace details about HTTP/2 handling.
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In the curl command line tool, built with `--enable-debug`, this environment
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variable adds to arguments like `--verbose`, `-vvv`. At least a single `-v`
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is needed to make the run emit trace output, but when it does, the contents
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of `CURL_DEBUG` are added and can override existing options.
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Example: **CURL_DEBUG=tcp,-http/2 curl -vv url** means trace protocol details,
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triggered by `-vv`, add tracing of TCP in addition and remove tracing of
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HTTP/2.
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## CURL_DEBUG_SIZE
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Fake the size returned by CURLINFO_HEADER_SIZE and CURLINFO_REQUEST_SIZE.
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## CURL_GETHOSTNAME
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Fake the local machine's unqualified hostname for NTLM and SMTP.
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## CURL_HSTS_HTTP
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Bypass the HSTS HTTPS protocol restriction if this variable exists.
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## CURL_FORCETIME
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A time of 0 is used for AWS signatures and NTLM if this variable exists.
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## CURL_ENTROPY
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A fixed faked value to use instead of a proper random number so that functions
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in libcurl that are otherwise getting random outputs can be tested for what
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they generate.
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## CURL_SMALLREQSEND
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An alternative size of HTTP data to be sent at a time only if smaller than the
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current.
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## CURL_SMALLSENDS
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An alternative size of socket data to be sent at a time only if smaller than
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the current.
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## CURL_TIME
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Fake Unix timestamp to use for AltSvc, HSTS and CURLINFO variables that are
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time related.
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This variable can also be used to fake the data returned by some CURLINFO
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variables that are not time-related (such as CURLINFO_LOCAL_PORT), and in that
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case the value is not a timestamp.
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## CURL_TRACE
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LDAP tracing is enabled if this variable exists and its value is 1 or greater.
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OpenLDAP tracing is separate. Refer to CURL_OPENLDAP_TRACE.
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## CURL_OPENLDAP_TRACE
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OpenLDAP tracing is enabled if this variable exists and its value is 1 or
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greater. There is a number of debug levels, refer to *openldap.c* comments.
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## CURL_WS_CHUNK_SIZE
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Used to influence the buffer chunk size used for WebSocket encoding and
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decoding.
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## CURL_FORBID_REUSE
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Used to set the CURLOPT_FORBID_REUSE flag on each transfer initiated
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by the curl command line tool. The value of the environment variable
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does not matter.
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## CURL_GRACEFUL_SHUTDOWN
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Make a blocking, graceful shutdown of all remaining connections when
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a multi handle is destroyed. This implicitly triggers for easy handles
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that are run via easy_perform. The value of the environment variable
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gives the shutdown timeout in milliseconds.
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