111 lines
3.4 KiB
Markdown
111 lines
3.4 KiB
Markdown
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---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_ACCEPT_ENCODING
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_HTTPHEADER (3)
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- CURLOPT_HTTP_CONTENT_DECODING (3)
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- CURLOPT_TRANSFER_ENCODING (3)
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---
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# NAME
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CURLOPT_ACCEPT_ENCODING - automatic decompression of HTTP downloads
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ACCEPT_ENCODING, char *enc);
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~~~
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# DESCRIPTION
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Pass a char pointer argument specifying what encoding you would like.
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Sets the contents of the Accept-Encoding: header sent in an HTTP request, and
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enables decoding of a response when a Content-Encoding: header is received.
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libcurl potentially supports several different compressed encodings depending
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on what support that has been built-in.
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To aid applications not having to bother about what specific algorithms this
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particular libcurl build supports, libcurl allows a zero-length string to be
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set ("") to ask for an Accept-Encoding: header to be used that contains all
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built-in supported encodings.
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Alternatively, you can specify exactly the encoding or list of encodings you
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want in the response. The following encodings are supported: *identity*,
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meaning non-compressed, *deflate* which requests the server to compress
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its response using the zlib algorithm, *gzip* which requests the gzip
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algorithm, (since curl 7.57.0) *br* which is brotli and (since curl
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7.72.0) *zstd* which is zstd. Provide them in the string as a
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comma-separated list of accepted encodings, like: **"br, gzip, deflate"**.
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Set CURLOPT_ACCEPT_ENCODING(3) to NULL to explicitly disable it, which
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makes libcurl not send an Accept-Encoding: header and not decompress received
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contents automatically.
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You can also opt to just include the Accept-Encoding: header in your request
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with CURLOPT_HTTPHEADER(3) but then there is no automatic decompressing
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when receiving data.
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This is a request, not an order; the server may or may not do it. This option
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must be set (to any non-NULL value) or else any unsolicited encoding done by
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the server is ignored.
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Servers might respond with Content-Encoding even without getting a
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Accept-Encoding: in the request. Servers might respond with a different
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Content-Encoding than what was asked for in the request.
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The Content-Length: servers send for a compressed response is supposed to
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indicate the length of the compressed content so when auto decoding is enabled
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it may not match the sum of bytes reported by the write callbacks (although,
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sending the length of the non-compressed content is a common server mistake).
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The application does not have to keep the string around after setting this
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option.
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# DEFAULT
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NULL
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# PROTOCOLS
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HTTP
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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/* enable all supported built-in compressions */
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curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "");
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/* Perform the request */
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curl_easy_perform(curl);
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}
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}
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~~~
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# AVAILABILITY
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This option was called CURLOPT_ENCODING before 7.21.6
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The specific libcurl you are using must have been built with zlib to be able to
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decompress gzip and deflate responses, with the brotli library to
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decompress brotli responses and with the zstd library to decompress zstd
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responses.
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# RETURN VALUE
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Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
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CURLE_OUT_OF_MEMORY if there was insufficient heap space.
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