84 lines
1.9 KiB
Markdown
84 lines
1.9 KiB
Markdown
---
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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_INTERFACE
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_SOCKOPTFUNCTION (3)
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- CURLOPT_TCP_NODELAY (3)
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---
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# NAME
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CURLOPT_INTERFACE - source interface for outgoing traffic
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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_INTERFACE, char *interface);
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~~~
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# DESCRIPTION
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Pass a char pointer as parameter. This sets the *interface* name to use as
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outgoing network interface. The name can be an interface name, an IP address,
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or a hostname.
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If the parameter starts with "if!" then it is treated only as an interface
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name. If the parameter starts with &"host!" it is treated as either an IP
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address or a hostname.
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If "if!" is specified but the parameter does not match an existing interface,
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*CURLE_INTERFACE_FAILED* is returned from the libcurl function used to
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perform the transfer.
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libcurl does not support using network interface names for this option on
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Windows.
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We strongly advise against specifying the interface with a hostname, as it
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causes libcurl to do a blocking name resolve call to retrieve the IP
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address. That name resolve operation does **not** use DNS-over-HTTPS even if
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CURLOPT_DOH_URL(3) is set.
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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, use whatever the TCP stack finds suitable
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# PROTOCOLS
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All
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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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CURLcode res;
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
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curl_easy_setopt(curl, CURLOPT_INTERFACE, "eth0");
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res = curl_easy_perform(curl);
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curl_easy_cleanup(curl);
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}
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}
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~~~
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# AVAILABILITY
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The "if!" and "host!" syntax was added in 7.24.0.
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# RETURN VALUE
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Returns CURLE_OK on success or
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CURLE_OUT_OF_MEMORY if there was insufficient heap space.
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