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--- |
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c: Copyright (C) Daniel Stenberg, <[email protected]>, et al. |
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SPDX-License-Identifier: curl |
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Title: curl_easy_nextheader |
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Section: 3 |
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Source: libcurl |
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See-also: |
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- curl_easy_header (3) |
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- curl_easy_perform (3) |
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Protocol: |
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- HTTP |
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Added-in: 7.83.0 |
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--- |
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# NAME |
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curl_easy_nextheader - get the next HTTP header |
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# SYNOPSIS |
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~~~c |
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#include <curl/curl.h> |
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struct curl_header *curl_easy_nextheader(CURL *easy, |
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unsigned int origin, |
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int request, |
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struct curl_header *prev); |
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~~~ |
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# DESCRIPTION |
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This function lets an application iterate over all previously received HTTP |
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headers. |
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The *origin* argument is for specifying which headers to receive, as a single |
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HTTP transfer might provide headers from several different places and they may |
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then have different importance to the user and headers using the same name |
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might be used. The *origin* is a bitmask for what header sources you want. See |
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the curl_easy_header(3) man page for the origin descriptions. |
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The *request* argument tells libcurl from which request you want headers |
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from. A single transfer might consist of a series of HTTP requests and this |
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argument lets you specify which particular individual request you want the |
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headers from. 0 being the first request and then the number increases for |
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further redirects or when multi-state authentication is used. Passing in -1 is |
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a shortcut to "the last" request in the series, independently of the actual |
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amount of requests used. |
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It is suggested that you pass in the same **origin** and **request** when |
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iterating over a range of headers as changing the value mid-loop might give |
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you unexpected results. |
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If *prev* is NULL, this function returns a pointer to the first header stored |
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within the given scope (origin + request). |
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If *prev* is a pointer to a previously returned header struct, |
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curl_easy_nextheader(3) returns a pointer the next header stored within the |
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given scope. This way, an application can iterate over all available headers. |
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The memory for the struct this points to, is owned and managed by libcurl and |
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is associated with the easy handle. Applications must copy the data if they |
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want it to survive subsequent API calls or the life-time of the easy handle. |
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# %PROTOCOLS% |
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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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struct curl_header *prev = NULL; |
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struct curl_header *h; |
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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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curl_easy_perform(curl); |
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/* extract the normal headers from the first request */ |
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while((h = curl_easy_nextheader(curl, CURLH_HEADER, 0, prev))) { |
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printf("%s: %s\n", h->name, h->value); |
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prev = h; |
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} |
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/* extract the normal headers + 1xx + trailers from the last request */ |
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unsigned int origin = CURLH_HEADER| CURLH_1XX | CURLH_TRAILER; |
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while((h = curl_easy_nextheader(curl, origin, -1, prev))) { |
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printf("%s: %s\n", h->name, h->value); |
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prev = h; |
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} |
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} |
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} |
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~~~ |
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# %AVAILABILITY% |
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# RETURN VALUE |
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This function returns the next header, or NULL when there are no more |
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(matching) headers or an error occurred. |
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If this function returns NULL when *prev* was set to NULL, then there are no |
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headers available within the scope to return. |
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