1--- 2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al. 3SPDX-License-Identifier: curl 4Title: curl_easy_nextheader 5Section: 3 6Source: libcurl 7See-also: 8 - curl_easy_header (3) 9 - curl_easy_perform (3) 10--- 11 12# NAME 13 14curl_easy_nextheader - get the next HTTP header 15 16# SYNOPSIS 17 18~~~c 19#include <curl/curl.h> 20 21struct curl_header *curl_easy_nextheader(CURL *easy, 22 unsigned int origin, 23 int request, 24 struct curl_header *prev); 25~~~ 26 27# DESCRIPTION 28 29This function lets an application iterate over all previously received HTTP 30headers. 31 32The *origin* argument is for specifying which headers to receive, as a single 33HTTP transfer might provide headers from several different places and they may 34then have different importance to the user and headers using the same name 35might be used. The *origin* is a bitmask for what header sources you want. See 36the curl_easy_header(3) man page for the origin descriptions. 37 38The *request* argument tells libcurl from which request you want headers 39from. A single transfer might consist of a series of HTTP requests and this 40argument lets you specify which particular individual request you want the 41headers from. 0 being the first request and then the number increases for 42further redirects or when multi-state authentication is used. Passing in -1 is 43a shortcut to "the last" request in the series, independently of the actual 44amount of requests used. 45 46It is suggested that you pass in the same **origin** and **request** when 47iterating over a range of headers as changing the value mid-loop might give 48you unexpected results. 49 50If *prev* is NULL, this function returns a pointer to the first header stored 51within the given scope (origin + request). 52 53If *prev* is a pointer to a previously returned header struct, 54curl_easy_nextheader(3) returns a pointer the next header stored within the 55given scope. This way, an application can iterate over all available headers. 56 57The memory for the struct this points to, is owned and managed by libcurl and 58is associated with the easy handle. Applications must copy the data if they 59want it to survive subsequent API calls or the life-time of the easy handle. 60 61# EXAMPLE 62 63~~~c 64int main(void) 65{ 66 struct curl_header *prev = NULL; 67 struct curl_header *h; 68 69 CURL *curl = curl_easy_init(); 70 if(curl) { 71 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); 72 curl_easy_perform(curl); 73 74 /* extract the normal headers from the first request */ 75 while((h = curl_easy_nextheader(curl, CURLH_HEADER, 0, prev))) { 76 printf("%s: %s\n", h->name, h->value); 77 prev = h; 78 } 79 80 /* extract the normal headers + 1xx + trailers from the last request */ 81 unsigned int origin = CURLH_HEADER| CURLH_1XX | CURLH_TRAILER; 82 while((h = curl_easy_nextheader(curl, origin, -1, prev))) { 83 printf("%s: %s\n", h->name, h->value); 84 prev = h; 85 } 86 } 87} 88~~~ 89 90# AVAILABILITY 91 92Added in 7.83.0. Officially supported since 7.84.0. 93 94# RETURN VALUE 95 96This function returns the next header, or NULL when there are no more 97(matching) headers or an error occurred. 98 99If this function returns NULL when *prev* was set to NULL, then there are no 100headers available within the scope to return. 101