Update networking layer w/ CURL and emscripten impl

2025-11-08 01:50:36 +11:00
parent a17925904d
commit f6874dc55a
4105 changed files with 694617 additions and 179 deletions
@@ -0,0 +1,95 @@
+---
+c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Title: CURLOPT_DNS_CACHE_TIMEOUT
+Section: 3
+Source: libcurl
+See-also:
+  - CURLOPT_CONNECTTIMEOUT_MS (3)
+  - CURLOPT_DNS_SERVERS (3)
+  - CURLOPT_DNS_USE_GLOBAL_CACHE (3)
+  - CURLOPT_MAXAGE_CONN (3)
+  - CURLOPT_RESOLVE (3)
+  - CURLMOPT_NETWORK_CHANGED (3)
+Protocol:
+  - All
+Added-in: 7.9.3
+---
+
+# NAME
+
+CURLOPT_DNS_CACHE_TIMEOUT - life-time for DNS cache entries
+
+# SYNOPSIS
+
+~~~c
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_CACHE_TIMEOUT, long age);
+~~~
+
+# DESCRIPTION
+
+Pass a long, this sets the timeout in seconds. Name resolve results are kept
+in memory and used for this number of seconds. Set to zero to completely
+disable caching, or set to -1 to make the cached entries remain forever. By
+default, libcurl caches this info for 60 seconds.
+
+We recommend users not to tamper with this option unless strictly necessary.
+If you do, be careful of using large values that can make the cache size grow
+significantly if many different hostnames are used within that timeout period.
+
+The name resolve functions of various libc implementations do not re-read name
+server information unless explicitly told so (for example, by calling
+*res_init(3)*). This may cause libcurl to keep using the older server even
+if DHCP has updated the server info, and this may look like a DNS cache issue
+to the casual libcurl-app user.
+
+DNS entries have a "TTL" property but libcurl does not use that. This DNS
+cache timeout is entirely speculative that a name resolves to the same address
+for a small amount of time into the future.
+
+libcurl prunes entries from the DNS cache if it exceeds 30,000 entries no
+matter which timeout value is used. (Added in version 8.1.0)
+
+Since curl 8.16.0, failed name resolves are stored in the DNS cache for half
+the set timeout period.
+
+# DEFAULT
+
+60
+
+# %PROTOCOLS%
+
+# EXAMPLE
+
+~~~c
+int main(void)
+{
+  CURL *curl = curl_easy_init();
+  if(curl) {
+    CURLcode res;
+    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
+
+    /* only reuse addresses for a short time */
+    curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 2L);
+
+    res = curl_easy_perform(curl);
+
+    /* in this second request, the cache is not be used if more than
+       two seconds have passed since the previous name resolve */
+    res = curl_easy_perform(curl);
+
+    curl_easy_cleanup(curl);
+  }
+}
+~~~
+
+# %AVAILABILITY%
+
+# RETURN VALUE
+
+curl_easy_setopt(3) returns a CURLcode indicating success or error.
+
+CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
+libcurl-errors(3).