--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/docs/examples/externalsocket.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,174 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * An example demonstrating how an application can pass in a custom
+ * socket to libcurl to use. This example also handles the connect itself.
+ * </DESC>
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <curl/curl.h>
+
+#ifdef WIN32
+#include <windows.h>
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#define close closesocket
+#else
+#include <sys/types.h>        /*  socket types              */
+#include <sys/socket.h>       /*  socket definitions        */
+#include <netinet/in.h>
+#include <arpa/inet.h>        /*  inet (3) functions         */
+#include <unistd.h>           /*  misc. Unix functions      */
+#endif
+
+#include <errno.h>
+
+/* The IP address and port number to connect to */
+#define IPADDR "127.0.0.1"
+#define PORTNUM 80
+
+#ifndef INADDR_NONE
+#define INADDR_NONE 0xffffffff
+#endif
+
+static size_t write_data(void *ptr, size_t size, size_t nmemb, void *stream)
+{
+  size_t written = fwrite(ptr, size, nmemb, (FILE *)stream);
+  return written;
+}
+
+static int closecb(void *clientp, curl_socket_t item)
+{
+  (void)clientp;
+  printf("libcurl wants to close %d now\n", (int)item);
+  return 0;
+}
+
+static curl_socket_t opensocket(void *clientp,
+                                curlsocktype purpose,
+                                struct curl_sockaddr *address)
+{
+  curl_socket_t sockfd;
+  (void)purpose;
+  (void)address;
+  sockfd = *(curl_socket_t *)clientp;
+  /* the actual externally set socket is passed in via the OPENSOCKETDATA
+     option */
+  return sockfd;
+}
+
+static int sockopt_callback(void *clientp, curl_socket_t curlfd,
+                            curlsocktype purpose)
+{
+  (void)clientp;
+  (void)curlfd;
+  (void)purpose;
+  /* This return code was added in libcurl 7.21.5 */
+  return CURL_SOCKOPT_ALREADY_CONNECTED;
+}
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+  struct sockaddr_in servaddr;  /*  socket address structure  */
+  curl_socket_t sockfd;
+
+#ifdef WIN32
+  WSADATA wsaData;
+  int initwsa = WSAStartup(MAKEWORD(2, 0), &wsaData);
+  if(initwsa != 0) {
+    printf("WSAStartup failed: %d\n", initwsa);
+    return 1;
+  }
+#endif
+
+  curl = curl_easy_init();
+  if(curl) {
+    /*
+     * Note that libcurl will internally think that you connect to the host
+     * and port that you specify in the URL option.
+     */
+    curl_easy_setopt(curl, CURLOPT_URL, "http://99.99.99.99:9999");
+
+    /* Create the socket "manually" */
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if(sockfd == CURL_SOCKET_BAD) {
+      printf("Error creating listening socket.\n");
+      return 3;
+    }
+
+    memset(&servaddr, 0, sizeof(servaddr));
+    servaddr.sin_family = AF_INET;
+    servaddr.sin_port   = htons(PORTNUM);
+
+    servaddr.sin_addr.s_addr = inet_addr(IPADDR);
+    if(INADDR_NONE == servaddr.sin_addr.s_addr) {
+      close(sockfd);
+      return 2;
+    }
+
+    if(connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) ==
+       -1) {
+      close(sockfd);
+      printf("client error: connect: %s\n", strerror(errno));
+      return 1;
+    }
+
+    /* no progress meter please */
+    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);
+
+    /* send all data to this function  */
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
+
+    /* call this function to get a socket */
+    curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket);
+    curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, &sockfd);
+
+    /* call this function to close sockets */
+    curl_easy_setopt(curl, CURLOPT_CLOSESOCKETFUNCTION, closecb);
+    curl_easy_setopt(curl, CURLOPT_CLOSESOCKETDATA, &sockfd);
+
+    /* call this function to set options for the socket */
+    curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
+
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
+
+    res = curl_easy_perform(curl);
+
+    curl_easy_cleanup(curl);
+
+    close(sockfd);
+
+    if(res) {
+      printf("libcurl error: %d\n", res);
+      return 4;
+    }
+  }
+
+#ifdef WIN32
+  WSACleanup();
+#endif
+  return 0;
+}