Update networking layer w/ CURL and emscripten impl
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/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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***************************************************************************/
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/* <DESC>
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* Show how CURLOPT_OPENSOCKETFUNCTION can be used to block IP addresses.
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* </DESC>
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*/
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/* This is an advanced example that defines a whitelist or a blacklist to
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* filter IP addresses.
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*/
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#if defined(__AMIGA__) || defined(UNDER_CE)
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#include <stdio.h>
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int main(void) { printf("Platform not supported.\n"); return 1; }
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#else
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#ifdef _WIN32
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#ifndef _CRT_SECURE_NO_WARNINGS
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#define _CRT_SECURE_NO_WARNINGS
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#endif
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#ifndef _CRT_NONSTDC_NO_DEPRECATE
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#define _CRT_NONSTDC_NO_DEPRECATE
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#endif
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#if !defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600
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#undef _WIN32_WINNT
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#define _WIN32_WINNT 0x0600 /* Requires Windows Vista */
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#endif
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#include <winsock2.h>
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#include <ws2tcpip.h>
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#include <windows.h>
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#else
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <curl/curl.h>
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#ifndef TRUE
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#define TRUE 1
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#endif
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#ifndef FALSE
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#define FALSE 0
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#endif
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struct ip {
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/* The user-provided IP address or network (use CIDR) to filter */
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char *str;
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/* IP address family AF_INET (IPv4) or AF_INET6 (IPv6) */
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int family;
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/* IP in network byte format */
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union netaddr {
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struct in_addr ipv4;
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#ifdef AF_INET6
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struct in6_addr ipv6;
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#endif
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} netaddr;
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/* IP bits to match against.
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* This is equal to the CIDR notation or max bits if no CIDR.
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* For example if ip->str is 127.0.0.0/8 then ip->maskbits is 8.
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*/
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int maskbits;
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struct ip *next;
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};
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enum connection_filter_t {
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CONNECTION_FILTER_BLACKLIST,
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CONNECTION_FILTER_WHITELIST
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};
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struct connection_filter {
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struct ip *list;
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enum connection_filter_t type;
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int verbose;
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#ifdef AF_INET6
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/* If the address being filtered is an IPv4-mapped IPv6 address then it is
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* checked against IPv4 list entries as well, unless ipv6_v6only is set TRUE.
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*/
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int ipv6_v6only;
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#endif
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};
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static struct ip *ip_list_append(struct ip *list, const char *data)
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{
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struct ip *ip, *last;
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char *cidr;
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ip = (struct ip *)calloc(1, sizeof(*ip));
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if(!ip)
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return NULL;
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if(strchr(data, ':')) {
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#ifdef AF_INET6
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ip->family = AF_INET6;
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#else
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free(ip);
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return NULL;
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#endif
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}
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else
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ip->family = AF_INET;
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ip->str = strdup(data);
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if(!ip->str) {
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free(ip);
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return NULL;
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}
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/* determine the number of bits that this IP will match against */
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cidr = strchr(ip->str, '/');
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if(cidr) {
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ip->maskbits = atoi(cidr + 1);
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if(ip->maskbits <= 0 ||
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#ifdef AF_INET6
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(ip->family == AF_INET6 && ip->maskbits > 128) ||
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#endif
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(ip->family == AF_INET && ip->maskbits > 32)) {
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free(ip->str);
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free(ip);
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return NULL;
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}
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/* ignore the CIDR notation when converting ip->str to ip->netaddr */
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*cidr = '\0';
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}
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else if(ip->family == AF_INET)
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ip->maskbits = 32;
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#ifdef AF_INET6
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else if(ip->family == AF_INET6)
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ip->maskbits = 128;
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#endif
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if(inet_pton(ip->family, ip->str, &ip->netaddr) != 1) {
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free(ip->str);
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free(ip);
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return NULL;
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}
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if(cidr)
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*cidr = '/';
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if(!list)
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return ip;
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for(last = list; last->next; last = last->next)
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;
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last->next = ip;
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return list;
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}
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static void ip_list_free_all(struct ip *list)
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{
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struct ip *next;
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while(list) {
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next = list->next;
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free(list->str);
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free(list);
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list = next;
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}
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}
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static void free_connection_filter(struct connection_filter *filter)
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{
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if(filter) {
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ip_list_free_all(filter->list);
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free(filter);
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}
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}
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static int ip_match(struct ip *ip, void *netaddr)
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{
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int bytes, tailbits;
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const unsigned char *x, *y;
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x = (unsigned char *)&ip->netaddr;
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y = (unsigned char *)netaddr;
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for(bytes = ip->maskbits / 8; bytes; --bytes) {
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if(*x++ != *y++)
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return FALSE;
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}
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tailbits = ip->maskbits % 8;
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if(tailbits) {
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unsigned char tailmask = (unsigned char)((0xFF << (8 - tailbits)) & 0xFF);
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if((*x & tailmask) != (*y & tailmask))
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return FALSE;
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}
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return TRUE;
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}
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#ifdef AF_INET6
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static int is_ipv4_mapped_ipv6_address(int family, void *netaddr)
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{
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if(family == AF_INET6) {
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int i;
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unsigned char *x = (unsigned char *)netaddr;
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for(i = 0; i < 12; ++i) {
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if(x[i])
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break;
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}
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/* support formats ::x.x.x.x (deprecated) and ::ffff:x.x.x.x */
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if((i == 12 && (x[i] || x[i + 1] || x[i + 2] || x[i + 3])) ||
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(i == 10 && (x[i] == 0xFF && x[i + 1] == 0xFF)))
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return TRUE;
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}
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return FALSE;
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}
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#endif /* AF_INET6 */
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static curl_socket_t opensocket(void *clientp,
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curlsocktype purpose,
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struct curl_sockaddr *address)
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{
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/* filter the address */
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if(purpose == CURLSOCKTYPE_IPCXN) {
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void *cinaddr = NULL;
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if(address->family == AF_INET)
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cinaddr = &((struct sockaddr_in *)(void *)&address->addr)->sin_addr;
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#ifdef AF_INET6
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else if(address->family == AF_INET6)
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cinaddr = &((struct sockaddr_in6 *)(void *)&address->addr)->sin6_addr;
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#endif
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if(cinaddr) {
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struct ip *ip;
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struct connection_filter *filter = (struct connection_filter *)clientp;
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#ifdef AF_INET6
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int mapped = !filter->ipv6_v6only &&
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is_ipv4_mapped_ipv6_address(address->family, cinaddr);
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#endif
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for(ip = filter->list; ip; ip = ip->next) {
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if(ip->family == address->family && ip_match(ip, cinaddr))
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break;
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#ifdef AF_INET6
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if(mapped && ip->family == AF_INET && address->family == AF_INET6 &&
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ip_match(ip, (unsigned char *)cinaddr + 12))
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break;
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#endif
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}
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if(ip && filter->type == CONNECTION_FILTER_BLACKLIST) {
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if(filter->verbose) {
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char buf[128] = {0};
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inet_ntop(address->family, cinaddr, buf, sizeof(buf));
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fprintf(stderr, "* Rejecting IP %s due to blacklist entry %s.\n",
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buf, ip->str);
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}
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return CURL_SOCKET_BAD;
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}
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else if(!ip && filter->type == CONNECTION_FILTER_WHITELIST) {
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if(filter->verbose) {
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char buf[128] = {0};
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inet_ntop(address->family, cinaddr, buf, sizeof(buf));
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fprintf(stderr,
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"* Rejecting IP %s due to missing whitelist entry.\n", buf);
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}
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return CURL_SOCKET_BAD;
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}
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}
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}
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return socket(address->family, address->socktype, address->protocol);
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}
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int main(void)
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{
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CURL *curl;
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CURLcode res;
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struct connection_filter *filter;
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filter = (struct connection_filter *)calloc(1, sizeof(*filter));
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if(!filter)
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return 1;
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res = curl_global_init(CURL_GLOBAL_ALL);
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if(res) {
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free(filter);
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return (int)res;
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}
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curl = curl_easy_init();
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if(!curl) {
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curl_global_cleanup();
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free(filter);
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return 1;
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}
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/* Set the target URL */
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curl_easy_setopt(curl, CURLOPT_URL, "http://localhost");
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/* Define an IP connection filter.
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* If an address has CIDR notation then it matches the network.
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* For example 74.6.143.25/24 matches 74.6.143.0 - 74.6.143.255.
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*/
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filter->type = CONNECTION_FILTER_BLACKLIST;
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filter->list = ip_list_append(filter->list, "98.137.11.164");
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filter->list = ip_list_append(filter->list, "127.0.0.0/8");
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#ifdef AF_INET6
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filter->list = ip_list_append(filter->list, "::1");
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#endif
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/* Set the socket function which does the filtering */
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curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket);
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curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, filter);
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/* Verbose mode */
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filter->verbose = TRUE;
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curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
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/* Perform the request */
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res = curl_easy_perform(curl);
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/* Check for errors */
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if(res != CURLE_OK) {
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fprintf(stderr, "curl_easy_perform() failed: %s\n",
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curl_easy_strerror(res));
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}
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/* Clean up */
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curl_easy_cleanup(curl);
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free_connection_filter(filter);
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/* Clean up libcurl */
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curl_global_cleanup();
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return 0;
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}
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#endif
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