275 lines
7.2 KiB
C
275 lines
7.2 KiB
C
/*
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* Copyright (c) 1998 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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RCSID("$Id: roken_gethostby.c,v 1.5 1999/12/05 13:16:44 assar Exp $");
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#endif
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#include <roken.h>
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#undef roken_gethostbyname
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#undef roken_gethostbyaddr
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static struct sockaddr_in dns_addr;
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static char *dns_req;
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static int
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make_address(const char *address, struct in_addr *ip)
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{
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if(inet_aton(address, ip) == 0){
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/* try to resolve as hostname, it might work if the address we
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are trying to lookup is local, for instance a web proxy */
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struct hostent *he = gethostbyname(address);
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if(he) {
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unsigned char *p = (unsigned char*)he->h_addr;
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ip->s_addr = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
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} else {
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return -1;
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}
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}
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return 0;
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}
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static int
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setup_int(const char *proxy_host, short proxy_port,
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const char *dns_host, short dns_port,
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const char *dns_path)
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{
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memset(&dns_addr, 0, sizeof(dns_addr));
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if(dns_req)
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free(dns_req);
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if(proxy_host) {
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if(make_address(proxy_host, &dns_addr.sin_addr) != 0)
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return -1;
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dns_addr.sin_port = htons(proxy_port);
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asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path);
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} else {
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if(make_address(dns_host, &dns_addr.sin_addr) != 0)
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return -1;
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dns_addr.sin_port = htons(dns_port);
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asprintf(&dns_req, "%s", dns_path);
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}
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dns_addr.sin_family = AF_INET;
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return 0;
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}
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static void
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split_spec(const char *spec, char **host, int *port, char **path, int def_port)
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{
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char *p;
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*host = strdup(spec);
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p = strchr(*host, ':');
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if(p) {
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*p++ = '\0';
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if(sscanf(p, "%d", port) != 1)
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*port = def_port;
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} else
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*port = def_port;
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p = strchr(p ? p : *host, '/');
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if(p) {
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if(path)
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*path = strdup(p);
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*p = '\0';
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}else
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if(path)
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*path = NULL;
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}
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int
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roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
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{
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char *proxy_host = NULL;
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int proxy_port;
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char *dns_host, *dns_path;
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int dns_port;
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int ret = -1;
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split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
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if(dns_path == NULL)
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goto out;
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if(proxy_spec)
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split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
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ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
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out:
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free(proxy_host);
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free(dns_host);
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free(dns_path);
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return ret;
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}
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/* Try to lookup a name or an ip-address using http as transport
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mechanism. See the end of this file for an example program. */
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static struct hostent*
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roken_gethostby(const char *hostname)
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{
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int s;
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struct sockaddr_in sin;
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char *request;
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char buf[1024];
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int offset = 0;
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int n;
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char *p, *foo;
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if(dns_addr.sin_family == 0)
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return NULL; /* no configured host */
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sin = dns_addr;
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asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname);
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if(request == NULL)
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return NULL;
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s = socket(AF_INET, SOCK_STREAM, 0);
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if(s < 0) {
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free(request);
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return NULL;
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}
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if(connect(s, (struct sockaddr*)&sin, sizeof(sin)) < 0) {
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close(s);
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free(request);
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return NULL;
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}
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if(write(s, request, strlen(request)) != strlen(request)) {
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close(s);
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free(request);
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return NULL;
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}
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free(request);
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while(1) {
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n = read(s, buf + offset, sizeof(buf) - offset);
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if(n <= 0)
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break;
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offset += n;
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}
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buf[offset] = '\0';
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close(s);
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p = strstr(buf, "\r\n\r\n"); /* find end of header */
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if(p) p += 4;
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else return NULL;
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foo = NULL;
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p = strtok_r(p, " \t\r\n", &foo);
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if(p == NULL)
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return NULL;
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{
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/* make a hostent to return */
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#define MAX_ADDRS 16
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static struct hostent he;
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static char addrs[4 * MAX_ADDRS];
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static char *addr_list[MAX_ADDRS];
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int num_addrs = 0;
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he.h_name = p;
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he.h_aliases = NULL;
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he.h_addrtype = AF_INET;
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he.h_length = 4;
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while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
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struct in_addr ip;
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inet_aton(p, &ip);
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ip.s_addr = ntohl(ip.s_addr);
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addr_list[num_addrs] = &addrs[num_addrs * 4];
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addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
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addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
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addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
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addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
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addr_list[++num_addrs] = NULL;
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}
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he.h_addr_list = addr_list;
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return &he;
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}
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}
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struct hostent*
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roken_gethostbyname(const char *hostname)
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{
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struct hostent *he;
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he = gethostbyname(hostname);
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if(he)
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return he;
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return roken_gethostby(hostname);
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}
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struct hostent*
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roken_gethostbyaddr(const void *addr, size_t len, int type)
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{
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struct in_addr a;
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const char *p;
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struct hostent *he;
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he = gethostbyaddr(addr, len, type);
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if(he)
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return he;
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if(type != AF_INET || len != 4)
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return NULL;
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p = addr;
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a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
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return roken_gethostby(inet_ntoa(a));
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}
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#if 0
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/* this program can be used as a cgi `script' to lookup names and
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ip-addresses */
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#include <stdio.h>
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#include <stdlib.h>
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#include <netdb.h>
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#include <sys/param.h>
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int
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main(int argc, char **argv)
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{
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char *query = getenv("QUERY_STRING");
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char host[MAXHOSTNAMELEN];
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int i;
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struct hostent *he;
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printf("Content-type: text/plain\n\n");
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if(query == NULL)
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exit(0);
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he = gethostbyname(query);
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strncpy(host, he->h_name, sizeof(host));
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host[sizeof(host) - 1] = '\0';
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he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
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printf("%s\n", he->h_name);
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for(i = 0; he->h_addr_list[i]; i++) {
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struct in_addr ip;
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unsigned char *p = (unsigned char*)he->h_addr_list[i];
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ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
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printf("%s\n", inet_ntoa(ip));
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}
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exit(0);
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}
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#endif
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