431 lines
12 KiB
C
431 lines
12 KiB
C
/*
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* This module determines the type of socket (datagram, stream), the client
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* socket address and port, the server socket address and port. In addition,
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* it provides methods to map a transport address to a printable host name
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* or address. Socket address information results are in static memory.
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*
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* The result from the hostname lookup method is STRING_PARANOID when a host
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* pretends to have someone elses name, or when a host name is available but
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* could not be verified.
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*
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* When lookup or conversion fails the result is set to STRING_UNKNOWN.
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*
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* Diagnostics are reported through syslog(3).
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*
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* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
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*
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* $FreeBSD$
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*/
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#ifndef lint
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static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24";
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#endif
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/* System libraries. */
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <syslog.h>
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#include <string.h>
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#ifdef INET6
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#ifndef NI_WITHSCOPEID
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#define NI_WITHSCOPEID 0
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#endif
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#else
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extern char *inet_ntoa();
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#endif
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/* Local stuff. */
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#include "tcpd.h"
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/* Forward declarations. */
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static void sock_sink();
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#ifdef APPEND_DOT
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/*
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* Speed up DNS lookups by terminating the host name with a dot. Should be
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* done with care. The speedup can give problems with lookups from sources
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* that lack DNS-style trailing dot magic, such as local files or NIS maps.
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*/
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static struct hostent *gethostbyname_dot(name)
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char *name;
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{
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char dot_name[MAXHOSTNAMELEN + 1];
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/*
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* Don't append dots to unqualified names. Such names are likely to come
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* from local hosts files or from NIS.
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*/
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if (strchr(name, '.') == 0 || strlen(name) >= MAXHOSTNAMELEN - 1) {
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return (gethostbyname(name));
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} else {
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sprintf(dot_name, "%s.", name);
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return (gethostbyname(dot_name));
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}
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}
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#define gethostbyname gethostbyname_dot
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#endif
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/* sock_host - look up endpoint addresses and install conversion methods */
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void sock_host(request)
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struct request_info *request;
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{
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#ifdef INET6
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static struct sockaddr_storage client;
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static struct sockaddr_storage server;
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#else
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static struct sockaddr_in client;
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static struct sockaddr_in server;
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#endif
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int len;
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char buf[BUFSIZ];
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int fd = request->fd;
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sock_methods(request);
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/*
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* Look up the client host address. Hal R. Brand <BRAND@addvax.llnl.gov>
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* suggested how to get the client host info in case of UDP connections:
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* peek at the first message without actually looking at its contents. We
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* really should verify that client.sin_family gets the value AF_INET,
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* but this program has already caused too much grief on systems with
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* broken library code.
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*/
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len = sizeof(client);
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if (getpeername(fd, (struct sockaddr *) & client, &len) < 0) {
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request->sink = sock_sink;
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len = sizeof(client);
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if (recvfrom(fd, buf, sizeof(buf), MSG_PEEK,
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(struct sockaddr *) & client, &len) < 0) {
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tcpd_warn("can't get client address: %m");
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return; /* give up */
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}
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#ifdef really_paranoid
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memset(buf, 0, sizeof(buf));
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#endif
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}
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#ifdef INET6
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request->client->sin = (struct sockaddr *)&client;
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#else
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request->client->sin = &client;
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#endif
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/*
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* Determine the server binding. This is used for client username
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* lookups, and for access control rules that trigger on the server
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* address or name.
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*/
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len = sizeof(server);
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if (getsockname(fd, (struct sockaddr *) & server, &len) < 0) {
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tcpd_warn("getsockname: %m");
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return;
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}
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#ifdef INET6
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request->server->sin = (struct sockaddr *)&server;
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#else
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request->server->sin = &server;
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#endif
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}
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/* sock_hostaddr - map endpoint address to printable form */
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void sock_hostaddr(host)
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struct host_info *host;
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{
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#ifdef INET6
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struct sockaddr *sin = host->sin;
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int salen;
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if (!sin)
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return;
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#ifdef SIN6_LEN
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salen = sin->sa_len;
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#else
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salen = (sin->sa_family == AF_INET) ? sizeof(struct sockaddr_in)
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: sizeof(struct sockaddr_in6);
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#endif
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getnameinfo(sin, salen, host->addr, sizeof(host->addr),
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NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
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#else
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struct sockaddr_in *sin = host->sin;
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if (sin != 0)
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STRN_CPY(host->addr, inet_ntoa(sin->sin_addr), sizeof(host->addr));
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#endif
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}
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/* sock_hostname - map endpoint address to host name */
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void sock_hostname(host)
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struct host_info *host;
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{
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#ifdef INET6
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struct sockaddr *sin = host->sin;
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struct sockaddr_in sin4;
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struct addrinfo hints, *res, *res0 = NULL;
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int salen, alen, err = 1;
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char *ap = NULL, *rap, hname[NI_MAXHOST];
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if (sin != NULL) {
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if (sin->sa_family == AF_INET6) {
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struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sin;
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if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
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memset(&sin4, 0, sizeof(sin4));
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#ifdef SIN6_LEN
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sin4.sin_len = sizeof(sin4);
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#endif
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sin4.sin_family = AF_INET;
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sin4.sin_port = sin6->sin6_port;
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sin4.sin_addr.s_addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12];
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sin = (struct sockaddr *)&sin4;
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}
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}
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switch (sin->sa_family) {
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case AF_INET:
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ap = (char *)&((struct sockaddr_in *)sin)->sin_addr;
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alen = sizeof(struct in_addr);
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salen = sizeof(struct sockaddr_in);
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break;
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case AF_INET6:
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ap = (char *)&((struct sockaddr_in6 *)sin)->sin6_addr;
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alen = sizeof(struct in6_addr);
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salen = sizeof(struct sockaddr_in6);
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break;
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default:
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break;
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}
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if (ap)
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err = getnameinfo(sin, salen, hname, sizeof(hname),
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NULL, 0, NI_WITHSCOPEID | NI_NAMEREQD);
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}
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if (!err) {
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STRN_CPY(host->name, hname, sizeof(host->name));
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/* reject numeric addresses */
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = sin->sa_family;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST;
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if ((err = getaddrinfo(host->name, NULL, &hints, &res0)) == 0) {
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freeaddrinfo(res0);
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tcpd_warn("host name/name mismatch: "
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"reverse lookup results in non-FQDN %s",
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host->name);
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strcpy(host->name, paranoid); /* name is bad, clobber it */
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}
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err = !err;
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}
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if (!err) {
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/* we are now sure that this is non-numeric */
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/*
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* Verify that the address is a member of the address list returned
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* by gethostbyname(hostname).
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*
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* Verify also that gethostbyaddr() and gethostbyname() return the same
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* hostname, or rshd and rlogind may still end up being spoofed.
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*
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* On some sites, gethostbyname("localhost") returns "localhost.domain".
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* This is a DNS artefact. We treat it as a special case. When we
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* can't believe the address list from gethostbyname("localhost")
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* we're in big trouble anyway.
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = sin->sa_family;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE | AI_CANONNAME;
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if (getaddrinfo(host->name, NULL, &hints, &res0) != 0) {
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/*
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* Unable to verify that the host name matches the address. This
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* may be a transient problem or a botched name server setup.
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*/
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tcpd_warn("can't verify hostname: getaddrinfo(%s, %s) failed",
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host->name,
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(sin->sa_family == AF_INET) ? "AF_INET" : "AF_INET6");
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} else if ((res0->ai_canonname == NULL
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|| STR_NE(host->name, res0->ai_canonname))
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&& STR_NE(host->name, "localhost")) {
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/*
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* The gethostbyaddr() and gethostbyname() calls did not return
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* the same hostname. This could be a nameserver configuration
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* problem. It could also be that someone is trying to spoof us.
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*/
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tcpd_warn("host name/name mismatch: %s != %.*s",
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host->name, STRING_LENGTH,
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(res0->ai_canonname == NULL) ? "" : res0->ai_canonname);
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} else {
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/*
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* The address should be a member of the address list returned by
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* gethostbyname(). We should first verify that the h_addrtype
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* field is AF_INET, but this program has already caused too much
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* grief on systems with broken library code.
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*/
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for (res = res0; res; res = res->ai_next) {
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if (res->ai_family != sin->sa_family)
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continue;
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switch (res->ai_family) {
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case AF_INET:
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rap = (char *)&((struct sockaddr_in *)res->ai_addr)->sin_addr;
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break;
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case AF_INET6:
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/* need to check scope_id */
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if (((struct sockaddr_in6 *)sin)->sin6_scope_id !=
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((struct sockaddr_in6 *)res->ai_addr)->sin6_scope_id) {
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continue;
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}
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rap = (char *)&((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
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break;
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default:
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continue;
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}
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if (memcmp(rap, ap, alen) == 0) {
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freeaddrinfo(res0);
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return; /* name is good, keep it */
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}
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}
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/*
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* The host name does not map to the initial address. Perhaps
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* someone has messed up. Perhaps someone compromised a name
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* server.
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*/
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getnameinfo(sin, salen, hname, sizeof(hname),
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NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
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tcpd_warn("host name/address mismatch: %s != %.*s",
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hname, STRING_LENGTH,
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(res0->ai_canonname == NULL) ? "" : res0->ai_canonname);
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}
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strcpy(host->name, paranoid); /* name is bad, clobber it */
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if (res0)
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freeaddrinfo(res0);
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}
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#else /* INET6 */
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struct sockaddr_in *sin = host->sin;
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struct hostent *hp;
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int i;
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/*
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* On some systems, for example Solaris 2.3, gethostbyaddr(0.0.0.0) does
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* not fail. Instead it returns "INADDR_ANY". Unfortunately, this does
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* not work the other way around: gethostbyname("INADDR_ANY") fails. We
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* have to special-case 0.0.0.0, in order to avoid false alerts from the
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* host name/address checking code below.
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*/
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if (sin != 0 && sin->sin_addr.s_addr != 0
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&& (hp = gethostbyaddr((char *) &(sin->sin_addr),
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sizeof(sin->sin_addr), AF_INET)) != 0) {
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STRN_CPY(host->name, hp->h_name, sizeof(host->name));
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/*
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* Verify that the address is a member of the address list returned
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* by gethostbyname(hostname).
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*
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* Verify also that gethostbyaddr() and gethostbyname() return the same
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* hostname, or rshd and rlogind may still end up being spoofed.
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*
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* On some sites, gethostbyname("localhost") returns "localhost.domain".
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* This is a DNS artefact. We treat it as a special case. When we
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* can't believe the address list from gethostbyname("localhost")
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* we're in big trouble anyway.
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*/
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if ((hp = gethostbyname(host->name)) == 0) {
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/*
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* Unable to verify that the host name matches the address. This
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* may be a transient problem or a botched name server setup.
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*/
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tcpd_warn("can't verify hostname: gethostbyname(%s) failed",
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host->name);
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} else if (STR_NE(host->name, hp->h_name)
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&& STR_NE(host->name, "localhost")) {
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/*
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* The gethostbyaddr() and gethostbyname() calls did not return
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* the same hostname. This could be a nameserver configuration
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* problem. It could also be that someone is trying to spoof us.
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*/
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tcpd_warn("host name/name mismatch: %s != %.*s",
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host->name, STRING_LENGTH, hp->h_name);
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} else {
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/*
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* The address should be a member of the address list returned by
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* gethostbyname(). We should first verify that the h_addrtype
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* field is AF_INET, but this program has already caused too much
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* grief on systems with broken library code.
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*/
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for (i = 0; hp->h_addr_list[i]; i++) {
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if (memcmp(hp->h_addr_list[i],
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(char *) &sin->sin_addr,
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sizeof(sin->sin_addr)) == 0)
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return; /* name is good, keep it */
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}
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/*
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* The host name does not map to the initial address. Perhaps
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* someone has messed up. Perhaps someone compromised a name
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* server.
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*/
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tcpd_warn("host name/address mismatch: %s != %.*s",
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inet_ntoa(sin->sin_addr), STRING_LENGTH, hp->h_name);
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}
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strcpy(host->name, paranoid); /* name is bad, clobber it */
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}
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#endif /* INET6 */
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}
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/* sock_sink - absorb unreceived IP datagram */
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static void sock_sink(fd)
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int fd;
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{
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char buf[BUFSIZ];
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#ifdef INET6
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struct sockaddr_storage sin;
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#else
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struct sockaddr_in sin;
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#endif
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int size = sizeof(sin);
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/*
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* Eat up the not-yet received datagram. Some systems insist on a
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* non-zero source address argument in the recvfrom() call below.
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*/
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(void) recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *) & sin, &size);
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}
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