- djm@cvs.openbsd.org 2014/02/23 20:11:36
[readconf.c readconf.h ssh.c ssh_config.5]
reparse ssh_config and ~/.ssh/config if hostname canonicalisation changes
the hostname. This allows users to write configurations that always
refer to canonical hostnames, e.g.
CanonicalizeHostname yes
CanonicalDomains int.example.org example.org
CanonicalizeFallbackLocal no
Host *.int.example.org
Compression off
Host *.example.org
User djm
ok markus@
This commit is contained in:
Damien Miller
parent
bee3a234f3
commit
13f97b2286
16
ChangeLog
16
ChangeLog
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@ -16,6 +16,22 @@
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[ssh-ed25519.c]
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check for unsigned overflow; not reachable in OpenSSH but others might
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copy our code...
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- djm@cvs.openbsd.org 2014/02/23 20:11:36
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[readconf.c readconf.h ssh.c ssh_config.5]
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reparse ssh_config and ~/.ssh/config if hostname canonicalisation changes
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the hostname. This allows users to write configurations that always
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refer to canonical hostnames, e.g.
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CanonicalizeHostname yes
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CanonicalDomains int.example.org example.org
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CanonicalizeFallbackLocal no
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Host *.int.example.org
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Compression off
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Host *.example.org
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User djm
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ok markus@
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20140213
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- (dtucker) [configure.ac openbsd-compat/openssl-compat.{c,h}] Add compat
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27
readconf.c
27
readconf.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: readconf.c,v 1.217 2014/02/22 01:32:19 djm Exp $ */
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/* $OpenBSD: readconf.c,v 1.218 2014/02/23 20:11:36 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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@ -1467,6 +1467,13 @@ read_config_file(const char *filename, struct passwd *pw, const char *host,
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return 1;
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}
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/* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */
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int
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option_clear_or_none(const char *o)
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{
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return o == NULL || strcasecmp(o, "none") == 0;
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}
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/*
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* Initializes options to special values that indicate that they have not yet
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* been set. Read_config_file will only set options with this value. Options
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@ -1563,11 +1570,25 @@ initialize_options(Options * options)
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options->canonicalize_hostname = -1;
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}
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/*
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* A petite version of fill_default_options() that just fills the options
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* needed for hostname canonicalization to proceed.
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*/
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void
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fill_default_options_for_canonicalization(Options *options)
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{
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if (options->canonicalize_max_dots == -1)
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options->canonicalize_max_dots = 1;
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if (options->canonicalize_fallback_local == -1)
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options->canonicalize_fallback_local = 1;
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if (options->canonicalize_hostname == -1)
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options->canonicalize_hostname = SSH_CANONICALISE_NO;
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}
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/*
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* Called after processing other sources of option data, this fills those
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* options for which no value has been specified with their default values.
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*/
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void
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fill_default_options(Options * options)
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{
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@ -1722,7 +1743,7 @@ fill_default_options(Options * options)
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options->canonicalize_hostname = SSH_CANONICALISE_NO;
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#define CLEAR_ON_NONE(v) \
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do { \
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if (v != NULL && strcasecmp(v, "none") == 0) { \
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if (option_clear_or_none(v)) { \
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free(v); \
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v = NULL; \
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} \
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@ -1,4 +1,4 @@
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/* $OpenBSD: readconf.h,v 1.100 2014/01/29 06:18:35 djm Exp $ */
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/* $OpenBSD: readconf.h,v 1.101 2014/02/23 20:11:36 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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@ -176,12 +176,14 @@ typedef struct {
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void initialize_options(Options *);
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void fill_default_options(Options *);
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void fill_default_options_for_canonicalization(Options *);
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int process_config_line(Options *, struct passwd *, const char *, char *,
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const char *, int, int *, int);
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int read_config_file(const char *, struct passwd *, const char *,
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Options *, int);
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int parse_forward(Forward *, const char *, int, int);
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int default_ssh_port(void);
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int option_clear_or_none(const char *);
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void add_local_forward(Options *, const Forward *);
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void add_remote_forward(Options *, const Forward *);
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154
ssh.c
154
ssh.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: ssh.c,v 1.399 2014/02/04 00:24:29 djm Exp $ */
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/* $OpenBSD: ssh.c,v 1.400 2014/02/23 20:11:36 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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@ -231,16 +231,26 @@ tilde_expand_paths(char **paths, u_int num_paths)
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}
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}
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/*
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* Attempt to resolve a host name / port to a set of addresses and
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* optionally return any CNAMEs encountered along the way.
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* Returns NULL on failure.
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* NB. this function must operate with a options having undefined members.
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*/
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static struct addrinfo *
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resolve_host(const char *name, u_int port, int logerr, char *cname, size_t clen)
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resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
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{
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char strport[NI_MAXSERV];
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struct addrinfo hints, *res;
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int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
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if (port <= 0)
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port = default_ssh_port();
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snprintf(strport, sizeof strport, "%u", port);
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = options.address_family;
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hints.ai_family = options.address_family == -1 ?
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AF_UNSPEC : options.address_family;
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hints.ai_socktype = SOCK_STREAM;
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if (cname != NULL)
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hints.ai_flags = AI_CANONNAME;
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@ -265,6 +275,7 @@ resolve_host(const char *name, u_int port, int logerr, char *cname, size_t clen)
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/*
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* Check whether the cname is a permitted replacement for the hostname
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* and perform the replacement if it is.
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* NB. this function must operate with a options having undefined members.
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*/
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static int
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check_follow_cname(char **namep, const char *cname)
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@ -281,7 +292,7 @@ check_follow_cname(char **namep, const char *cname)
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* Don't attempt to canonicalize names that will be interpreted by
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* a proxy unless the user specifically requests so.
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*/
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if (options.proxy_command != NULL &&
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if (!option_clear_or_none(options.proxy_command) &&
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options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
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return 0;
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debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
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@ -305,9 +316,10 @@ check_follow_cname(char **namep, const char *cname)
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* Attempt to resolve the supplied hostname after applying the user's
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* canonicalization rules. Returns the address list for the host or NULL
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* if no name was found after canonicalization.
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* NB. this function must operate with a options having undefined members.
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*/
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static struct addrinfo *
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resolve_canonicalize(char **hostp, u_int port)
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resolve_canonicalize(char **hostp, int port)
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{
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int i, ndots;
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char *cp, *fullhost, cname_target[NI_MAXHOST];
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@ -315,13 +327,15 @@ resolve_canonicalize(char **hostp, u_int port)
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if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
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return NULL;
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/*
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* Don't attempt to canonicalize names that will be interpreted by
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* a proxy unless the user specifically requests so.
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*/
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if (options.proxy_command != NULL &&
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if (!option_clear_or_none(options.proxy_command) &&
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options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
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return NULL;
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/* Don't apply canonicalization to sufficiently-qualified hostnames */
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ndots = 0;
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for (cp = *hostp; *cp != '\0'; cp++) {
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@ -338,7 +352,9 @@ resolve_canonicalize(char **hostp, u_int port)
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*cname_target = '\0';
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xasprintf(&fullhost, "%s.%s.", *hostp,
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options.canonical_domains[i]);
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if ((addrs = resolve_host(fullhost, options.port, 0,
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debug3("%s: attempting \"%s\" => \"%s\"", __func__,
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*hostp, fullhost);
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if ((addrs = resolve_host(fullhost, port, 0,
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cname_target, sizeof(cname_target))) == NULL) {
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free(fullhost);
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continue;
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@ -355,10 +371,40 @@ resolve_canonicalize(char **hostp, u_int port)
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return addrs;
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}
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if (!options.canonicalize_fallback_local)
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fatal("%s: Could not resolve host \"%s\"", __progname, host);
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fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
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debug2("%s: host %s not found in any suffix", __func__, *hostp);
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return NULL;
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}
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/*
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* Read per-user configuration file. Ignore the system wide config
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* file if the user specifies a config file on the command line.
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*/
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static void
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process_config_files(struct passwd *pw)
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{
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char buf[MAXPATHLEN];
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int r;
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if (config != NULL) {
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if (strcasecmp(config, "none") != 0 &&
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!read_config_file(config, pw, host, &options,
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SSHCONF_USERCONF))
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fatal("Can't open user config file %.100s: "
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"%.100s", config, strerror(errno));
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} else {
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r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
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_PATH_SSH_USER_CONFFILE);
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if (r > 0 && (size_t)r < sizeof(buf))
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(void)read_config_file(buf, pw, host, &options,
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SSHCONF_CHECKPERM|SSHCONF_USERCONF);
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/* Read systemwide configuration file after user config. */
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(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, host,
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&options, 0);
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}
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}
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/*
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* Main program for the ssh client.
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*/
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@ -832,31 +878,54 @@ main(int ac, char **av)
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if (debug_flag)
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logit("%s, %s", SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
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/*
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* Read per-user configuration file. Ignore the system wide config
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* file if the user specifies a config file on the command line.
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*/
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if (config != NULL) {
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if (strcasecmp(config, "none") != 0 &&
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!read_config_file(config, pw, host, &options,
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SSHCONF_USERCONF))
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fatal("Can't open user config file %.100s: "
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"%.100s", config, strerror(errno));
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} else {
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r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
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_PATH_SSH_USER_CONFFILE);
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if (r > 0 && (size_t)r < sizeof(buf))
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(void)read_config_file(buf, pw, host, &options,
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SSHCONF_CHECKPERM|SSHCONF_USERCONF);
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/* Parse the configuration files */
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process_config_files(pw);
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/* Read systemwide configuration file after user config. */
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(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, host,
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&options, 0);
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/* Hostname canonicalisation needs a few options filled. */
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fill_default_options_for_canonicalization(&options);
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/* If the user has replaced the hostname then take it into use now */
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if (options.hostname != NULL) {
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/* NB. Please keep in sync with readconf.c:match_cfg_line() */
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cp = percent_expand(options.hostname,
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"h", host, (char *)NULL);
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free(host);
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host = cp;
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}
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/* If canonicalization requested then try to apply it */
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lowercase(host);
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if (options.canonicalize_hostname != SSH_CANONICALISE_NO)
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addrs = resolve_canonicalize(&host, options.port);
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/*
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* If canonicalization not requested, or if it failed then try to
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* resolve the bare hostname name using the system resolver's usual
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* search rules. Skip the lookup if a ProxyCommand is being used
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* unless the user has specifically requested canonicalisation.
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*/
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if (addrs == NULL && (option_clear_or_none(options.proxy_command) ||
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options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
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if ((addrs = resolve_host(host, options.port, 1,
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cname, sizeof(cname))) == NULL)
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cleanup_exit(255); /* resolve_host logs the error */
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check_follow_cname(&host, cname);
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}
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/*
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* If the target hostname has changed as a result of canonicalisation
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* then re-parse the configuration files as new stanzas may match.
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*/
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if (strcasecmp(host_arg, host) != 0) {
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debug("Hostname has changed; re-reading configuration");
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process_config_files(pw);
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}
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/* Fill configuration defaults. */
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fill_default_options(&options);
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if (options.port == 0)
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options.port = default_ssh_port();
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channel_set_af(options.address_family);
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/* Tidy and check options */
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@ -899,37 +968,6 @@ main(int ac, char **av)
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if (options.user == NULL)
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options.user = xstrdup(pw->pw_name);
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/* Get default port if port has not been set. */
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if (options.port == 0)
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options.port = default_ssh_port();
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/* preserve host name given on command line for %n expansion */
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if (options.hostname != NULL) {
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/* NB. Please keep in sync with readconf.c:match_cfg_line() */
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cp = percent_expand(options.hostname,
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"h", host, (char *)NULL);
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free(host);
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host = cp;
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}
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/* If canonicalization requested then try to apply it */
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lowercase(host);
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if (options.canonicalize_hostname != SSH_CANONICALISE_NO)
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addrs = resolve_canonicalize(&host, options.port);
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/*
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* If canonicalization not requested, or if it failed then try to
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* resolve the bare hostname name using the system resolver's usual
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* search rules. Skip the lookup if a ProxyCommand is being used
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* unless the user has specifically requested canonicalisation.
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*/
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if (addrs == NULL && (options.proxy_command == NULL ||
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options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
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if ((addrs = resolve_host(host, options.port, 1,
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cname, sizeof(cname))) == NULL)
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cleanup_exit(255); /* resolve_host logs the error */
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check_follow_cname(&host, cname);
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}
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if (gethostname(thishost, sizeof(thishost)) == -1)
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fatal("gethostname: %s", strerror(errno));
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strlcpy(shorthost, thishost, sizeof(shorthost));
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10
ssh_config.5
10
ssh_config.5
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@ -33,8 +33,8 @@
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $OpenBSD: ssh_config.5,v 1.184 2014/01/19 04:48:08 djm Exp $
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.Dd $Mdocdate: January 19 2014 $
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.\" $OpenBSD: ssh_config.5,v 1.185 2014/02/23 20:11:36 djm Exp $
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.Dd $Mdocdate: February 23 2014 $
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.Dt SSH_CONFIG 5
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.Os
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.Sh NAME
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@ -263,6 +263,12 @@ If
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is set to
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.Dq always ,
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then canonicalization is applied to proxied connections too.
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.Pp
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If this option is enabled and canonicalisation results in the target hostname
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changing, then the configuration files are processed again using the new
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target name to pick up any new configuration in matching
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.Cm Host
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stanzas.
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.It Cm CanonicalizeMaxDots
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Specifies the maximum number of dot characters in a hostname before
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canonicalization is disabled.
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Loading…
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