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4b1b4c8be9
Some places pass hostnames rather than UNC paths to resolve them to ip addresses, so provide helpers to handle both cases and then stop converting hostnames to UNC paths by inserting path delimiters into them. Also kill @expiry parameter as it's not used anywhere. Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
// SPDX-License-Identifier: LGPL-2.1
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/*
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*
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* Copyright (c) 2007 Igor Mammedov
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* Author(s): Igor Mammedov (niallain@gmail.com)
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* Steve French (sfrench@us.ibm.com)
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* Wang Lei (wang840925@gmail.com)
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* David Howells (dhowells@redhat.com)
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*
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* Contains the CIFS DFS upcall routines used for hostname to
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* IP address translation.
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*
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*/
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#include <linux/inet.h>
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#include <linux/slab.h>
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#include <linux/dns_resolver.h>
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#include "dns_resolve.h"
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifs_debug.h"
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static int resolve_name(const char *name, size_t namelen, struct sockaddr *addr)
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{
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char *ip;
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int rc;
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rc = dns_query(current->nsproxy->net_ns, NULL, name,
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namelen, NULL, &ip, NULL, false);
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if (rc < 0) {
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cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n",
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__func__, (int)namelen, (int)namelen, name);
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} else {
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cifs_dbg(FYI, "%s: resolved: %*.*s to %s\n",
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__func__, (int)namelen, (int)namelen, name, ip);
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rc = cifs_convert_address(addr, ip, strlen(ip));
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kfree(ip);
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if (!rc) {
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cifs_dbg(FYI, "%s: unable to determine ip address\n",
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__func__);
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rc = -EHOSTUNREACH;
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} else {
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rc = 0;
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}
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}
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return rc;
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}
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/**
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* dns_resolve_name - Perform an upcall to resolve hostname to an ip address.
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* @dom: DNS domain name (or NULL)
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* @name: Name to look up
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* @namelen: Length of name
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* @ip_addr: Where to return the IP address
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*
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* Returns zero on success, -ve code otherwise.
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*/
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int dns_resolve_name(const char *dom, const char *name,
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size_t namelen, struct sockaddr *ip_addr)
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{
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size_t len;
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char *s;
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int rc;
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cifs_dbg(FYI, "%s: dom=%s name=%.*s\n", __func__, dom, (int)namelen, name);
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if (!ip_addr || !name || !*name || !namelen)
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return -EINVAL;
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cifs_dbg(FYI, "%s: hostname=%.*s\n", __func__, (int)namelen, name);
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/* Try to interpret hostname as an IPv4 or IPv6 address */
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rc = cifs_convert_address(ip_addr, name, namelen);
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if (rc > 0) {
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cifs_dbg(FYI, "%s: unc is IP, skipping dns upcall: %*.*s\n",
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__func__, (int)namelen, (int)namelen, name);
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return 0;
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}
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/*
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* If @name contains a NetBIOS name and @dom has been specified, then
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* convert @name to an FQDN and try resolving it first.
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*/
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if (dom && *dom && cifs_netbios_name(name, namelen)) {
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len = strnlen(dom, CIFS_MAX_DOMAINNAME_LEN) + namelen + 2;
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s = kmalloc(len, GFP_KERNEL);
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if (!s)
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return -ENOMEM;
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scnprintf(s, len, "%.*s.%s", (int)namelen, name, dom);
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rc = resolve_name(s, len - 1, ip_addr);
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kfree(s);
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if (!rc)
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return 0;
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}
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return resolve_name(name, namelen, ip_addr);
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}
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