From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/smb/client/dns_resolve.c | 89 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) create mode 100644 fs/smb/client/dns_resolve.c (limited to 'fs/smb/client/dns_resolve.c') diff --git a/fs/smb/client/dns_resolve.c b/fs/smb/client/dns_resolve.c new file mode 100644 index 000000000..0458d28d7 --- /dev/null +++ b/fs/smb/client/dns_resolve.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: LGPL-2.1 +/* + * + * Copyright (c) 2007 Igor Mammedov + * Author(s): Igor Mammedov (niallain@gmail.com) + * Steve French (sfrench@us.ibm.com) + * Wang Lei (wang840925@gmail.com) + * David Howells (dhowells@redhat.com) + * + * Contains the CIFS DFS upcall routines used for hostname to + * IP address translation. + * + */ + +#include +#include +#include "dns_resolve.h" +#include "cifsglob.h" +#include "cifsproto.h" +#include "cifs_debug.h" + +/** + * dns_resolve_server_name_to_ip - Resolve UNC server name to ip address. + * @unc: UNC path specifying the server (with '/' as delimiter) + * @ip_addr: Where to return the IP address. + * @expiry: Where to return the expiry time for the dns record. + * + * The IP address will be returned in string form, and the caller is + * responsible for freeing it. + * + * Returns length of result on success, -ve on error. + */ +int +dns_resolve_server_name_to_ip(const char *unc, char **ip_addr, time64_t *expiry) +{ + struct sockaddr_storage ss; + const char *hostname, *sep; + char *name; + int len, rc; + + if (!ip_addr || !unc) + return -EINVAL; + + len = strlen(unc); + if (len < 3) { + cifs_dbg(FYI, "%s: unc is too short: %s\n", __func__, unc); + return -EINVAL; + } + + /* Discount leading slashes for cifs */ + len -= 2; + hostname = unc + 2; + + /* Search for server name delimiter */ + sep = memchr(hostname, '/', len); + if (sep) + len = sep - hostname; + else + cifs_dbg(FYI, "%s: probably server name is whole unc: %s\n", + __func__, unc); + + /* Try to interpret hostname as an IPv4 or IPv6 address */ + rc = cifs_convert_address((struct sockaddr *)&ss, hostname, len); + if (rc > 0) + goto name_is_IP_address; + + /* Perform the upcall */ + rc = dns_query(current->nsproxy->net_ns, NULL, hostname, len, + NULL, ip_addr, expiry, false); + if (rc < 0) + cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n", + __func__, len, len, hostname); + else + cifs_dbg(FYI, "%s: resolved: %*.*s to %s expiry %llu\n", + __func__, len, len, hostname, *ip_addr, + expiry ? (*expiry) : 0); + return rc; + +name_is_IP_address: + name = kmalloc(len + 1, GFP_KERNEL); + if (!name) + return -ENOMEM; + memcpy(name, hostname, len); + name[len] = 0; + cifs_dbg(FYI, "%s: unc is IP, skipping dns upcall: %s\n", + __func__, name); + *ip_addr = name; + return 0; +} -- cgit v1.2.3