// SPDX-License-Identifier: GPL-2.0-or-later
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/* Server address list management
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*
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* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/slab.h>
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#include <linux/ctype.h>
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#include <linux/dns_resolver.h>
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#include <linux/inet.h>
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#include <keys/rxrpc-type.h>
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#include "internal.h"
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#include "afs_fs.h"
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/*
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* Release an address list.
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*/
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void afs_put_addrlist(struct afs_addr_list *alist)
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{
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if (alist && refcount_dec_and_test(&alist->usage))
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kfree_rcu(alist, rcu);
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}
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/*
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* Allocate an address list.
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*/
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struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
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unsigned short service,
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unsigned short port)
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{
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struct afs_addr_list *alist;
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unsigned int i;
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_enter("%u,%u,%u", nr, service, port);
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if (nr > AFS_MAX_ADDRESSES)
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nr = AFS_MAX_ADDRESSES;
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alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
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if (!alist)
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return NULL;
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refcount_set(&alist->usage, 1);
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alist->max_addrs = nr;
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for (i = 0; i < nr; i++) {
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struct sockaddr_rxrpc *srx = &alist->addrs[i];
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srx->srx_family = AF_RXRPC;
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srx->srx_service = service;
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srx->transport_type = SOCK_DGRAM;
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srx->transport_len = sizeof(srx->transport.sin6);
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srx->transport.sin6.sin6_family = AF_INET6;
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srx->transport.sin6.sin6_port = htons(port);
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}
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return alist;
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}
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/*
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* Parse a text string consisting of delimited addresses.
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*/
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struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
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const char *text, size_t len,
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char delim,
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unsigned short service,
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unsigned short port)
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{
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struct afs_vlserver_list *vllist;
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struct afs_addr_list *alist;
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const char *p, *end = text + len;
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const char *problem;
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unsigned int nr = 0;
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int ret = -ENOMEM;
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_enter("%*.*s,%c", (int)len, (int)len, text, delim);
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if (!len) {
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_leave(" = -EDESTADDRREQ [empty]");
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return ERR_PTR(-EDESTADDRREQ);
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}
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if (delim == ':' && (memchr(text, ',', len) || !memchr(text, '.', len)))
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delim = ',';
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/* Count the addresses */
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p = text;
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do {
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if (!*p) {
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problem = "nul";
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goto inval;
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}
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if (*p == delim)
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continue;
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nr++;
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if (*p == '[') {
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p++;
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if (p == end) {
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problem = "brace1";
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goto inval;
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}
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p = memchr(p, ']', end - p);
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if (!p) {
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problem = "brace2";
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goto inval;
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}
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p++;
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if (p >= end)
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break;
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}
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p = memchr(p, delim, end - p);
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if (!p)
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break;
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p++;
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} while (p < end);
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_debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);
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vllist = afs_alloc_vlserver_list(1);
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if (!vllist)
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return ERR_PTR(-ENOMEM);
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vllist->nr_servers = 1;
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vllist->servers[0].server = afs_alloc_vlserver("<dummy>", 7, AFS_VL_PORT);
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if (!vllist->servers[0].server)
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goto error_vl;
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alist = afs_alloc_addrlist(nr, service, AFS_VL_PORT);
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if (!alist)
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goto error;
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/* Extract the addresses */
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p = text;
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do {
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const char *q, *stop;
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unsigned int xport = port;
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__be32 x[4];
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int family;
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if (*p == delim) {
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p++;
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continue;
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}
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if (*p == '[') {
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p++;
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q = memchr(p, ']', end - p);
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} else {
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for (q = p; q < end; q++)
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if (*q == '+' || *q == delim)
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break;
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}
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if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop)) {
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family = AF_INET;
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} else if (in6_pton(p, q - p, (u8 *)x, -1, &stop)) {
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family = AF_INET6;
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} else {
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problem = "family";
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goto bad_address;
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}
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p = q;
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if (stop != p) {
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problem = "nostop";
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goto bad_address;
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}
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if (q < end && *q == ']')
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p++;
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if (p < end) {
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if (*p == '+') {
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/* Port number specification "+1234" */
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xport = 0;
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p++;
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if (p >= end || !isdigit(*p)) {
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problem = "port";
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goto bad_address;
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}
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do {
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xport *= 10;
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xport += *p - '0';
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if (xport > 65535) {
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problem = "pval";
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goto bad_address;
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}
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p++;
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} while (p < end && isdigit(*p));
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} else if (*p == delim) {
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p++;
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} else {
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problem = "weird";
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goto bad_address;
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}
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}
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if (family == AF_INET)
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afs_merge_fs_addr4(alist, x[0], xport);
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else
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afs_merge_fs_addr6(alist, x, xport);
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} while (p < end);
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rcu_assign_pointer(vllist->servers[0].server->addresses, alist);
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_leave(" = [nr %u]", alist->nr_addrs);
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return vllist;
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inval:
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_leave(" = -EINVAL [%s %zu %*.*s]",
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problem, p - text, (int)len, (int)len, text);
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return ERR_PTR(-EINVAL);
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bad_address:
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_leave(" = -EINVAL [%s %zu %*.*s]",
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problem, p - text, (int)len, (int)len, text);
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ret = -EINVAL;
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error:
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afs_put_addrlist(alist);
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error_vl:
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afs_put_vlserverlist(net, vllist);
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return ERR_PTR(ret);
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}
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/*
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* Compare old and new address lists to see if there's been any change.
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* - How to do this in better than O(Nlog(N)) time?
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* - We don't really want to sort the address list, but would rather take the
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* list as we got it so as not to undo record rotation by the DNS server.
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*/
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#if 0
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static int afs_cmp_addr_list(const struct afs_addr_list *a1,
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const struct afs_addr_list *a2)
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{
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}
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#endif
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/*
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* Perform a DNS query for VL servers and build a up an address list.
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*/
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struct afs_vlserver_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry)
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{
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struct afs_vlserver_list *vllist;
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char *result = NULL;
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int ret;
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_enter("%s", cell->name);
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ret = dns_query(cell->net->net, "afsdb", cell->name, cell->name_len,
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"srv=1", &result, _expiry, true);
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if (ret < 0) {
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_leave(" = %d [dns]", ret);
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return ERR_PTR(ret);
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}
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if (*_expiry == 0)
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*_expiry = ktime_get_real_seconds() + 60;
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if (ret > 1 && result[0] == 0)
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vllist = afs_extract_vlserver_list(cell, result, ret);
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else
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vllist = afs_parse_text_addrs(cell->net, result, ret, ',',
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VL_SERVICE, AFS_VL_PORT);
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kfree(result);
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if (IS_ERR(vllist) && vllist != ERR_PTR(-ENOMEM))
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pr_err("Failed to parse DNS data %ld\n", PTR_ERR(vllist));
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return vllist;
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}
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/*
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* Merge an IPv4 entry into a fileserver address list.
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*/
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void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
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{
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struct sockaddr_rxrpc *srx;
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u32 addr = ntohl(xdr);
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int i;
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if (alist->nr_addrs >= alist->max_addrs)
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return;
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for (i = 0; i < alist->nr_ipv4; i++) {
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struct sockaddr_in *a = &alist->addrs[i].transport.sin;
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u32 a_addr = ntohl(a->sin_addr.s_addr);
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u16 a_port = ntohs(a->sin_port);
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if (addr == a_addr && port == a_port)
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return;
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if (addr == a_addr && port < a_port)
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break;
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if (addr < a_addr)
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break;
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}
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if (i < alist->nr_addrs)
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memmove(alist->addrs + i + 1,
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alist->addrs + i,
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sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
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srx = &alist->addrs[i];
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srx->srx_family = AF_RXRPC;
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srx->transport_type = SOCK_DGRAM;
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srx->transport_len = sizeof(srx->transport.sin);
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srx->transport.sin.sin_family = AF_INET;
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srx->transport.sin.sin_port = htons(port);
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srx->transport.sin.sin_addr.s_addr = xdr;
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alist->nr_ipv4++;
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alist->nr_addrs++;
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}
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/*
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* Merge an IPv6 entry into a fileserver address list.
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*/
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void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
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{
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struct sockaddr_rxrpc *srx;
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int i, diff;
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if (alist->nr_addrs >= alist->max_addrs)
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return;
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for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
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struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
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u16 a_port = ntohs(a->sin6_port);
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diff = memcmp(xdr, &a->sin6_addr, 16);
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if (diff == 0 && port == a_port)
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return;
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if (diff == 0 && port < a_port)
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break;
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if (diff < 0)
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break;
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}
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if (i < alist->nr_addrs)
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memmove(alist->addrs + i + 1,
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alist->addrs + i,
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sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
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srx = &alist->addrs[i];
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srx->srx_family = AF_RXRPC;
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srx->transport_type = SOCK_DGRAM;
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srx->transport_len = sizeof(srx->transport.sin6);
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srx->transport.sin6.sin6_family = AF_INET6;
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srx->transport.sin6.sin6_port = htons(port);
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memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
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alist->nr_addrs++;
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}
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/*
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* Get an address to try.
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*/
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bool afs_iterate_addresses(struct afs_addr_cursor *ac)
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{
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unsigned long set, failed;
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int index;
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if (!ac->alist)
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return false;
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set = ac->alist->responded;
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failed = ac->alist->failed;
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_enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);
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ac->nr_iterations++;
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set &= ~(failed | ac->tried);
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if (!set)
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return false;
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index = READ_ONCE(ac->alist->preferred);
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if (test_bit(index, &set))
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goto selected;
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index = __ffs(set);
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selected:
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ac->index = index;
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set_bit(index, &ac->tried);
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ac->responded = false;
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return true;
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}
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/*
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* Release an address list cursor.
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*/
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int afs_end_cursor(struct afs_addr_cursor *ac)
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{
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struct afs_addr_list *alist;
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alist = ac->alist;
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if (alist) {
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if (ac->responded &&
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ac->index != alist->preferred &&
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test_bit(ac->alist->preferred, &ac->tried))
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WRITE_ONCE(alist->preferred, ac->index);
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afs_put_addrlist(alist);
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ac->alist = NULL;
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}
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return ac->error;
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}
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