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- Fix to stop possible loops in the tcp reuse code (write_wait list

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and tcp_wait list). Based on analysis and patch from Prad Seniappan
  and Karthik Umashankar.
This commit is contained in:
George Thessalonikefs 2022-10-07 11:25:36 +02:00
parent bf1cce6f9b
commit 2569b12b9c
4 changed files with 354 additions and 59 deletions
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5
doc/Changelog
View File

@ -1,3 +1,8 @@
7 October 2022: George
- Fix to stop possible loops in the tcp reuse code (write_wait list
and tcp_wait list). Based on analysis and patch from Prad Seniappan
and Karthik Umashankar.
6 October 2022: Wouter
- Fix to stop responses with TC flag from resulting in partial
responses. It retries to fetch the data elsewhere, or fails the

131
services/outside_network.c
View File

@ -86,10 +86,6 @@ static void serviced_tcp_initiate(struct serviced_query* sq, sldns_buffer* buff)
static int randomize_and_send_udp(struct pending* pend, sldns_buffer* packet,
int timeout);
/** remove waiting tcp from the outnet waiting list */
static void waiting_list_remove(struct outside_network* outnet,
struct waiting_tcp* w);
/** select a DNS ID for a TCP stream */
static uint16_t tcp_select_id(struct outside_network* outnet,
struct reuse_tcp* reuse);
@ -372,7 +368,8 @@ log_reuse_tcp(enum verbosity_value v, const char* msg, struct reuse_tcp* reuse)
}
/** pop the first element from the writewait list */
static struct waiting_tcp* reuse_write_wait_pop(struct reuse_tcp* reuse)
struct waiting_tcp*
reuse_write_wait_pop(struct reuse_tcp* reuse)
{
struct waiting_tcp* w = reuse->write_wait_first;
if(!w)
@ -390,8 +387,8 @@ static struct waiting_tcp* reuse_write_wait_pop(struct reuse_tcp* reuse)
}
/** remove the element from the writewait list */
static void reuse_write_wait_remove(struct reuse_tcp* reuse,
struct waiting_tcp* w)
void
reuse_write_wait_remove(struct reuse_tcp* reuse, struct waiting_tcp* w)
{
log_assert(w);
log_assert(w->write_wait_queued);
@ -415,8 +412,8 @@ static void reuse_write_wait_remove(struct reuse_tcp* reuse,
}
/** push the element after the last on the writewait list */
static void reuse_write_wait_push_back(struct reuse_tcp* reuse,
struct waiting_tcp* w)
void
reuse_write_wait_push_back(struct reuse_tcp* reuse, struct waiting_tcp* w)
{
if(!w) return;
log_assert(!w->write_wait_queued);
@ -427,7 +424,9 @@ static void reuse_write_wait_push_back(struct reuse_tcp* reuse,
w->write_wait_prev = reuse->write_wait_last;
} else {
reuse->write_wait_first = w;
w->write_wait_prev = NULL;
}
w->write_wait_next = NULL;
reuse->write_wait_last = w;
w->write_wait_queued = 1;
}
@ -810,20 +809,50 @@ reuse_tcp_lru_snip(struct outside_network* outnet)
return reuse;
}
/** call callback on waiting_tcp, if not NULL */
static void
waiting_tcp_callback(struct waiting_tcp* w, struct comm_point* c, int error,
struct comm_reply* reply_info)
/** remove waiting tcp from the outnet waiting list */
void
outnet_waiting_tcp_list_remove(struct outside_network* outnet, struct waiting_tcp* w)
{
if(w && w->cb) {
fptr_ok(fptr_whitelist_pending_tcp(w->cb));
(void)(*w->cb)(c, w->cb_arg, error, reply_info);
struct waiting_tcp* p = outnet->tcp_wait_first, *prev = NULL;
w->on_tcp_waiting_list = 0;
while(p) {
if(p == w) {
/* remove w */
if(prev)
prev->next_waiting = w->next_waiting;
else outnet->tcp_wait_first = w->next_waiting;
if(outnet->tcp_wait_last == w)
outnet->tcp_wait_last = prev;
w->next_waiting = NULL;
return;
}
prev = p;
p = p->next_waiting;
}
/* outnet_waiting_tcp_list_remove is currently called only with items
* that are already in the waiting list. */
log_assert(0);
}
/** pop the first waiting tcp from the outnet waiting list */
struct waiting_tcp*
outnet_waiting_tcp_list_pop(struct outside_network* outnet)
{
struct waiting_tcp* w = outnet->tcp_wait_first;
if(!outnet->tcp_wait_first) return NULL;
log_assert(w->on_tcp_waiting_list);
outnet->tcp_wait_first = w->next_waiting;
if(outnet->tcp_wait_last == w)
outnet->tcp_wait_last = NULL;
w->on_tcp_waiting_list = 0;
w->next_waiting = NULL;
return w;
}
/** add waiting_tcp element to the outnet tcp waiting list */
static void
outnet_add_tcp_waiting(struct outside_network* outnet, struct waiting_tcp* w)
void
outnet_waiting_tcp_list_add(struct outside_network* outnet,
struct waiting_tcp* w, int set_timer)
{
struct timeval tv;
log_assert(!w->on_tcp_waiting_list);
@ -835,16 +864,18 @@ outnet_add_tcp_waiting(struct outside_network* outnet, struct waiting_tcp* w)
else outnet->tcp_wait_first = w;
outnet->tcp_wait_last = w;
w->on_tcp_waiting_list = 1;
if(set_timer) {
#ifndef S_SPLINT_S
tv.tv_sec = w->timeout/1000;
tv.tv_usec = (w->timeout%1000)*1000;
tv.tv_sec = w->timeout/1000;
tv.tv_usec = (w->timeout%1000)*1000;
#endif
comm_timer_set(w->timer, &tv);
comm_timer_set(w->timer, &tv);
}
}
/** add waiting_tcp element as first to the outnet tcp waiting list */
static void
outnet_add_tcp_waiting_first(struct outside_network* outnet,
void
outnet_waiting_tcp_list_add_first(struct outside_network* outnet,
struct waiting_tcp* w, int reset_timer)
{
struct timeval tv;
@ -869,6 +900,17 @@ outnet_add_tcp_waiting_first(struct outside_network* outnet,
(outnet->tcp_reuse_first && outnet->tcp_reuse_last));
}
/** call callback on waiting_tcp, if not NULL */
static void
waiting_tcp_callback(struct waiting_tcp* w, struct comm_point* c, int error,
struct comm_reply* reply_info)
{
if(w && w->cb) {
fptr_ok(fptr_whitelist_pending_tcp(w->cb));
(void)(*w->cb)(c, w->cb_arg, error, reply_info);
}
}
/** see if buffers can be used to service TCP queries */
static void
use_free_buffer(struct outside_network* outnet)
@ -879,15 +921,10 @@ use_free_buffer(struct outside_network* outnet)
struct pending_tcp* pend_tcp = NULL;
#endif
struct reuse_tcp* reuse = NULL;
w = outnet->tcp_wait_first;
log_assert(w->on_tcp_waiting_list);
outnet->tcp_wait_first = w->next_waiting;
if(outnet->tcp_wait_last == w)
outnet->tcp_wait_last = NULL;
w = outnet_waiting_tcp_list_pop(outnet);
log_assert(
(!outnet->tcp_reuse_first && !outnet->tcp_reuse_last) ||
(outnet->tcp_reuse_first && outnet->tcp_reuse_last));
w->on_tcp_waiting_list = 0;
reuse = reuse_tcp_find(outnet, &w->addr, w->addrlen,
w->ssl_upstream);
/* re-select an ID when moving to a new TCP buffer */
@ -934,7 +971,7 @@ use_free_buffer(struct outside_network* outnet)
#endif
} else {
/* no reuse and no free buffer, put back at the start */
outnet_add_tcp_waiting_first(outnet, w, 0);
outnet_waiting_tcp_list_add_first(outnet, w, 0);
break;
}
#ifdef USE_DNSTAP
@ -1008,7 +1045,7 @@ reuse_move_writewait_away(struct outside_network* outnet,
* fail the query */
w->error_count ++;
reuse_tree_by_id_delete(&pend->reuse, w);
outnet_add_tcp_waiting(outnet, w);
outnet_waiting_tcp_list_add(outnet, w, 1);
}
while((w = reuse_write_wait_pop(&pend->reuse)) != NULL) {
if(verbosity >= VERB_CLIENT && w->pkt_len > 12+2+2 &&
@ -1019,7 +1056,7 @@ reuse_move_writewait_away(struct outside_network* outnet,
verbose(VERB_CLIENT, "reuse_move_writewait_away item %s", buf);
}
reuse_tree_by_id_delete(&pend->reuse, w);
outnet_add_tcp_waiting(outnet, w);
outnet_waiting_tcp_list_add(outnet, w, 1);
}
}
@ -2237,7 +2274,7 @@ outnet_tcptimer(void* arg)
verbose(VERB_CLIENT, "outnet_tcptimer");
if(w->on_tcp_waiting_list) {
/* it is on the waiting list */
waiting_list_remove(outnet, w);
outnet_waiting_tcp_list_remove(outnet, w);
waiting_tcp_callback(w, NULL, NETEVENT_TIMEOUT, NULL);
waiting_tcp_delete(w);
} else {
@ -2464,7 +2501,7 @@ pending_tcp_query(struct serviced_query* sq, sldns_buffer* packet,
#ifdef USE_DNSTAP
w->sq = sq;
#endif
outnet_add_tcp_waiting(sq->outnet, w);
outnet_waiting_tcp_list_add(sq->outnet, w, 1);
}
return w;
}
@ -2612,30 +2649,6 @@ serviced_create(struct outside_network* outnet, sldns_buffer* buff, int dnssec,
return sq;
}
/** remove waiting tcp from the outnet waiting list */
static void
waiting_list_remove(struct outside_network* outnet, struct waiting_tcp* w)
{
struct waiting_tcp* p = outnet->tcp_wait_first, *prev = NULL;
w->on_tcp_waiting_list = 0;
while(p) {
if(p == w) {
/* remove w */
if(prev)
prev->next_waiting = w->next_waiting;
else outnet->tcp_wait_first = w->next_waiting;
if(outnet->tcp_wait_last == w)
outnet->tcp_wait_last = prev;
return;
}
prev = p;
p = p->next_waiting;
}
/* waiting_list_remove is currently called only with items that are
* already in the waiting list. */
log_assert(0);
}
/** reuse tcp stream, remove serviced query from stream,
* return true if the stream is kept, false if it is to be closed */
static int
@ -2730,7 +2743,7 @@ serviced_delete(struct serviced_query* sq)
sq->pending = NULL;
} else {
verbose(VERB_CLIENT, "serviced_delete: tcpwait");
waiting_list_remove(sq->outnet, w);
outnet_waiting_tcp_list_remove(sq->outnet, w);
if(!w->in_cb_and_decommission)
waiting_tcp_delete(w);
}

24
services/outside_network.h
View File

@ -718,6 +718,30 @@ struct reuse_tcp* reuse_tcp_lru_snip(struct outside_network* outnet);
/** delete readwait waiting_tcp elements, deletes the elements in the list */
void reuse_del_readwait(rbtree_type* tree_by_id);
/** remove waiting tcp from the outnet waiting list */
void outnet_waiting_tcp_list_remove(struct outside_network* outnet,
struct waiting_tcp* w);
/** pop the first waiting tcp from the outnet waiting list */
struct waiting_tcp* outnet_waiting_tcp_list_pop(struct outside_network* outnet);
/** add waiting_tcp element to the outnet tcp waiting list */
void outnet_waiting_tcp_list_add(struct outside_network* outnet,
struct waiting_tcp* w, int set_timer);
/** add waiting_tcp element as first to the outnet tcp waiting list */
void outnet_waiting_tcp_list_add_first(struct outside_network* outnet,
struct waiting_tcp* w, int reset_timer);
/** pop the first element from the writewait list */
struct waiting_tcp* reuse_write_wait_pop(struct reuse_tcp* reuse);
/** remove the element from the writewait list */
void reuse_write_wait_remove(struct reuse_tcp* reuse, struct waiting_tcp* w);
/** push the element after the last on the writewait list */
void reuse_write_wait_push_back(struct reuse_tcp* reuse, struct waiting_tcp* w);
/** get TCP file descriptor for address, returns -1 on failure,
* tcp_mss is 0 or maxseg size to set for TCP packets. */
int outnet_get_tcp_fd(struct sockaddr_storage* addr, socklen_t addrlen,

253
testcode/unittcpreuse.c
View File

@ -44,6 +44,8 @@
#include "util/random.h"
#include "services/outside_network.h"
#define MAX_TCP_WAITING_NODES 5
/** add number of new IDs to the reuse tree, randomly chosen */
static void tcpid_addmore(struct reuse_tcp* reuse,
struct outside_network* outnet, unsigned int addnum)
@ -228,9 +230,260 @@ static void tcp_reuse_tree_list_test(void)
free(outnet.tcp_conns);
}
static void check_waiting_tcp_list(struct outside_network* outnet,
struct waiting_tcp* first, struct waiting_tcp* last, size_t total)
{
size_t i, j;
struct waiting_tcp* w = outnet->tcp_wait_first;
struct waiting_tcp* n = NULL;
if(first) unit_assert(outnet->tcp_wait_first == first);
if(last) unit_assert(outnet->tcp_wait_last == last && !last->next_waiting);
for(i=0; w; i++) {
unit_assert(i<total); /* otherwise we are looping */
unit_assert(w->on_tcp_waiting_list);
n = w->next_waiting;
for(j=0; n; j++) {
unit_assert(j<total-i-1); /* otherwise we are looping */
unit_assert(n != w);
n = n->next_waiting;
}
w = w->next_waiting;
}
}
/** clear the tcp waiting list */
static void waiting_tcp_list_clear(struct outside_network* outnet)
{
struct waiting_tcp* w = outnet->tcp_wait_first, *n = NULL;
if(!w) return;
unit_assert(outnet->tcp_wait_first);
unit_assert(outnet->tcp_wait_last);
while(w) {
n = w->next_waiting;
w->on_tcp_waiting_list = 0;
w->next_waiting = (struct waiting_tcp*)1; /* In purpose faux value */
w = n;
}
outnet->tcp_wait_first = NULL;
outnet->tcp_wait_last = NULL;
}
/** check removal of the waiting_tcp element on the given position of total
* elements */
static void check_waiting_tcp_removal(int is_pop,
struct outside_network* outnet, struct waiting_tcp* store,
size_t position, size_t total)
{
size_t i;
struct waiting_tcp* w;
waiting_tcp_list_clear(outnet);
for(i=0; i<total; i++) {
outnet_waiting_tcp_list_add(outnet, &store[i], 0);
}
check_waiting_tcp_list(outnet, &store[0], &store[total-1], total);
if(is_pop) {
w = outnet_waiting_tcp_list_pop(outnet);
unit_assert(w); /* please clang-analyser */
} else {
w = outnet->tcp_wait_first;
for(i=0; i<position; i++) {
unit_assert(w); /* please clang-analyser */
w = w->next_waiting;
}
unit_assert(w); /* please clang-analyser */
outnet_waiting_tcp_list_remove(outnet, w);
}
unit_assert(!(w->on_tcp_waiting_list || w->next_waiting));
if(position == 0 && total == 1) {
/* the list should be empty */
check_waiting_tcp_list(outnet, NULL, NULL, total-1);
} else if(position == 0) {
/* first element should be gone */
check_waiting_tcp_list(outnet, &store[1], &store[total-1], total-1);
} else if(position == total - 1) {
/* last element should be gone */
check_waiting_tcp_list(outnet, &store[0], &store[total-2], total-1);
} else {
/* an element should be gone */
check_waiting_tcp_list(outnet, &store[0], &store[total-1], total-1);
}
}
static void waiting_tcp_list_test(void)
{
size_t i = 0;
struct outside_network outnet;
struct waiting_tcp* w, *t = NULL;
struct waiting_tcp store[MAX_TCP_WAITING_NODES];
memset(&outnet, 0, sizeof(outnet));
memset(&store, 0, sizeof(store));
/* Check add first on empty list */
unit_show_func("services/outside_network.c", "outnet_waiting_tcp_list_add_first");
t = &store[i];
outnet_waiting_tcp_list_add_first(&outnet, t, 0);
check_waiting_tcp_list(&outnet, t, t, 1);
/* Check add */
unit_show_func("services/outside_network.c", "outnet_waiting_tcp_list_add");
for(i=1; i<MAX_TCP_WAITING_NODES-1; i++) {
w = &store[i];
outnet_waiting_tcp_list_add(&outnet, w, 0);
}
check_waiting_tcp_list(&outnet, t, w, MAX_TCP_WAITING_NODES-1);
/* Check add first on populated list */
unit_show_func("services/outside_network.c", "outnet_waiting_tcp_list_add_first");
w = &store[i];
t = outnet.tcp_wait_last;
outnet_waiting_tcp_list_add_first(&outnet, w, 0);
check_waiting_tcp_list(&outnet, w, t, MAX_TCP_WAITING_NODES);
/* Check removal */
unit_show_func("services/outside_network.c", "outnet_waiting_tcp_list_remove");
check_waiting_tcp_removal(0, &outnet, store, 2, 5);
check_waiting_tcp_removal(0, &outnet, store, 1, 3);
check_waiting_tcp_removal(0, &outnet, store, 0, 2);
check_waiting_tcp_removal(0, &outnet, store, 1, 2);
check_waiting_tcp_removal(0, &outnet, store, 0, 1);
/* Check pop */
unit_show_func("services/outside_network.c", "outnet_waiting_tcp_list_pop");
check_waiting_tcp_removal(1, &outnet, store, 0, 3);
check_waiting_tcp_removal(1, &outnet, store, 0, 2);
check_waiting_tcp_removal(1, &outnet, store, 0, 1);
}
static void check_reuse_write_wait(struct reuse_tcp* reuse,
struct waiting_tcp* first, struct waiting_tcp* last, size_t total)
{
size_t i, j;
struct waiting_tcp* w = reuse->write_wait_first;
struct waiting_tcp* n = NULL;
if(first) unit_assert(reuse->write_wait_first == first && !first->write_wait_prev);
if(last) unit_assert(reuse->write_wait_last == last && !last->write_wait_next);
/* check one way */
for(i=0; w; i++) {
unit_assert(i<total); /* otherwise we are looping */
unit_assert(w->write_wait_queued);
n = w->write_wait_next;
for(j=0; n; j++) {
unit_assert(j<total-i-1); /* otherwise we are looping */
unit_assert(n != w);
n = n->write_wait_next;
}
w = w->write_wait_next;
}
/* check the other way */
w = reuse->write_wait_last;
for(i=0; w; i++) {
unit_assert(i<total); /* otherwise we are looping */
unit_assert(w->write_wait_queued);
n = w->write_wait_prev;
for(j=0; n; j++) {
unit_assert(j<total-i-1); /* otherwise we are looping */
unit_assert(n != w);
n = n->write_wait_prev;
}
w = w->write_wait_prev;
}
}
/** clear the tcp waiting list */
static void reuse_write_wait_clear(struct reuse_tcp* reuse)
{
struct waiting_tcp* w = reuse->write_wait_first, *n = NULL;
if(!w) return;
unit_assert(reuse->write_wait_first);
unit_assert(reuse->write_wait_last);
while(w) {
n = w->write_wait_next;
w->write_wait_queued = 0;
w->write_wait_next = (struct waiting_tcp*)1; /* In purpose faux value */
w->write_wait_prev = (struct waiting_tcp*)1; /* In purpose faux value */
w = n;
}
reuse->write_wait_first = NULL;
reuse->write_wait_last = NULL;
}
/** check removal of the reuse_write_wait element on the given position of total
* elements */
static void check_reuse_write_wait_removal(int is_pop,
struct reuse_tcp* reuse, struct waiting_tcp* store,
size_t position, size_t total)
{
size_t i;
struct waiting_tcp* w;
reuse_write_wait_clear(reuse);
for(i=0; i<total; i++) {
reuse_write_wait_push_back(reuse, &store[i]);
}
check_reuse_write_wait(reuse, &store[0], &store[total-1], total);
if(is_pop) {
w = reuse_write_wait_pop(reuse);
} else {
w = reuse->write_wait_first;
for(i=0; i<position; i++) w = w->write_wait_next;
reuse_write_wait_remove(reuse, w);
}
unit_assert(!(w->write_wait_queued || w->write_wait_next || w->write_wait_prev));
if(position == 0 && total == 1) {
/* the list should be empty */
check_reuse_write_wait(reuse, NULL, NULL, total-1);
} else if(position == 0) {
/* first element should be gone */
check_reuse_write_wait(reuse, &store[1], &store[total-1], total-1);
} else if(position == total - 1) {
/* last element should be gone */
check_reuse_write_wait(reuse, &store[0], &store[total-2], total-1);
} else {
/* an element should be gone */
check_reuse_write_wait(reuse, &store[0], &store[total-1], total-1);
}
}
static void reuse_write_wait_test(void)
{
size_t i;
struct reuse_tcp reuse;
struct waiting_tcp store[MAX_TCP_WAITING_NODES];
struct waiting_tcp* w;
memset(&reuse, 0, sizeof(reuse));
memset(&store, 0, sizeof(store));
/* Check adding */
unit_show_func("services/outside_network.c", "reuse_write_wait_push_back");
for(i=0; i<MAX_TCP_WAITING_NODES; i++) {
w = &store[i];
reuse_write_wait_push_back(&reuse, w);
}
check_reuse_write_wait(&reuse, &store[0], w, MAX_TCP_WAITING_NODES);
/* Check removal */
unit_show_func("services/outside_network.c", "reuse_write_wait_remove");
check_reuse_write_wait_removal(0, &reuse, store, 2, 5);
check_reuse_write_wait_removal(0, &reuse, store, 1, 3);
check_reuse_write_wait_removal(0, &reuse, store, 0, 2);
check_reuse_write_wait_removal(0, &reuse, store, 1, 2);
check_reuse_write_wait_removal(0, &reuse, store, 0, 1);
/* Check pop */
unit_show_func("services/outside_network.c", "reuse_write_wait_pop");
check_reuse_write_wait_removal(0, &reuse, store, 0, 3);
check_reuse_write_wait_removal(0, &reuse, store, 0, 2);
check_reuse_write_wait_removal(0, &reuse, store, 0, 1);
}
void tcpreuse_test(void)
{
unit_show_feature("tcp_reuse");
tcpid_test();
tcp_reuse_tree_list_test();
waiting_tcp_list_test();
reuse_write_wait_test();
}