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disconnect: separate connections and easy handles better

Do not assume/store assocation between a given easy handle and the
connection if it can be avoided.

Long-term, the 'conn->data' pointer should probably be removed as it is a
little too error-prone. Still used very widely though.

Reported-by: masbug on github
Fixes #3391
Closes #3400
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bagder committed Dec 20, 2018
1 parent d18a5af commit fb445a1e18d12f577964c9347bc5bca74b37cd08
Showing with 13 additions and 13 deletions.
  1. +8 −2 lib/conncache.c
  2. +2 −1 lib/conncache.h
  3. +1 −3 lib/multi.c
  4. +2 −7 lib/url.c
@@ -302,9 +302,14 @@ CURLcode Curl_conncache_add_conn(struct conncache *connc,
return result;
}

void Curl_conncache_remove_conn(struct connectdata *conn, bool lock)
/*
* Removes the connectdata object from the connection cache *and* clears the
* ->data pointer association. Pass TRUE/FALSE in the 'lock' argument
* depending on if the parent function already holds the lock or not.
*/
void Curl_conncache_remove_conn(struct Curl_easy *data,
struct connectdata *conn, bool lock)
{
struct Curl_easy *data = conn->data;
struct connectbundle *bundle = conn->bundle;
struct conncache *connc = data->state.conn_cache;

@@ -323,6 +328,7 @@ void Curl_conncache_remove_conn(struct connectdata *conn, bool lock)
DEBUGF(infof(data, "The cache now contains %zu members\n",
connc->num_conn));
}
conn->data = NULL; /* clear the association */
if(lock) {
CONN_UNLOCK(data);
}
@@ -64,7 +64,8 @@ size_t Curl_conncache_bundle_size(struct connectdata *conn);
bool Curl_conncache_return_conn(struct connectdata *conn);
CURLcode Curl_conncache_add_conn(struct conncache *connc,
struct connectdata *conn) WARN_UNUSED_RESULT;
void Curl_conncache_remove_conn(struct connectdata *conn,
void Curl_conncache_remove_conn(struct Curl_easy *data,
struct connectdata *conn,
bool lock);
bool Curl_conncache_foreach(struct Curl_easy *data,
struct conncache *connc,
@@ -761,10 +761,8 @@ CURLMcode curl_multi_remove_handle(struct Curl_multi *multi,
vanish with this handle */

/* Remove the association between the connection and the handle */
if(data->easy_conn) {
data->easy_conn->data = NULL;
if(data->easy_conn)
data->easy_conn = NULL;
}

#ifdef USE_LIBPSL
/* Remove the PSL association. */
@@ -769,7 +769,6 @@ CURLcode Curl_disconnect(struct Curl_easy *data,
return CURLE_OK;
}

conn->data = data;
if(conn->dns_entry != NULL) {
Curl_resolv_unlock(data, conn->dns_entry);
conn->dns_entry = NULL;
@@ -788,14 +787,13 @@ CURLcode Curl_disconnect(struct Curl_easy *data,

/* unlink ourselves! */
infof(data, "Closing connection %ld\n", conn->connection_id);
Curl_conncache_remove_conn(conn, TRUE);
Curl_conncache_remove_conn(data, conn, TRUE);

free_idnconverted_hostname(&conn->host);
free_idnconverted_hostname(&conn->conn_to_host);
free_idnconverted_hostname(&conn->http_proxy.host);
free_idnconverted_hostname(&conn->socks_proxy.host);

DEBUGASSERT(conn->data == data);
/* this assumes that the pointer is still there after the connection was
detected from the cache */
Curl_ssl_close(conn, FIRSTSOCKET);
@@ -960,8 +958,6 @@ static bool extract_if_dead(struct connectdata *conn,
handles in pipeline and the connection isn't already marked in
use */
bool dead;

conn->data = data;
if(conn->handler->connection_check) {
/* The protocol has a special method for checking the state of the
connection. Use it to check if the connection is dead. */
@@ -977,8 +973,7 @@ static bool extract_if_dead(struct connectdata *conn,

if(dead) {
infof(data, "Connection %ld seems to be dead!\n", conn->connection_id);
Curl_conncache_remove_conn(conn, FALSE);
conn->data = NULL; /* detach */
Curl_conncache_remove_conn(data, conn, FALSE);
return TRUE;
}
}

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