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mod_proxy: restore reuse of ProxyRemote connections when possible. #531

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mod_proxy: restore reuse of ProxyRemote connections when possible. #531

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126 changes: 59 additions & 67 deletions modules/proxy/proxy_util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,16 +45,16 @@
APLOG_USE_MODULE(proxy);

/*
* Opaque structure containing target server info when
* using a forward proxy.
* Up to now only used in combination with HTTP CONNECT to ProxyRemote
* Opaque structure containing infos for CONNECT-ing an origin server through a
* remote (forward) proxy. Saved in the (opaque) proxy_conn_rec::forward pointer
* field for backend connections kept alive, allowing for reuse when subsequent
* requests should be routed through the same remote proxy.
*/
typedef struct {
int use_http_connect; /* Use SSL Tunneling via HTTP CONNECT */
const char *target_host; /* Target hostname */
apr_port_t target_port; /* Target port */
const char *proxy_auth; /* Proxy authorization */
} forward_info;
const char *target_host; /* Target/origin hostname */
apr_port_t target_port; /* Target/origin port */
} remote_connect_info;

/*
* Opaque structure containing a refcounted and TTL'ed address.
Expand Down Expand Up @@ -1608,9 +1608,7 @@ PROXY_DECLARE(int) ap_proxy_connection_reusable(proxy_conn_rec *conn)
{
proxy_worker *worker = conn->worker;

return !(conn->close
|| conn->forward
|| worker->s->disablereuse);
return !(conn->close || worker->s->disablereuse);
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@jfclere jfclere May 22, 2025

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That is the dirty patch I proposed, correct?

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@ylavic ylavic May 22, 2025 •
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Yes, this allows to reuse remote CONNECT proxy connections eventually, and it's probably enough to recover the performances.
But the code (of mine) in ap_proxy_determine_connection() made no sense too, starting by setting conn->forward = NULL and then checking if it didn't change (while the connection was closed anyway in connection_cleanup()..). Since both the connection and conn->forward are reusable now we'd better change that part too ;)

}

static proxy_conn_rec *connection_make(apr_pool_t *p, proxy_worker *worker)
Expand Down Expand Up @@ -3329,12 +3327,10 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
uri->scheme, conn->uds_path, conn->hostname, conn->port);
}
else {
remote_connect_info *connect_info = NULL;
const char *hostname = uri->hostname;
apr_port_t hostport = uri->port;

/* Not a remote CONNECT until further notice */
conn->forward = NULL;

if (proxyname) {
hostname = proxyname;
hostport = proxyport;
Expand All @@ -3345,7 +3341,6 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
* sending our actual HTTPS requests.
*/
if (conn->is_ssl) {
forward_info *forward;
const char *proxy_auth;

/* Do we want to pass Proxy-Authorization along?
Expand All @@ -3364,13 +3359,15 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
proxy_auth = NULL;
}

/* Reset forward info if they changed */
if (!(forward = conn->forward)
|| forward->target_port != uri->port
|| ap_cstr_casecmp(forward->target_host, uri->hostname) != 0
|| (forward->proxy_auth != NULL) != (proxy_auth != NULL)
|| (forward->proxy_auth != NULL && proxy_auth != NULL &&
strcmp(forward->proxy_auth, proxy_auth) != 0)) {
/* Save our real backend data for using it later during HTTP CONNECT */
connect_info = conn->forward;
if (!connect_info
/* reset connect info if they changed */
|| connect_info->target_port != uri->port
|| ap_cstr_casecmp(connect_info->target_host, uri->hostname) != 0
|| (connect_info->proxy_auth != NULL) != (proxy_auth != NULL)
|| (connect_info->proxy_auth != NULL && proxy_auth != NULL &&
strcmp(connect_info->proxy_auth, proxy_auth) != 0)) {
apr_pool_t *fwd_pool = conn->pool;
if (worker->s->is_address_reusable) {
if (conn->fwd_pool) {
Expand All @@ -3381,26 +3378,24 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
}
fwd_pool = conn->fwd_pool;
}
forward = apr_pcalloc(fwd_pool, sizeof(forward_info));
conn->forward = forward;

/*
* Save our real backend data for using it later during HTTP CONNECT.
*/
forward->use_http_connect = 1;
forward->target_host = apr_pstrdup(fwd_pool, uri->hostname);
forward->target_port = uri->port;
connect_info = apr_pcalloc(fwd_pool, sizeof(*connect_info));
connect_info->target_host = apr_pstrdup(fwd_pool, uri->hostname);
connect_info->target_port = uri->port;
if (proxy_auth) {
forward->proxy_auth = apr_pstrdup(fwd_pool, proxy_auth);
connect_info->proxy_auth = apr_pstrdup(fwd_pool, proxy_auth);
}
conn->forward = NULL;
}
}
}

if (conn->hostname
&& (conn->port != hostport
|| ap_cstr_casecmp(conn->hostname, hostname) != 0)) {
/* Close the connection if the remote proxy or origin server don't match */
if (conn->forward != connect_info
|| (conn->hostname
&& (conn->port != hostport
|| ap_cstr_casecmp(conn->hostname, hostname) != 0))) {
conn_cleanup(conn);
conn->forward = connect_info;
}

/* Resolve the connection address with the determined hostname/port */
Expand Down Expand Up @@ -3444,9 +3439,8 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
if (dconf->preserve_host) {
ssl_hostname = r->hostname;
}
else if (conn->forward
&& ((forward_info *)(conn->forward))->use_http_connect) {
ssl_hostname = ((forward_info *)conn->forward)->target_host;
else if (conn->forward) {
ssl_hostname = ((remote_connect_info *)conn->forward)->target_host;
}
else {
ssl_hostname = conn->hostname;
Expand Down Expand Up @@ -3543,7 +3537,7 @@ PROXY_DECLARE(int) ap_proxy_is_socket_connected(apr_socket_t *sock)


/*
* Send a HTTP CONNECT request to a forward proxy.
* Send a HTTP CONNECT request to a remote proxy.
* The proxy is given by "backend", the target server
* is contained in the "forward" member of "backend".
*/
Expand All @@ -3556,24 +3550,24 @@ static apr_status_t send_http_connect(proxy_conn_rec *backend,
int complete = 0;
char buffer[HUGE_STRING_LEN];
char drain_buffer[HUGE_STRING_LEN];
forward_info *forward = (forward_info *)backend->forward;
remote_connect_info *connect_info = backend->forward;
int len = 0;

ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00948)
"CONNECT: sending the CONNECT request for %s:%d "
"to the remote proxy %pI (%s)",
forward->target_host, forward->target_port,
connect_info->target_host, connect_info->target_port,
backend->addr, backend->hostname);
/* Create the CONNECT request */
nbytes = apr_snprintf(buffer, sizeof(buffer),
"CONNECT %s:%d HTTP/1.0" CRLF,
forward->target_host, forward->target_port);
connect_info->target_host, connect_info->target_port);
/* Add proxy authorization from the configuration, or initial
* request if necessary */
if (forward->proxy_auth != NULL) {
if (connect_info->proxy_auth != NULL) {
nbytes += apr_snprintf(buffer + nbytes, sizeof(buffer) - nbytes,
"Proxy-Authorization: %s" CRLF,
forward->proxy_auth);
connect_info->proxy_auth);
}
/* Set a reasonable agent and send everything */
nbytes += apr_snprintf(buffer + nbytes, sizeof(buffer) - nbytes,
Expand Down Expand Up @@ -3617,7 +3611,7 @@ static apr_status_t send_http_connect(proxy_conn_rec *backend,
char code_str[4];

ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00949)
"send_http_connect: response from the forward proxy: %s",
"send_http_connect: response from the remote proxy: %s",
buffer);

/* Extract the returned code */
Expand All @@ -3628,7 +3622,7 @@ static apr_status_t send_http_connect(proxy_conn_rec *backend,
}
else {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00950)
"send_http_connect: the forward proxy returned code is '%s'",
"send_http_connect: the remote proxy returned code is '%s'",
code_str);
status = APR_INCOMPLETE;
}
Expand Down Expand Up @@ -3792,7 +3786,7 @@ PROXY_DECLARE(int) ap_proxy_connect_backend(const char *proxy_function,
{
apr_status_t rv;
int loglevel;
forward_info *forward = conn->forward;
remote_connect_info *connect_info = conn->forward;
apr_sockaddr_t *backend_addr;
/* the local address to use for the outgoing connection */
apr_sockaddr_t *local_addr;
Expand Down Expand Up @@ -3993,27 +3987,25 @@ PROXY_DECLARE(int) ap_proxy_connect_backend(const char *proxy_function,

conn->sock = newsock;

if (forward && forward->use_http_connect) {
/*
* For HTTP CONNECT we need to prepend CONNECT request before
* sending our actual HTTPS requests.
*/
{
rv = send_http_connect(conn, s);
/* If an error occurred, loop round and try again */
if (rv != APR_SUCCESS) {
conn->sock = NULL;
apr_socket_close(newsock);
loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00958)
"%s: attempt to connect to %s:%hu "
"via http CONNECT through %pI (%s:%hu) failed",
proxy_function,
forward->target_host, forward->target_port,
backend_addr, conn->hostname, conn->port);
backend_addr = backend_addr->next;
continue;
}
/*
* For HTTP CONNECT we need to prepend CONNECT request before
* sending our actual HTTPS requests.
*/
if (connect_info) {
rv = send_http_connect(conn, s);
/* If an error occurred, loop round and try again */
if (rv != APR_SUCCESS) {
conn->sock = NULL;
apr_socket_close(newsock);
loglevel = backend_addr->next ? APLOG_DEBUG : APLOG_ERR;
ap_log_error(APLOG_MARK, loglevel, rv, s, APLOGNO(00958)
"%s: attempt to connect to %s:%hu "
"via http CONNECT through %pI (%s:%hu) failed",
proxy_function,
connect_info->target_host, connect_info->target_port,
backend_addr, conn->hostname, conn->port);
backend_addr = backend_addr->next;
continue;
}
}
}
Expand Down