http2: remove conn->data use

... but instead use a private alternative that points to the "driving
transfer" from the connection. We set the "user data" associated with
the connection to be the connectdata struct, but when we drive transfers
the code still needs to know the pointer to the transfer. We can change
the user data to become the Curl_easy handle, but with older nghttp2
version we cannot dynamically update that pointer properly when
different transfers are used over the same connection.

Closes #6520

4 files changed, 67 insertions, 40 deletions

diff --git a/lib/http.c b/lib/http.c
index 33e4c62e5..5823bb9b4 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -3162,7 +3162,7 @@ CURLcode Curl_http(struct Curl_easy *data, bool *done)
      (data->state.httpwant == CURL_HTTP_VERSION_2)) {
     /* append HTTP2 upgrade magic stuff to the HTTP request if it isn't done
        over SSL */
-    result = Curl_http2_request_upgrade(&req, conn);
+    result = Curl_http2_request_upgrade(&req, data);
     if(result) {
       Curl_dyn_free(&req);
       return result;
diff --git a/lib/http.h b/lib/http.h
index 28f9341f6..587e032cd 100644
--- a/lib/http.h
+++ b/lib/http.h
@@ -251,9 +251,16 @@ struct h2settings {
 struct http_conn {
 #ifdef USE_NGHTTP2
 #define H2_BINSETTINGS_LEN 80
-  nghttp2_session *h2;
   uint8_t binsettings[H2_BINSETTINGS_LEN];
   size_t  binlen; /* length of the binsettings data */
+
+  /* We associate the connnectdata struct with the connection, but we need to
+     make sure we can identify the current "driving" transfer. This is a
+     work-around for the lack of nghttp2_session_set_user_data() in older
+     nghttp2 versions that we want to support. (Added in 1.31.0) */
+  struct Curl_easy *trnsfr;
+
+  nghttp2_session *h2;
   Curl_send *send_underlying; /* underlying send Curl_send callback */
   Curl_recv *recv_underlying; /* underlying recv Curl_recv callback */
   char *inbuf; /* buffer to receive data from underlying socket */
diff --git a/lib/http2.c b/lib/http2.c
index be4c71242..c6507e6f6 100644
--- a/lib/http2.c
+++ b/lib/http2.c
@@ -211,6 +211,24 @@ static bool http2_connisdead(struct Curl_easy *data, struct connectdata *conn)
   return dead;
 }
 
+/*
+ * Set the transfer that is currently using this HTTP/2 connection.
+ */
+static void set_transfer(struct http_conn *c,
+                         struct Curl_easy *data)
+{
+  c->trnsfr = data;
+}
+
+/*
+ * Get the transfer that is currently using this HTTP/2 connection.
+ */
+static struct Curl_easy *get_transfer(struct http_conn *c)
+{
+  DEBUGASSERT(c && c->trnsfr);
+  return c->trnsfr;
+}
+
 static unsigned int http2_conncheck(struct Curl_easy *data,
                                     struct connectdata *conn,
                                     unsigned int checks_to_perform)
@@ -247,6 +265,7 @@ static unsigned int http2_conncheck(struct Curl_easy *data,
   }
 
   if(send_frames) {
+    set_transfer(c, data); /* set the transfer */
     rc = nghttp2_session_send(c->h2);
     if(rc)
       failf(data, "nghttp2_session_send() failed: %s(%d)",
@@ -349,6 +368,7 @@ static ssize_t send_callback(nghttp2_session *h2,
 {
   struct connectdata *conn = (struct connectdata *)userp;
   struct http_conn *c = &conn->proto.httpc;
+  struct Curl_easy *data = get_transfer(c);
   ssize_t written;
   CURLcode result = CURLE_OK;
 
@@ -359,7 +379,7 @@ static ssize_t send_callback(nghttp2_session *h2,
     /* called before setup properly! */
     return NGHTTP2_ERR_CALLBACK_FAILURE;
 
-  written = ((Curl_send*)c->send_underlying)(conn->data, FIRSTSOCKET,
+  written = ((Curl_send*)c->send_underlying)(data, FIRSTSOCKET,
                                              mem, length, &result);
 
   if(result == CURLE_AGAIN) {
@@ -367,7 +387,7 @@ static ssize_t send_callback(nghttp2_session *h2,
   }
 
   if(written == -1) {
-    failf(conn->data, "Failed sending HTTP2 data");
+    failf(data, "Failed sending HTTP2 data");
     return NGHTTP2_ERR_CALLBACK_FAILURE;
   }
 
@@ -633,6 +653,7 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
   struct http_conn *httpc = &conn->proto.httpc;
   struct Curl_easy *data_s = NULL;
   struct HTTP *stream = NULL;
+  struct Curl_easy *data = get_transfer(httpc);
   int rv;
   size_t left, ncopy;
   int32_t stream_id = frame->hd.stream_id;
@@ -642,30 +663,30 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
     /* stream ID zero is for connection-oriented stuff */
     if(frame->hd.type == NGHTTP2_SETTINGS) {
       uint32_t max_conn = httpc->settings.max_concurrent_streams;
-      H2BUGF(infof(conn->data, "Got SETTINGS\n"));
+      H2BUGF(infof(data, "Got SETTINGS\n"));
       httpc->settings.max_concurrent_streams =
         nghttp2_session_get_remote_settings(
           session, NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS);
       httpc->settings.enable_push =
         nghttp2_session_get_remote_settings(
           session, NGHTTP2_SETTINGS_ENABLE_PUSH);
-      H2BUGF(infof(conn->data, "MAX_CONCURRENT_STREAMS == %d\n",
+      H2BUGF(infof(data, "MAX_CONCURRENT_STREAMS == %d\n",
                    httpc->settings.max_concurrent_streams));
-      H2BUGF(infof(conn->data, "ENABLE_PUSH == %s\n",
+      H2BUGF(infof(data, "ENABLE_PUSH == %s\n",
                    httpc->settings.enable_push?"TRUE":"false"));
       if(max_conn != httpc->settings.max_concurrent_streams) {
         /* only signal change if the value actually changed */
-        infof(conn->data,
+        infof(data,
               "Connection state changed (MAX_CONCURRENT_STREAMS == %u)!\n",
               httpc->settings.max_concurrent_streams);
-        multi_connchanged(conn->data->multi);
+        multi_connchanged(data->multi);
       }
     }
     return 0;
   }
   data_s = nghttp2_session_get_stream_user_data(session, stream_id);
   if(!data_s) {
-    H2BUGF(infof(conn->data,
+    H2BUGF(infof(data,
                  "No Curl_easy associated with stream: %x\n",
                  stream_id));
     return 0;
@@ -733,14 +754,9 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
     stream->memlen += ncopy;
 
     drain_this(data_s, httpc);
-    {
-      /* get the pointer from userp again since it was re-assigned above */
-      struct connectdata *conn_s = (struct connectdata *)userp;
-
-      /* if we receive data for another handle, wake that up */
-      if(conn_s->data != data_s)
-        Curl_expire(data_s, 0, EXPIRE_RUN_NOW);
-    }
+    /* if we receive data for another handle, wake that up */
+    if(get_transfer(httpc) != data_s)
+      Curl_expire(data_s, 0, EXPIRE_RUN_NOW);
     break;
   case NGHTTP2_PUSH_PROMISE:
     rv = push_promise(data_s, conn, &frame->push_promise);
@@ -768,15 +784,15 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
 
 static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
                               int32_t stream_id,
-                              const uint8_t *data, size_t len, void *userp)
+                              const uint8_t *mem, size_t len, void *userp)
 {
   struct HTTP *stream;
   struct Curl_easy *data_s;
   size_t nread;
   struct connectdata *conn = (struct connectdata *)userp;
+  struct http_conn *httpc = &conn->proto.httpc;
   (void)session;
   (void)flags;
-  (void)data;
 
   DEBUGASSERT(stream_id); /* should never be a zero stream ID here */
 
@@ -792,7 +808,7 @@ static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
     return NGHTTP2_ERR_CALLBACK_FAILURE;
 
   nread = CURLMIN(stream->len, len);
-  memcpy(&stream->mem[stream->memlen], data, nread);
+  memcpy(&stream->mem[stream->memlen], mem, nread);
 
   stream->len -= nread;
   stream->memlen += nread;
@@ -800,7 +816,7 @@ static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
   drain_this(data_s, &conn->proto.httpc);
 
   /* if we receive data for another handle, wake that up */
-  if(conn->data != data_s)
+  if(get_transfer(httpc) != data_s)
     Curl_expire(data_s, 0, EXPIRE_RUN_NOW);
 
   H2BUGF(infof(data_s, "%zu data received for stream %u "
@@ -810,7 +826,7 @@ static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
                stream->memlen));
 
   if(nread < len) {
-    stream->pausedata = data + nread;
+    stream->pausedata = mem + nread;
     stream->pauselen = len - nread;
     H2BUGF(infof(data_s, "NGHTTP2_ERR_PAUSE - %zu bytes out of buffer"
                  ", stream %u\n",
@@ -822,7 +838,7 @@ static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
 
   /* pause execution of nghttp2 if we received data for another handle
      in order to process them first. */
-  if(conn->data != data_s) {
+  if(get_transfer(httpc) != data_s) {
     data_s->conn->proto.httpc.pause_stream_id = stream_id;
 
     return NGHTTP2_ERR_PAUSE;
@@ -944,6 +960,7 @@ static int on_header(nghttp2_session *session, const nghttp2_frame *frame,
   struct Curl_easy *data_s;
   int32_t stream_id = frame->hd.stream_id;
   struct connectdata *conn = (struct connectdata *)userp;
+  struct http_conn *httpc = &conn->proto.httpc;
   CURLcode result;
   (void)flags;
 
@@ -1049,7 +1066,7 @@ static int on_header(nghttp2_session *session, const nghttp2_frame *frame,
     if(result)
       return NGHTTP2_ERR_CALLBACK_FAILURE;
     /* if we receive data for another handle, wake that up */
-    if(conn->data != data_s)
+    if(get_transfer(httpc) != data_s)
       Curl_expire(data_s, 0, EXPIRE_RUN_NOW);
 
     H2BUGF(infof(data_s, "h2 status: HTTP/2 %03d (easy %p)\n",
@@ -1073,7 +1090,7 @@ static int on_header(nghttp2_session *session, const nghttp2_frame *frame,
   if(result)
     return NGHTTP2_ERR_CALLBACK_FAILURE;
   /* if we receive data for another handle, wake that up */
-  if(conn->data != data_s)
+  if(get_transfer(httpc) != data_s)
     Curl_expire(data_s, 0, EXPIRE_RUN_NOW);
 
   H2BUGF(infof(data_s, "h2 header: %.*s: %.*s\n", namelen, name, valuelen,
@@ -1138,27 +1155,27 @@ static int error_callback(nghttp2_session *session,
                           size_t len,
                           void *userp)
 {
-  struct connectdata *conn = (struct connectdata *)userp;
   (void)session;
-  infof(conn->data, "http2 error: %.*s\n", len, msg);
+  (void)msg;
+  (void)len;
+  (void)userp;
   return 0;
 }
 #endif
 
-static void populate_settings(struct connectdata *conn,
+static void populate_settings(struct Curl_easy *data,
                               struct http_conn *httpc)
 {
   nghttp2_settings_entry *iv = httpc->local_settings;
-  DEBUGASSERT(conn->data);
 
   iv[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
-  iv[0].value = Curl_multi_max_concurrent_streams(conn->data->multi);
+  iv[0].value = Curl_multi_max_concurrent_streams(data->multi);
 
   iv[1].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   iv[1].value = HTTP2_HUGE_WINDOW_SIZE;
 
   iv[2].settings_id = NGHTTP2_SETTINGS_ENABLE_PUSH;
-  iv[2].value = conn->data->multi->push_cb != NULL;
+  iv[2].value = data->multi->push_cb != NULL;
 
   httpc->local_settings_num = 3;
 }
@@ -1187,6 +1204,7 @@ void Curl_http2_done(struct Curl_easy *data, bool premature)
 
   if(premature) {
     /* RST_STREAM */
+    set_transfer(httpc, data); /* set the transfer */
     if(!nghttp2_submit_rst_stream(httpc->h2, NGHTTP2_FLAG_NONE,
                                   http->stream_id, NGHTTP2_STREAM_CLOSED))
       (void)nghttp2_session_send(httpc->h2);
@@ -1209,6 +1227,7 @@ void Curl_http2_done(struct Curl_easy *data, bool premature)
             http->stream_id);
       DEBUGASSERT(0);
     }
+    set_transfer(httpc, NULL);
     http->stream_id = 0;
   }
 }
@@ -1269,18 +1288,18 @@ static CURLcode http2_init(struct Curl_easy *data, struct connectdata *conn)
  * Append headers to ask for a HTTP1.1 to HTTP2 upgrade.
  */
 CURLcode Curl_http2_request_upgrade(struct dynbuf *req,
-                                    struct connectdata *conn)
+                                    struct Curl_easy *data)
 {
   CURLcode result;
   ssize_t binlen;
   char *base64;
   size_t blen;
-  struct Curl_easy *data = conn->data;
+  struct connectdata *conn = data->conn;
   struct SingleRequest *k = &data->req;
   uint8_t *binsettings = conn->proto.httpc.binsettings;
   struct http_conn *httpc = &conn->proto.httpc;
 
-  populate_settings(conn, httpc);
+  populate_settings(data, httpc);
 
   /* this returns number of bytes it wrote */
   binlen = nghttp2_pack_settings_payload(binsettings, H2_BINSETTINGS_LEN,
@@ -1338,6 +1357,7 @@ static int h2_process_pending_input(struct Curl_easy *data,
   nread = httpc->inbuflen - httpc->nread_inbuf;
   inbuf = httpc->inbuf + httpc->nread_inbuf;
 
+  set_transfer(httpc, data); /* set the transfer */
   rv = nghttp2_session_mem_recv(httpc->h2, (const uint8_t *)inbuf, nread);
   if(rv < 0) {
     failf(data,
@@ -1542,6 +1562,8 @@ static int h2_session_send(struct Curl_easy *data,
                            nghttp2_session *h2)
 {
   struct HTTP *stream = data->req.p.http;
+  struct http_conn *httpc = &data->conn->proto.httpc;
+  set_transfer(httpc, data);
   if((data->set.stream_weight != data->state.stream_weight) ||
      (data->set.stream_depends_e != data->state.stream_depends_e) ||
      (data->set.stream_depends_on != data->state.stream_depends_on) ) {
@@ -2117,9 +2139,7 @@ static ssize_t http2_send(struct Curl_easy *data, int sockindex,
         stream_id, (void *)data);
   stream->stream_id = stream_id;
 
-  /* this does not call h2_session_send() since there can not have been any
-   * priority update since the nghttp2_submit_request() call above */
-  rv = nghttp2_session_send(h2);
+  rv = h2_session_send(data, h2);
   if(rv != 0) {
     H2BUGF(infof(data,
                  "http2_send() nghttp2_session_send error (%s)%d\n",
@@ -2244,7 +2264,7 @@ CURLcode Curl_http2_switched(struct Curl_easy *data,
     }
   }
   else {
-    populate_settings(conn, httpc);
+    populate_settings(data, httpc);
 
     /* stream ID is unknown at this point */
     stream->stream_id = -1;
diff --git a/lib/http2.h b/lib/http2.h
index 119e584a8..150f7219f 100644
--- a/lib/http2.h
+++ b/lib/http2.h
@@ -43,7 +43,7 @@ CURLcode Curl_http2_init(struct connectdata *conn);
 void Curl_http2_init_state(struct UrlState *state);
 void Curl_http2_init_userset(struct UserDefined *set);
 CURLcode Curl_http2_request_upgrade(struct dynbuf *req,
-                                    struct connectdata *conn);
+                                    struct Curl_easy *data);
 CURLcode Curl_http2_setup(struct Curl_easy *data, struct connectdata *conn);
 CURLcode Curl_http2_switched(struct Curl_easy *data,
                              const char *ptr, size_t nread);