transfer: fix upload rate limiting, add test cases

- add test cases for rate limiting uploads for all
  http versions
- fix transfer loop handling of limits. Signal a re-receive
  attempt only on exhausting maxloops without an EAGAIN
- fix `data->state.selectbits` forcing re-receive to also
  set re-sending when transfer is doing this.

Reported-by: Karthikdasari0423 on github
Fixes curl#12559
Closes curl#12586

lib/transfer.c

@@ -428,7 +428,7 @@ static CURLcode readwrite_data(struct Curl_easy *data,
   size_t blen;
   size_t consumed;
   int maxloops = 10;
-  curl_off_t max_recv = data->set.max_recv_speed ? 0 : CURL_OFF_T_MAX;
+  curl_off_t total_received = 0;
   bool data_eof_handled = FALSE;
 
   DEBUGASSERT(data->state.buffer);
@@ -439,6 +439,7 @@ static CURLcode readwrite_data(struct Curl_easy *data,
   do {
     bool is_empty_data = FALSE;
     size_t bytestoread = data->set.buffer_size;
+
     /* For HTTP/2 and HTTP/3, read data without caring about the content
        length. This is safe because body in HTTP/2 is always segmented
        thanks to its framing layer. Meanwhile, we have to call Curl_read
@@ -447,6 +448,15 @@ static CURLcode readwrite_data(struct Curl_easy *data,
     bool is_http3 = Curl_conn_is_http3(data, conn, FIRSTSOCKET);
     data_eof_handled = is_http3 || Curl_conn_is_http2(data, conn, FIRSTSOCKET);
 
+    if(data->set.max_recv_speed) {
+      /* Limit the amount we read here, break on reaching it */
+      curl_off_t net_limit = data->set.max_recv_speed - total_received;
+      if(net_limit <= 0)
+        break;
+      if((size_t)net_limit < bytestoread)
+        bytestoread = (size_t)net_limit;
+    }
+
     /* Each loop iteration starts with a fresh buffer and handles
      * all data read into it. */
     buf = data->state.buffer;
@@ -654,7 +664,7 @@ static CURLcode readwrite_data(struct Curl_easy *data,
       }
 #endif   /* CURL_DISABLE_HTTP */
 
-      max_recv -= blen;
+      total_received += blen;
 
       if(!k->chunk && (blen || k->badheader || is_empty_data)) {
         /* If this is chunky transfer, it was already written */
@@ -712,11 +722,13 @@ static CURLcode readwrite_data(struct Curl_easy *data,
       break;
     }
 
-  } while((max_recv > 0) && data_pending(data) && maxloops--);
+  } while(maxloops-- && data_pending(data));
 
-  if(maxloops <= 0 || max_recv <= 0) {
-    /* we mark it as read-again-please */
+  if(maxloops <= 0) {
+    /* did not read until EAGAIN, mark read-again-please */
     data->state.select_bits = CURL_CSELECT_IN;
+    if((k->keepon & KEEP_SENDBITS) == KEEP_SEND)
+      data->state.select_bits |= CURL_CSELECT_OUT;
   }
 
   if(((k->keepon & (KEEP_RECV|KEEP_SEND)) == KEEP_SEND) &&

tests/http/test_07_upload.py

@@ -461,3 +461,42 @@ def check_download(self, count, srcfile, curl):
                                                     tofile=dfile,
                                                     n=1))
                 assert False, f'download {dfile} differs:\n{diff}'
+
+    # speed limited on put handler
+    @pytest.mark.parametrize("proto", ['http/1.1', 'h2', 'h3'])
+    def test_07_50_put_speed_limit(self, env: Env, httpd, nghttpx, proto, repeat):
+        if proto == 'h3' and not env.have_h3():
+            pytest.skip("h3 not supported")
+        count = 1
+        fdata = os.path.join(env.gen_dir, 'data-100k')
+        up_len = 100 * 1024
+        speed_limit = 20 * 1024
+        curl = CurlClient(env=env)
+        url = f'https://{env.authority_for(env.domain1, proto)}/curltest/put?id=[0-0]'
+        r = curl.http_put(urls=[url], fdata=fdata, alpn_proto=proto,
+                          with_headers=True, extra_args=[
+            '--limit-rate', f'{speed_limit}'
+        ])
+        r.check_response(count=count, http_status=200)
+        assert r.responses[0]['header']['received-length'] == f'{up_len}', f'{r.responses[0]}'
+        up_speed = r.stats[0]['speed_upload']
+        assert (speed_limit * 0.5) <= up_speed <= (speed_limit * 1.5), f'{r.stats[0]}'
+
+    # speed limited on echo handler
+    @pytest.mark.parametrize("proto", ['http/1.1', 'h2', 'h3'])
+    def test_07_51_echo_speed_limit(self, env: Env, httpd, nghttpx, proto, repeat):
+        if proto == 'h3' and not env.have_h3():
+            pytest.skip("h3 not supported")
+        count = 1
+        fdata = os.path.join(env.gen_dir, 'data-100k')
+        speed_limit = 20 * 1024
+        curl = CurlClient(env=env)
+        url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-0]'
+        r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto,
+                             with_headers=True, extra_args=[
+            '--limit-rate', f'{speed_limit}'
+        ])
+        r.check_response(count=count, http_status=200)
+        up_speed = r.stats[0]['speed_upload']
+        assert (speed_limit * 0.5) <= up_speed <= (speed_limit * 1.5), f'{r.stats[0]}'
+

tests/http/testenv/mod_curltest/mod_curltest.c

@@ -423,6 +423,7 @@ static int curltest_put_handler(request_rec *r)
   char buffer[16*1024];
   const char *ct;
   apr_off_t rbody_len = 0;
+  const char *s_rbody_len;
   const char *request_id = "none";
   apr_time_t chunk_delay = 0;
   apr_array_header_t *args = NULL;
@@ -491,7 +492,9 @@ static int curltest_put_handler(request_rec *r)
     }
   }
   /* we are done */
-  rv = apr_brigade_printf(bb, NULL, NULL, "%"APR_OFF_T_FMT, rbody_len);
+  s_rbody_len = apr_psprintf(r->pool, "%"APR_OFF_T_FMT, rbody_len);
+  apr_table_setn(r->headers_out, "Received-Length", s_rbody_len);
+  rv = apr_brigade_puts(bb, NULL, NULL, s_rbody_len);
   if(APR_SUCCESS != rv) goto cleanup;
   b = apr_bucket_eos_create(c->bucket_alloc);
   APR_BRIGADE_INSERT_TAIL(bb, b);