Change ReceiveTimeout to use CURLOPT_LOW_SPEED_TIME

Currently ReceiveTimeout sets CURLOPT_TIMEOUT which is an absolute timeout
on the HTTP download and not particularly useful without knowing the size
of the file or the throughput available to download it.

Change it to use CURLOPT_LOW_SPEED_TIME instead, and set the related low
speed limit (CURLOPT_LOW_SPEED_LIMIT) to 1 byte per second. This will allow
the ReceiveTimeout to abort the attempt if the download is not making
any significant progress.

Restore the documentation, default and sample options back to before
2fd28e1d09 and
f5d465a864.

This fixes #266 and avoids problems caused by the Ubuntu default
ReceiveTimeout of 30 seconds.

common/optparser.c

@@ -555,7 +555,7 @@ const struct clam_option __clam_options[] = {
 
     {"ConnectTimeout", NULL, 0, CLOPT_TYPE_NUMBER, MATCH_NUMBER, 30, NULL, 0, OPT_FRESHCLAM, "Timeout in seconds when connecting to database server.", "30"},
 
-    {"ReceiveTimeout", NULL, 0, CLOPT_TYPE_NUMBER, MATCH_NUMBER, 0, NULL, 0, OPT_FRESHCLAM, "Maximum time in seconds for each download operation. 0 means no timeout.", "0"},
+    {"ReceiveTimeout", NULL, 0, CLOPT_TYPE_NUMBER, MATCH_NUMBER, 60, NULL, 0, OPT_FRESHCLAM, "Timeout in seconds when reading from database server. 0 means no timeout.", "60"},
 
     {"Bytecode", NULL, 0, CLOPT_TYPE_BOOL, MATCH_BOOL, 1, NULL, 0, OPT_FRESHCLAM, "This option enables downloading of bytecode.cvd, which includes additional\ndetection mechanisms and improvements to the ClamAV engine.", "yes"},
 

etc/freshclam.conf.sample

@@ -175,9 +175,9 @@ DatabaseMirror database.clamav.net
 # Default: 30
 #ConnectTimeout 60
 
-# Maximum time in seconds for each download operation. 0 means no timeout.
-# Default: 0
-#ReceiveTimeout 1800
+# Timeout in seconds when reading from database server. 0 means no timeout.
+# Default: 60
+#ReceiveTimeout 300
 
 # With this option enabled, freshclam will attempt to load new databases into
 # memory to make sure they are properly handled by libclamav before replacing

libfreshclam/libfreshclam.h

@@ -48,7 +48,7 @@ typedef struct fc_config_ {
     uint64_t maxLogSize;             /**< Max size of logfile, if enabled. */
     uint32_t maxAttempts;            /**< Max # of download attempts. Must be > 0 */
     uint32_t connectTimeout;         /**< CURLOPT_CONNECTTIMEOUT, Timeout for the. connection phase (seconds). */
-    uint32_t requestTimeout;         /**< CURLOPT_TIMEOUT, Timeout for libcurl transfer operation (seconds). */
+    uint32_t requestTimeout;         /**< CURLOPT_LOW_SPEED_TIME, Timeout for libcurl transfer operation (seconds). */
     uint32_t bCompressLocalDatabase; /**< If set, will apply gz compression to CLD databases. */
     const char *logFile;             /**< (optional) Filepath to use for log output, if desired. */
     const char *logFacility;         /**< (optional) System logging facility (I.e. "syslog"), if desired. */

libfreshclam/libfreshclam_internal.c

@@ -623,8 +623,16 @@ static fc_error_t create_curl_handle(
         if (CURLE_OK != curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, g_connectTimeout)) {
             logg("!create_curl_handle: Failed to set CURLOPT_CONNECTTIMEOUT (%u)!\n", g_connectTimeout);
         }
-        if (CURLE_OK != curl_easy_setopt(curl, CURLOPT_TIMEOUT, g_requestTimeout)) {
-            logg("!create_curl_handle: Failed to set CURLOPT_TIMEOUT (%u)!\n", g_requestTimeout);
+        if (CURLE_OK != curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, g_requestTimeout)) {
+            logg("!create_curl_handle: Failed to set CURLOPT_LOW_SPEED_TIME  (%u)!\n", g_requestTimeout);
+        }
+        if (g_requestTimeout > 0) {
+            /* Minimum speed is 1 byte/second over the previous g_requestTimeout seconds. */
+            int minimumSpeed = 1;
+
+            if (CURLE_OK != curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, minimumSpeed)) {
+                logg("!create_curl_handle: Failed to set CURLOPT_LOW_SPEED_LIMIT  (%u)!\n", minimumSpeed);
+            }
         }
 
         if (bAllowRedirect) {

win32/conf_examples/freshclam.conf.sample

@@ -172,9 +172,9 @@ DatabaseMirror database.clamav.net
 # Default: 30
 #ConnectTimeout 60
 
-# Maximum time in seconds for each download operation. 0 means no timeout.
-# Default: 0
-#ReceiveTimeout 1800
+# Timeout in seconds when reading from database server. 0 means no timeout.
+# Default: 60
+#ReceiveTimeout 300
 
 # With this option enabled, freshclam will attempt to load new databases into
 # memory to make sure they are properly handled by libclamav before replacing