block.curl: adding 'timeout' option

The curl hardcoded timeout (5 seconds) sometimes is not long
enough depending on the remote server configuration and network
traffic. The user should be able to set how much long he is
willing to wait for the connection.

Adding a new option to set this timeout gives the user this
flexibility. The previous default timeout of 5 seconds will be
used if this option is not present.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NDaniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
Reviewed-by: NBenoit Canet <benoit.canet@nodalink.com>
Tested-by: NRichard W.M. Jones <rjones@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

block/curl.c

@@ -63,6 +63,7 @@ static CURLMcode __curl_multi_socket_action(CURLM *multi_handle,
 #define CURL_NUM_ACB    8
 #define SECTOR_SIZE     512
 #define READ_AHEAD_DEFAULT (256 * 1024)
+#define CURL_TIMEOUT_DEFAULT 5
 
 #define FIND_RET_NONE   0
 #define FIND_RET_OK     1
@@ -71,6 +72,7 @@ static CURLMcode __curl_multi_socket_action(CURLM *multi_handle,
 #define CURL_BLOCK_OPT_URL       "url"
 #define CURL_BLOCK_OPT_READAHEAD "readahead"
 #define CURL_BLOCK_OPT_SSLVERIFY "sslverify"
+#define CURL_BLOCK_OPT_TIMEOUT "timeout"
 
 struct BDRVCURLState;
 
@@ -109,6 +111,7 @@ typedef struct BDRVCURLState {
     char *url;
     size_t readahead_size;
     bool sslverify;
+    int timeout;
     bool accept_range;
     AioContext *aio_context;
 } BDRVCURLState;
@@ -382,7 +385,7 @@ static CURLState *curl_init_state(BDRVCURLState *s)
         curl_easy_setopt(state->curl, CURLOPT_URL, s->url);
         curl_easy_setopt(state->curl, CURLOPT_SSL_VERIFYPEER,
                          (long) s->sslverify);
-        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, 5);
+        curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, s->timeout);
         curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION,
                          (void *)curl_read_cb);
         curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
@@ -489,6 +492,11 @@ static QemuOptsList runtime_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "Verify SSL certificate"
         },
+        {
+            .name = CURL_BLOCK_OPT_TIMEOUT,
+            .type = QEMU_OPT_NUMBER,
+            .help = "Curl timeout"
+        },
         { /* end of list */ }
     },
 };
@@ -525,6 +533,9 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
         goto out_noclean;
     }
 
+    s->timeout = qemu_opt_get_number(opts, CURL_BLOCK_OPT_TIMEOUT,
+                                     CURL_TIMEOUT_DEFAULT);
+
     s->sslverify = qemu_opt_get_bool(opts, CURL_BLOCK_OPT_SSLVERIFY, true);
 
     file = qemu_opt_get(opts, CURL_BLOCK_OPT_URL);

qemu-options.hx

@@ -2351,6 +2351,11 @@ multiple of 512 bytes. It defaults to 256k.
 @item sslverify
 Whether to verify the remote server's certificate when connecting over SSL. It
 can have the value 'on' or 'off'. It defaults to 'on'.
+
+@item timeout
+Set the timeout in seconds of the CURL connection. This timeout is the time
+that CURL waits for a response from the remote server to get the size of the
+image to be downloaded. If not set, the default timeout of 5 seconds is used.
 @end table
 
 Note that when passing options to qemu explicitly, @option{driver} is the value
@@ -2372,9 +2377,10 @@ qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-o
 @end example
 
 Example: boot from an image stored on a VMware vSphere server with a self-signed
-certificate using a local overlay for writes and a readahead of 64k
+certificate using a local overlay for writes, a readahead of 64k and a timeout
+of 10 seconds.
 @example
-qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"https",, "file.url":"https://user:password@@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k"@}' /tmp/test.qcow2
+qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"https",, "file.url":"https://user:password@@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10@}' /tmp/test.qcow2
 
 qemu-system-x86_64 -drive file=/tmp/test.qcow2
 @end example