[Qemu-devel] [PATCH 1/2] block: curl: Allow arbitrary HTTP request headers to be set.

[Richard W.M. Jones]

Allow arbitrary HTTP request headers to be set, like this:

  qemu-img create -f qcow2 \
      -b 'json:{ "file.driver":"http",
                 "file.url":"http://192.168.0.249/scratch/test.img";,
                 "file.header": ["Authorization: letmein"] }' \
      test.qcow2

which adds the ‘Authorization: letmein’ header to the outgoing request
for the backing file.  Multiple headers can be set, and curl built-in
headers can be removed (using "Header:").

Note this uses the same format as curl's CURLOPT_HTTPHEADER, thus
pulling in curl API guarantees into qemu, but curl has had very strong
API backward compatibility since the start of the project.

Signed-off-by: Richard W.M. Jones <address@hidden>
---
 block/curl.c         | 21 ++++++++++++++++++++-
 qapi/block-core.json | 10 ++++++++--
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/block/curl.c b/block/curl.c
index aa42535783..972673ba5c 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -83,6 +83,7 @@ static CURLMcode __curl_multi_socket_action(CURLM 
*multi_handle,
 #define CURL_BLOCK_OPT_TIMEOUT "timeout"
 #define CURL_BLOCK_OPT_COOKIE    "cookie"
 #define CURL_BLOCK_OPT_COOKIE_SECRET "cookie-secret"
+#define CURL_BLOCK_OPT_HEADER_PATTERN "header."
 #define CURL_BLOCK_OPT_USERNAME "username"
 #define CURL_BLOCK_OPT_PASSWORD_SECRET "password-secret"
 #define CURL_BLOCK_OPT_PROXY_USERNAME "proxy-username"
@@ -134,6 +135,7 @@ typedef struct BDRVCURLState {
     bool sslverify;
     uint64_t timeout;
     char *cookie;
+    struct curl_slist *headers;
     bool accept_range;
     AioContext *aio_context;
     QemuMutex mutex;
@@ -486,6 +488,9 @@ static int curl_init_state(BDRVCURLState *s, CURLState 
*state)
         if (s->cookie) {
             curl_easy_setopt(state->curl, CURLOPT_COOKIE, s->cookie);
         }
+        if (s->headers) {
+            curl_easy_setopt(state->curl, CURLOPT_HTTPHEADER, s->headers);
+        }
         curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, (long)s->timeout);
         curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION,
                          (void *)curl_read_cb);
@@ -680,7 +685,7 @@ static int curl_open(BlockDriverState *bs, QDict *options, 
int flags,
     double d;
     const char *secretid;
     const char *protocol_delimiter;
-    int ret;
+    int i, nr, ret;
 
 
     if (flags & BDRV_O_RDWR) {
@@ -740,6 +745,18 @@ static int curl_open(BlockDriverState *bs, QDict *options, 
int flags,
         s->cookie = g_strdup(cookie);
     }
 
+    s->headers = NULL;
+    nr = qdict_array_entries(options, CURL_BLOCK_OPT_HEADER_PATTERN);
+    for (i = 0; i < nr; ++i) {
+        char key[32];
+        const char *header;
+
+        snprintf(key, sizeof key, CURL_BLOCK_OPT_HEADER_PATTERN "%d", i);
+        header = qdict_get_str(options, key);
+        s->headers = curl_slist_append(s->headers, header);
+        qdict_del(options, key);
+    }
+
     file = qemu_opt_get(opts, CURL_BLOCK_OPT_URL);
     if (file == NULL) {
         error_setg(errp, "curl block driver requires an 'url' option");
@@ -847,6 +864,7 @@ out:
     state->curl = NULL;
 out_noclean:
     qemu_mutex_destroy(&s->mutex);
+    curl_slist_free_all(s->headers);
     g_free(s->cookie);
     g_free(s->url);
     g_free(s->username);
@@ -945,6 +963,7 @@ static void curl_close(BlockDriverState *bs)
     curl_detach_aio_context(bs);
     qemu_mutex_destroy(&s->mutex);
 
+    curl_slist_free_all(s->headers);
     g_free(s->cookie);
     g_free(s->url);
     g_free(s->username);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 5c5921bfb7..ca1ebdbef1 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3047,12 +3047,15 @@
 # @cookie-secret: ID of a QCryptoSecret object providing the cookie data in a
 #                 secure way. See @cookie for the format. (since 2.10)
 #
+# @header:      List of HTTP request headers, see CURLOPT_HTTPHEADER(3).
+#
 # Since: 2.9
 ##
 { 'struct': 'BlockdevOptionsCurlHttp',
   'base': 'BlockdevOptionsCurlBase',
   'data': { '*cookie': 'str',
-            '*cookie-secret': 'str'} }
+            '*cookie-secret': 'str',
+            '*header': [ 'str' ] } }
 
 ##
 # @BlockdevOptionsCurlHttps:
@@ -3070,13 +3073,16 @@
 # @cookie-secret: ID of a QCryptoSecret object providing the cookie data in a
 #                 secure way. See @cookie for the format. (since 2.10)
 #
+# @header:      List of HTTP request headers, see CURLOPT_HTTPHEADER(3).
+#
 # Since: 2.9
 ##
 { 'struct': 'BlockdevOptionsCurlHttps',
   'base': 'BlockdevOptionsCurlBase',
   'data': { '*cookie': 'str',
             '*sslverify': 'bool',
-            '*cookie-secret': 'str'} }
+            '*cookie-secret': 'str',
+            '*header': [ 'str' ] } }
 
 ##
 # @BlockdevOptionsCurlFtp:
-- 
2.13.2