protocol: introduce protocol extension mechanisms

[thirdparty/git.git] / protocol.c

diff --git a/protocol.c b/protocol.c
new file mode 100644 (file)
index 0000000..43012b7
--- /dev/null
+++ b/protocol.c
@@ -0,0 +1,79 @@
+#include "cache.h"
+#include "config.h"
+#include "protocol.h"
+
+static enum protocol_version parse_protocol_version(const char *value)
+{
+       if (!strcmp(value, "0"))
+               return protocol_v0;
+       else if (!strcmp(value, "1"))
+               return protocol_v1;
+       else
+               return protocol_unknown_version;
+}
+
+enum protocol_version get_protocol_version_config(void)
+{
+       const char *value;
+       if (!git_config_get_string_const("protocol.version", &value)) {
+               enum protocol_version version = parse_protocol_version(value);
+
+               if (version == protocol_unknown_version)
+                       die("unknown value for config 'protocol.version': %s",
+                           value);
+
+               return version;
+       }
+
+       return protocol_v0;
+}
+
+enum protocol_version determine_protocol_version_server(void)
+{
+       const char *git_protocol = getenv(GIT_PROTOCOL_ENVIRONMENT);
+       enum protocol_version version = protocol_v0;
+
+       /*
+        * Determine which protocol version the client has requested.  Since
+        * multiple 'version' keys can be sent by the client, indicating that
+        * the client is okay to speak any of them, select the greatest version
+        * that the client has requested.  This is due to the assumption that
+        * the most recent protocol version will be the most state-of-the-art.
+        */
+       if (git_protocol) {
+               struct string_list list = STRING_LIST_INIT_DUP;
+               const struct string_list_item *item;
+               string_list_split(&list, git_protocol, ':', -1);
+
+               for_each_string_list_item(item, &list) {
+                       const char *value;
+                       enum protocol_version v;
+
+                       if (skip_prefix(item->string, "version=", &value)) {
+                               v = parse_protocol_version(value);
+                               if (v > version)
+                                       version = v;
+                       }
+               }
+
+               string_list_clear(&list, 0);
+       }
+
+       return version;
+}
+
+enum protocol_version determine_protocol_version_client(const char *server_response)
+{
+       enum protocol_version version = protocol_v0;
+
+       if (skip_prefix(server_response, "version ", &server_response)) {
+               version = parse_protocol_version(server_response);
+
+               if (version == protocol_unknown_version)
+                       die("server is speaking an unknown protocol");
+               if (version == protocol_v0)
+                       die("protocol error: server explicitly said version 0");
+       }
+
+       return version;
+}