add user agent header

fixes #628

include/mbgl/util/constants.hpp

@@ -8,6 +8,7 @@ namespace mbgl {
 namespace util {
 
 extern const float tileSize;
+extern const char *userAgent;
 
 }
 

platform/darwin/http_request_baton_cocoa.mm

@@ -2,6 +2,7 @@
 #include <mbgl/util/std.hpp>
 #include <mbgl/util/parsedate.h>
 #include <mbgl/util/time.hpp>
+#include <mbgl/util/constants.hpp>
 
 #include <uv.h>
 
@@ -40,6 +41,8 @@ void HTTPRequestBaton::start(const util::ptr<HTTPRequestBaton> &ptr) {
         }
     }
 
+    [request addValue:@(util::userAgent) forHTTPHeaderField:@"User-Agent"];
+
     NSURLSessionDataTask *task = [session dataTaskWithRequest:request
                                             completionHandler:^(NSData *data, NSURLResponse *res, NSError *error) {
         if (error) {

platform/default/http_request_baton_curl.cpp

@@ -3,6 +3,7 @@
 #include <mbgl/util/time.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/util/std.hpp>
+#include <mbgl/util/constants.hpp>
 
 #include <uv.h>
 #include <curl/curl.h>
@@ -444,6 +445,7 @@ void start_request(void *const ptr) {
     curl_easy_setopt(context->handle, CURLOPT_HEADERFUNCTION, curl_header_cb);
     curl_easy_setopt(context->handle, CURLOPT_HEADERDATA, &context->baton->response);
     curl_easy_setopt(context->handle, CURLOPT_ACCEPT_ENCODING, "gzip, deflate");
+    curl_easy_setopt(context->handle, CURLOPT_USERAGENT, util::userAgent);
     curl_easy_setopt(context->handle, CURLOPT_SHARE, share);
 
     // Start requesting the information.

src/mbgl/util/constants.cpp

@@ -1,6 +1,7 @@
 #include <mbgl/util/constants.hpp>
 
 const float mbgl::util::tileSize = 512.0f;
+const char *mbgl::util::userAgent = "MapboxGL/1.0 (+https://mapbox.com/mapbox-gl/)";
 
 #if defined(DEBUG)
 const bool mbgl::debug::tileParseWarnings = false;