web: move useragent to its own package

2 files changed, 55 insertions, 0 deletions

diff --git a/web/useragent/user_agent.go b/web/useragent/user_agent.go
new file mode 100644
index 0000000..0f521c9
--- /dev/null
+++ b/web/useragent/user_agent.go
@@ -0,0 +1,43 @@
+package useragent
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"runtime"
+)
+
+var (
+	hostname = "<unknown>"
+)
+
+func init() {
+	name, _ := os.Hostname()
+	if name != "" {
+		hostname = name
+	}
+}
+
+// GenUserAgent creates a unique User-Agent string for outgoing HTTP requests.
+func GenUserAgent(prefix, infoURL string) string {
+	return fmt.Sprintf(
+		"%s (%s/%s/%s; %s; +%s) Hostname/%s",
+		prefix, runtime.Version(), runtime.GOOS, runtime.GOARCH, infoURL,
+		os.Args[0], hostname,
+	)
+}
+
+// Transport wraps a http transport with user agent information.
+func Transport(prefix, infoURL string, rt http.RoundTripper) http.RoundTripper {
+	return userAgentTransport{prefix: prefix, rt: rt}
+}
+
+type userAgentTransport struct {
+	prefix, infoURL string
+	rt              http.RoundTripper
+}
+
+func (uat userAgentTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	r.Header.Set("User-Agent", GenUserAgent(uat.prefix))
+	return uat.rt.RoundTrip(r)
+}
diff --git a/web/useragent/user_agent_test.go b/web/useragent/user_agent_test.go
new file mode 100644
index 0000000..702bcf7
--- /dev/null
+++ b/web/useragent/user_agent_test.go
@@ -0,0 +1,12 @@
+package useragent
+
+import "testing"
+
+func TestGenUserAgent(t *testing.T) {
+	ua := GenUserAgent()
+	if ua == "" {
+		t.Fatal("no user agent generated")
+	}
+
+	t.Log(ua)
+}