Initial Commit

server_info.go

@@ -0,0 +1,63 @@
+package profilefed
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+)
+
+// ServerInfoHandler handles the server info endpoint
+// defined by ProfileFed.
+type ServerInfoHandler struct {
+	// ServerName is the current name of the server. This
+	// should be the same as the domain used to access it.
+	ServerName string
+	// PreviousNames should contain any previous names this server used.
+	PreviousNames []string
+
+	// Pubkey should contain the server's public Ed25519 key.
+	Pubkey ed25519.PublicKey
+	// Privkey should contain the server's private Ed25519 key.
+	Privkey ed25519.PrivateKey
+	// PreviousKeys should contain any previously-used private keys.
+	// If this is not provided when the key changes, servers will not
+	// trust the new key and all responses will be rejected.
+	PreviousKeys []ed25519.PrivateKey
+
+	// ErrorHandler is called whenever an error is encountered.
+	ErrorHandler func(err error, res http.ResponseWriter)
+}
+
+type serverInfoData struct {
+	ServerName    string   `json:"server_name"`
+	PreviousNames []string `json:"previous_names"`
+	Pubkey        string   `json:"pubkey"`
+}
+
+// ServeHTTP implements the http.Handler interface
+func (sih ServerInfoHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
+	data, err := json.Marshal(serverInfoData{
+		ServerName:    sih.ServerName,
+		PreviousNames: sih.PreviousNames,
+		Pubkey:        base64.StdEncoding.EncodeToString(sih.Pubkey),
+	})
+	if err != nil {
+		sih.ErrorHandler(err, res)
+		return
+	}
+
+	for _, key := range sih.PreviousKeys {
+		sig := ed25519.Sign(key, data)
+		res.Header().Add("X-ProfileFed-Previous", base64.StdEncoding.EncodeToString(sig))
+	}
+
+	sig := ed25519.Sign(sih.Privkey, data)
+	res.Header().Set("X-ProfileFed-Sig", base64.StdEncoding.EncodeToString(sig))
+
+	_, err = res.Write(data)
+	if err != nil {
+		sih.ErrorHandler(err, res)
+		return
+	}
+}