1 files changed, 64 insertions, 0 deletions
diff --git a/internal/httpclient/sanitizer.go b/internal/httpclient/sanitizer.go
new file mode 100644
index 000000000..6eef6898a
--- /dev/null
+++ b/internal/httpclient/sanitizer.go
@@ -0,0 +1,64 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package httpclient
+
+import (
+	"net/netip"
+	"syscall"
+
+	"github.com/superseriousbusiness/gotosocial/internal/netutil"
+)
+
+type sanitizer struct {
+	allow []netip.Prefix
+	block []netip.Prefix
+}
+
+// Sanitize implements the required net.Dialer.Control function signature.
+func (s *sanitizer) Sanitize(ntwrk, addr string, _ syscall.RawConn) error {
+	// Parse IP+port from addr
+	ipport, err := netip.ParseAddrPort(addr)
+	if err != nil {
+		return err
+	}
+
+	// Seperate the IP
+	ip := ipport.Addr()
+
+	// Check if this is explicitly allowed
+	for i := 0; i < len(s.allow); i++ {
+		if s.allow[i].Contains(ip) {
+			return nil
+		}
+	}
+
+	// Now check if explicity blocked
+	for i := 0; i < len(s.block); i++ {
+		if s.block[i].Contains(ip) {
+			return ErrReservedAddr
+		}
+	}
+
+	// Validate this is a safe IP
+	if !netutil.ValidateIP(ip) {
+		return ErrReservedAddr
+	}
+
+	return nil
+}