Support batched relay,unrelay,local,unlocal messages

websocket/version.go

@@ -0,0 +1,75 @@
+package websocket
+
+import (
+	"strconv"
+	"strings"
+)
+
+// minBatchedSiteMessagesVersion is the first pangolin server version that understands the
+// batched siteIds/chainIds (and endpoints/relayEndpoints) form of the olm/wg/relay,
+// olm/wg/unrelay, olm/wg/local and olm/wg/unlocal messages. Servers older than this only
+// understand the singular siteId/chainId form, so olm must fall back to sending those
+// messages one at a time.
+const minBatchedSiteMessagesVersion = "1.24.0"
+
+// SupportsBatchedSiteMessages reports whether the server we're connected to is new enough
+// to understand batched relay/unrelay/local/unlocal messages, based on the serverVersion
+// returned in the last token exchange.
+func (c *Client) SupportsBatchedSiteMessages() bool {
+	return supportsBatchedSiteMessages(c.ServerVersion())
+}
+
+// ServerVersion returns the version reported by the server during the last token exchange,
+// or "" if unknown (e.g. no successful connection has completed yet).
+func (c *Client) ServerVersion() string {
+	c.tokenMux.RLock()
+	defer c.tokenMux.RUnlock()
+	return c.serverVersion
+}
+
+func supportsBatchedSiteMessages(serverVersion string) bool {
+	if serverVersion == "" {
+		// Unknown server version: assume it predates batching rather than risk sending a
+		// format an old server can't parse.
+		return false
+	}
+	return compareVersions(baseVersion(serverVersion), minBatchedSiteMessagesVersion) >= 0
+}
+
+// baseVersion strips any "-suffix" build metadata (e.g. "1.24.0-s.5" -> "1.24.0").
+func baseVersion(v string) string {
+	if i := strings.IndexByte(v, '-'); i >= 0 {
+		return v[:i]
+	}
+	return v
+}
+
+// compareVersions compares two dotted numeric version strings (e.g. "1.24.0"), returning
+// -1 if a < b, 0 if equal, or 1 if a > b. Missing or non-numeric components are treated as
+// 0, so a partial or malformed version degrades gracefully instead of panicking.
+func compareVersions(a, b string) int {
+	as := strings.Split(a, ".")
+	bs := strings.Split(b, ".")
+
+	max := len(as)
+	if len(bs) > max {
+		max = len(bs)
+	}
+
+	for i := 0; i < max; i++ {
+		var an, bn int
+		if i < len(as) {
+			an, _ = strconv.Atoi(as[i])
+		}
+		if i < len(bs) {
+			bn, _ = strconv.Atoi(bs[i])
+		}
+		if an != bn {
+			if an < bn {
+				return -1
+			}
+			return 1
+		}
+	}
+	return 0
+}