initial commit

2026-07-15 14:28:58 +08:00
commit 6e0d7ec33f
47 changed files with 4022 additions and 0 deletions
@@ -0,0 +1,43 @@
+package client
+
+import (
+	"encoding/binary"
+	"net"
+)
+
+// proxyV2Signature is the fixed 12-byte HAProxy v2 signature.
+var proxyV2Signature = []byte{
+	0x0D, 0x0A, 0x0D, 0x0A, 0x00, 0x0D, 0x0A, 0x51, 0x55, 0x49, 0x54, 0x0A,
+}
+
+// BuildProxyV2 builds a HAProxy protocol v2 PROXY header conveying the real
+// source (player) and destination addresses (PROTOCOL.md §8).
+func BuildProxyV2(srcIP net.IP, srcPort int, dstIP net.IP, dstPort int) []byte {
+	s4, d4 := srcIP.To4(), dstIP.To4()
+	out := make([]byte, 0, 16+36)
+	out = append(out, proxyV2Signature...)
+	out = append(out, 0x21) // version 2, PROXY command
+
+	var addr []byte
+	if s4 != nil && d4 != nil {
+		out = append(out, 0x11) // TCP over IPv4
+		addr = make([]byte, 0, 12)
+		addr = append(addr, s4...)
+		addr = append(addr, d4...)
+	} else {
+		out = append(out, 0x21) // TCP over IPv6
+		addr = make([]byte, 0, 36)
+		addr = append(addr, srcIP.To16()...)
+		addr = append(addr, dstIP.To16()...)
+	}
+	var ports [4]byte
+	binary.BigEndian.PutUint16(ports[0:], uint16(srcPort))
+	binary.BigEndian.PutUint16(ports[2:], uint16(dstPort))
+	addr = append(addr, ports[:]...)
+
+	var lenField [2]byte
+	binary.BigEndian.PutUint16(lenField[:], uint16(len(addr)))
+	out = append(out, lenField[:]...)
+	out = append(out, addr...)
+	return out
+}