From 8bfd1088d5ae78ab071df0273317a7c0944fab89 Mon Sep 17 00:00:00 2001
From: Jonatan Chaverri <jonatan.chaverri@kyndryl.com>
Date: Tue, 24 Sep 2024 12:19:07 -0400
Subject: [PATCH] add support for ipv4 peers

---
 src/network/message/utils.zig | 18 ++++++++++++++++++
 src/network/peer.zig          |  7 +++++--
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 src/network/message/utils.zig

diff --git a/src/network/message/utils.zig b/src/network/message/utils.zig
new file mode 100644
index 0000000..2314ca0
--- /dev/null
+++ b/src/network/message/utils.zig
@@ -0,0 +1,18 @@
+const std = @import("std");
+
+pub fn convertIPv4ToIPv6(address: std.net.Address) std.net.Address {
+    // Convert IPv4 to IPv6-mapped IPv4 address
+    const ipv4_address = address.in;
+
+    var ipv6_mapped: [16]u8 = [_]u8{0} ** 16;
+
+    // Set bytes 10 and 11 to 0xff
+    ipv6_mapped[10] = 0xff;
+    ipv6_mapped[11] = 0xff;
+
+    // Copy the IPv4 address into the last 4 bytes of the IPv6-mapped address
+    const ipv4_bytes = std.mem.asBytes(&ipv4_address.sa.addr);
+    @memcpy(ipv6_mapped[12..16], ipv4_bytes[0..4]);
+
+    return std.net.Address.initIp6(ipv6_mapped, ipv4_address.getPort(), 0, 0);
+}
diff --git a/src/network/peer.zig b/src/network/peer.zig
index e281efa..4a2b8a8 100644
--- a/src/network/peer.zig
+++ b/src/network/peer.zig
@@ -3,6 +3,7 @@ const net = std.net;
 const protocol = @import("./protocol/lib.zig");
 const wire = @import("./wire/lib.zig");
 const Config = @import("../config/config.zig").Config;
+const MessageUtils = @import("./message/utils.zig");
 
 pub const Boundness = enum {
     inbound,
@@ -89,11 +90,13 @@ pub const Peer = struct {
     }
 
     /// Send version message to peer
-    fn sendVersionMessage(self: *Peer) !void {
+    fn sendVersionMessage(self: *const Peer) !void {
+        const address = if (self.address.any.family == std.posix.AF.INET) MessageUtils.convertIPv4ToIPv6(self.address) else self.address;
+
         const message = protocol.messages.VersionMessage.new(
             self.config.protocol_version,
             .{ .ip = std.mem.zeroes([16]u8), .port = 0, .services = self.config.services },
-            .{ .ip = self.address.in6.sa.addr, .port = self.address.in6.getPort(), .services = 0 },
+            .{ .ip = address.in6.sa.addr, .port = address.in6.getPort(), .services = 0 },
             std.crypto.random.int(u64),
             self.config.bestBlock(),
         );