From 98264d26e1c54c869cc7fb0d485a60e1de3ee635 Mon Sep 17 00:00:00 2001
From: Muaz Ahmad <mahmad2000@protonmail.com>
Date: Sat, 11 May 2024 17:40:56 +0500
Subject: [PATCH] Add receiving UDP impl

---
 src/mdns.zig | 48 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 17 deletions(-)

diff --git a/src/mdns.zig b/src/mdns.zig
index 4878094..9da7dd4 100644
--- a/src/mdns.zig
+++ b/src/mdns.zig
@@ -6,6 +6,7 @@ const MDNSError = error{
     SocketInitFail,
     UDPConnectFail,
     UDPSendFail,
+    UDPRecvFail,
 };
 
 pub fn get_mdns(domain: util.Domain, ip_info: util.IPInfo) !util.IPs {
@@ -14,19 +15,9 @@ pub fn get_mdns(domain: util.Domain, ip_info: util.IPInfo) !util.IPs {
 }
 
 const socket = c_int;
+const MSG_BUFF_SIZE = 200;
 
 fn get_mdns_socket(ip_info: util.IPInfo) !socket {
-    const target_addr: []const u8 = switch (ip_info.version) {
-        util.IP_VER_ENUM.IPv4 => "224.0.0.251",
-        util.IP_VER_ENUM.IPv6 => blk: {
-            var buf = [_]u8{0x00} ** 100;
-            var byte_buf = std.io.fixedBufferStream(&buf);
-            const writer = byte_buf.writer();
-            try std.fmt.format(writer, "ff02::fb%{s}", .{ip_info.interface.?});
-            break :blk buf[0..writer.context.pos];
-        },
-    };
-    const addr = try std.net.Address.resolveIp(target_addr, 5353);
     const sock = std.c.socket(switch (ip_info.version) {
         util.IP_VER_ENUM.IPv4 => std.c.AF.INET,
         util.IP_VER_ENUM.IPv6 => std.c.AF.INET6,
@@ -34,9 +25,6 @@ fn get_mdns_socket(ip_info: util.IPInfo) !socket {
     if (sock == -1) {
         return MDNSError.SocketInitFail;
     }
-    if (std.c.connect(sock, &addr.any, addr.getOsSockLen()) == -1) {
-        return MDNSError.UDPConnectFail;
-    }
     return sock;
 }
 
@@ -74,17 +62,43 @@ fn construct_mdns_query(domain: util.Domain, ip_info: util.IPInfo, buff: []u8) !
 fn send_query(domain: util.Domain, ip_info: util.IPInfo) !socket {
     const sock = try get_mdns_socket(ip_info);
     errdefer _ = std.c.close(sock);
-    var buff = [_]u8{0x00} ** 100;
+
+    const target_addr: []const u8 = switch (ip_info.version) {
+        util.IP_VER_ENUM.IPv4 => "224.0.0.251",
+        util.IP_VER_ENUM.IPv6 => blk: {
+            var buf = [_]u8{0x00} ** MSG_BUFF_SIZE;
+            var byte_buf = std.io.fixedBufferStream(&buf);
+            const writer = byte_buf.writer();
+            try std.fmt.format(writer, "ff02::fb%{s}", .{ip_info.interface.?});
+            break :blk buf[0..writer.context.pos];
+        },
+    };
+    const addr = try std.net.Address.resolveIp(target_addr, 5353);
+
+    var buff = [_]u8{0x00} ** MSG_BUFF_SIZE;
 
     const n = try construct_mdns_query(domain, ip_info, &buff);
-    if (std.c.send(sock, &buff, n, 0) == -1) {
+    if (std.c.sendto(sock, &buff, n, 0, &addr.any, addr.getOsSockLen()) == -1) {
         return MDNSError.UDPSendFail;
     }
     return sock;
 }
 
 fn receive_query(sock: socket) !util.IPs {
-    _ = sock;
+    defer _ = std.c.close(sock);
+    var buff = [_]u8{0x00} ** MSG_BUFF_SIZE;
+
+    const n: usize = blk: {
+        const ret = std.c.recv(sock, &buff, MSG_BUFF_SIZE, 0);
+        if (ret < 0) {
+            return MDNSError.UDPRecvFail;
+        } else {
+            break :blk @bitCast(ret);
+        }
+    };
+
+    std.debug.print("{any}\n", .{buff[0..n]});
+
     return util.IPs{
         .v4 = "",
         .v6 = "",