From 0730e77eb4aa9841e90a17f190b9ae7d80565054 Mon Sep 17 00:00:00 2001
From: Toni Uhlig <matzeton@googlemail.com>
Date: Mon, 16 Jun 2025 17:09:43 +0200
Subject: Initial commit

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>
---
 user_server.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 user_server.c

(limited to 'user_server.c')

diff --git a/user_server.c b/user_server.c
new file mode 100644
index 0000000..de2054f
--- /dev/null
+++ b/user_server.c
@@ -0,0 +1,52 @@
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h"
+
+static const unsigned char payload_response[] = {PAYLOAD_RESPONSE};
+
+int main() {
+  unsigned char buffer[BUFSIZ];
+  int listenfd;
+  socklen_t len;
+  struct sockaddr_in servaddr = {};
+  struct sockaddr_in cliaddr;
+
+  listenfd = socket(AF_INET, SOCK_DGRAM, 0);
+  servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+  servaddr.sin_port = htons(UDP_PORT);
+  servaddr.sin_family = AF_INET;
+
+  if (bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0) {
+    perror("udp bind");
+    return 1;
+  }
+
+  size_t i;
+  ssize_t n;
+  for (i = 0; i < MAX_UDP_PACKETS; ++i) {
+    len = sizeof(cliaddr);
+    n = recvfrom(listenfd, buffer, sizeof(buffer), 0,
+                 (struct sockaddr *)&cliaddr, &len);
+    if (n < 0) {
+      perror("udp recvfrom");
+      break;
+    }
+
+    n = sendto(listenfd, payload_response, sizeof(payload_response), 0,
+               (struct sockaddr *)&cliaddr, sizeof(cliaddr));
+    if (n < 0) {
+      perror("udp sendto");
+      break;
+    }
+  }
+
+  close(listenfd);
+
+  return !(i == MAX_UDP_PACKETS);
+}
-- 
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