diff --git a/src/acl.c b/src/acl.c
index 740fbc56..aa1da28c 100644
--- a/src/acl.c
+++ b/src/acl.c
@@ -33,6 +33,7 @@
 #endif
 
 #include "rule.h"
+#include "netutils.h"
 #include "utils.h"
 #include "cache.h"
 #include "acl.h"
@@ -193,7 +194,8 @@ init_acl(const char *path)
         return -1;
     }
 
-    char buf[257];
+    char buf[MAX_HOSTNAME_LEN];
+
     while (!feof(f))
         if (fgets(buf, 256, f)) {
             // Discards the whole line if longer than 255 characters
@@ -256,7 +258,7 @@ init_acl(const char *path)
                 continue;
             }
 
-            char host[257];
+            char host[MAX_HOSTNAME_LEN];
             int cidr;
             parse_addr_cidr(line, host, &cidr);
 
diff --git a/src/netutils.h b/src/netutils.h
index 25c5dd92..075f1dd1 100644
--- a/src/netutils.h
+++ b/src/netutils.h
@@ -52,6 +52,9 @@
 #endif
 #endif
 
+#define MAX_HOSTNAME_LEN 256 // FQCN <= 255 characters
+#define MAX_PORT_STR_LEN 6   // PORT < 65536
+
 typedef struct {
     char *host;
     char *port;
diff --git a/src/server.c b/src/server.c
index e336b698..36ca409a 100644
--- a/src/server.c
+++ b/src/server.c
@@ -966,7 +966,7 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
             memset(query, 0, sizeof(query_t));
             query->server = server;
             server->query = query;
-            snprintf(query->hostname, 257, "%s", host);
+            snprintf(query->hostname, MAX_HOSTNAME_LEN, "%s", host);
 
             server->stage = STAGE_RESOLVE;
             resolv_start(host, port, resolv_cb, resolv_free_cb, query);
diff --git a/src/server.h b/src/server.h
index 714878b1..9f5f6814 100644
--- a/src/server.h
+++ b/src/server.h
@@ -39,6 +39,7 @@
 #include "crypto.h"
 #include "jconf.h"
 #include "resolv.h"
+#include "netutils.h"
 
 #include "common.h"
 
@@ -97,7 +98,7 @@ typedef struct server {
 
 typedef struct query {
     server_t *server;
-    char hostname[257];
+    char hostname[MAX_HOSTNAME_LEN];
 } query_t;
 
 typedef struct remote_ctx {
diff --git a/src/udprelay.c b/src/udprelay.c
index a3273ae8..df49d9ef 100644
--- a/src/udprelay.c
+++ b/src/udprelay.c
@@ -200,14 +200,17 @@ hash_key(const int af, const struct sockaddr_storage *addr)
 }
 
 #if defined(MODULE_REDIR) || defined(MODULE_REMOTE)
+
 static int
 construct_udprelay_header(const struct sockaddr_storage *in_addr,
                           char *addr_header)
 {
     int addr_header_len = 0;
+
     if (in_addr->ss_family == AF_INET) {
         struct sockaddr_in *addr = (struct sockaddr_in *)in_addr;
         size_t addr_len          = sizeof(struct in_addr);
+
         addr_header[addr_header_len++] = 1;
         memcpy(addr_header + addr_header_len, &addr->sin_addr, addr_len);
         addr_header_len += addr_len;
@@ -216,6 +219,7 @@ construct_udprelay_header(const struct sockaddr_storage *in_addr,
     } else if (in_addr->ss_family == AF_INET6) {
         struct sockaddr_in6 *addr = (struct sockaddr_in6 *)in_addr;
         size_t addr_len           = sizeof(struct in6_addr);
+
         addr_header[addr_header_len++] = 4;
         memcpy(addr_header + addr_header_len, &addr->sin6_addr, addr_len);
         addr_header_len += addr_len;
@@ -224,6 +228,7 @@ construct_udprelay_header(const struct sockaddr_storage *in_addr,
     } else {
         return 0;
     }
+
     return addr_header_len;
 }
 
@@ -258,7 +263,7 @@ parse_udprelay_header(const char *buf, const size_t buf_len,
         uint8_t name_len = *(uint8_t *)(buf + offset);
         if (name_len + 4 <= buf_len) {
             if (storage != NULL) {
-                char tmp[257] = { 0 };
+                char tmp[MAX_HOSTNAME_LEN] = { 0 };
                 struct cork_ip ip;
                 memcpy(tmp, buf + offset + 1, name_len);
                 if (cork_ip_init(&ip, tmp) != -1) {
@@ -655,9 +660,6 @@ resolv_cb(struct sockaddr *addr, void *data)
                 remote_ctx                  = new_remote(remotefd, query_ctx->server_ctx);
                 remote_ctx->src_addr        = query_ctx->src_addr;
                 remote_ctx->server_ctx      = query_ctx->server_ctx;
-                remote_ctx->addr_header_len = query_ctx->addr_header_len;
-                memcpy(remote_ctx->addr_header, query_ctx->addr_header,
-                       query_ctx->addr_header_len);
             } else {
                 ERROR("[udp] bind() error");
             }
@@ -785,7 +787,7 @@ remote_recv_cb(EV_P_ ev_io *w, int revents)
     rx += buf->len;
 
     // Reconstruct UDP response header
-    char addr_header[512];
+    char addr_header[MAX_ADDR_HEADER_SIZE];
     int addr_header_len = construct_udprelay_header(&src_addr, addr_header);
 
     // Construct packet
@@ -1002,7 +1004,7 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
      */
 
 #ifdef MODULE_REDIR
-    char addr_header[512] = { 0 };
+    char addr_header[MAX_ADDR_HEADER_SIZE] = { 0 };
     int addr_header_len   = construct_udprelay_header(&dst_addr, addr_header);
 
     if (addr_header_len == 0) {
@@ -1018,7 +1020,7 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
 
 #elif MODULE_TUNNEL
 
-    char addr_header[512] = { 0 };
+    char addr_header[MAX_ADDR_HEADER_SIZE] = { 0 };
     char *host            = server_ctx->tunnel_addr.host;
     char *port            = server_ctx->tunnel_addr.port;
     uint16_t port_num     = (uint16_t)atoi(port);
@@ -1074,8 +1076,8 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
 
 #else
 
-    char host[257] = { 0 };
-    char port[64]  = { 0 };
+    char host[MAX_HOSTNAME_LEN] = { 0 };
+    char port[MAX_PORT_STR_LEN]  = { 0 };
     struct sockaddr_storage dst_addr;
     memset(&dst_addr, 0, sizeof(struct sockaddr_storage));
 
@@ -1086,7 +1088,6 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
         goto CLEAN_UP;
     }
 
-    char *addr_header = buf->data + offset;
 #endif
 
 #ifdef MODULE_LOCAL
@@ -1198,9 +1199,6 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
         ev_timer_start(EV_A_ & remote_ctx->watcher);
     }
 
-    remote_ctx->addr_header_len = addr_header_len;
-    memcpy(remote_ctx->addr_header, addr_header, addr_header_len);
-
     if (offset > 0) {
         buf->len -= offset;
         memmove(buf->data, buf->data + offset, buf->len);
@@ -1230,6 +1228,8 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
     int cache_hit  = 0;
     int need_query = 0;
 
+    char *addr_header = buf->data + offset;
+
     if (buf->len - addr_header_len > packet_size) {
         if (verbose) {
             LOGI("[udp] server_recv_sendto fragmentation, MTU at least be: " SSIZE_FMT,
@@ -1267,8 +1267,6 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
                 remote_ctx                  = new_remote(remotefd, server_ctx);
                 remote_ctx->src_addr        = src_addr;
                 remote_ctx->server_ctx      = server_ctx;
-                remote_ctx->addr_header_len = addr_header_len;
-                memcpy(remote_ctx->addr_header, addr_header, addr_header_len);
                 memcpy(&remote_ctx->dst_addr, &dst_addr, sizeof(struct sockaddr_storage));
             } else {
                 ERROR("[udp] bind() error");
diff --git a/src/udprelay.h b/src/udprelay.h
index 46e27368..72424918 100644
--- a/src/udprelay.h
+++ b/src/udprelay.h
@@ -46,6 +46,7 @@
 
 #define PACKET_HEADER_SIZE (1 + 28 + 2 + 64)
 #define DEFAULT_PACKET_SIZE 1397 // 1492 - PACKET_HEADER_SIZE = 1397, the default MTU for UDP relay
+#define MAX_ADDR_HEADER_SIZE (1 + 256 + 2) // 1-byte atyp + 256-byte hostname + 2-byte port
 
 typedef struct server_ctx {
     ev_io io;
@@ -71,7 +72,7 @@ typedef struct query_ctx {
     struct sockaddr_storage src_addr;
     buffer_t *buf;
     int addr_header_len;
-    char addr_header[384];
+    char addr_header[MAX_ADDR_HEADER_SIZE];
     struct server_ctx *server_ctx;
     struct remote_ctx *remote_ctx;
 } query_ctx_t;
@@ -82,8 +83,6 @@ typedef struct remote_ctx {
     ev_timer watcher;
     int af;
     int fd;
-    int addr_header_len;
-    char addr_header[384];
     struct sockaddr_storage src_addr;
 #ifdef MODULE_REMOTE
     struct sockaddr_storage dst_addr;