From d6e7f8ee836c92e64b4ac08b37cf5e997c0825fd Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Thu, 4 Dec 2025 12:18:45 -0300
Subject: [PATCH] fix mg_aton not setting is_ip6 with scope_ids

---
 mongoose.c       | 11 ++++++++---
 src/net.c        | 11 ++++++++---
 test/unit_test.c |  8 ++++----
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/mongoose.c b/mongoose.c
index c577088f..1ef80b22 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -4162,7 +4162,7 @@ static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
   size_t i, j = 0, n = 0, dc = 42;
   addr->scope_id = 0;
   if (str.len > 2 && str.buf[0] == '[') str.buf++, str.len -= 2;
-  if (mg_v4mapped(str, addr)) return true;
+  if (mg_v4mapped(str, addr)) return true;  // sets addr->is_ip6
   for (i = 0; i < str.len; i++) {
     if ((str.buf[i] >= '0' && str.buf[i] <= '9') ||
         (str.buf[i] >= 'a' && str.buf[i] <= 'f') ||
@@ -4184,8 +4184,13 @@ static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
       if (n > 14) return false;
       addr->ip[n] = addr->ip[n + 1] = 0;  // For trailing ::
     } else if (str.buf[i] == '%') {       // Scope ID, last in string
-      return mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
-                           &addr->scope_id, sizeof(uint8_t));
+      if (mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
+                        &addr->scope_id, sizeof(uint8_t))) {
+        addr->is_ip6 = true;
+        return true;
+      } else {
+        return false;
+      }
     } else {
       return false;
     }
diff --git a/src/net.c b/src/net.c
index 4d6bfeeb..50231335 100644
--- a/src/net.c
+++ b/src/net.c
@@ -86,7 +86,7 @@ static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
   size_t i, j = 0, n = 0, dc = 42;
   addr->scope_id = 0;
   if (str.len > 2 && str.buf[0] == '[') str.buf++, str.len -= 2;
-  if (mg_v4mapped(str, addr)) return true;
+  if (mg_v4mapped(str, addr)) return true;  // sets addr->is_ip6
   for (i = 0; i < str.len; i++) {
     if ((str.buf[i] >= '0' && str.buf[i] <= '9') ||
         (str.buf[i] >= 'a' && str.buf[i] <= 'f') ||
@@ -108,8 +108,13 @@ static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
       if (n > 14) return false;
       addr->ip[n] = addr->ip[n + 1] = 0;  // For trailing ::
     } else if (str.buf[i] == '%') {       // Scope ID, last in string
-      return mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
-                           &addr->scope_id, sizeof(uint8_t));
+      if (mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
+                        &addr->scope_id, sizeof(uint8_t))) {
+        addr->is_ip6 = true;
+        return true;
+      } else {
+        return false;
+      }
     } else {
       return false;
     }
diff --git a/test/unit_test.c b/test/unit_test.c
index 52632595..bc5267ad 100644
--- a/test/unit_test.c
+++ b/test/unit_test.c
@@ -2717,22 +2717,22 @@ static void test_util(void) {
   ASSERT(mg_url_decode("a=%123", 6, buf, sizeof(buf), 0) == 4 &&
          buf[2] == 0x12 && buf[3] == '3');
 
-  memset(a.ip, 0xaa, sizeof(a.ip));
+  memset(&a, 0, sizeof(a));
   ASSERT(mg_aton(mg_str("::1%1"), &a) == true);
   ASSERT(a.is_ip6 == true);
   ASSERT(a.scope_id == 1);
 
-  memset(a.ip, 0xaa, sizeof(a.ip));
+  memset(&a, 0, sizeof(a));
   ASSERT(mg_aton(mg_str("abcd::aabb:ccdd%17"), &a) == true);
   ASSERT(a.is_ip6 == true);
   ASSERT(a.scope_id == 17);
 
-  memset(a.ip, 0xaa, sizeof(a.ip));
+  memset(&a, 0xaa, sizeof(a)), a.is_ip6 = false;
   ASSERT(mg_aton(mg_str("::1%17"), &a) == true);
   ASSERT(a.is_ip6 == true);
   ASSERT(a.scope_id == 17);
 
-  memset(a.ip, 0xaa, sizeof(a.ip));
+  memset(&a, 0xaa, sizeof(a)), a.is_ip6 = false;
   ASSERT(mg_aton(mg_str("::1%255"), &a) == true);
   ASSERT(a.is_ip6 == true);
   ASSERT(a.scope_id == 255);