[libc-commits] [libc] [libc] Implement IPv6 (AF_INET6) support in inet_pton (PR #226550)

[Pavel Labath via libc-commits]

================
@@ -67,6 +69,109 @@ namespace net {
   return true;
 }
 
+[[nodiscard]] bool str_to_ipv6(cpp::string_view src, struct in6_addr &dst) {
+  if (src.empty())
+    return false;
+
+  bool has_double_colon = false;
+  FixedVector<uint16_t, 8> parts[2];
+  size_t part_idx = 0;
+
+  if (src.starts_with("::")) {
+    has_double_colon = true;
+    part_idx = 1;
+    src.remove_prefix(2);
+    if (src.empty()) {
+      inline_bzero(&dst.s6_addr, 16);
+      return true;
+    }
+    if (src.starts_with(':'))
+      return false;
+  } else if (src.starts_with(':')) {
+    return false;
+  }
+
+  while (!src.empty()) {
+    if (src.starts_with("::")) {
+      if (has_double_colon)
+        return false;
+      has_double_colon = true;
+      part_idx = 1;
+      src.remove_prefix(2);
+      if (src.empty())
+        break;
+      if (src.starts_with(':'))
+        return false;
+    } else if (src.starts_with(':')) {
+      src.remove_prefix(1);
+      if (src.empty() || src.starts_with(':'))
+        return false;
+    }
+
+    // Check if the current component is an embedded IPv4 address.
+    // In IPv6, an embedded IPv4 address can only appear at the very end.
+    size_t colon_pos = src.find_first_of(':');
+    cpp::string_view token =
+        (colon_pos == cpp::string_view::npos) ? src : src.substr(0, colon_pos);
----------------
labath wrote:

```suggestion
    cpp::string_view token = src.substr(0, colon_pos);
```

(`substr(..., npos)` is valid)

https://github.com/llvm/llvm-project/pull/226550