feat(socks): add IsSocksLike helper, info-modal display, and tests

Second-pass on the SOCKS5 inbound scaffold (PR #4452). This commit
ticks off two of the 'help wanted' items from the scaffold's TODO
list and tightens the existing dispatcher so that adding a new
protocol-without-link in the future is a one-line change instead
of an audit through every switch.

Backend (Go)
------------
* database/model/model.go: new IsSocksLike(p) helper that returns
  true for both 'socks' and 'mixed'. Mirrors the existing IsHysteria
  pattern (one helper, two underlying constants) so call sites
  don't have to re-list both protocols every time they need to
  treat 'this inbound speaks SOCKS5' uniformly.

* database/model/model_test.go:
  - TestSocksProtocolConstant pins the wire value 'socks' so a
    future refactor can't silently rename it (which would orphan
    every stored inbound row).
  - TestIsSocksLike covers Socks, Mixed, every other declared
    protocol, the empty Protocol, and a wrong-case input.

* sub/subService.go GetLink:
  - Replace bare string literals ('vmess', 'vless', …) with the
    typed model.* constants so a typo can't silently fall through.
  - Add an explicit link-less case for
    Socks/Mixed/HTTP/Tunnel/WireGuard with a comment explaining
    why we don't emit 'socks://…' URLs (follow-up #1 in the
    scaffold PR description).

Frontend (JS/Vue)
-----------------
* frontend/src/models/dbinbound.js: add 'isSocks' getter (pure
  SOCKS5 inbound) and 'isSocksLike' getter (Socks OR Mixed), matching
  the pattern used by isMixed/isHTTP/isWireguard above.

* frontend/src/pages/inbounds/InboundInfoModal.vue: the existing
  'Mixed' info block (auth/UDP/IP/accounts) now also renders for
  the new SOCKS protocol via isSocksLike, since Xray's mixed and
  socks inbounds accept the exact same settings keys. Without
  this, opening the info modal for a SOCKS inbound would show an
  empty body. Header comment updated to list SOCKS alongside
  Mixed/HTTP/Tunnel.

Still outstanding from the scaffold's TODO list:
  - Xray runtime AddUser hooks (web/service/inbound.go)
  - Translations for the 'socks' label across all 13 locales
  - Routing UI protocol == socks helper

database/model/model.go

@@ -37,6 +37,18 @@ func IsHysteria(p Protocol) bool {
 	return p == Hysteria || p == Hysteria2
 }
 
+// IsSocksLike returns true for both the dedicated "socks" inbound and
+// the combined "mixed" inbound, since Mixed exposes SOCKS5 alongside
+// HTTP on the same port and accepts the exact same settings shape
+// (auth/accounts/udp/ip) that the pure Socks inbound does.
+//
+// Use this helper anywhere routing, sub-link generation, or UI code
+// needs to treat "this inbound speaks SOCKS5" uniformly without
+// re-listing both constants at every call site.
+func IsSocksLike(p Protocol) bool {
+	return p == Socks || p == Mixed
+}
+
 // User represents a user account in the 3x-ui panel.
 type User struct {
 	Id         int    `json:"id" gorm:"primaryKey;autoIncrement"`

database/model/model_test.go

@@ -20,3 +20,42 @@ func TestIsHysteria(t *testing.T) {
 		}
 	}
 }
+
+// TestSocksProtocolConstant pins the wire value of the SOCKS5 protocol
+// constant. It must stay "socks" because that's the literal Xray expects
+// in inbound.protocol JSON (see https://xtls.github.io/config/inbounds/socks.html);
+// changing it would silently break every stored inbound row.
+func TestSocksProtocolConstant(t *testing.T) {
+	if got, want := string(Socks), "socks"; got != want {
+		t.Errorf("Socks protocol constant = %q, want %q", got, want)
+	}
+	if Socks == Mixed {
+		t.Error("Socks and Mixed must be distinct protocols")
+	}
+}
+
+func TestIsSocksLike(t *testing.T) {
+	cases := []struct {
+		in   Protocol
+		want bool
+	}{
+		{Socks, true},
+		{Mixed, true},
+		{HTTP, false},
+		{VLESS, false},
+		{VMESS, false},
+		{Trojan, false},
+		{Shadowsocks, false},
+		{WireGuard, false},
+		{Hysteria, false},
+		{Hysteria2, false},
+		{Tunnel, false},
+		{Protocol(""), false},
+		{Protocol("SOCKS"), false}, // case-sensitive: must match the stored lowercase value
+	}
+	for _, c := range cases {
+		if got := IsSocksLike(c.in); got != c.want {
+			t.Errorf("IsSocksLike(%q) = %v, want %v", c.in, got, c.want)
+		}
+	}
+}

frontend/src/models/dbinbound.js

@@ -62,6 +62,20 @@ export class DBInbound {
         return this.protocol === Protocols.MIXED;
     }
 
+    // Pure SOCKS5 inbound (Xray "socks" protocol, RFC 1928). Distinct
+    // from `isMixed`, which is HTTP+SOCKS on the same port. Use
+    // `isSocksLike` when you want either one.
+    get isSocks() {
+        return this.protocol === Protocols.SOCKS;
+    }
+
+    // True for both the dedicated SOCKS5 inbound and the combined
+    // Mixed inbound, since both speak SOCKS5 and share the same
+    // settings shape (auth/accounts/udp/ip).
+    get isSocksLike() {
+        return this.protocol === Protocols.SOCKS || this.protocol === Protocols.MIXED;
+    }
+
     get isHTTP() {
         return this.protocol === Protocols.HTTP;
     }

frontend/src/pages/inbounds/InboundInfoModal.vue

@@ -26,7 +26,7 @@ const { datepicker } = useDatepicker();
 //     client row + share links
 //   • SS single-user → connection details + share link
 //   • WireGuard → secret/peers + per-peer config download
-//   • Mixed/HTTP/Tunnel → connection details only
+//   • Mixed/SOCKS/HTTP/Tunnel → connection details only
 //
 // We display links via QrPanel — each link gets its own QR + copy +
 // (for WireGuard configs) download button.
@@ -640,8 +640,9 @@ const showSubscriptionTab = computed(
             </div>
           </dl>
 
-          <!-- Mixed -->
+          <!-- Mixed / SOCKS: share the same auth/udp/ip + accounts shape
-          <dl v-if="dbInbound.isMixed" class="info-list info-list-block">
+               (Xray's mixed and socks inbounds accept the same keys). -->
+          <dl v-if="dbInbound.isSocksLike" class="info-list info-list-block">
             <div class="info-row">
               <dt>Auth</dt>
               <dd>

sub/subService.go

@@ -209,18 +209,27 @@ func (s *SubService) getFallbackMaster(dest string, streamSettings string) (stri
 // pair. Returns "" when the inbound's protocol doesn't produce a subscription URL
 // (socks, http, mixed, wireguard, dokodemo, tunnel). The returned string may
 // contain multiple `\n`-separated URLs when the inbound has externalProxy set.
+//
+// SOCKS5 and Mixed are deliberately link-less here. A `socks://user:pass@host:port`
+// form exists in some client ecosystems but is not standardised across the
+// xray/v2ray clients we target, and emitting one would mislead users into
+// pasting it into clients that silently ignore it. Tracked as follow-up #1
+// in the SOCKS5 scaffold PR description.
 func (s *SubService) GetLink(inbound *model.Inbound, email string) string {
 	switch inbound.Protocol {
-	case "vmess":
+	case model.VMESS:
 		return s.genVmessLink(inbound, email)
-	case "vless":
+	case model.VLESS:
 		return s.genVlessLink(inbound, email)
-	case "trojan":
+	case model.Trojan:
 		return s.genTrojanLink(inbound, email)
-	case "shadowsocks":
+	case model.Shadowsocks:
 		return s.genShadowsocksLink(inbound, email)
-	case "hysteria", "hysteria2":
+	case model.Hysteria, model.Hysteria2:
 		return s.genHysteriaLink(inbound, email)
+	case model.Socks, model.Mixed, model.HTTP, model.Tunnel, model.WireGuard:
+		// Tunnel-style or proxy-listener protocols: no per-client URL.
+		return ""
 	}
 	return ""
 }