feat: add Snell v3–v6 protocol support

app/src/main/AndroidManifest.xml

@@ -198,6 +198,8 @@
             android:name="io.nekohasekai.sagernet.ui.profile.ShadowQUICSettingsActivity" />
         <activity
             android:name="io.nekohasekai.sagernet.ui.profile.TrustTunnelSettingsActivity" />
+        <activity
+            android:name="io.nekohasekai.sagernet.ui.profile.SnellSettingsActivity" />
         <activity
             android:name="io.nekohasekai.sagernet.ui.profile.ConfigSettingsActivity" />
         <activity

app/src/main/java/io/nekohasekai/sagernet/database/Migrations.kt

@@ -169,4 +169,25 @@ class SagerDatabase_Migration_33_34 : AutoMigrationSpec
         columnName = "redirect"
     ),
 )
-class SagerDatabase_Migration_35_36 : AutoMigrationSpec
+class SagerDatabase_Migration_35_36 : AutoMigrationSpec
+/**
+ * Reintroduce Snell support. The snellBean column may already exist from
+ * SagerNet-era migration 3_4 and was never dropped.
+ */
+object SagerDatabase_Migration_36_37 : Migration(36, 37) {
+    override fun migrate(database: SupportSQLiteDatabase) {
+        val cursor = database.query("PRAGMA table_info(`proxy_entities`)")
+        var hasSnell = false
+        while (cursor.moveToNext()) {
+            val name = cursor.getString(cursor.getColumnIndex("name"))
+            if (name == "snellBean") {
+                hasSnell = true
+                break
+            }
+        }
+        cursor.close()
+        if (!hasSnell) {
+            database.execSQL("""ALTER TABLE `proxy_entities` ADD `snellBean` BLOB DEFAULT NULL""")
+        }
+    }
+}

app/src/main/java/io/nekohasekai/sagernet/database/ProxyEntity.kt

@@ -61,6 +61,9 @@ import io.nekohasekai.sagernet.fmt.ssh.SSHBean
 import io.nekohasekai.sagernet.fmt.trojan.TrojanBean
 import io.nekohasekai.sagernet.fmt.trojan.toUri
 import io.nekohasekai.sagernet.fmt.trusttunnel.TrustTunnelBean
+import io.nekohasekai.sagernet.fmt.snell.SnellBean
+import io.nekohasekai.sagernet.fmt.snell.toUri
+import io.nekohasekai.sagernet.ui.profile.SnellSettingsActivity
 import io.nekohasekai.sagernet.fmt.trusttunnel.toUri
 import io.nekohasekai.sagernet.fmt.tuic5.Tuic5Bean
 import io.nekohasekai.sagernet.fmt.tuic5.toUri
@@ -104,6 +107,7 @@ data class ProxyEntity(
     var anytlsBean: AnyTLSBean? = null,
     var shadowquicBean: ShadowQUICBean? = null,
     var trustTunnelBean: TrustTunnelBean? = null,
+    var snellBean: SnellBean? = null,
     var configBean: ConfigBean? = null,
     var chainBean: ChainBean? = null,
     var balancerBean: BalancerBean? = null
@@ -128,6 +132,7 @@ data class ProxyEntity(
         const val TYPE_ANYTLS = 27
         const val TYPE_SHADOWQUIC = 28
         const val TYPE_TRUSTTUNNEL = 29
+        const val TYPE_SNELL = 30
         const val TYPE_CHAIN = 8
         const val TYPE_BALANCER = 14
         const val TYPE_CONFIG = 13
@@ -220,6 +225,7 @@ data class ProxyEntity(
             TYPE_ANYTLS -> anytlsBean = KryoConverters.anytlsDeserialize(byteArray)
             TYPE_SHADOWQUIC -> shadowquicBean = KryoConverters.shadowquicDeserialize(byteArray)
             TYPE_TRUSTTUNNEL -> trustTunnelBean = KryoConverters.trusttunnelDeserialize(byteArray)
+            TYPE_SNELL -> snellBean = KryoConverters.snellDeserialize(byteArray)
 
             TYPE_CONFIG -> configBean = KryoConverters.configDeserialize(byteArray)
             TYPE_CHAIN -> chainBean = KryoConverters.chainDeserialize(byteArray)
@@ -246,6 +252,7 @@ data class ProxyEntity(
         TYPE_ANYTLS -> "AnyTLS"
         TYPE_SHADOWQUIC -> "ShadowQUIC"
         TYPE_TRUSTTUNNEL -> "TrustTunnel"
+        TYPE_SNELL -> "Snell"
 
         TYPE_CHAIN -> chainName
         TYPE_CONFIG -> configName
@@ -276,6 +283,7 @@ data class ProxyEntity(
             TYPE_ANYTLS -> anytlsBean
             TYPE_SHADOWQUIC -> shadowquicBean
             TYPE_TRUSTTUNNEL -> trustTunnelBean
+            TYPE_SNELL -> snellBean
 
             TYPE_CONFIG -> configBean
             TYPE_CHAIN -> chainBean
@@ -317,6 +325,7 @@ data class ProxyEntity(
             is Http3Bean -> toUri()
             is AnyTLSBean -> toUri()
             is TrustTunnelBean -> toUri()
+            is SnellBean -> toUri()
             is ShadowQUICBean -> toUri()
             else -> null
         }
@@ -382,6 +391,7 @@ data class ProxyEntity(
         anytlsBean = null
         shadowquicBean = null
         trustTunnelBean = null
+        snellBean = null
 
         configBean = null
         chainBean = null
@@ -460,6 +470,10 @@ data class ProxyEntity(
                 type = TYPE_TRUSTTUNNEL
                 trustTunnelBean = bean
             }
+            is SnellBean -> {
+                type = TYPE_SNELL
+                snellBean = bean
+            }
 
             is ConfigBean -> {
                 type = TYPE_CONFIG
@@ -498,6 +512,7 @@ data class ProxyEntity(
             TYPE_ANYTLS -> AnyTLSSettingsActivity::class.java
             TYPE_SHADOWQUIC -> ShadowQUICSettingsActivity::class.java
             TYPE_TRUSTTUNNEL -> TrustTunnelSettingsActivity::class.java
+            TYPE_SNELL -> SnellSettingsActivity::class.java
 
             TYPE_CONFIG -> ConfigSettingsActivity::class.java
             TYPE_CHAIN -> ChainSettingsActivity::class.java

app/src/main/java/io/nekohasekai/sagernet/database/SagerDatabase.kt

@@ -29,7 +29,7 @@ import kotlinx.coroutines.launch
 
 @Database(
     entities = [ProxyGroup::class, ProxyEntity::class, RuleEntity::class, StatsEntity::class, AssetEntity::class],
-    version = 36,
+    version = 37,
     autoMigrations = [AutoMigration(
         from = 12,
         to = 14,
@@ -126,7 +126,8 @@ abstract class SagerDatabase : RoomDatabase() {
                     SagerDatabase_Migration_8_9,
                     SagerDatabase_Migration_9_10,
                     SagerDatabase_Migration_10_11,
-                    SagerDatabase_Migration_11_12
+                    SagerDatabase_Migration_11_12,
+                    SagerDatabase_Migration_36_37
                 )
                 .fallbackToDestructiveMigrationOnDowngrade()
                 .allowMainThreadQueries()

app/src/main/java/io/nekohasekai/sagernet/fmt/ConfigBuilder.kt

@@ -54,6 +54,7 @@ import io.nekohasekai.sagernet.fmt.socks.SOCKSBean
 import io.nekohasekai.sagernet.fmt.ssh.SSHBean
 import io.nekohasekai.sagernet.fmt.trojan.TrojanBean
 import io.nekohasekai.sagernet.fmt.trusttunnel.TrustTunnelBean
+import io.nekohasekai.sagernet.fmt.snell.SnellBean
 import io.nekohasekai.sagernet.fmt.tuic5.Tuic5Bean
 import io.nekohasekai.sagernet.fmt.v2ray.StandardV2RayBean
 import io.nekohasekai.sagernet.fmt.v2ray.V2RayConfig
@@ -1740,6 +1741,19 @@ fun buildV2RayConfig(
                                         }
                                     }
                                 }
+                            } else if (bean is SnellBean) {
+                                protocol = "snell"
+                                settings = LazyOutboundConfigurationObject(this, V2RayConfig.SnellOutboundConfigurationObject().apply {
+                                    address = bean.serverAddress
+                                    port = bean.serverPort
+                                    psk = bean.psk
+                                    userPSK = bean.userPSK
+                                    obfsMode = bean.obfsMode
+                                    obfsHost = bean.obfsHost
+                                    version = bean.version
+                                    reuse = bean.reuse
+                                    mode = bean.mode
+                                })
                             } else if (bean is MieruBean) {
                                 protocol = "mieru"
                                 settings = LazyOutboundConfigurationObject(this,

app/src/main/java/io/nekohasekai/sagernet/fmt/KryoConverters.java

@@ -46,6 +46,7 @@
 import io.nekohasekai.sagernet.fmt.ssh.SSHBean;
 import io.nekohasekai.sagernet.fmt.trojan.TrojanBean;
 import io.nekohasekai.sagernet.fmt.trusttunnel.TrustTunnelBean;
+import io.nekohasekai.sagernet.fmt.snell.SnellBean;
 import io.nekohasekai.sagernet.fmt.tuic5.Tuic5Bean;
 import io.nekohasekai.sagernet.fmt.v2ray.VLESSBean;
 import io.nekohasekai.sagernet.fmt.v2ray.VMessBean;
@@ -189,6 +190,12 @@ public static TrustTunnelBean trusttunnelDeserialize(byte[] bytes) {
         return deserialize(new TrustTunnelBean(), bytes);
     }
 
+    @TypeConverter
+    public static SnellBean snellDeserialize(byte[] bytes) {
+        if (bytes == null || bytes.length == 0) return null;
+        return deserialize(new SnellBean(), bytes);
+    }
+
     @TypeConverter
     public static ConfigBean configDeserialize(byte[] bytes) {
         if (bytes == null || bytes.length == 0) return null;

app/src/main/java/io/nekohasekai/sagernet/fmt/TypeMap.kt

@@ -42,6 +42,7 @@ object TypeMap : HashMap<String, Int>() {
         this["anytls"] = ProxyEntity.TYPE_ANYTLS
         this["shadowquic"] = ProxyEntity.TYPE_SHADOWQUIC
         this["trusttunnel"] = ProxyEntity.TYPE_TRUSTTUNNEL
+        this["snell"] = ProxyEntity.TYPE_SNELL
     }
 
     val reversed = HashMap<Int, String>()

app/src/main/java/io/nekohasekai/sagernet/fmt/snell/SnellBean.java

@@ -0,0 +1,124 @@
+/******************************************************************************
+ *                                                                            *
+ * Copyright (C) 2026  Snell support for Exclave                              *
+ *                                                                            *
+ * This program is free software: you can redistribute it and/or modify       *
+ * it under the terms of the GNU General Public License as published by       *
+ * the Free Software Foundation, either version 3 of the License, or          *
+ *  (at your option) any later version.                                       *
+ *                                                                            *
+ ******************************************************************************/
+
+package io.nekohasekai.sagernet.fmt.snell;
+
+import androidx.annotation.NonNull;
+
+import com.esotericsoftware.kryo.io.ByteBufferInput;
+import com.esotericsoftware.kryo.io.ByteBufferOutput;
+
+import org.jetbrains.annotations.NotNull;
+
+import io.nekohasekai.sagernet.fmt.AbstractBean;
+import io.nekohasekai.sagernet.fmt.KryoConverters;
+
+public class SnellBean extends AbstractBean {
+
+    public static final int VERSION_4 = 4;
+    public static final int VERSION_6 = 6;
+
+    public static final String OBFS_NONE = "none";
+    public static final String OBFS_HTTP = "http";
+    public static final String OBFS_TLS = "tls";
+
+    public static final String MODE_DEFAULT = "default";
+    public static final String MODE_UNSHAPED = "unshaped";
+    public static final String MODE_UNSAFE_RAW = "unsafe-raw";
+
+    public String psk;
+    /** sing-box private extension; only compatible with sing-box Snell server. */
+    public String userPSK;
+    public String obfsMode;
+    /** v4-only */
+    public String obfsHost;
+    public Integer version;
+    public Boolean reuse;
+    /** v6-only */
+    public String mode;
+
+    @Override
+    public void initializeDefaultValues() {
+        super.initializeDefaultValues();
+        if (psk == null) psk = "";
+        if (userPSK == null) userPSK = "";
+        if (obfsMode == null || obfsMode.isEmpty()) obfsMode = OBFS_NONE;
+        if (obfsHost == null) obfsHost = "";
+        if (version == null || version == 0) version = VERSION_4;
+        if (reuse == null) reuse = true;
+        if (mode == null || mode.isEmpty()) mode = MODE_DEFAULT;
+    }
+
+    @Override
+    public void serialize(ByteBufferOutput output) {
+        // v3: rename obfs->obfsMode, add userPSK; version 4/6 only
+        output.writeInt(3);
+        super.serialize(output);
+        output.writeString(psk);
+        output.writeString(obfsMode);
+        output.writeInt(version);
+        output.writeBoolean(reuse);
+        output.writeString(obfsHost);
+        output.writeString(mode);
+        output.writeString(userPSK);
+    }
+
+    @Override
+    public void deserialize(ByteBufferInput input) {
+        int ver = input.readInt();
+        super.deserialize(input);
+        psk = input.readString();
+        obfsMode = input.readString();
+        // migrate legacy "off" -> "none" for old profiles only
+        if ("off".equals(obfsMode)) {
+            obfsMode = OBFS_NONE;
+        }
+        version = input.readInt();
+        // migrate legacy 3/5 to 4
+        if (version != null && version != VERSION_4 && version != VERSION_6) {
+            version = VERSION_4;
+        }
+        if (ver >= 1) {
+            reuse = input.readBoolean();
+        }
+        if (ver >= 2) {
+            obfsHost = input.readString();
+            mode = input.readString();
+        }
+        if (ver >= 3) {
+            userPSK = input.readString();
+        }
+    }
+
+    @Override
+    public String network() {
+        return "tcp,udp";
+    }
+
+    @NotNull
+    @Override
+    public SnellBean clone() {
+        return KryoConverters.deserialize(new SnellBean(), KryoConverters.serialize(this));
+    }
+
+    public static final Creator<SnellBean> CREATOR = new CREATOR<>() {
+        @NonNull
+        @Override
+        public SnellBean newInstance() {
+            return new SnellBean();
+        }
+
+        @Override
+        public SnellBean[] newArray(int size) {
+            return new SnellBean[size];
+        }
+    };
+}

app/src/main/java/io/nekohasekai/sagernet/fmt/snell/SnellFmt.kt

@@ -0,0 +1,64 @@
+package io.nekohasekai.sagernet.fmt.snell
+
+import io.nekohasekai.sagernet.ktx.*
+import libexclavecore.Libexclavecore
+
+fun parseSnell(url: String): SnellBean {
+    val link = Libexclavecore.parseURL(url)
+    return SnellBean().apply {
+        name = link.fragment
+        serverAddress = link.host.ifEmpty { error("empty host") }
+        serverPort = link.port
+        psk = when {
+            link.username.isNotEmpty() -> link.username
+            link.password.isNotEmpty() -> link.password
+            else -> link.queryParameter("psk") ?: ""
+        }
+        link.queryParameter("version")?.toIntOrNull()?.also {
+            if (it != 4 && it != 6) error("snell version must be 4 or 6")
+            version = it
+        }
+        // accept only exact values; map legacy "off" only from share links that used it historically
+        (link.queryParameter("obfsMode") ?: link.queryParameter("obfs"))?.also {
+            obfsMode = if (it == "off") SnellBean.OBFS_NONE else it
+        }
+        link.queryParameter("obfs-host")?.also { obfsHost = it }
+        link.queryParameter("mode")?.also { mode = it }
+        link.queryParameter("user-psk")?.also { userPSK = it }
+        link.queryParameter("userPSK")?.also { userPSK = it }
+        link.queryParameter("reuse")?.also {
+            reuse = it == "1" || it.equals("true", ignoreCase = true)
+        }
+        initializeDefaultValues()
+    }
+}
+
+fun SnellBean.toUri(): String? {
+    val builder = Libexclavecore.newURL("snell").apply {
+        setHostPort(serverAddress.ifEmpty { error("empty server address") }, serverPort)
+        if (!psk.isNullOrEmpty()) {
+            username = psk
+        }
+        if (name.isNotEmpty()) {
+            fragment = name
+        }
+    }
+    val v = version ?: 4
+    builder.addQueryParameter("version", v.toString())
+    if (!obfsMode.isNullOrEmpty() && obfsMode != SnellBean.OBFS_NONE) {
+        builder.addQueryParameter("obfsMode", obfsMode)
+    }
+    if (!obfsHost.isNullOrEmpty()) {
+        builder.addQueryParameter("obfs-host", obfsHost)
+    }
+    if (v >= 6 && !mode.isNullOrEmpty() && mode != SnellBean.MODE_DEFAULT) {
+        builder.addQueryParameter("mode", mode)
+    }
+    if (!userPSK.isNullOrEmpty()) {
+        builder.addQueryParameter("user-psk", userPSK)
+    }
+    if (reuse == true) {
+        builder.addQueryParameter("reuse", "1")
+    }
+    return builder.string
+}