Fix Tor v3 onion address checksum: SHA-256 -> SHA3-256

The Tor v3 spec requires SHA3-256 (FIPS-202) for the .onion address
checksum computation, but ToStringIP() was using SHA-256 (double-hash).
This caused every reconstructed .onion address to have incorrect suffix
characters, making all outbound Tor connections fail with SOCKS5 'general
failure' - the entire network had 0 Tor peers despite working Tor instances.

Fix: Replace Hash() call with OpenSSL EVP_sha3_256() which is available
in OpenSSL 3.0+ and produces the correct FIPS-202 SHA3-256 checksum.

Tested: All 5 onion seed nodes now connect successfully.

src/clientversion.h

@@ -8,7 +8,7 @@
 // These need to be macros, as version.cpp's and triangles-qt.rc's voodoo requires it
 #define CLIENT_VERSION_MAJOR       5
 #define CLIENT_VERSION_MINOR       5
-#define CLIENT_VERSION_REVISION    0
+#define CLIENT_VERSION_REVISION    1
 #define CLIENT_VERSION_BUILD       0
 
 // Converts the parameter X to a string after macro replacement on X has been performed.

src/net.cpp

@@ -1553,7 +1553,15 @@ void ThreadHTTPSeedFetch2(void* parg)
                 port = GetDefaultPort();
 
             CNetAddr parsed;
-            if (parsed.SetSpecial(addrStr) || LookupHost(addrStr.c_str(), parsed, false)) {
+            bool resolved = parsed.SetSpecial(addrStr);
+            if (!resolved) {
+                std::vector<CNetAddr> vIP;
+                if (LookupHost(addrStr.c_str(), vIP, 1, false) && !vIP.empty()) {
+                    parsed = vIP[0];
+                    resolved = true;
+                }
+            }
+            if (resolved) {
                 CAddress addr(CService(parsed, port));
                 addr.nTime = GetTime() - 3*24*60*60; // 3 days ago
                 addrman.Add(addr, CNetAddr("http-seed", true));

src/netbase.cpp

@@ -6,6 +6,7 @@
 #include "netbase.h"
 #include "util.h"
 #include "sync.h"
+#include <openssl/evp.h>
 
 #ifndef WIN32
 #include <sys/fcntl.h>
@@ -860,15 +861,19 @@ std::string CNetAddr::ToStringIP() const
         unsigned char addr35[35];
         memcpy(addr35, tor_v3_pubkey, 32);
         // Compute checksum: SHA3-256(".onion checksum" || pubkey || version)[:2]
-        // For now use a simplified checksum from the stored data
         unsigned char checksumInput[15 + 32 + 1];
         memcpy(checksumInput, ".onion checksum", 15);
         memcpy(checksumInput + 15, tor_v3_pubkey, 32);
         checksumInput[47] = 0x03; // version
-        // SHA-256 as fallback (SHA3-256 via tor_crypto_compat.h for full impl)
-        uint256 hash = Hash(checksumInput, checksumInput + 48);
-        addr35[32] = ((unsigned char*)&hash)[0];
-        addr35[33] = ((unsigned char*)&hash)[1];
+        unsigned char sha3hash[32];
+        unsigned int sha3len = 0;
+        EVP_MD_CTX *mdctx = EVP_MD_CTX_new();
+        EVP_DigestInit_ex(mdctx, EVP_sha3_256(), NULL);
+        EVP_DigestUpdate(mdctx, checksumInput, 48);
+        EVP_DigestFinal_ex(mdctx, sha3hash, &sha3len);
+        EVP_MD_CTX_free(mdctx);
+        addr35[32] = sha3hash[0];
+        addr35[33] = sha3hash[1];
         addr35[34] = 0x03; // version
         return EncodeBase32(addr35, 35) + ".onion";
     }