net: extend CNetAddr::SetSpecial() to support I2P

Recognize also I2P addresses in the form `base32hashofpublickey.b32.i2p`
from `CNetAddr::SetSpecial()`.

This makes `Lookup()` support them, which in turn makes it possible to
manually connect to an I2P node by using
`-proxy=i2p_socks5_proxy:port -addnode=i2p_address.b32.i2p:port`

Co-authored-by: Lucas Ontivero <lucasontivero@gmail.com>

1 files changed, 48 insertions, 11 deletions

diff --git a/src/netaddress.cpp b/src/netaddress.cpp
index 85e46fd373..80313b88ce 100644
--- a/src/netaddress.cpp
+++ b/src/netaddress.cpp
@@ -221,25 +221,34 @@ static void Checksum(Span<const uint8_t> addr_pubkey, uint8_t (&checksum)[CHECKS
 
 }; // namespace torv3
 
-/**
- * Parse a TOR address and set this object to it.
- *
- * @returns Whether or not the operation was successful.
- *
- * @see CNetAddr::IsTor()
- */
-bool CNetAddr::SetSpecial(const std::string& str)
+bool CNetAddr::SetSpecial(const std::string& addr)
+{
+    if (!ValidAsCString(addr)) {
+        return false;
+    }
+
+    if (SetTor(addr)) {
+        return true;
+    }
+
+    if (SetI2P(addr)) {
+        return true;
+    }
+
+    return false;
+}
+
+bool CNetAddr::SetTor(const std::string& addr)
 {
     static const char* suffix{".onion"};
     static constexpr size_t suffix_len{6};
 
-    if (!ValidAsCString(str) || str.size() <= suffix_len ||
-        str.substr(str.size() - suffix_len) != suffix) {
+    if (addr.size() <= suffix_len || addr.substr(addr.size() - suffix_len) != suffix) {
         return false;
     }
 
     bool invalid;
-    const auto& input = DecodeBase32(str.substr(0, str.size() - suffix_len).c_str(), &invalid);
+    const auto& input = DecodeBase32(addr.substr(0, addr.size() - suffix_len).c_str(), &invalid);
 
     if (invalid) {
         return false;
@@ -275,6 +284,34 @@ bool CNetAddr::SetSpecial(const std::string& str)
     return false;
 }
 
+bool CNetAddr::SetI2P(const std::string& addr)
+{
+    // I2P addresses that we support consist of 52 base32 characters + ".b32.i2p".
+    static constexpr size_t b32_len{52};
+    static const char* suffix{".b32.i2p"};
+    static constexpr size_t suffix_len{8};
+
+    if (addr.size() != b32_len + suffix_len || ToLower(addr.substr(b32_len)) != suffix) {
+        return false;
+    }
+
+    // Remove the ".b32.i2p" suffix and pad to a multiple of 8 chars, so DecodeBase32()
+    // can decode it.
+    const std::string b32_padded = addr.substr(0, b32_len) + "====";
+
+    bool invalid;
+    const auto& address_bytes = DecodeBase32(b32_padded.c_str(), &invalid);
+
+    if (invalid || address_bytes.size() != ADDR_I2P_SIZE) {
+        return false;
+    }
+
+    m_net = NET_I2P;
+    m_addr.assign(address_bytes.begin(), address_bytes.end());
+
+    return true;
+}
+
 CNetAddr::CNetAddr(const struct in_addr& ipv4Addr)
 {
     m_net = NET_IPV4;