The Collection of Worlds: Iterating the Network Topology

[!NOTE] Technical Context: netbase.cpp | Lines 127-133

In lines 127 through 133 of netbase.cpp, we see the implementation of GetNetworkNames. This function is the "Discovery Tool" for the node's supported networks. It provides a way for the node to list its entire "Vocabulary of Networks" to a user or another internal module.

1. GetNetworkNames: The Batch Inquiry

Line 129 defines the function: std::vector<std::string> GetNetworkNames(bool append_unroutable).

While the previous function (GetNetworkName) translated a single enum, this function returns a List of All Names. This is used to populate UI dropdowns, help menus, and RPC results (like the networks list in getnetworkinfo).

The append_unroutable Flag

The function takes a Boolean parameter that controls whether the "Unroutable" category should be included. This is an architectural "Option."

• True: Include everything, even the void. (Useful for developers and diagnostics).

• False: Only show the "Real" networks. (Useful for end-users).

2. The Vector of Discovery

Line 131 initializes the result vector: std::vector<std::string> names;.

By using a std::vector, the architect ensures that the order of the networks is preserved. This is a subtle but important part of User Experience. The order of networks in the code (IPv4, IPv6, Onion, etc.) will be the same order the user sees in the logs.

3. The Enum Loop: 0 to NET_MAX

Line 132 contains the core iteration: for (int n = 0; n < NET_MAX; ++n) {.

The Beauty of the Enum Pattern

This loop demonstrates why the NET_MAX sentinel we discussed in Part 048 is so important. By setting the loop limit to NET_MAX, the node automatically "Knows" how many networks exist.

If a developer adds a new network type tomorrow, they don't have to change this loop. The loop will automatically pick up the new network because NET_MAX (by definition) will have been incremented by the compiler. This is "Extensible by Design" architecture.

4. The Complexity of Type Casting

Note that the loop uses an int n, but it will eventually need to call GetNetworkName(enum Network).

Internally, C++ enums are just integers. This loop leverages that fact to "Scan" the entire range of possible networks. It is a "Brute-Force Discovery" of the node's own capabilities.

5. Architectural Synthesis: The Comprehensive Registry

GetNetworkNames is the "Registry" of the network stack. It provides a single point of truth for what "Worlds" the node is capable of speaking to.

This batch operation is essential for Configuration Validation. When a user starts the node with a command-line flag like -onlynet=ipv4, the node uses this function to verify that "ipv4" is actually a valid network name. It provides the "Vocabulary" against which all user input is measured.

Conclusion: The Map is Fully Drawn

Lines 127-133 provide the final "Overview" of the network world. We have moved from individual names to a complete, iterable list of all supported protocols. The node now has a full "Index" of the global internet topology.

In the final Article 0050 of this batch, we will see how the unroutable flag is handled and examine the SetProxy function, the master configuration method for the entire netbase module.