nostr: make /rvrelay a true pin -- never merge discovered relays

A pool started with /rvrelay=ONE still spawned an accept thread for every
Nostr-discovered relay (BtfAllRelays always merged g_discoveredRelays), and
each thread optimistically overwrote the advertised meeting node before
registering -- so a discovered Tailscale-only relay (a mesh host)
flapped the published .btf descriptor and public miners could not connect.

fBtfRelayPinned (set only when /rvrelay parses) makes BtfAllRelays return
exactly the pinned list. Also validate the /rvrelay value at parse time:
with the pin in place no discovered relay can mask a typo.

(cherry picked from commit 0a4d2b02fa5382c5e788b5f0e2f8a844695dec47)

1 files changed, 9 insertions, 1 deletions

diff --git a/src/nostr.cpp b/src/nostr.cpp
index 21104bc..6d85bf6 100644
--- a/src/nostr.cpp
+++ b/src/nostr.cpp
@@ -110,6 +110,12 @@ vector<string> vBtfMeetingRelays = {
     "31.44.4.249:8434",     // New Jersey, US
     "90.156.222.107:8434",  // Almaty, KZ
 };
+// True when the operator pinned the relay list with /rvrelay: discovered
+// relays must NOT be merged in (BtfAllRelays), otherwise one accept thread
+// per discovered relay is spawned and each one optimistically overwrites the
+// advertised meeting node (BtfSetActiveRelay) before registering -- a
+// discovered but unreachable relay then flaps the published .btf descriptor.
+bool fBtfRelayPinned = false;
 string strBtfActiveRelay;
 static CCriticalSection cs_activeRelay;
 
@@ -144,7 +150,7 @@ static map<string, BtfPoolAnnouncement> g_discoveredPools;
 static CCriticalSection cs_discoveredPools;
 
 // Basic sanity: "host:port" with a numeric 1..65535 port and a plausible host.
-static bool LooksLikeRelay(const string& r)
+bool LooksLikeRelay(const string& r)
 {
     size_t colon = r.rfind(':');
     if (colon == string::npos || colon == 0 || colon + 1 >= r.size())
@@ -172,6 +178,8 @@ static bool LooksLikeRelay(const string& r)
 vector<string> BtfAllRelays()
 {
     vector<string> all = vBtfMeetingRelays;
+    if (fBtfRelayPinned)
+        return all;
     CRITICAL_BLOCK(cs_discoveredRelays)
         foreach(const string& r, g_discoveredRelays)
             if (find(all.begin(), all.end(), r) == all.end())