nmap-0002 + haproxy-0004 + nginx-0004 + weechat-0003 + zeek-0002 + curl-0004: 6 new CWE-407 defects in network tools; count 693→699

nmap-0002:     nmap.cc merge_port_lists O(N²) port dedup → unordered_set O(N); ~65000x at max range
haproxy-0004:  http_ana.c http_capture_headers O(H×C) cap_hdr walk per request → pre-built HashMap O(H)
nginx-0004:    ngx_http_upstream_keepalive_module.c keepalive_get_peer O(C) sockaddr scan per upstream request → HashMap O(1)
weechat-0003:  irc-channel.c irc_channel_search O(C) linked-list scan per message handler → channels_hashtable O(1)
zeek-0002:     Attr.cc Attributes::AddAttrs O(A²) triple-Find/RemoveAttr per attr → unordered_map index O(A)
curl-0004:     mime.c search_header O(P×H) 3x per part per mime_add_headers → pre-indexed header name set O(P)

defects/weechat/patch/weechat-0003-irc-channel-search-hashmap.md

@@ -0,0 +1,102 @@
+# weechat-0003 — irc_channel_search O(C) linked-list scan — no hash index
+
+## Ecosystem
+weechat (C)
+
+## Severity
+MEDIUM — hot path: irc_channel_search() is called ~30+ times per IRC protocol
+message in irc-protocol.c (JOIN, PART, KICK, MODE, TOPIC, PRIVMSG, etc.)
+
+## Location
+`src/plugins/irc/irc-channel.c`
+- Function: `irc_channel_search` (~line 92): O(C) linear walk of `server->channels`
+
+`src/plugins/irc/irc-protocol.c`
+- ~30+ call sites including: JOIN (~line 1560, 1587), PART (~line 1753),
+  KICK (~line 1928), MODE (~line 2180), NICK (~line 2297), PRIVMSG (~line 3112),
+  numeric 353/366/332 handlers, etc.
+
+## Description
+
+`irc_channel_search` scans a linked list of all channels on a server to find
+a channel by name:
+
+```c
+// irc-channel.c:92
+struct t_irc_channel *
+irc_channel_search (struct t_irc_server *server, const char *channel_name)
+{
+    struct t_irc_channel *ptr_channel;
+
+    if (!server || !channel_name)
+        return NULL;
+
+    for (ptr_channel = server->channels; ptr_channel;
+         ptr_channel = ptr_channel->next_channel)      // O(C) walk
+    {
+        if (irc_server_strcasecmp (server, ptr_channel->name, channel_name) == 0)
+            return ptr_channel;
+    }
+    return NULL;
+}
+```
+
+With C channels on a server, each call is O(C). In `irc-protocol.c`, this
+function is called ~30+ times across different protocol message handlers,
+each of which processes one message. The cost per message is O(C) per
+`irc_channel_search` call.
+
+In extreme cases (e.g., a bot joined to thousands of channels, or an IRC
+network with large JOIN parameter lists), the cumulative cost per protocol
+event grows significantly.
+
+The NICK handler at line ~2297 calls `irc_channel_search` once, then
+iterates over all C channels calling `irc_nick_search` (O(N) each) — that
+O(C×N) pattern is weechat-0001. The standalone `irc_channel_search` O(C)
+cost itself is weechat-0003.
+
+## Fix
+
+Add a `channels_hashtable` to `struct t_irc_server` (channel_name → `t_irc_channel*`),
+mirroring the `nicks_hashtable` fix from weechat-0001:
+
+```c
+--- a/src/plugins/irc/irc-server.h
++++ b/src/plugins/irc/irc-server.h
+@@ struct t_irc_server {
+    struct t_irc_channel *channels;
++   struct t_hashtable *channels_hashtable; /* channel_name(lower) → t_irc_channel* */
+
+--- a/src/plugins/irc/irc-channel.c
++++ b/src/plugins/irc/irc-channel.c
+ struct t_irc_channel *
+ irc_channel_search (struct t_irc_server *server, const char *channel_name)
+ {
+-    for (ptr_channel = server->channels; ptr_channel; ...)
+-        if (irc_server_strcasecmp (...) == 0) return ptr_channel;
++    if (server->channels_hashtable) {
++        char lower[512];
++        snprintf(lower, sizeof(lower), "%s", channel_name);
++        /* lowercase using irc_server_casemapping */
++        return weechat_hashtable_get(server->channels_hashtable, lower);
++    }
++    /* fallback to linear scan */
++    ...
+}
+```
+
+## Complexity
+
+| Variant | Cost per lookup |
+|---------|----------------|
+| Before  | O(C) — linear scan through all channels |
+| After   | O(1) — hash table lookup |
+| Speedup | C× — at C=1000 channels: 1000× |
+
+## Notes
+- IRC servers typically allow users to join 100-2000 channels
+- Bots joining many channels (monitoring, bridging) are common and hit this hard
+- The `t_irc_server.channels` list is modified on JOIN/PART; the hashtable
+  must be kept in sync in `irc_channel_new()` and `irc_channel_free()`
+- weechat-0001 fixed `nicks_hashtable`; this defect is the parallel issue
+  for channel lookup on the server