From f0936ca1b231df3c5cb7cf80a1d6a88d7ea980af Mon Sep 17 00:00:00 2001
From: Luke Bratch <luke@bratch.co.uk>
Date: Mon, 27 May 2019 12:37:46 +0100
Subject: Only do CAP multi-prefix negotiation with clients if the server
 approved it in the first place.

---
 blabouncer.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'blabouncer.c')

diff --git a/blabouncer.c b/blabouncer.c
index db0d384..efb2474 100644
--- a/blabouncer.c
+++ b/blabouncer.c
@@ -76,6 +76,7 @@ struct ircdstrings {
   char ircusername[MAXUSERNAMELEN];
   char currentmsg[MAXDATASIZE]; // Holding area for the current server-received IRC message being processed in case it needs building across multiple reads (i.e. a truncated/split message)
   char mode[MAXDATASIZE];
+  int capmultiprefix; // Whether the server approved our CAP multi-prefix request
 };
 
 // Structure of settings either to be read from the configuration file or set/changed at runtime
@@ -1260,6 +1261,21 @@ int processircmessage(SSL *server_ssl, char *str, int source, struct client *cli
           free(strcopyPtr);
           return 1;
         }
+
+        // Server CAP received?
+        if (strncmp(tokens[1], "CAP", strlen(tokens[1])) == 0) {
+          printf("Server CAP found and it is: %s with length %zd!  Analysing...\n", tokens[1], strlen(tokens[1]));
+          // If the server said "CAP <ournick> ACK :multi-prefix" then it must have approved our CAP multi-prefix request
+          if (counter == 5) {
+            if (strncmp(tokens[2], ircdstrings->ircnick, strlen(tokens[2])) == 0 &&
+                strncmp(tokens[3], "ACK", strlen(tokens[3])) == 0 &&
+                strncmp(tokens[4], ":multi-prefix", strlen(tokens[4])) == 0) {
+              ircdstrings->capmultiprefix = 1;
+            }
+          }
+          // We didn't handle it
+          printf("Unhandled server CAP response.\n");
+        }
       }
 
       // Don't return if we got here because this means we didn't process something above
@@ -1305,6 +1321,14 @@ int processircmessage(SSL *server_ssl, char *str, int source, struct client *cli
 
       // CAP received?  Clients can send CAP before PASS so we have to deal with this even if they are not authenticated yet.
       if (strncasecmp(tokens[0], "CAP", strlen(tokens[0])) == 0) {
+        // But only do something if the real server told us it had a CAP (only multi-prefix for now)
+        if (ircdstrings->capmultiprefix == 1) {
+          printf("Client CAP received and the server supports CAPs, continuing.\n");
+        } else {
+          printf("Client CAP received but the server doesn't support CAPs, returning.\n");
+          free(strcopyPtr);
+          return 1;
+        }
         // Get the real IRC server name from greeting001
         // They are now pending CAP negotiation
         clients[arrindex(clients, sourcefd)].pendingcap = 1;
@@ -1875,6 +1899,8 @@ void dochat(int *serversockfd, int *clientsockfd, struct settings *settings) {
   ircdstrings.ircusername[0] = '\0';
   ircdstrings.currentmsg[0] = '\0';
   ircdstrings.mode[0] = '\0';
+  // And set non-string things to zero (TODO - Rename this from ircdstrings since it's not all strings any more)
+  ircdstrings.capmultiprefix = 0;
 
   // Populate nick and username from our configuration file for now, real IRCd may change them later (TODO - Is this true of username?)
   strcpy(ircdstrings.ircnick, settings->ircnick);
-- 
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