--- ip_masq_irc.c.old	Mon Aug  9 14:04:41 1999
+++ ip_masq_irc.c	Tue Aug  1 22:43:33 2000
@@ -20,9 +20,8 @@
  *	Juan Jose Ciarlante	:  put new ms entry to listen()
  *	Scottie Shore		:  added support for clients that add extra args
  *	  <sshore@escape.ca>
- *
- * FIXME:
- *	- detect also previous "PRIVMSG" string ?.
+ *	Scottie Shore		:  added support for mIRC DCC resume negotiation
+ *	  <sshore@escape.ca>
  *
  *	This program is free software; you can redistribute it and/or
  *	modify it under the terms of the GNU General Public License
@@ -91,9 +90,10 @@
  { "CHAT ", 5 },
  { "MOVE ", 5 },
  { "TSEND ", 6 },
- { "SCHAT ", 6 }
+ { "SCHAT ", 6 },
+ { "ACCEPT ", 7 },
 };
-#define MAXMATCHLEN 6
+#define MAXMATCHLEN 7
 
 static int
 masq_irc_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
@@ -137,6 +137,7 @@
 	 *	strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
 	 *	strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
 	 *	strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
+	 *	strlen("\1DCC ACCEPT F AAAAAAAA P S\1\n")=28
 	 *		AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits)
 	 *		P:         bound port (min 1 d )
 	 *		F:         filename   (min 1 d )
@@ -197,17 +198,26 @@
 				s_port = simple_strtoul(data,&data,10);
 				addr_end_p = data;
 
+				/*	Do we already have a port open for this client?
+				 *	If so, use it (for DCC ACCEPT)
+				 */
+
+				n_ms = ip_masq_out_get(IPPROTO_TCP,
+						htonl(s_addr),htons(s_port),
+						0, 0);
+
 				/*
-				 *	Now create an masquerade entry for it
-				 * 	must set NO_DPORT and NO_DADDR because
+				 *	If we didn't already have a port, we need to make one.
+				 * 	We must set NO_DPORT and NO_DADDR because
 				 *	connection is requested by another client.
 				 */
 
-				n_ms = ip_masq_new(IPPROTO_TCP,
-						maddr, 0,
-						htonl(s_addr),htons(s_port),
-						0, 0,
-						IP_MASQ_F_NO_DPORT|IP_MASQ_F_NO_DADDR);
+				if (n_ms==NULL)
+					n_ms = ip_masq_new(IPPROTO_TCP,
+							maddr, 0,
+							htonl(s_addr),htons(s_port),
+							0, 0,
+							IP_MASQ_F_NO_DPORT|IP_MASQ_F_NO_DADDR);
 				if (n_ms==NULL)
 					return 0;
 
@@ -252,6 +262,125 @@
 
 }
 
+int
+masq_irc_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr)
+{
+        struct sk_buff *skb;
+	struct iphdr *iph;
+	struct tcphdr *th;
+	char *data, *data_limit;
+	__u32 s_addr;
+	__u16 s_port;
+	struct ip_masq *n_ms;
+	char buf[20];		/* "m_addr m_port" (dec base)*/
+        unsigned buf_len;
+	int diff;
+        char *dcc_p, *addr_beg_p, *addr_end_p;
+
+        skb = *skb_p;
+	iph = skb->nh.iph;
+        th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
+        data = (char *)&th[1];
+
+        /*
+	 *	Hunt irc DCC RESUME string:
+	 *
+	 *	strlen("\1DCC RESUME chat AAAAAAAA P\1\n")=29
+	 *		AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits)
+	 *		P:         bound port (min 1 d )
+	 *		F:         filename   (min 1 d )
+	 *		S:         size       (min 1 d ) 
+	 *		0x01, \n:  terminators
+         */
+
+        data_limit = skb->h.raw + skb->len;
+        
+	while (data < (data_limit - 29 ) )
+	{
+		if (memcmp(data,"\1DCC RESUME ",12))  {
+			data ++;
+			continue;
+		}
+
+		dcc_p = data;
+		data += 12;
+
+		while( *data++ != ' ')
+			/*
+			 *	must still parse, at least, "AAAAAAAA P\1\n",
+			 *      12 bytes left.
+			 */
+			if (data > (data_limit-12)) return 0;
+
+
+		addr_beg_p = data;
+
+		/*
+		 *	masq bound address in dec base
+		 */
+
+		s_addr = simple_strtoul(data,&data,10);
+		if (*data++ !=' ')
+		continue;
+
+		/*
+		 *	masq bound port in dec base
+		 */
+
+		s_port = simple_strtoul(data,&data,10);
+		addr_end_p = data;
+
+		/*
+		 *	Find the masq entry associated with this connection.
+		 *	The entry should have no dest addr/port yet.
+		 *	If there is no entry, return 0.
+		 */
+
+		n_ms = ip_masq_in_get(IPPROTO_TCP,
+			0, 0,
+			htonl(s_addr), htons(s_port));
+					
+		if (n_ms==NULL)
+			return 0;
+
+		/*
+		 * Replace the outside address with the inside address
+		 */
+
+		buf_len = sprintf(buf,"%lu %u",
+			ntohl(n_ms->saddr),ntohs(n_ms->sport));
+
+		/*
+		 * Calculate required delta-offset to keep TCP happy
+		 */
+
+		diff = buf_len - (addr_end_p-addr_beg_p);
+
+		*addr_beg_p = '\0';
+		IP_MASQ_DEBUG(1-debug, "masq_irc_in(): '%s' %X:%X detected (diff=%d)\n", dcc_p, s_addr,s_port, diff);
+
+		/*
+		 *	No shift.
+		 */
+
+		if (diff==0) {
+			/*
+			 * simple case, just copy.
+			 */
+			memcpy(addr_beg_p,buf,buf_len);
+		} else {
+			*skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC,
+				addr_beg_p, addr_end_p-addr_beg_p,
+				buf, buf_len);
+		}
+
+		return diff;
+
+	}
+	return 0;
+
+}
+
 /*
  *	Main irc object
  *     	You need 1 object per port in case you need
@@ -263,12 +392,12 @@
 struct ip_masq_app ip_masq_irc = {
         NULL,			/* next */
 	"irc",			/* name */
-        0,                      /* type */
-        0,                      /* n_attach */
-        masq_irc_init_1,        /* init_1 */
-        masq_irc_done_1,        /* done_1 */
-        masq_irc_out,           /* pkt_out */
-        NULL                    /* pkt_in */
+        0,			/* type */
+        0,			/* n_attach */
+        masq_irc_init_1,	/* init_1 */
+        masq_irc_done_1,	/* done_1 */
+        masq_irc_out,		/* pkt_out */
+        masq_irc_in		/* pkt_in */
 };
 
 /*