patch-pre2.0.10 linux/net/ipv4/ip_masq_raudio.c

• Lines: 233
• Date: Fri May 31 13:46:27 1996
• Orig file: pre2.0.9/linux/net/ipv4/ip_masq_raudio.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file pre2.0.9/linux/net/ipv4/ip_masq_raudio.c linux/net/ipv4/ip_masq_raudio.c
@@ -0,0 +1,232 @@
+/*
+ *		IP_MASQ_RAUDIO  - Real Audio masquerading module
+ *
+ *
+ * Version:	@(#)$Id: ip_masq_raudio.c,v 1.3 1996/05/20 13:24:26 nigel Exp $
+ *
+ * Author:	Nigel Metheringham
+ *		[strongly based on ftp module by Juan Jose Ciarlante & Wouter Gadeyne]
+ *		[Real Audio information taken from Progressive Networks firewall docs]
+ *
+ *
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *
+ * Limitations
+ *	The IP Masquerading proxies at present do not have access to a processed
+ *	data stream.  Hence for a protocol like the Real Audio control protocol,
+ *	which depends on knowing where you are in the data stream, you either
+ *	to keep a *lot* of state in your proxy, or you cheat and simplify the
+ *	problem [needless to say I did the latter].
+ *
+ *	This proxy only handles data in the first packet.  Everything else is
+ *	passed transparently.  This means it should work under all normal
+ *	circumstances, but it could be fooled by new data formats or a
+ *	malicious application!
+ *
+ *	At present the "first packet" is defined as a packet starting with
+ *	the protocol ID string - "PNA".
+ *	When the link is up there appears to be enough control data 
+ *	crossing the control link to keep it open even if a long audio
+ *	piece is playing.
+ *	
+ */
+
+#include <linux/module.h>
+#include <asm/system.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <net/protocol.h>
+#include <net/tcp.h>
+#include <net/ip_masq.h>
+
+#ifndef DEBUG_CONFIG_IP_MASQ_RAUDIO
+#define DEBUG_CONFIG_IP_MASQ_RAUDIO 0
+#endif
+
+struct raudio_priv_data {
+	/* Associated data connection - setup but not used at present */
+	struct	ip_masq *data_conn;
+	/* Have we seen and performed setup */
+	short	seen_start;
+};
+
+static int
+masq_raudio_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
+{
+        MOD_INC_USE_COUNT;
+	if ((ms->app_data = kmalloc(sizeof(struct raudio_priv_data),
+				    GFP_ATOMIC)) == NULL) 
+		printk(KERN_INFO "RealAudio: No memory for application data\n");
+	else 
+	{
+		struct raudio_priv_data *priv = 
+			(struct raudio_priv_data *)ms->app_data;
+		priv->seen_start = 0;
+		priv->data_conn = NULL;
+	}
+        return 0;
+}
+
+static int
+masq_raudio_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
+{
+        MOD_DEC_USE_COUNT;
+	if (ms->app_data)
+		kfree_s(ms->app_data, sizeof(struct raudio_priv_data));
+        return 0;
+}
+
+int
+masq_raudio_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev)
+{
+        struct sk_buff *skb;
+	struct iphdr *iph;
+	struct tcphdr *th;
+	char *p, *data, *data_limit;
+	struct ip_masq *n_ms;
+	unsigned short version, msg_id, msg_len, udp_port;
+	struct raudio_priv_data *priv = 
+		(struct raudio_priv_data *)ms->app_data;
+
+	/* Everything running correctly already */
+	if (priv && priv->seen_start)
+		return 0;
+
+        skb = *skb_p;
+	iph = skb->h.iph;
+        th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
+        data = (char *)&th[1];
+
+        data_limit = skb->h.raw + skb->len - 18;
+
+	/* Check to see if this is the first packet with protocol ID */
+	if (memcmp(data, "PNA", 3)) {
+#if DEBUG_CONFIG_IP_MASQ_RAUDIO
+		printk("RealAudio: not initial protocol packet - ignored\n");
+#endif
+		return(0);
+	}
+	data += 3;
+	memcpy(&version, data, 2);
+
+#if DEBUG_CONFIG_IP_MASQ_RAUDIO
+	printk("RealAudio: initial seen - protocol version %d\n",
+	       ntohs(version));
+#endif
+	if (priv)
+		priv->seen_start = 1;
+
+	if (ntohs(version) >= 256)
+	{
+		printk(KERN_INFO "RealAudio: version (%d) not supported\n",
+		       ntohs(version));
+		return 0;
+	}
+
+	data += 2;
+	while (data < data_limit) {
+		memcpy(&msg_id, data, 2);
+		data += 2;
+		memcpy(&msg_len, data, 2);
+		data += 2;
+#if DEBUG_CONFIG_IP_MASQ_RAUDIO
+		printk("RealAudio: msg %d - %d byte\n",
+		       ntohs(msg_id), ntohs(msg_len));
+#endif
+		p = data;
+		data += ntohs(msg_len);
+		if (data > data_limit)
+		{
+			printk(KERN_INFO "RealAudio: Packet too short for data\n");
+			return 0;
+		}
+		if (ntohs(msg_id) == 1) {
+			/* This is a message detailing the UDP port to be used */
+			memcpy(&udp_port, p, 2);
+			n_ms = ip_masq_new(dev, IPPROTO_UDP,
+					   ms->saddr, udp_port,
+					   ms->daddr, 0,
+					   IP_MASQ_F_NO_DPORT);
+					
+			if (n_ms==NULL)
+				return 0;
+
+			memcpy(p, &(n_ms->mport), 2);
+#if DEBUG_CONFIG_IP_MASQ_RAUDIO
+			printk("RealAudio: rewrote UDP port %d -> %d\n",
+			       ntohs(udp_port), ntohs(n_ms->mport));
+#endif
+			ip_masq_set_expire(n_ms, ip_masq_expire->udp_timeout);
+
+			/* Make ref in application data to data connection */
+			if (priv)
+				priv->data_conn = n_ms;
+
+			/* 
+			 * There is nothing else useful we can do
+			 * Maybe a development could do more, but for now
+			 * we exit gracefully!
+			 */
+			return 0;
+
+		} else if (ntohs(msg_id) == 0)
+			return 0;
+	}
+	return 0;
+}
+
+struct ip_masq_app ip_masq_raudio = {
+        NULL,			/* next */
+	"RealAudio",	       	/* name */
+        0,                      /* type */
+        0,                      /* n_attach */
+        masq_raudio_init_1,     /* ip_masq_init_1 */
+        masq_raudio_done_1,     /* ip_masq_done_1 */
+        masq_raudio_out,        /* pkt_out */
+        NULL                    /* pkt_in */
+};
+
+/*
+ * 	ip_masq_raudio initialization
+ */
+
+int ip_masq_raudio_init(void)
+{
+        return register_ip_masq_app(&ip_masq_raudio, IPPROTO_TCP, 7070);
+}
+
+/*
+ * 	ip_masq_raudio fin.
+ */
+
+int ip_masq_raudio_done(void)
+{
+        return unregister_ip_masq_app(&ip_masq_raudio);
+}
+
+#ifdef MODULE
+
+int init_module(void)
+{
+        if (ip_masq_raudio_init() != 0)
+                return -EIO;
+        register_symtab(0);
+        return 0;
+}
+
+void cleanup_module(void)
+{
+        if (ip_masq_raudio_done() != 0)
+                printk("ip_masq_raudio: can't remove module");
+}
+
+#endif /* MODULE */