a couple patches

Incorporated Mario and Dmitry's patches.  See the ChangeLog

darcs-hash:20061010213746-28bda-1874bbfb40a1ffb92516d57782302ab09eedc368.gz

AUTHORS

@@ -1,3 +1,5 @@
 Hans Fugal wrote it.
 Von Fugal patched it. 
 Leonard Ritter (paniq) made it sound cool.
+Mario Lang added filter expressions.
+Dmitry Baikov added suid and privilege dropping, and got rid of the evil mutex.

ChangeLog

@@ -1,11 +1,27 @@
+2006-10-10  Dmitry Baikov <dsbaikov@gmail.com>
+
+    * make hearnet suid and drop privileges right after libpcap
+      initialization.
+    * Mutex in jack_process is a very bad thing. Moreover, it seems
+      there's no need for it, as voice->active field serves as a mutex.
+
+      N.B. It's good enough I think, but I wonder if we might need some
+      sort of memory barrier, as noted in the comments. -- Hans
+
+2005-09-30  Mario Lang <mlang@delysid.org>
+
+    * Added filter expression support, so now you can say
+      ./hearnet eth0 "udp port 53"
+      or whatever kind of filter expression you can think of.  Very nice for
+      listening in on just specific traffic patterns!
+
 2005-07-26  Leonard Ritter <paniq|paniq-org>
 
-	* changed code so that it uses 32-voice polyphony and plays bridges / 
-	  chromatic orders.
-
-	  as an effect, you get very harmonic sounds if packet sizes on a 
-	  site are the same, and quite weird stuff if packet sizes vary.
-
+    * changed code so that it uses 32-voice polyphony and plays bridges / 
+      chromatic orders.
+
+      as an effect, you get very harmonic sounds if packet sizes on a 
+      site are the same, and quite weird stuff if packet sizes vary.
 
 2004-11-12  Hans Fugal  <hans@fugal.net>
 

Makefile

@@ -1,13 +1,20 @@
 CFLAGS+=-g
 LDFLAGS+=`pkg-config --cflags --libs jack` -lpcap
-version=0.0.4
+version=0.0.9
 
 all: hearnet grain.raw
+	-sudo make suid
 
 %.raw: %.wav
 	sox $< -r 44800 -s -w $@
 clean: 
 	rm -f hearnet *.o core*
 
+suid: hearnet
+	chown root $<
+	chmod u+s $<
+
 dist: all
 	darcs dist -d hearnet-$(version)
+
+.PHONY: suid dist all clean

README

@@ -1,17 +1,33 @@
 hearnet - listen to your network
 
 Requirements:
-libpcap
-libjack
+- libpcap
+- libjack
 
-This is how I run hearnet:
-$ sudo jackd -d alsa &
-$ sudo ./hearnet &
+Synopsis:
+    make
+    sudo make suid
+    # start jack if necessary
+    ./hearnet
 
+Details:
+
+hearnet now drops priveleges when run with the suid bit set, which means
+you can hook it into your regular non-root jackd, and run it as a normal
+user. 
+
+You can specify a filter expression (a la tcpdump), e.g.:
+
+    ./hearnet eth0 udp port 53
+
+Very nice for listening to just one kind of traffic. Try this for an
+accompaniment to your VOIP conversation:
+
+    ./hearnet eth0 udp port sip
 
 License:
 
-    Copyright (C) 2003-2005  Hans Fugal <hans@fugal.net>
+    Copyright (C) 2003-2006  Hans Fugal <hans@fugal.net>
 
     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

hearnet.cpp

@@ -21,6 +21,7 @@
 #include <math.h>
 #include <memory.h>
 #include <time.h>
+#include <string>
 
 /* macros */
 /// length of grain in samples
@@ -31,7 +32,6 @@
 #define MAX_VOICES 16
 
 /* data */
-pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 jack_port_t *output_port;
 jack_nframes_t srate;
 
@@ -75,8 +75,6 @@ int process (jack_nframes_t nframes, void *arg)/*{{{*/
 {
     jack_default_audio_sample_t *out = (jack_default_audio_sample_t *) jack_port_get_buffer (output_port, nframes);
 
-    pthread_mutex_lock(&mutex);
-
     memset(out, 0, sizeof(jack_default_audio_sample_t)*nframes);
 
 	for (int index = 0; index != MAX_VOICES; index++)
@@ -114,8 +112,6 @@ int process (jack_nframes_t nframes, void *arg)/*{{{*/
 		}
 	}
 
-    pthread_mutex_unlock(&mutex);
-
     return 0;
 }/*}}}*/
 /** jack callback to set sample rate */
@@ -138,8 +134,6 @@ void shutdown(void *arg)/*{{{*/
 /** packet handler called by pcap_dispatch in main() */
 void packet_handler(u_char * args, const struct pcap_pkthdr *pcap_hdr, const u_char * p)/*{{{*/
 {
-    pthread_mutex_lock(&mutex);
-
 	voice* new_voice = get_free_voice();
 	if (new_voice)
 	{
@@ -153,17 +147,21 @@ void packet_handler(u_char * args, const struct pcap_pkthdr *pcap_hdr, const u_c
 		new_voice->decaylength = (rand()%100 + 100) / 1000.0f; 
 		new_voice->attack = 0.0f;
 		new_voice->attacklength = (rand()%20 + 1) / 1000.0f; // 10ms
-		new_voice->active = true;
+		// Since we took out the mutex, we depend on this last
+		// assignment not happening out-of-order. I don't know of a
+		// portable memory barrier, so we'll just let it float. I
+		// doubt it will be a noticeable problem, but if it is then
+		// figure out some way to put a barrier here.
+		new_voice->active = true; 
 	}
-    pthread_mutex_unlock(&mutex);
 
 }/*}}}*/
 
 void usage(void)/*{{{*/ 
 {
     fprintf(stderr,
 	    "\n"
-	    "usage: hearnet [interface]\n"
+	    "usage: hearnet [interface [filter-expression]]\n"
 	    "Default interface is eth0.\n"
 	    );
     exit(1);
@@ -178,6 +176,37 @@ int main(int argc, char **argv)/*{{{*/
 
     if (argc > 1)
 	dev = argv[1];
+
+    // libpcap stuff /*{{{*/
+    pcap_t *hdl_pcap;
+    char perrbuf[PCAP_ERRBUF_SIZE];
+    hdl_pcap = pcap_open_live(dev, BUFSIZ, 0, 0, perrbuf);
+    if (hdl_pcap == NULL)
+    {
+	fprintf(stderr,"pcap_open_live; %s\n", perrbuf);
+	usage();
+    }
+
+    if (argc > 2) {
+      bpf_program bpfprog;
+      std::string s;
+      for (int i=2; i<argc; i++)
+	  s += std::string(argv[i]) + std::string(" ");
+      char *cstr = (char*)malloc(s.size()+1);
+      strncpy(cstr,s.c_str(),s.size()+1);
+
+      if (pcap_compile(hdl_pcap, &bpfprog, cstr, 1, 0XFFFFFFFF) != -1) {
+          pcap_setfilter(hdl_pcap, &bpfprog);
+      } else {
+	  printf("Error compiling filter: %s\n", pcap_geterr(hdl_pcap));
+	  exit(1);
+      }
+    }
+
+    seteuid(getuid());
+
+    /*}}}*/
+
 
     snprintf(client_name, sizeof(client_name), "hearnet %s", dev);
     // jack stuff {{{
@@ -219,18 +248,6 @@ int main(int argc, char **argv)/*{{{*/
 	init_voices();
 
 
-    // libpcap stuff /*{{{*/
-    pcap_t *hdl_pcap;
-    char perrbuf[PCAP_ERRBUF_SIZE];
-    hdl_pcap = pcap_open_live(dev, BUFSIZ, 0, 0, perrbuf);
-    if (hdl_pcap == NULL)
-    {
-	fprintf(stderr,"pcap_open_live; %s\n", perrbuf);
-	usage();
-    }
-
-    /*}}}*/
-
 	timeval tv_start;
 	gettimeofday(&tv_start,0);
 	srand(tv_start.tv_sec);