ip/torrent: fix usage, add -A option to set user-agent

trackers do like the new default Mozilla/5.0 (compatible)
user agent. so force useragent to hjdicks and give option
to override it in case trackers get even more clever in
the future.

2 files changed, 19 insertions, 2 deletions

diff --git a/sys/man/1/torrent b/sys/man/1/torrent
index f7708a4ae..e71964e86 100644
--- a/sys/man/1/torrent
+++ b/sys/man/1/torrent
@@ -26,6 +26,9 @@ torrent \- bittorrent client
 .B -i
 .I peer-id
 ] [
+.B -A
+.I user-agent
+] [
 .I file
 ]
 .SH DESCRIPTION
@@ -114,9 +117,15 @@ option allows you to set the 20-byte
 .I peer-id
 that is sent to trackers and peers. If less than 20 bytes, the
 .I peer-id
-will be padded on the right with random ASCII numbers. This is
+will be padded on the right with random ASCII numbers. The
+.B -A
+option allows setting the http 
+.I user-agent
+string that is used to contact the tracker. These options are
 useful to fool trackers that filter clients based on the
 .I peer-id
+or
+.I user-agent
 .
 .SH EXAMPLES
 Create new torrent file
diff --git a/sys/src/cmd/ip/torrent.c b/sys/src/cmd/ip/torrent.c
index 36e437f21..d84ea4fb2 100644
--- a/sys/src/cmd/ip/torrent.c
+++ b/sys/src/cmd/ip/torrent.c
@@ -54,6 +54,7 @@ int killgroup = -1;
 int port = 6881;
 char *deftrack = "http://exodus.desync.com/announce";
 char *mntweb = "/mnt/web";
+char *useragent = "hjdicks";
 uchar infohash[20];
 uchar peerid[20];
 int blocksize;
@@ -726,6 +727,10 @@ hopen(char *url, ...)
 		close(ctlfd);
 		return -1;
 	}
+	if(useragent != nil && useragent[0] != '\0'){
+		n = snprint(buf, sizeof buf, "useragent %s", useragent);
+		write(ctlfd, buf, n);
+	}
 	snprint(buf, sizeof buf, "%s/%d/body", mntweb, conn);
 	if((fd = open(buf, OREAD)) < 0)
 		goto ErrOut;
@@ -1157,7 +1162,7 @@ void
 usage(void)
 {
 	fprint(2, "usage: %s [ -vsdpc ] [ -m mtpt ] [ -t tracker-url ] "
-		  "[ -w webseed-url ] [ file ]\n", argv0);
+		  "[ -w webseed-url ] [ -i peerid ] [ -A useragent ] [ file ]\n", argv0);
 	exits("usage");
 }
 
@@ -1217,6 +1222,9 @@ main(int argc, char *argv[])
 	case 'i':
 		strncpy((char*)peerid, EARGF(usage()), sizeof(peerid));
 		break;
+	case 'A':
+		useragent = EARGF(usage());
+		break;
 	default:
 		usage();
 	} ARGEND;