From: Niels Provos <provos@gmail.com>
Date: Mon, 13 Feb 2006 01:51:58 +0000 (+0000)
Subject: limit the amount of data bufferevents are going to consume to something
X-Git-Tag: release-2.0.1-alpha~747
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7b78c82823a8d65338503b8aabd3a606116d7cfc;p=libevent

limit the amount of data bufferevents are going to consume to something
reasonable; in some circumstances it could happen that libevent happily
allocated 100MB in read buffers without telling the user; found by
christopher maxwell - parts of these changes are from his patch.


svn:r200
---

diff --git a/buffer.c b/buffer.c
index 7ce5bef1..e3c0ef9a 100644
--- a/buffer.c
+++ b/buffer.c
@@ -340,8 +340,21 @@ evbuffer_read(struct evbuffer *buf, int fd, int howmuch)
 #endif
 
 #ifdef FIONREAD
-	if (ioctl(fd, FIONREAD, &n) == -1 || n == 0)
+	if (ioctl(fd, FIONREAD, &n) == -1 || n == 0) {
 		n = EVBUFFER_MAX_READ;
+	} else if (n > EVBUFFER_MAX_READ && n > howmuch) {
+		/*
+		 * It's possible that a lot of data is available for
+		 * reading.  We do not want to exhaust resources
+		 * before the reader has a chance to do something
+		 * about it.  If the reader does not tell us how much
+		 * data we should read, we artifically limit it.
+		 */
+		if (n > buf->totallen << 2)
+			n = buf->totallen << 2;
+		if (n < EVBUFFER_MAX_READ)
+			n = EVBUFFER_MAX_READ;
+	}
 #endif	
 	if (howmuch < 0 || howmuch > n)
 		howmuch = n;
diff --git a/evbuffer.c b/evbuffer.c
index 0e7ef00c..7bd8d49a 100644
--- a/evbuffer.c
+++ b/evbuffer.c
@@ -92,13 +92,21 @@ bufferevent_readcb(int fd, short event, void *arg)
 	int res = 0;
 	short what = EVBUFFER_READ;
 	size_t len;
+	int howmuch = -1;
 
 	if (event == EV_TIMEOUT) {
 		what |= EVBUFFER_TIMEOUT;
 		goto error;
 	}
 
-	res = evbuffer_read(bufev->input, fd, -1);
+	/*
+	 * If we have a high watermark configured then we don't want to
+	 * read more data than would make us reach the watermark.
+	 */
+	if (bufev->wm_read.high != 0)
+		howmuch = bufev->wm_read.high;
+
+	res = evbuffer_read(bufev->input, fd, howmuch);
 	if (res == -1) {
 		if (errno == EAGAIN || errno == EINTR)
 			goto reschedule;