[hackers] [quark] Fix handling of unexpected hangups || Laslo Hunhold

From: <git_AT_suckless.org>
Date: Sun, 31 Jan 2021 00:50:19 +0100 (CET)

commit f1892c4dffa7df6995cd8c9ebd47e0ce7f0e457e
Author: Laslo Hunhold <dev_AT_frign.de>
AuthorDate: Sun Jan 31 00:39:11 2021 +0100
Commit: Laslo Hunhold <dev_AT_frign.de>
CommitDate: Sun Jan 31 00:39:11 2021 +0100

    Fix handling of unexpected hangups
    
    During slowloris-stress-testing I noticed that closing the tool would
    pretty reliably trigger a case where quark was continuously getting
    edge-triggered on EPOLLIN and notified that there was something to read
    on the now definitely closed client-sockets.
    
    This was wrong and due to the fact that I mishandled the case when
    read() returns 0 in http_recv_header(). The condition read()==0 and
    EPOLL or EWOULDBLOCK does not indicate that you should try again. It's
    an EOF-condition and should be handled as such.
    
    Given the request is incomplete at this point, this is handled as a
    bad request (HTTP status 400) mostly for the logs at this point, as
    being able to transmit the error page itself is highly unlikely.
    
    Signed-off-by: Laslo Hunhold <dev_AT_frign.de>

diff --git a/http.c b/http.c
index f52da8a..1e43035 100644
--- a/http.c
+++ b/http.c
_AT_@ -154,7 +154,7 @@ http_recv_header(int fd, struct buffer *buf, int *done)
 
         while (1) {
                 if ((r = read(fd, buf->data + buf->len,
- sizeof(buf->data) - buf->len)) <= 0) {
+ sizeof(buf->data) - buf->len)) < 0) {
                         if (errno == EAGAIN || errno == EWOULDBLOCK) {
                                 /*
                                  * socket is drained, return normally,
_AT_@ -166,6 +166,14 @@ http_recv_header(int fd, struct buffer *buf, int *done)
                                 s = S_REQUEST_TIMEOUT;
                                 goto err;
                         }
+ } else if (r == 0) {
+ /*
+ * unexpected EOF because the client probably
+ * hung up. This is technically a bad request,
+ * because it's incomplete
+ */
+ s = S_BAD_REQUEST;
+ goto err;
                 }
                 buf->len += r;
 
Received on Sun Jan 31 2021 - 00:50:19 CET