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BUG/MEDIUM: dns: Properly handle error when a response consumed

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When a response is consumed, result for co_getblk() is never checked. It
seems ok because amount of output data is always checked first. But There is
an issue when we try to get the first 2 bytes to read the message length. If
there is only one byte followed by a shutdown, the applet ignore the
shutdown and loop till the timeout to get more data.

So to avoid any issue and improve shutdown detection, the co_getblk() return
value is always tested. In addition, if there is not enough data, the applet
explicitly ask for more data by calling applet_need_more_data().

This patch relies on the previous one:

   * BUG/MEDIUM: channel: Improve reports for shut in co_getblk()

Both should be backported as far as 2.4. On 2.5 and 2.4,
applet_need_more_data() must be replaced by si_rx_endp_more().
This commit is contained in:
Christopher Faulet 2023-03-30 15:49:30 +02:00
parent 5f5c94617e
commit 28975e1e10
1 changed files with 24 additions and 12 deletions
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36
src/dns.c
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@ -661,30 +661,35 @@ read:
struct dns_query *query;
if (!ds->rx_msg.len) {
/* next message len is not fully available into the channel */
if (co_data(sc_oc(sc)) < 2)
break;
/* retrieve message len */
co_getblk(sc_oc(sc), (char *)&msg_len, 2, 0);
ret = co_getblk(sc_oc(sc), (char *)&msg_len, 2, 0);
if (ret <= 0) {
if (ret == -1)
goto close;
applet_need_more_data(appctx);
break;
}
/* mark as consumed */
co_skip(sc_oc(sc), 2);
/* store message len */
ds->rx_msg.len = ntohs(msg_len);
}
if (!co_data(sc_oc(sc))) {
/* we need more data but nothing is available */
break;
if (!ds->rx_msg.len)
continue;
}
if (co_data(sc_oc(sc)) + ds->rx_msg.offset < ds->rx_msg.len) {
/* message only partially available */
/* read available data */
co_getblk(sc_oc(sc), ds->rx_msg.area + ds->rx_msg.offset, co_data(sc_oc(sc)), 0);
ret = co_getblk(sc_oc(sc), ds->rx_msg.area + ds->rx_msg.offset, co_data(sc_oc(sc)), 0);
if (ret <= 0) {
if (ret == -1)
goto close;
applet_need_more_data(appctx);
break;
}
/* update message offset */
ds->rx_msg.offset += co_data(sc_oc(sc));
@ -693,13 +698,20 @@ read:
co_skip(sc_oc(sc), co_data(sc_oc(sc)));
/* we need to wait for more data */
applet_need_more_data(appctx);
break;
}
/* enough data is available into the channel to read the message until the end */
/* read from the channel until the end of the message */
co_getblk(sc_oc(sc), ds->rx_msg.area + ds->rx_msg.offset, ds->rx_msg.len - ds->rx_msg.offset, 0);
ret = co_getblk(sc_oc(sc), ds->rx_msg.area + ds->rx_msg.offset, ds->rx_msg.len - ds->rx_msg.offset, 0);
if (ret <= 0) {
if (ret == -1)
goto close;
applet_need_more_data(appctx);
break;
}
/* consume all data until the end of the message from the channel */
co_skip(sc_oc(sc), ds->rx_msg.len - ds->rx_msg.offset);