Pi-Hole/dnsmasq
1
0
Fork 0
mirror of https://github.com/pi-hole/dnsmasq.git synced 2025-12-19 10:18:25 +00:00
Code Issues Packages Projects Releases Wiki Activity

Workaround for reported recvmsg() ignoring MSG_PEEK.

Browse Source
This commit is contained in:
Simon Kelley
2020-04-28 14:02:53 +01:00
parent 8baf583a3f
commit 4890bcdea2
1 changed files with 12 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
src/dhcp-common.c
View File

@@ -38,7 +38,7 @@ void dhcp_common_init(void)
ssize_t recv_dhcp_packet(int fd, struct msghdr *msg) ssize_t recv_dhcp_packet(int fd, struct msghdr *msg)
{ {
ssize_t sz; ssize_t sz, new_sz;
while (1) while (1)
{ {
@@ -65,9 +65,18 @@ ssize_t recv_dhcp_packet(int fd, struct msghdr *msg)
} }
} }
while ((sz = recvmsg(fd, msg, 0)) == -1 && errno == EINTR); while ((new_sz = recvmsg(fd, msg, 0)) == -1 && errno == EINTR);
/* Some kernels seem to ignore MSG_PEEK, and dequeue the packet anyway.
If that happens we get EAGAIN here because the socket is non-blocking.
Use the result of the original testing recvmsg as long as the buffer
was big enough. There's a small race here that may lose the odd packet,
but it's UDP anyway. */
return (msg->msg_flags & MSG_TRUNC) ? -1 : sz; if (new_sz == -1 && (errno == EWOULDBLOCK || errno == EAGAIN))
new_sz = sz;
return (msg->msg_flags & MSG_TRUNC) ? -1 : new_sz;
} }
struct dhcp_netid *run_tag_if(struct dhcp_netid *tags) struct dhcp_netid *run_tag_if(struct dhcp_netid *tags)