qemu/slirp/libslirp.h
Ed Swierk df7a86ed73 slirp: Read host DNS config on demand
Currently the qemu user-mode networking stack reads the host DNS
configuration (/etc/resolv.conf or the Windows equivalent) only once
when qemu starts.  This causes name lookups in the guest to fail if the
host is moved to a different network from which the original DNS servers
are unreachable, a common occurrence when the host is a laptop.

This patch changes the slirp code to read the host DNS configuration on
demand, caching the results for at most 1 second to avoid unnecessary
overhead if name lookups occur in rapid succession.  On non-Windows
hosts, /etc/resolv.conf is re-read only if the file has been replaced or
if its size or mtime has changed.

Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-08-27 20:46:58 -05:00

57 lines
2.0 KiB
C

#ifndef _LIBSLIRP_H
#define _LIBSLIRP_H
#include <qemu-common.h>
#ifdef CONFIG_SLIRP
struct Slirp;
typedef struct Slirp Slirp;
int get_dns_addr(struct in_addr *pdns_addr);
Slirp *slirp_init(int restricted, struct in_addr vnetwork,
struct in_addr vnetmask, struct in_addr vhost,
const char *vhostname, const char *tftp_path,
const char *bootfile, struct in_addr vdhcp_start,
struct in_addr vnameserver, void *opaque);
void slirp_cleanup(Slirp *slirp);
void slirp_select_fill(int *pnfds,
fd_set *readfds, fd_set *writefds, fd_set *xfds);
void slirp_select_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds,
int select_error);
void slirp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len);
/* you must provide the following functions: */
int slirp_can_output(void *opaque);
void slirp_output(void *opaque, const uint8_t *pkt, int pkt_len);
int slirp_add_hostfwd(Slirp *slirp, int is_udp,
struct in_addr host_addr, int host_port,
struct in_addr guest_addr, int guest_port);
int slirp_remove_hostfwd(Slirp *slirp, int is_udp,
struct in_addr host_addr, int host_port);
int slirp_add_exec(Slirp *slirp, int do_pty, const void *args,
struct in_addr *guest_addr, int guest_port);
void slirp_connection_info(Slirp *slirp, Monitor *mon);
void slirp_socket_recv(Slirp *slirp, struct in_addr guest_addr,
int guest_port, const uint8_t *buf, int size);
size_t slirp_socket_can_recv(Slirp *slirp, struct in_addr guest_addr,
int guest_port);
#else /* !CONFIG_SLIRP */
static inline void slirp_select_fill(int *pnfds, fd_set *readfds,
fd_set *writefds, fd_set *xfds) { }
static inline void slirp_select_poll(fd_set *readfds, fd_set *writefds,
fd_set *xfds, int select_error) { }
#endif /* !CONFIG_SLIRP */
#endif