kvm tools: Get domain name and nameserver from host

This patch get domain name and nameserver information from host config
file /etc/resolv.conf.

Guest can obtain DNS information through DHCP.

Signed-off-by: Asias He <asias.hejun@gmail.com>
[ penberg@kernel.org: check fscanf() for errors ]
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/include/kvm/uip.h b/tools/kvm/include/kvm/uip.h
index 6534c7f19e95259f0fe3d87709842bcee390e414..e645d3f15be9e288739d65e0e75daf26e45d97d6 100644 (file)
--- a/tools/kvm/include/kvm/uip.h
+++ b/tools/kvm/include/kvm/uip.h
@@ -42,6 +42,8 @@
 #define UIP_DHCP_OFFER                 2
 #define UIP_DHCP_REQUEST               3
 #define UIP_DHCP_ACK                   5
+#define UIP_DHCP_MAX_DNS_SERVER_NR     3
+#define UIP_DHCP_MAX_DOMAIN_NAME_LEN   256
 #define UIP_DHCP_TAG_MSG_TYPE          53
 #define UIP_DHCP_TAG_MSG_TYPE_LEN      1
 /*
@@ -178,6 +180,8 @@ struct uip_info {
        int buf_free_nr;
        int buf_used_nr;
        u32 host_ip;
+       u32 dns_ip[UIP_DHCP_MAX_DNS_SERVER_NR];
+       char *domain_name;
        u32 buf_nr;
 };
 
@@ -327,4 +331,6 @@ struct uip_buf *uip_buf_clone(struct uip_tx_arg *arg);
 
 int uip_udp_make_pkg(struct uip_info *info, struct uip_udp_socket *sk, struct uip_buf *buf, u8 *payload, int payload_len);
 bool uip_udp_is_dhcp(struct uip_udp *udp);
+
+int uip_dhcp_get_dns(struct uip_info *info);
 #endif /* KVM__UIP_H */

diff --git a/tools/kvm/net/uip/dhcp.c b/tools/kvm/net/uip/dhcp.c
index 0a6293a1edff9242327746de73ad936afcf6c9ca..be8b616f0ac6c1b2b9894bb0feab25a16e24dd10 100644 (file)
--- a/tools/kvm/net/uip/dhcp.c
+++ b/tools/kvm/net/uip/dhcp.c
@@ -1,5 +1,7 @@
 #include "kvm/uip.h"
 
+#include <arpa/inet.h>
+
 static inline bool uip_dhcp_is_discovery(struct uip_dhcp *dhcp)
 {
        return (dhcp->option[2] == UIP_DHCP_DISCOVER &&
@@ -29,3 +31,36 @@ bool uip_udp_is_dhcp(struct uip_udp *udp)
 
        return true;
 }
+
+int uip_dhcp_get_dns(struct uip_info *info)
+{
+       char key[256], val[256];
+       struct in_addr addr;
+       int ret = -1;
+       int n = 0;
+       FILE *fp;
+       u32 ip;
+
+       fp = fopen("/etc/resolv.conf", "r");
+       if (!fp)
+               goto out;
+
+       while (!feof(fp)) {
+               if (fscanf(fp, "%s %s\n", key, val) != 2)
+                       continue;
+               if (strncmp("domain", key, 6) == 0)
+                       info->domain_name = strndup(val, UIP_DHCP_MAX_DOMAIN_NAME_LEN);
+               else if (strncmp("nameserver", key, 10) == 0) {
+                       if (!inet_aton(val, &addr))
+                               continue;
+                       ip = ntohl(addr.s_addr);
+                       if (n < UIP_DHCP_MAX_DNS_SERVER_NR)
+                               info->dns_ip[n++] = ip;
+                       ret = 0;
+               }
+       }
+
+out:
+       fclose(fp);
+       return ret;
+}