Added sequential dns resolver function for netconn api (netconn_gethostbyname)

CHANGELOG

@@ -19,6 +19,10 @@ HISTORY
 
   ++ New features:
 
+  2007-11-16 Simon Goldschmidt
+  * api.h, api_msg.h, api_lib.c, api_msg.c: Added sequential dns resolver
+    function for netconn api (netconn_gethostbyname).  
+
   2007-11-15 Jim Pettinato, Frédéric Bernon
   * opt.h, init.c, tcpip.c, dhcp.c, dns.h, dns.c: add DNS client for simple name
     requests with RAW api interface. Initialization is done in lwip_init() with

src/api/api_lib.c

@@ -566,4 +566,40 @@ netconn_join_leave_group(struct netconn *conn,
 }
 #endif /* LWIP_IGMP */
 
+#if LWIP_DNS
+/**
+ * Execute a DNS query, only one IP address is returned
+ *
+ * @param name a string representation of the DNS host name to query
+ * @param addr a preallocated struct ip_addr where to store the resolved IP address
+ * @return an error returned by the dns module, ERR_OK if resolving succeeded
+ */
+err_t
+netconn_gethostbyname(const char *name, struct ip_addr *addr)
+{
+  struct dns_api_msg msg;
+  err_t err;
+  sys_sem_t sem;
+
+  LWIP_ERROR("netconn_gethostbyname: invalid name", (name != NULL), return ERR_ARG;);
+  LWIP_ERROR("netconn_gethostbyname: invalid addr", (addr != NULL), return ERR_ARG;);
+
+  sem = sys_sem_new(0);
+  if (sem == SYS_SEM_NULL) {
+    return ERR_MEM;
+  }
+
+  msg.name = name;
+  msg.addr = addr;
+  msg.err = &err;
+  msg.sem = sem;
+
+  tcpip_callback(do_gethostbyname, &msg);
+  sys_sem_wait(sem);
+  sys_sem_free(sem);
+
+  return err;
+}
+#endif /* LWIP_DNS*/
+
 #endif /* LWIP_NETCONN */

src/api/api_msg.c

@@ -50,6 +50,7 @@
 #include "lwip/memp.h"
 #include "lwip/tcpip.h"
 #include "lwip/igmp.h"
+#include "lwip/dns.h"
 
 /* forward declarations */
 #if LWIP_TCP
@@ -989,5 +990,58 @@ do_join_leave_group(struct api_msg_msg *msg)
 }
 #endif /* LWIP_IGMP */
 
+#if LWIP_DNS
+/**
+ * Callback function that is called when DNS name is resolved
+ * (or on timeout).
+ */
+static void
+do_dns_found(const char *name, struct ip_addr *ipaddr, void *arg)
+{
+  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
+
+  LWIP_ASSERT("DNS response for wrong host name", strcmp(msg->name, name) == 0);
+
+  if (ipaddr == NULL) {
+    /* timeout or memory error */
+    *msg->err = ERR_VAL;
+  } else {
+    /* address was resolved */
+    *msg->err = ERR_OK;
+    *msg->addr = *ipaddr;
+  }
+  /* wake up the application task waiting in netconn_gethostbyname */
+  sys_sem_signal(msg->sem);
+}
+
+/**
+ * Execute a DNS query
+ * Called from netconn_gethostbyname
+ *
+ * @param msg the dns_api_msg pointing to the query
+ */
+void
+do_gethostbyname(void *arg)
+{
+  DNS_RESULT res;
+  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
+
+  res = dns_gethostbyname(msg->name, msg->addr, do_dns_found, msg);
+  if (res != DNS_QUERY_QUEUED) {
+    /* If not queued, return to app thread directly */
+    if (res == DNS_QUERY_INVALID) {
+      /* some error occurred */
+      *msg->err = ERR_ARG;
+    } else if (res == DNS_COMPLETE) {
+      /* name was already in octet notation or cached */
+      *msg->err = ERR_OK;
+    }
+    /* on error or immediate success, wake up the application
+     * task waiting in netconn_gethostbyname */
+    sys_sem_signal(msg->sem);
+  }
+}
+#endif /* LWIP_DNS */
+
 #endif /* LWIP_NETCONN */
 

src/include/lwip/api.h

@@ -181,6 +181,9 @@ err_t             netconn_join_leave_group (struct netconn *conn,
                                             struct ip_addr *interface,
                                             enum netconn_igmp join_or_leave);
 #endif /* LWIP_IGMP */
+#if LWIP_DNS
+err_t             netconn_gethostbyname(const char *name, struct ip_addr *addr);
+#endif /* LWIP_DNS */
 
 #define netconn_err(conn)          ((conn)->err)
 #define netconn_recv_bufsize(conn) ((conn)->recv_bufsize)

src/include/lwip/api_msg.h

@@ -37,6 +37,8 @@
 #if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/ip_addr.h"
+#include "lwip/err.h"
+#include "lwip/sys.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -86,6 +88,15 @@ struct api_msg {
   struct api_msg_msg msg;
 };
 
+#if LWIP_DNS
+struct dns_api_msg {
+  const char *name;
+  struct ip_addr *addr;
+  sys_sem_t sem;
+  err_t *err;
+};
+#endif /* LWIP_DNS */
+
 void do_newconn         ( struct api_msg_msg *msg);
 void do_delconn         ( struct api_msg_msg *msg);
 void do_bind            ( struct api_msg_msg *msg);
@@ -101,6 +112,10 @@ void do_close           ( struct api_msg_msg *msg);
 void do_join_leave_group( struct api_msg_msg *msg);
 #endif /* LWIP_IGMP */
 
+#if LWIP_DNS
+void do_gethostbyname(void *arg);
+#endif /* LWIP_DNS */
+
 #ifdef __cplusplus
 }
 #endif