c-ares · kylebevans · Jan 25, 2021 · Jan 25, 2021 · Jan 30, 2021 · Jan 30, 2021
diff --git a/.gitignore b/.gitignore
@@ -54,3 +54,4 @@ CHANGES.dist
 c-ares-*.tar.gz.asc
 ares_parse_mx_reply.pdf
 /[0-9]*.patch
+.dirstamp
diff --git a/include/ares.h b/include/ares.h
@@ -545,6 +545,10 @@ struct ares_srv_reply {
   unsigned short          port;
 };
 
+struct cares_srv_reply;
+
+typedef struct cares_srv_reply cares_srv_reply;
+
 struct ares_mx_reply {
   struct ares_mx_reply   *next;
   char                   *host;
@@ -647,8 +651,8 @@ CARES_EXTERN int ares_parse_aaaa_reply(const unsigned char *abuf,
                                        int *naddrttls);
 
 CARES_EXTERN int ares_parse_caa_reply(const unsigned char* abuf,
-				      int alen,
-				      struct ares_caa_reply** caa_out);
+				                              int alen,
+				                              struct ares_caa_reply** caa_out);
 
 CARES_EXTERN int ares_parse_ptr_reply(const unsigned char *abuf,
                                       int alen,
@@ -665,9 +669,47 @@ CARES_EXTERN int ares_parse_srv_reply(const unsigned char* abuf,
                                       int alen,
                                       struct ares_srv_reply** srv_out);
 
+CARES_EXTERN int cares_parse_srv_reply(const unsigned char* abuf,
+                                          int alen,
+                                          struct cares_srv_reply** srv_out);
+
+CARES_EXTERN struct cares_srv_reply*
+cares_srv_reply_get_next(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN char* cares_srv_reply_get_host(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN unsigned short
+cares_srv_reply_get_priority(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN unsigned short
+cares_srv_reply_get_weight(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN unsigned short
+cares_srv_reply_get_port(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN int cares_srv_reply_get_ttl(const cares_srv_reply* srv_reply);
+
+CARES_EXTERN void cares_srv_reply_set_next(cares_srv_reply* srv_reply,
+                                           struct cares_srv_reply* next);
+
+CARES_EXTERN void
+cares_srv_reply_set_host(cares_srv_reply* srv_reply, char* host);
+
+CARES_EXTERN void cares_srv_reply_set_priority(cares_srv_reply* srv_reply,
+                                               const unsigned short priority);
+
+CARES_EXTERN void cares_srv_reply_set_weight(cares_srv_reply* srv_reply,
+                                             const unsigned short weight);
+
+CARES_EXTERN void cares_srv_reply_set_port(cares_srv_reply* srv_reply,
+                                           const unsigned short port);
+
+CARES_EXTERN void cares_srv_reply_set_ttl(cares_srv_reply* srv_reply,
+                                          const int ttl);
+
 CARES_EXTERN int ares_parse_mx_reply(const unsigned char* abuf,
-                                      int alen,
-                                      struct ares_mx_reply** mx_out);
+                                     int alen,
+                                     struct ares_mx_reply** mx_out);
 
 CARES_EXTERN int ares_parse_txt_reply(const unsigned char* abuf,
                                       int alen,
@@ -682,8 +724,8 @@ CARES_EXTERN int ares_parse_naptr_reply(const unsigned char* abuf,
                                         struct ares_naptr_reply** naptr_out);
 
 CARES_EXTERN int ares_parse_soa_reply(const unsigned char* abuf,
-				      int alen,
-				      struct ares_soa_reply** soa_out);
+				                              int alen,
+				                              struct ares_soa_reply** soa_out);
 
 CARES_EXTERN void ares_free_string(void *str);
 

diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc
@@ -38,10 +38,12 @@ CSOURCES = ares__close_sockets.c	\
   ares_parse_ptr_reply.c		\
   ares_parse_soa_reply.c		\
   ares_parse_srv_reply.c		\
+  cares_parse_srv_reply.c		\
   ares_parse_txt_reply.c		\
   ares_platform.c			\
   ares_process.c			\
   ares_query.c				\
+  cares_reply.c				\
   ares_search.c				\
   ares_send.c				\
   ares_strcasecmp.c			\

diff --git a/src/lib/ares_data.c b/src/lib/ares_data.c
@@ -34,6 +34,7 @@
 ** function is:
 **
 **   ares_get_servers()
+**   cares_parse_srv_reply()
 **   ares_parse_srv_reply()
 **   ares_parse_txt_reply()
 */
@@ -70,6 +71,7 @@ void ares_free_data(void *dataptr)
           break;
 
         case ARES_DATATYPE_SRV_REPLY:
+        case ARES_DATATYPE_CSRV_REPLY:
 
           if (ptr->data.srv_reply.next)
             next_data = ptr->data.srv_reply.next;
@@ -120,7 +122,7 @@ void ares_free_data(void *dataptr)
           break;
 
         case ARES_DATATYPE_CAA_REPLY:
- 
+
           if (ptr->data.caa_reply.next)
             next_data = ptr->data.caa_reply.next;
           if (ptr->data.caa_reply.property)
@@ -166,6 +168,10 @@ void *ares_malloc_data(ares_datatype type)
         ptr->data.mx_reply.priority = 0;
         break;
 
+      case ARES_DATATYPE_CSRV_REPLY:
+        ptr->data.csrv_reply.ttl = 0;
+        /* FALLTHROUGH */
+
       case ARES_DATATYPE_SRV_REPLY:
         ptr->data.srv_reply.next = NULL;
         ptr->data.srv_reply.host = NULL;

diff --git a/src/lib/ares_data.h b/src/lib/ares_data.h
@@ -14,9 +14,11 @@
  * without express or implied warranty.
  */
 
+#include "ares_private.h"
 typedef enum {
   ARES_DATATYPE_UNKNOWN = 1,  /* unknown data type     - introduced in 1.7.0 */
   ARES_DATATYPE_SRV_REPLY,    /* struct ares_srv_reply - introduced in 1.7.0 */
+  ARES_DATATYPE_CSRV_REPLY,      /* struct cares_srv_reply */
   ARES_DATATYPE_TXT_REPLY,    /* struct ares_txt_reply - introduced in 1.7.0 */
   ARES_DATATYPE_TXT_EXT,      /* struct ares_txt_ext   - introduced in 1.11.0 */
   ARES_DATATYPE_ADDR_NODE,    /* struct ares_addr_node - introduced in 1.7.1 */
@@ -61,6 +63,7 @@ struct ares_data {
     struct ares_txt_reply    txt_reply;
     struct ares_txt_ext      txt_ext;
     struct ares_srv_reply    srv_reply;
+    struct cares_srv_reply   csrv_reply;
     struct ares_addr_node    addr_node;
     struct ares_addr_port_node  addr_port_node;
     struct ares_mx_reply     mx_reply;

diff --git a/src/lib/ares_parse_srv_reply.c b/src/lib/ares_parse_srv_reply.c
@@ -38,128 +38,73 @@ int
 ares_parse_srv_reply (const unsigned char *abuf, int alen,
                       struct ares_srv_reply **srv_out)
 {
-  unsigned int qdcount, ancount, i;
-  const unsigned char *aptr, *vptr;
-  int status, rr_type, rr_class, rr_len;
-  long len;
-  char *hostname = NULL, *rr_name = NULL;
+
+  /* call cares_parse_srv_reply, iterate through the result and
+   * create a linked list of struct ares_srv_reply to return */
+
+  int status;
   struct ares_srv_reply *srv_head = NULL;
+  struct ares_srv_reply *srv_curr = NULL;
   struct ares_srv_reply *srv_last = NULL;
-  struct ares_srv_reply *srv_curr;
+  struct cares_srv_reply *csrv_curr = NULL;
+  struct cares_srv_reply *csrv_out = NULL;
 
   /* Set *srv_out to NULL for all failure cases. */
   *srv_out = NULL;
 
-  /* Give up if abuf doesn't have room for a header. */
-  if (alen < HFIXEDSZ)
-    return ARES_EBADRESP;
-
-  /* Fetch the question and answer count from the header. */
-  qdcount = DNS_HEADER_QDCOUNT (abuf);
-  ancount = DNS_HEADER_ANCOUNT (abuf);
-  if (qdcount != 1)
-    return ARES_EBADRESP;
-  if (ancount == 0)
-    return ARES_ENODATA;
-
-  /* Expand the name from the question, and skip past the question. */
-  aptr = abuf + HFIXEDSZ;
-  status = ares_expand_name (aptr, abuf, alen, &hostname, &len);
+  status = cares_parse_srv_reply(abuf, alen, &csrv_out);
+
+  /* clean up on error */
   if (status != ARES_SUCCESS)
+  {
+    if (srv_out)
+      ares_free_data (*srv_out);
     return status;
-
-  if (aptr + len + QFIXEDSZ > abuf + alen)
+  }
+
+  /* iterate through the cares_srv_reply list and
+   * create a new ares_srv_reply */
+  for (csrv_curr = csrv_out; csrv_curr;
+    csrv_curr = cares_srv_reply_get_next(csrv_curr))
+  {
+    srv_curr = ares_malloc_data(ARES_DATATYPE_SRV_REPLY);
+    if (!srv_curr)
     {
-      ares_free (hostname);
-      return ARES_EBADRESP;
+      status = ARES_ENOMEM;
+      break;
     }
-  aptr += len + QFIXEDSZ;
-
-  /* Examine each answer resource record (RR) in turn. */
-  for (i = 0; i < ancount; i++)
+    if (srv_last)
+    {
+      srv_last->next = srv_curr;
+    }
+    else
+    {
+      srv_head = srv_curr;
+    }
+    srv_last = srv_curr;
+    srv_curr->host = cares_srv_reply_get_host(csrv_curr);
+    if (!srv_curr->host)
     {
-      /* Decode the RR up to the data field. */
-      status = ares_expand_name (aptr, abuf, alen, &rr_name, &len);
-      if (status != ARES_SUCCESS)
-        {
-          break;
-        }
-      aptr += len;
-      if (aptr + RRFIXEDSZ > abuf + alen)
-        {
-          status = ARES_EBADRESP;
-          break;
-        }
-      rr_type = DNS_RR_TYPE (aptr);
-      rr_class = DNS_RR_CLASS (aptr);
-      rr_len = DNS_RR_LEN (aptr);
-      aptr += RRFIXEDSZ;
-      if (aptr + rr_len > abuf + alen)
-        {
-          status = ARES_EBADRESP;
-          break;
-        }
-
-      /* Check if we are really looking at a SRV record */
-      if (rr_class == C_IN && rr_type == T_SRV)
-        {
-          /* parse the SRV record itself */
-          if (rr_len < 6)
-            {
-              status = ARES_EBADRESP;
-              break;
-            }
-
-          /* Allocate storage for this SRV answer appending it to the list */
-          srv_curr = ares_malloc_data(ARES_DATATYPE_SRV_REPLY);
-          if (!srv_curr)
-            {
-              status = ARES_ENOMEM;
-              break;
-            }
-          if (srv_last)
-            {
-              srv_last->next = srv_curr;
-            }
-          else
-            {
-              srv_head = srv_curr;
-            }
-          srv_last = srv_curr;
-
-          vptr = aptr;
-          srv_curr->priority = DNS__16BIT(vptr);
-          vptr += sizeof(unsigned short);
-          srv_curr->weight = DNS__16BIT(vptr);
-          vptr += sizeof(unsigned short);
-          srv_curr->port = DNS__16BIT(vptr);
-          vptr += sizeof(unsigned short);
-
-          status = ares_expand_name (vptr, abuf, alen, &srv_curr->host, &len);
-          if (status != ARES_SUCCESS)
-            break;
-        }
-
-      /* Don't lose memory in the next iteration */
-      ares_free (rr_name);
-      rr_name = NULL;
-
-      /* Move on to the next record */
-      aptr += rr_len;
+      status = ARES_ENOMEM;
+      break;
     }
+    srv_curr->priority = cares_srv_reply_get_priority(csrv_curr);
+    srv_curr->weight = cares_srv_reply_get_weight(csrv_curr);
+    srv_curr->port = cares_srv_reply_get_port(csrv_curr);
+  }
 
-  if (hostname)
-    ares_free (hostname);
-  if (rr_name)
-    ares_free (rr_name);
+  if (csrv_out)
+  {
+    ares_free_data (csrv_out);
+  }
 
-  /* clean up on error */
+    /* clean up on error */
   if (status != ARES_SUCCESS)
-    {
-      if (srv_head)
-        ares_free_data (srv_head);
-      return status;
-    }
+  {
+    if (srv_head)
+      ares_free_data (srv_head);
+    return status;
+  }
 
   /* everything looks fine, return the data */
   *srv_out = srv_head;

diff --git a/src/lib/ares_private.h b/src/lib/ares_private.h
@@ -416,4 +416,18 @@ int ares__connect_socket(ares_channel channel,
       (c)->sock_state_cb((c)->sock_state_cb_data, (s), (r), (w));       \
   } WHILE_FALSE
 
+/* Private definition of c-ares srv reply so that c-ares users
+ * only have access to the type definition in ares.h and must use
+ * accessor functions to interact with the struct.  This way,
+ * cares_srv_reply can be modified without breaking ABI.
+ */
+ struct cares_srv_reply {
+  struct cares_srv_reply *next;
+  char                   *host;
+  unsigned short          priority;
+  unsigned short          weight;
+  unsigned short          port;
+  int                     ttl;
+};
+
 #endif /* __ARES_PRIVATE_H */