Changeset d531bd6 in mainline

Timestamp:

2013-05-08T09:24:24Z (12 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

9f029aa

Parents:

06fe3b6

Message:

Handle CNAME records.

Location:

uspace/srv/net/dnsrsrv

Files:

• dns_msg.c (modified) (4 diffs)
• dns_msg.h (modified) (1 diff)
• dns_type.h (modified) (2 diffs)
• query.c (modified) (5 diffs)

uspace/srv/net/dnsrsrv/dns_msg.c

@@ -135 +135 @@
 }
 
-static int dns_name_decode(uint8_t *buf, size_t size, size_t boff, char **rname,
+int dns_name_decode(uint8_t *buf, size_t size, size_t boff, char **rname,
     size_t *eoff)
 {
@@ -405 +405 @@
 
         memcpy(rr->rdata, bp, rdlength);
+        rr->roff = bp - buf;
         bp += rdlength;
         bsz -= rdlength;
@@ -491 +492 @@
                 return ENOMEM;
 
-        if (size < sizeof(dns_header_t))
-                return EINVAL;
+        if (size < sizeof(dns_header_t)) {
+                rc = EINVAL;
+                goto error;
+        }
+
+        /* Store a copy of raw message data for string decompression */
+
+        msg->raw = malloc(size);
+        if (msg->raw == NULL) {
+                rc = EINVAL;
+                goto error;
+        }
+
+        memcpy(msg->raw, data, size);
+        msg->raw_size = size;
+        log_msg(LOG_DEFAULT, LVL_NOTE, "dns_message_decode: msg->raw = %p, msg->raw_size=%zu",
+            msg->raw, msg->raw_size);
 
         hdr = data;
@@ -605 +621 @@
         }
 
+        free(msg->raw);
         free(msg);
 }

uspace/srv/net/dnsrsrv/dns_msg.h

@@ -47 +47 @@
 extern dns_message_t *dns_message_new(void);
 extern void dns_message_destroy(dns_message_t *);
+extern int dns_name_decode(uint8_t *, size_t, size_t, char **, size_t *);
 extern uint32_t dns_uint32_t_decode(uint8_t *, size_t);
 

uspace/srv/net/dnsrsrv/dns_type.h

@@ -43 +43 @@
 #include "dns_std.h"
 
-/** Unencoded DNS message */
+/** DNS message */
 typedef struct {
+        /** Raw message data */
+        void *raw;
+        /** Raw message size */
+        size_t raw_size;
+
         /** Identifier */
         uint16_t id;
@@ -95 +100 @@
         /** Number of bytes in @c *rdata */
         size_t rdata_size;
+        /** Offset in the raw message */
+        size_t roff;
 } dns_rr_t;
 

uspace/srv/net/dnsrsrv/query.c

@@ -54 +54 @@
         dns_question_t *question;
         dns_host_info_t *info;
+        char *sname, *cname;
+        size_t eoff;
         int rc;
 
@@ -83 +85 @@
         }
 
+        /* Start with the caller-provided name */
+        sname = str_dup(name);
+
         list_foreach(amsg->answer, link) {
                 dns_rr_t *rr = list_get_instance(link, dns_rr_t, msg);
@@ -89 +94 @@
                         rr->name, rr->rtype, rr->rclass, rr->rdata_size);
 
+                if (rr->rtype == DTYPE_CNAME && rr->rclass == DC_IN &&
+                    str_cmp(rr->name, sname) == 0) {
+                        log_msg(LOG_DEFAULT, LVL_DEBUG, "decode cname (%p, %zu, %zu)",
+                            amsg->raw, amsg->raw_size, rr->roff);
+                        rc = dns_name_decode(amsg->raw, amsg->raw_size, rr->roff,
+                            &cname, &eoff);
+                        if (rc != EOK) {
+                                log_msg(LOG_DEFAULT, LVL_DEBUG,
+                                    "error decoding cname");
+                                assert(rc == EINVAL || rc == ENOMEM);
+                                dns_message_destroy(msg);
+                                dns_message_destroy(amsg);
+                                return rc;
+                        }
+
+                        log_msg(LOG_DEFAULT, LVL_DEBUG, "name = '%s' "
+                            "cname = '%s'", sname, cname);
+
+                        free(sname);
+                        /* Continue looking for the more canonical name */
+                        sname = cname;
+                }
+
                 if (rr->rtype == DTYPE_A && rr->rclass == DC_IN &&
-                        rr->rdata_size == sizeof(uint32_t)) {
+                        rr->rdata_size == sizeof(uint32_t) &&
+                            str_cmp(rr->name, sname) == 0) {
 
                         info = calloc(1, sizeof(dns_host_info_t));
                         if (info == NULL) {
+                                dns_message_destroy(msg);
                                 dns_message_destroy(amsg);
                                 return ENOMEM;
@@ -100 +130 @@
                         info->name = str_dup(rr->name);
                         info->addr.ipv4 = dns_uint32_t_decode(rr->rdata, rr->rdata_size);
-                        log_msg(LOG_DEFAULT, LVL_DEBUG, "info->addr = %x",
-                            info->addr.ipv4);
+                        log_msg(LOG_DEFAULT, LVL_DEBUG, "info->name = '%s' "
+                            "info->addr = %x", info->name, info->addr.ipv4);
 
                         dns_message_destroy(msg);
@@ -112 +142 @@
         dns_message_destroy(msg);
         dns_message_destroy(amsg);
-        log_msg(LOG_DEFAULT, LVL_DEBUG, "No A/IN found, fail");
+        log_msg(LOG_DEFAULT, LVL_DEBUG, "'%s' not resolved, fail", sname);
 
         return EIO;