[dhcp] Allow use of custom reallocation functions for DHCP option blocks

Allow functions other than realloc() to be used to reallocate DHCP
option block data, and specify the reallocation function at the time
of calling dhcpopt_init().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/nvo.c b/src/core/nvo.c
index 1a886c0f865f5f4bf34c965b1208a8bb324d4d76..9b325db759d8c553352604a5d69d07265d4dc1e3 100644 (file)
--- a/src/core/nvo.c
+++ b/src/core/nvo.c
@@ -133,7 +133,8 @@ static void nvo_init_dhcpopts ( struct nvo_block *nvo ) {
                memset ( nvo->data, 0, nvo->total_len );
        }
 
-       dhcpopt_init ( &nvo->dhcpopts, options_data, options_len );
+       dhcpopt_init ( &nvo->dhcpopts, options_data, options_len,
+                      dhcpopt_no_realloc );
 }
 
 /**

diff --git a/src/include/ipxe/dhcpopts.h b/src/include/ipxe/dhcpopts.h
index d88036e3aca17c3b469c5be973159af2f4727166..fe07d903d3cd836ad4bbcc86294049008d9d5483 100644 (file)
--- a/src/include/ipxe/dhcpopts.h
+++ b/src/include/ipxe/dhcpopts.h
@@ -19,16 +19,23 @@ struct dhcp_options {
        size_t used_len;
        /** Option block allocated length */
        size_t alloc_len;
+       /** Reallocate option block raw data
+        *
+        * @v options           DHCP option block
+        * @v len               New length
+        * @ret rc              Return status code
+        */
+       int ( * realloc ) ( struct dhcp_options *options, size_t len );
 };
 
 extern int dhcpopt_store ( struct dhcp_options *options, unsigned int tag,
                           const void *data, size_t len );
-extern int dhcpopt_extensible_store ( struct dhcp_options *options,
-                                     unsigned int tag,
-                                     const void *data, size_t len );
 extern int dhcpopt_fetch ( struct dhcp_options *options, unsigned int tag,
                           void *data, size_t len );
 extern void dhcpopt_init ( struct dhcp_options *options,
-                          void *data, size_t alloc_len );
+                          void *data, size_t alloc_len,
+                          int ( * realloc ) ( struct dhcp_options *options,
+                                              size_t len ) );
+extern int dhcpopt_no_realloc ( struct dhcp_options *options, size_t len );
 
 #endif /* _IPXE_DHCPOPTS_H */

diff --git a/src/net/dhcpopts.c b/src/net/dhcpopts.c
index 214a8244ce6a6a359b1961835702d2702bd431d4..d1330eae50d319901317a4c35cfe8e784c02eaeb 100644 (file)
--- a/src/net/dhcpopts.c
+++ b/src/net/dhcpopts.c
@@ -169,6 +169,17 @@ static int find_dhcp_option_with_encap ( struct dhcp_options *options,
        return -ENOENT;
 }
 
+/**
+ * Refuse to reallocate DHCP option block
+ *
+ * @v options          DHCP option block
+ * @v len              New length
+ * @ret rc             Return status code
+ */
+int dhcpopt_no_realloc ( struct dhcp_options *options, size_t len ) {
+       return ( ( len <= options->alloc_len ) ? 0 : -ENOSPC );
+}
+
 /**
  * Resize a DHCP option
  *
@@ -177,46 +188,44 @@ static int find_dhcp_option_with_encap ( struct dhcp_options *options,
  * @v encap_offset     Offset of encapsulating offset (or -ve for none)
  * @v old_len          Old length (including header)
  * @v new_len          New length (including header)
- * @v can_realloc      Can reallocate options data if necessary
  * @ret rc             Return status code
  */
 static int resize_dhcp_option ( struct dhcp_options *options,
                                int offset, int encap_offset,
-                               size_t old_len, size_t new_len,
-                               int can_realloc ) {
+                               size_t old_len, size_t new_len ) {
        struct dhcp_option *encapsulator;
        struct dhcp_option *option;
        ssize_t delta = ( new_len - old_len );
-       size_t new_options_len;
+       size_t old_alloc_len;
+       size_t new_used_len;
        size_t new_encapsulator_len;
-       void *new_data;
        void *source;
        void *dest;
        void *end;
+       int rc;
 
-       /* Check for sufficient space, and update length fields */
+       /* Check for sufficient space */
        if ( new_len > DHCP_MAX_LEN ) {
                DBGC ( options, "DHCPOPT %p overlength option\n", options );
                return -ENOSPC;
        }
-       new_options_len = ( options->used_len + delta );
-       if ( new_options_len > options->alloc_len ) {
-               /* Reallocate options block if allowed to do so. */
-               if ( can_realloc ) {
-                       new_data = realloc ( options->data, new_options_len );
-                       if ( ! new_data ) {
-                               DBGC ( options, "DHCPOPT %p could not "
-                                      "reallocate to %zd bytes\n", options,
-                                      new_options_len );
-                               return -ENOMEM;
-                       }
-                       options->data = new_data;
-                       options->alloc_len = new_options_len;
-               } else {
-                       DBGC ( options, "DHCPOPT %p out of space\n", options );
-                       return -ENOMEM;
+       new_used_len = ( options->used_len + delta );
+
+       /* Expand options block, if necessary */
+       if ( new_used_len > options->alloc_len ) {
+               /* Reallocate options block */
+               old_alloc_len = options->alloc_len;
+               if ( ( rc = options->realloc ( options, new_used_len ) ) != 0 ){
+                       DBGC ( options, "DHCPOPT %p could not reallocate to "
+                              "%zd bytes\n", options, new_used_len );
+                       return rc;
                }
+               /* Clear newly allocated space */
+               memset ( ( options->data + old_alloc_len ), 0,
+                        ( options->alloc_len - old_alloc_len ) );
        }
+
+       /* Update encapsulator, if applicable */
        if ( encap_offset >= 0 ) {
                encapsulator = dhcp_option ( options, encap_offset );
                new_encapsulator_len = ( encapsulator->len + delta );
@@ -227,7 +236,9 @@ static int resize_dhcp_option ( struct dhcp_options *options,
                }
                encapsulator->len = new_encapsulator_len;
        }
-       options->used_len = new_options_len;
+
+       /* Update used length */
+       options->used_len = new_used_len;
 
        /* Move remainder of option data */
        option = dhcp_option ( options, offset );
@@ -236,6 +247,15 @@ static int resize_dhcp_option ( struct dhcp_options *options,
        end = ( options->data + options->alloc_len );
        memmove ( dest, source, ( end - dest ) );
 
+       /* Shrink options block, if applicable */
+       if ( new_used_len < options->alloc_len ) {
+               if ( ( rc = options->realloc ( options, new_used_len ) ) != 0 ){
+                       DBGC ( options, "DHCPOPT %p could not reallocate to "
+                              "%zd bytes\n", options, new_used_len );
+                       return rc;
+               }
+       }
+
        return 0;
 }
 
@@ -246,7 +266,6 @@ static int resize_dhcp_option ( struct dhcp_options *options,
  * @v tag              DHCP option tag
  * @v data             New value for DHCP option
  * @v len              Length of value, in bytes
- * @v can_realloc      Can reallocate options data if necessary
  * @ret offset         Offset of DHCP option, or negative error
  *
  * Sets the value of a DHCP option within the options block.  The
@@ -258,9 +277,8 @@ static int resize_dhcp_option ( struct dhcp_options *options,
  * be left with its original value.
  */
 static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
-                            const void *data, size_t len,
-                            int can_realloc ) {
-       static const uint8_t empty_encapsulator[] = { DHCP_END };
+                            const void *data, size_t len ) {
+       static const uint8_t empty_encap[] = { DHCP_END };
        int offset;
        int encap_offset = -1;
        int creation_offset;
@@ -291,10 +309,12 @@ static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
 
        /* Ensure that encapsulator exists, if required */
        if ( encap_tag ) {
-               if ( encap_offset < 0 )
-                       encap_offset = set_dhcp_option ( options, encap_tag,
-                                                        empty_encapsulator, 1,
-                                                        can_realloc );
+               if ( encap_offset < 0 ) {
+                       encap_offset =
+                               set_dhcp_option ( options, encap_tag,
+                                                 empty_encap,
+                                                 sizeof ( empty_encap ) );
+               }
                if ( encap_offset < 0 )
                        return encap_offset;
                creation_offset = ( encap_offset + DHCP_OPTION_HEADER_LEN );
@@ -306,8 +326,7 @@ static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
 
        /* Resize option to fit new data */
        if ( ( rc = resize_dhcp_option ( options, offset, encap_offset,
-                                        old_len, new_len,
-                                        can_realloc ) ) != 0 )
+                                        old_len, new_len ) ) != 0 )
                return rc;
 
        /* Copy new data into option, if applicable */
@@ -322,7 +341,7 @@ static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
        if ( encap_offset >= 0 ) {
                option = dhcp_option ( options, encap_offset );
                if ( option->len <= 1 )
-                       set_dhcp_option ( options, encap_tag, NULL, 0, 0 );
+                       set_dhcp_option ( options, encap_tag, NULL, 0 );
        }
 
        return offset;
@@ -341,26 +360,7 @@ int dhcpopt_store ( struct dhcp_options *options, unsigned int tag,
                    const void *data, size_t len ) {
        int offset;
 
-       offset = set_dhcp_option ( options, tag, data, len, 0 );
-       if ( offset < 0 )
-               return offset;
-       return 0;
-}
-
-/**
- * Store value of DHCP option setting, extending options block if necessary
- *
- * @v options          DHCP option block
- * @v tag              Setting tag number
- * @v data             Setting data, or NULL to clear setting
- * @v len              Length of setting data
- * @ret rc             Return status code
- */
-int dhcpopt_extensible_store ( struct dhcp_options *options, unsigned int tag,
-                              const void *data, size_t len ) {
-       int offset;
-
-       offset = set_dhcp_option ( options, tag, data, len, 1 );
+       offset = set_dhcp_option ( options, tag, data, len );
        if ( offset < 0 )
                return offset;
        return 0;
@@ -428,16 +428,19 @@ static void dhcpopt_update_used_len ( struct dhcp_options *options ) {
  * @v options          Uninitialised DHCP option block
  * @v data             Memory for DHCP option data
  * @v alloc_len                Length of memory for DHCP option data
+ * @v realloc          DHCP option block reallocator
  *
  * The memory content must already be filled with valid DHCP options.
  * A zeroed block counts as a block of valid DHCP options.
  */
-void dhcpopt_init ( struct dhcp_options *options, void *data,
-                   size_t alloc_len ) {
+void dhcpopt_init ( struct dhcp_options *options, void *data, size_t alloc_len,
+                   int ( * realloc ) ( struct dhcp_options *options,
+                                       size_t len ) ) {
 
        /* Fill in fields */
        options->data = data;
        options->alloc_len = alloc_len;
+       options->realloc = realloc;
 
        /* Update length */
        dhcpopt_update_used_len ( options );

diff --git a/src/net/dhcppkt.c b/src/net/dhcppkt.c
index e043bb5d4a601417ff62cda3e52a22d06b5d5206..237c3e2cf609b1da3e5ebcae29257d16e85d9133 100644 (file)
--- a/src/net/dhcppkt.c
+++ b/src/net/dhcppkt.c
@@ -267,7 +267,8 @@ void dhcppkt_init ( struct dhcp_packet *dhcppkt, struct dhcphdr *data,
        ref_init ( &dhcppkt->refcnt, NULL );
        dhcppkt->dhcphdr = data;
        dhcpopt_init ( &dhcppkt->options, &dhcppkt->dhcphdr->options,
-                      ( len - offsetof ( struct dhcphdr, options ) ) );
+                      ( len - offsetof ( struct dhcphdr, options ) ),
+                      dhcpopt_no_realloc );
        settings_init ( &dhcppkt->settings,
                        &dhcppkt_settings_operations, &dhcppkt->refcnt, 0 );
 }