use thread-local buffer for decoding

to save on heap memory allocation

diff --git a/src/protocols/dhcpv4/decode.c b/src/protocols/dhcpv4/decode.c
index 24147840867a96ea618dc75e2630176012a91f42..fefefc0132801eee456d32be7c9c323c04cacaa1 100644 (file)
--- a/src/protocols/dhcpv4/decode.c
+++ b/src/protocols/dhcpv4/decode.c
@@ -32,6 +32,8 @@
 #include "dhcpv4.h"
 #include "attrs.h"
 
+static _Thread_local uint8_t   concat_buffer[1500]; /* ethernet max */
+
 static ssize_t decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                              fr_dict_attr_t const *parent,
                              uint8_t const *data, size_t const data_len, void *decode_ctx);
@@ -579,18 +581,14 @@ ssize_t fr_dhcpv4_decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                uint8_t *q;
                fr_dict_attr_t const *da;
 
-               if (!packet_ctx->buffer) {
-                       packet_ctx->buffer = talloc_array(packet_ctx->tmp_ctx, uint8_t, data_len);
-                       if (!packet_ctx->buffer) return PAIR_DECODE_OOM;
-
-               } else if (talloc_array_length(packet_ctx->buffer) < data_len) {
-                       /*
-                        *      We're called in a loop from fr_dhcpv4_decode(), with the full packet, so the
-                        *      needed size should only go down as we decode the packet.
-                        */
+               /*
+                *      The maximum DHCPv4 packet size is 576 bytes,
+                *      unless the other end negotiates more.
+                */
+               if (sizeof(concat_buffer) < data_len) {
                        return -1;
                }
-               q = packet_ctx->buffer;
+               q = concat_buffer;
 
                for (next = data; next < end; next += 2 + next[1]) {
                        if ((end - next) < 2) return -1;
@@ -606,20 +604,20 @@ ssize_t fr_dhcpv4_decode_option(TALLOC_CTX *ctx, fr_pair_list_t *out,
                        da = fr_dict_unknown_attr_afrom_num(packet_ctx->tmp_ctx, fr_dict_root(dict_dhcpv4), p[0]);
                        if (!da) return -1;
 
-                       slen = fr_pair_raw_from_network(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer);
+                       slen = fr_pair_raw_from_network(ctx, out, da, concat_buffer, q - concat_buffer);
 
                } else if (da->type == FR_TYPE_VSA) {
-                       slen = decode_vsa(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx);
+                       slen = decode_vsa(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx);
 
                } else if (da->type == FR_TYPE_TLV) {
-                       slen = fr_pair_tlvs_from_network(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer,
+                       slen = fr_pair_tlvs_from_network(ctx, out, da, concat_buffer, q - concat_buffer,
                                                         packet_ctx, decode_option, verify_tlvs, true);
 
                } else if (da->flags.array) {
-                       slen = fr_pair_array_from_network(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx, decode_value);
+                       slen = fr_pair_array_from_network(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx, decode_value);
 
                } else {
-                       slen = decode_value(ctx, out, da, packet_ctx->buffer, q - packet_ctx->buffer, packet_ctx);
+                       slen = decode_value(ctx, out, da, concat_buffer, q - concat_buffer, packet_ctx);
                }
                if (slen <= 0) return slen;
 

diff --git a/src/protocols/dhcpv4/dhcpv4.h b/src/protocols/dhcpv4/dhcpv4.h
index 4a1a5ecbad23771f5be8f63822af2ad60d7d24cd..8bc8ef111ad843dfa569f65df08644ae79f61c62 100644 (file)
--- a/src/protocols/dhcpv4/dhcpv4.h
+++ b/src/protocols/dhcpv4/dhcpv4.h
@@ -151,7 +151,6 @@ extern HIDDEN fr_dict_attr_t const  *dhcp_option_82;
  */
 typedef struct {
        fr_dict_attr_t const *root;
-       uint8_t         *buffer;                //! for coalescing concatenated options
        TALLOC_CTX      *tmp_ctx;               //!< for temporary things cleaned up during decoding
 } fr_dhcpv4_ctx_t;