Add support for initialising WPACKETs from a static buffer

[openssl.git] / ssl / packet.c

diff --git a/ssl/packet.c b/ssl/packet.c
index 7d80ebc689096c2193bb21966669fa8a89028cc6..5c5513314bd3e9f2c1c16050a066a7c31edc9e40 100644 (file)
--- a/ssl/packet.c
+++ b/ssl/packet.c
@@ -13,6 +13,30 @@
 #define DEFAULT_BUF_SIZE    256
 
 int WPACKET_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)
+{
+    if (!WPACKET_reserve_bytes(pkt, len, allocbytes))
+        return 0;
+
+    pkt->written += len;
+    pkt->curr += len;
+    return 1;
+}
+
+int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len,
+                                 unsigned char **allocbytes, size_t lenbytes)
+{
+    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)
+            || !WPACKET_allocate_bytes(pkt, len, allocbytes)
+            || !WPACKET_close(pkt))
+        return 0;
+
+    return 1;
+}
+
+#define GETBUF(p)   (((p)->staticbuf != NULL) \
+                     ? (p)->staticbuf : (unsigned char *)(p)->buf->data)
+
+int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)
 {
     /* Internal API, so should not fail */
     assert(pkt->subs != NULL && len != 0);
@@ -22,33 +46,35 @@ int WPACKET_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)
     if (pkt->maxsize - pkt->written < len)
         return 0;
 
-    if (pkt->buf->length - pkt->written < len) {
+    if (pkt->staticbuf == NULL && (pkt->buf->length - pkt->written < len)) {
         size_t newlen;
+        size_t reflen;
+
+        reflen = (len > pkt->buf->length) ? len : pkt->buf->length;
 
-        if (pkt->buf->length > SIZE_MAX / 2) {
+        if (reflen > SIZE_MAX / 2) {
             newlen = SIZE_MAX;
         } else {
-            newlen = (pkt->buf->length == 0) ? DEFAULT_BUF_SIZE
-                                             : pkt->buf->length * 2;
+            newlen = reflen * 2;
+            if (newlen < DEFAULT_BUF_SIZE)
+                newlen = DEFAULT_BUF_SIZE;
         }
         if (BUF_MEM_grow(pkt->buf, newlen) == 0)
             return 0;
     }
-    *allocbytes = (unsigned char *)pkt->buf->data + pkt->curr;
-    pkt->written += len;
-    pkt->curr += len;
+    *allocbytes = GETBUF(pkt) + pkt->curr;
 
     return 1;
 }
 
-int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len,
-                                 unsigned char **allocbytes, size_t lenbytes)
+int WPACKET_sub_reserve_bytes__(WPACKET *pkt, size_t len,
+                                unsigned char **allocbytes, size_t lenbytes)
 {
-    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)
-            || !WPACKET_allocate_bytes(pkt, len, allocbytes)
-            || !WPACKET_close(pkt))
+    if (!WPACKET_reserve_bytes(pkt, lenbytes + len, allocbytes))
         return 0;
 
+    *allocbytes += lenbytes;
+
     return 1;
 }
 
@@ -60,19 +86,12 @@ static size_t maxmaxsize(size_t lenbytes)
     return ((size_t)1 << (lenbytes * 8)) - 1 + lenbytes;
 }
 
-int WPACKET_init_len(WPACKET *pkt, BUF_MEM *buf, size_t lenbytes)
+static int wpacket_intern_init_len(WPACKET *pkt, size_t lenbytes)
 {
     unsigned char *lenchars;
 
-    /* Internal API, so should not fail */
-    assert(buf != NULL);
-    if (buf == NULL)
-        return 0;
-
-    pkt->buf = buf;
     pkt->curr = 0;
     pkt->written = 0;
-    pkt->maxsize = maxmaxsize(lenbytes);
 
     pkt->subs = OPENSSL_zalloc(sizeof(*pkt->subs));
     if (pkt->subs == NULL)
@@ -89,11 +108,42 @@ int WPACKET_init_len(WPACKET *pkt, BUF_MEM *buf, size_t lenbytes)
         pkt->subs = NULL;
         return 0;
     }
-    pkt->subs->packet_len = lenchars - (unsigned char *)pkt->buf->data;
+    pkt->subs->packet_len = lenchars - GETBUF(pkt);
 
     return 1;
 }
 
+int WPACKET_init_static_len(WPACKET *pkt, unsigned char *buf, size_t len,
+                            size_t lenbytes)
+{
+    size_t max = maxmaxsize(lenbytes);
+
+    /* Internal API, so should not fail */
+    assert(buf != NULL && len > 0);
+    if (buf == NULL || len == 0)
+        return 0;
+
+    pkt->staticbuf = buf;
+    pkt->buf = NULL;
+    pkt->maxsize = (max < len) ? max : len;
+
+    return wpacket_intern_init_len(pkt, lenbytes);
+}
+
+int WPACKET_init_len(WPACKET *pkt, BUF_MEM *buf, size_t lenbytes)
+{
+    /* Internal API, so should not fail */
+    assert(buf != NULL);
+    if (buf == NULL)
+        return 0;
+
+    pkt->staticbuf = NULL;
+    pkt->buf = buf;
+    pkt->maxsize = maxmaxsize(lenbytes);
+
+    return wpacket_intern_init_len(pkt, lenbytes);
+}
+
 int WPACKET_init(WPACKET *pkt, BUF_MEM *buf)
 {
     return WPACKET_init_len(pkt, buf, 0);
@@ -155,9 +205,9 @@ static int wpacket_intern_close(WPACKET *pkt)
     }
 
     /* Write out the WPACKET length if needed */
-    if (sub->lenbytes > 0 
-                && !put_value((unsigned char *)&pkt->buf->data[sub->packet_len],
-                              packlen, sub->lenbytes))
+    if (sub->lenbytes > 0
+                && !put_value(&GETBUF(pkt)[sub->packet_len], packlen,
+                              sub->lenbytes))
             return 0;
 
     pkt->subs = sub->parent;
@@ -224,7 +274,8 @@ int WPACKET_start_sub_packet_len__(WPACKET *pkt, size_t lenbytes)
 
     if (!WPACKET_allocate_bytes(pkt, lenbytes, &lenchars))
         return 0;
-    sub->packet_len = lenchars - (unsigned char *)pkt->buf->data;
+    /* Convert to an offset in case the underlying BUF_MEM gets realloc'd */
+    sub->packet_len = lenchars - GETBUF(pkt);
 
     return 1;
 }
@@ -234,7 +285,7 @@ int WPACKET_start_sub_packet(WPACKET *pkt)
     return WPACKET_start_sub_packet_len__(pkt, 0);
 }
 
-int WPACKET_put_bytes(WPACKET *pkt, unsigned int val, size_t size)
+int WPACKET_put_bytes__(WPACKET *pkt, unsigned int val, size_t size)
 {
     unsigned char *data;