Optimized BIO mem read - without reallocation

Currently on every BIO mem read operation the remaining data is reallocated.
This commit solves the issue.
BIO mem structure includes additional pointer to the read position.
On every read the pointer moves instead of reallocating the memory for the remaining data.
Reallocation accures before write and some ioctl operations, if the read pointer doesn't point on the beginning of the buffer.
Also the flag is added to rewind the read pointer without losing the data.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>

1 files changed, 73 insertions, 30 deletions

diff --git a/crypto/bio/bss_mem.c b/crypto/bio/bss_mem.c
index 460e070a7d..cc7b6d908e 100644
--- a/crypto/bio/bss_mem.c
+++ b/crypto/bio/bss_mem.c
@@ -68,6 +68,8 @@ static long mem_ctrl(BIO *h, int cmd, long arg1, void *arg2);
 static int mem_new(BIO *h);
 static int secmem_new(BIO *h);
 static int mem_free(BIO *data);
+static int mem_buf_free(BIO *data, int free_all);
+static int mem_buf_sync(BIO *h);
 static const BIO_METHOD mem_method = {
     BIO_TYPE_MEM,
     "memory buffer",
@@ -112,6 +114,7 @@ BIO *BIO_new_mem_buf(const void *buf, int len)
 {
     BIO *ret;
     BUF_MEM *b;
+    BIO_BUF_MEM *bb;
     size_t sz;
 
     if (buf == NULL) {
@@ -121,11 +124,13 @@ BIO *BIO_new_mem_buf(const void *buf, int len)
     sz = (len < 0) ? strlen(buf) : (size_t)len;
     if ((ret = BIO_new(BIO_s_mem())) == NULL)
         return NULL;
-    b = (BUF_MEM *)ret->ptr;
+    bb = (BIO_BUF_MEM *)ret->ptr;
+    b = bb->buf;
     /* Cast away const and trust in the MEM_RDONLY flag. */
     b->data = (void *)buf;
     b->length = sz;
     b->max = sz;
+    *bb->readp = *bb->buf;
     ret->flags |= BIO_FLAGS_MEM_RDONLY;
     /* Since this is static data retrying wont help */
     ret->num = 0;
@@ -134,14 +139,19 @@ BIO *BIO_new_mem_buf(const void *buf, int len)
 
 static int mem_init(BIO *bi, unsigned long flags)
 {
-    BUF_MEM *b;
+    BIO_BUF_MEM *bb = OPENSSL_zalloc(sizeof(BIO_BUF_MEM));
 
-    if ((b = BUF_MEM_new_ex(flags)) == NULL)
+    if (bb == NULL)
+        return(0);
+    if ((bb->buf = BUF_MEM_new_ex(flags)) == NULL)
+        return(0);
+    if ((bb->readp = OPENSSL_zalloc(sizeof(BUF_MEM))) == NULL)
         return(0);
+    *bb->readp = *bb->buf;
     bi->shutdown = 1;
     bi->init = 1;
     bi->num = -1;
-    bi->ptr = (char *)b;
+    bi->ptr = (char *)bb;
     return(1);
 }
 
@@ -157,37 +167,63 @@ static int secmem_new(BIO *bi)
 
 static int mem_free(BIO *a)
 {
+    return (mem_buf_free(a, 1));
+}
+
+static int mem_buf_free(BIO *a, int free_all)
+{
     if (a == NULL)
         return (0);
     if (a->shutdown) {
         if ((a->init) && (a->ptr != NULL)) {
             BUF_MEM *b;
-            b = (BUF_MEM *)a->ptr;
-            if (a->flags & BIO_FLAGS_MEM_RDONLY)
-                b->data = NULL;
-            BUF_MEM_free(b);
+            BIO_BUF_MEM *bb = (BIO_BUF_MEM *)a->ptr;
+
+            if(bb != NULL) {
+                b = bb->buf;
+                if (a->flags & BIO_FLAGS_MEM_RDONLY)
+                    b->data = NULL;
+                BUF_MEM_free(b);
+                if(free_all) {
+                    OPENSSL_free(bb->readp);
+                    OPENSSL_free(bb);
+                }
+            }
             a->ptr = NULL;
         }
     }
     return (1);
 }
 
+/*
+ * Reallocate memory buffer if read pointer differs
+ */
+static int mem_buf_sync(BIO *b)
+{
+    if((b != NULL) && (b->init) && (b->ptr != NULL)) {
+        BIO_BUF_MEM *bbm = (BIO_BUF_MEM *)b->ptr;
+
+        if(bbm->readp->data != bbm->buf->data) {
+            memmove(bbm->buf->data, bbm->readp->data, bbm->readp->length);
+            bbm->buf->length = bbm->readp->length;
+            bbm->readp->data = bbm->buf->data;
+        }
+    }
+    return (0);
+}
+
 static int mem_read(BIO *b, char *out, int outl)
 {
     int ret = -1;
-    BUF_MEM *bm;
+    BIO_BUF_MEM *bbm = (BIO_BUF_MEM *)b->ptr;
+    BUF_MEM *bm = bbm->readp;
 
-    bm = (BUF_MEM *)b->ptr;
     BIO_clear_retry_flags(b);
     ret = (outl >= 0 && (size_t)outl > bm->length) ? (int)bm->length : outl;
     if ((out != NULL) && (ret > 0)) {
         memcpy(out, bm->data, ret);
         bm->length -= ret;
-        if (b->flags & BIO_FLAGS_MEM_RDONLY)
-            bm->data += ret;
-        else {
-            memmove(&(bm->data[0]), &(bm->data[ret]), bm->length);
-        }
+        bm->data += ret;
     } else if (bm->length == 0) {
         ret = b->num;
         if (ret != 0)
@@ -200,24 +236,23 @@ static int mem_write(BIO *b, const char *in, int inl)
 {
     int ret = -1;
     int blen;
-    BUF_MEM *bm;
+    BIO_BUF_MEM *bbm = (BIO_BUF_MEM *)b->ptr;
 
-    bm = (BUF_MEM *)b->ptr;
     if (in == NULL) {
         BIOerr(BIO_F_MEM_WRITE, BIO_R_NULL_PARAMETER);
         goto end;
     }
-
     if (b->flags & BIO_FLAGS_MEM_RDONLY) {
         BIOerr(BIO_F_MEM_WRITE, BIO_R_WRITE_TO_READ_ONLY_BIO);
         goto end;
     }
-
     BIO_clear_retry_flags(b);
-    blen = bm->length;
-    if (BUF_MEM_grow_clean(bm, blen + inl) == 0)
+    blen = bbm->readp->length;
+    mem_buf_sync(b);
+    if (BUF_MEM_grow_clean(bbm->buf, blen + inl) == 0)
         goto end;
-    memcpy(&(bm->data[blen]), in, inl);
+    memcpy(bbm->buf->data + blen, in, inl);
+    *bbm->readp = *bbm->buf;
     ret = inl;
  end:
     return (ret);
@@ -227,29 +262,32 @@ static long mem_ctrl(BIO *b, int cmd, long num, void *ptr)
 {
     long ret = 1;
     char **pptr;
-
-    BUF_MEM *bm = (BUF_MEM *)b->ptr;
+    BIO_BUF_MEM *bbm = (BIO_BUF_MEM *)b->ptr;
+    BUF_MEM *bm;
 
     switch (cmd) {
     case BIO_CTRL_RESET:
+        bm = bbm->buf;
         if (bm->data != NULL) {
             /* For read only case reset to the start again */
-            if (b->flags & BIO_FLAGS_MEM_RDONLY) {
-                bm->data -= bm->max - bm->length;
+            if ((b->flags & BIO_FLAGS_MEM_RDONLY) || (b->flags & BIO_FLAGS_NONCLEAR_RST)) {
                 bm->length = bm->max;
             } else {
                 memset(bm->data, 0, bm->max);
                 bm->length = 0;
             }
+            *bbm->readp = *bbm->buf;
         }
         break;
     case BIO_CTRL_EOF:
+        bm = bbm->readp;
         ret = (long)(bm->length == 0);
         break;
     case BIO_C_SET_BUF_MEM_EOF_RETURN:
         b->num = (int)num;
         break;
     case BIO_CTRL_INFO:
+        bm = bbm->readp;
         ret = (long)bm->length;
         if (ptr != NULL) {
             pptr = (char **)ptr;
@@ -257,12 +295,16 @@ static long mem_ctrl(BIO *b, int cmd, long num, void *ptr)
         }
         break;
     case BIO_C_SET_BUF_MEM:
-        mem_free(b);
+        mem_buf_free(b, 0);
         b->shutdown = (int)num;
-        b->ptr = ptr;
+        bbm->buf = ptr;
+        *bbm->readp = *bbm->buf;
+        b->ptr = bbm;
         break;
     case BIO_C_GET_BUF_MEM_PTR:
         if (ptr != NULL) {
+            mem_buf_sync(b);
+            bm = bbm->readp;
             pptr = (char **)ptr;
             *pptr = (char *)bm;
         }
@@ -273,11 +315,11 @@ static long mem_ctrl(BIO *b, int cmd, long num, void *ptr)
     case BIO_CTRL_SET_CLOSE:
         b->shutdown = (int)num;
         break;
-
     case BIO_CTRL_WPENDING:
         ret = 0L;
         break;
     case BIO_CTRL_PENDING:
+        bm = bbm->readp;
         ret = (long)bm->length;
         break;
     case BIO_CTRL_DUP:
@@ -298,7 +340,8 @@ static int mem_gets(BIO *bp, char *buf, int size)
     int i, j;
     int ret = -1;
     char *p;
-    BUF_MEM *bm = (BUF_MEM *)bp->ptr;
+    BIO_BUF_MEM *bbm = (BIO_BUF_MEM *)bp->ptr;
+    BUF_MEM *bm = bbm->readp;
 
     BIO_clear_retry_flags(bp);
     j = bm->length;