1 files changed, 38 insertions, 22 deletions

diff --git a/src/lib/libcrypto/bio/bss_mem.c b/src/lib/libcrypto/bio/bss_mem.c
index 6100a1861e..2d03083235 100644
--- a/src/lib/libcrypto/bio/bss_mem.c
+++ b/src/lib/libcrypto/bio/bss_mem.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bss_mem.c,v 1.20 2022/02/19 08:11:16 jsing Exp $ */
+/* $OpenBSD: bss_mem.c,v 1.21 2022/02/19 15:59:12 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -69,8 +69,24 @@
 
 struct bio_mem {
         BUF_MEM *buf;
+        size_t read_offset;
 };
 
+static size_t
+bio_mem_pending(struct bio_mem *bm)
+{
+        if (bm->read_offset > bm->buf->length)
+                return 0;
+
+        return bm->buf->length - bm->read_offset;
+}
+
+static uint8_t *
+bio_mem_read_ptr(struct bio_mem *bm)
+{
+        return &bm->buf->data[bm->read_offset];
+}
+
 static int mem_new(BIO *bio);
 static int mem_free(BIO *bio);
 static int mem_write(BIO *bio, const char *in, int in_len);
@@ -185,8 +201,8 @@ mem_read(BIO *bio, char *out, int out_len)
         if (out == NULL || out_len <= 0)
                 return 0;
 
-        if ((size_t)out_len > bm->buf->length)
-                out_len = bm->buf->length;
+        if ((size_t)out_len > bio_mem_pending(bm))
+                out_len = bio_mem_pending(bm);
 
         if (out_len == 0) {
                 if (bio->num != 0)
@@ -194,14 +210,9 @@ mem_read(BIO *bio, char *out, int out_len)
                 return bio->num;
         }
 
-        memcpy(out, bm->buf->data, out_len);
-        bm->buf->length -= out_len;
-        if (bio->flags & BIO_FLAGS_MEM_RDONLY) {
-                bm->buf->data += out_len;
-        } else {
-                memmove(&(bm->buf->data[0]), &(bm->buf->data[out_len]),
-                    bm->buf->length);
-        }
+        memcpy(out, bio_mem_read_ptr(bm), out_len);
+        bm->read_offset += out_len;
+
         return out_len;
 }
 
@@ -221,6 +232,13 @@ mem_write(BIO *bio, const char *in, int in_len)
                 return -1;
         }
 
+        if (bm->read_offset > 4096) {
+                memmove(bm->buf->data, bio_mem_read_ptr(bm),
+                    bio_mem_pending(bm));
+                bm->buf->length = bio_mem_pending(bm);
+                bm->read_offset = 0;
+        }
+
         /*
          * Check for overflow and ensure we do not exceed an int, otherwise we
          * cannot tell if BUF_MEM_grow_clean() succeeded.
@@ -247,18 +265,15 @@ mem_ctrl(BIO *bio, int cmd, long num, void *ptr)
         switch (cmd) {
         case BIO_CTRL_RESET:
                 if (bm->buf->data != NULL) {
-                        /* For read only case reset to the start again */
-                        if (bio->flags & BIO_FLAGS_MEM_RDONLY) {
-                                bm->buf->data -= bm->buf->max - bm->buf->length;
-                                bm->buf->length = bm->buf->max;
-                        } else {
+                        if (!(bio->flags & BIO_FLAGS_MEM_RDONLY)) {
                                 memset(bm->buf->data, 0, bm->buf->max);
                                 bm->buf->length = 0;
                         }
+                        bm->read_offset = 0;
                 }
                 break;
         case BIO_CTRL_EOF:
-                ret = (long)(bm->buf->length == 0);
+                ret = (long)(bio_mem_pending(bm) == 0);
                 break;
         case BIO_C_SET_BUF_MEM_EOF_RETURN:
                 bio->num = (int)num;
@@ -266,14 +281,15 @@ mem_ctrl(BIO *bio, int cmd, long num, void *ptr)
         case BIO_CTRL_INFO:
                 if (ptr != NULL) {
                         pptr = (void **)ptr;
-                        *pptr = bm->buf->data;
+                        *pptr = bio_mem_read_ptr(bm);
                 }
-                ret = (long)bm->buf->length;
+                ret = (long)bio_mem_pending(bm);
                 break;
         case BIO_C_SET_BUF_MEM:
                 BUF_MEM_free(bm->buf);
                 bio->shutdown = (int)num;
                 bm->buf = ptr;
+                bm->read_offset = 0;
                 break;
         case BIO_C_GET_BUF_MEM_PTR:
                 if (ptr != NULL) {
@@ -291,7 +307,7 @@ mem_ctrl(BIO *bio, int cmd, long num, void *ptr)
                 ret = 0L;
                 break;
         case BIO_CTRL_PENDING:
-                ret = (long)bm->buf->length;
+                ret = (long)bio_mem_pending(bm);
                 break;
         case BIO_CTRL_DUP:
         case BIO_CTRL_FLUSH:
@@ -316,7 +332,7 @@ mem_gets(BIO *bio, char *out, int out_len)
 
         BIO_clear_retry_flags(bio);
 
-        out_max = bm->buf->length;
+        out_max = bio_mem_pending(bm);
         if (out_len - 1 < out_max)
                 out_max = out_len - 1;
         if (out_max <= 0) {
@@ -324,7 +340,7 @@ mem_gets(BIO *bio, char *out, int out_len)
                 return 0;
         }
 
-        p = bm->buf->data;
+        p = bio_mem_read_ptr(bm);
         for (i = 0; i < out_max; i++) {
                 if (p[i] == '\n') {
                         i++;