--- /dev/null
+/*
+ * Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <openssl/bio.h>
+#include "apps.h"
+
+static int prefix_write(BIO *b, const char *out, size_t outl,
+ size_t *numwritten);
+static int prefix_read(BIO *b, char *buf, size_t size, size_t *numread);
+static int prefix_puts(BIO *b, const char *str);
+static int prefix_gets(BIO *b, char *str, int size);
+static long prefix_ctrl(BIO *b, int cmd, long arg1, void *arg2);
+static int prefix_create(BIO *b);
+static int prefix_destroy(BIO *b);
+static long prefix_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp);
+
+static BIO_METHOD *prefix_meth = NULL;
+
+BIO_METHOD *apps_bf_prefix(void)
+{
+ if (prefix_meth == NULL) {
+ if ((prefix_meth =
+ BIO_meth_new(BIO_TYPE_FILTER, "Prefix filter")) == NULL
+ || !BIO_meth_set_create(prefix_meth, prefix_create)
+ || !BIO_meth_set_destroy(prefix_meth, prefix_destroy)
+ || !BIO_meth_set_write_ex(prefix_meth, prefix_write)
+ || !BIO_meth_set_read_ex(prefix_meth, prefix_read)
+ || !BIO_meth_set_puts(prefix_meth, prefix_puts)
+ || !BIO_meth_set_gets(prefix_meth, prefix_gets)
+ || !BIO_meth_set_ctrl(prefix_meth, prefix_ctrl)
+ || !BIO_meth_set_callback_ctrl(prefix_meth, prefix_callback_ctrl)) {
+ BIO_meth_free(prefix_meth);
+ prefix_meth = NULL;
+ }
+ }
+ return prefix_meth;
+}
+
+typedef struct prefix_ctx_st {
+ char *prefix;
+ int linestart; /* flag to indicate we're at the line start */
+} PREFIX_CTX;
+
+static int prefix_create(BIO *b)
+{
+ PREFIX_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
+
+ if (ctx == NULL)
+ return 0;
+
+ ctx->prefix = NULL;
+ ctx->linestart = 1;
+ BIO_set_data(b, ctx);
+ BIO_set_init(b, 1);
+ return 1;
+}
+
+static int prefix_destroy(BIO *b)
+{
+ PREFIX_CTX *ctx = BIO_get_data(b);
+
+ OPENSSL_free(ctx->prefix);
+ OPENSSL_free(ctx);
+ return 1;
+}
+
+static int prefix_read(BIO *b, char *in, size_t size, size_t *numread)
+{
+ return BIO_read_ex(BIO_next(b), in, size, numread);
+}
+
+static int prefix_write(BIO *b, const char *out, size_t outl,
+ size_t *numwritten)
+{
+ PREFIX_CTX *ctx = BIO_get_data(b);
+
+ if (ctx == NULL)
+ return 0;
+
+ /* If no prefix is set or if it's empty, we've got nothing to do here */
+ if (ctx->prefix == NULL || *ctx->prefix == '\0') {
+ /* We do note if what comes next will be a new line, though */
+ if (outl > 0)
+ ctx->linestart = (out[outl-1] == '\n');
+ return BIO_write_ex(BIO_next(b), out, outl, numwritten);
+ }
+
+ *numwritten = 0;
+
+ while (*out != '\0') {
+ size_t i;
+ char c;
+
+ /* If we know that we're at the start of the line, output the prefix */
+ if (ctx->linestart) {
+ size_t dontcare;
+
+ if (!BIO_write_ex(BIO_next(b), ctx->prefix, strlen(ctx->prefix),
+ &dontcare))
+ return 0;
+ ctx->linestart = 0;
+ }
+
+ /* Now, go look for the next LF, or the end of the string */
+ for (i = 0; (c = out[i]) != '\n' && c != '\0'; i++)
+ continue;
+ if (c == '\n')
+ i++;
+
+ /* Output what we found so far */
+ while (i > 0) {
+ size_t num = 0;
+
+ if (!BIO_write_ex(BIO_next(b), out, i, &num))
+ return 0;
+ out += num;
+ *numwritten += num;
+ i -= num;
+ }
+
+ /* If we found a LF, what follows is a new line, so take note */
+ if (c == '\n')
+ ctx->linestart = 1;
+ }
+
+ return 1;
+}
+
+static long prefix_ctrl(BIO *b, int cmd, long num, void *ptr)
+{
+ long ret = 0;
+
+ switch (cmd) {
+ case PREFIX_CTRL_SET_PREFIX:
+ {
+ PREFIX_CTX *ctx = BIO_get_data(b);
+
+ if (ctx == NULL)
+ break;
+
+ OPENSSL_free(ctx->prefix);
+ ctx->prefix = OPENSSL_strdup((const char *)ptr);
+ ret = ctx->prefix != NULL;
+ }
+ break;
+ default:
+ if (BIO_next(b) != NULL)
+ ret = BIO_ctrl(BIO_next(b), cmd, num, ptr);
+ break;
+ }
+ return ret;
+}
+
+static long prefix_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
+{
+ return BIO_callback_ctrl(BIO_next(b), cmd, fp);
+}
+
+static int prefix_gets(BIO *b, char *buf, int size)
+{
+ return BIO_gets(BIO_next(b), buf, size);
+}
+
+static int prefix_puts(BIO *b, const char *str)
+{
+ return BIO_write(b, str, strlen(str));
+}