BIO: Add BIO_f_prefix(), a text line prefixing filter

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10531)

2 files changed, 208 insertions, 1 deletions

diff --git a/crypto/bio/bf_prefix.c b/crypto/bio/bf_prefix.c
new file mode 100644
index 0000000000..5727c14950
--- /dev/null
+++ b/crypto/bio/bf_prefix.c
@@ -0,0 +1,207 @@
+/*
+ * Copyright 2018-2019 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (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 "bio_local.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 const BIO_METHOD prefix_meth = {
+    BIO_TYPE_BUFFER,
+    "prefix",
+    prefix_write,
+    NULL,
+    prefix_read,
+    NULL,
+    prefix_puts,
+    prefix_gets,
+    prefix_ctrl,
+    prefix_create,
+    prefix_destroy,
+    prefix_callback_ctrl,
+};
+
+const BIO_METHOD *BIO_f_prefix(void)
+{
+    return &prefix_meth;
+}
+
+typedef struct prefix_ctx_st {
+    char *prefix;              /* Text prefix, given by user */
+    unsigned int indent;       /* Indentation amount, given by user */
+
+    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->indent = 0;
+    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, and no indentation amount is set,
+     * we've got nothing to do here
+     */
+    if ((ctx->prefix == NULL || *ctx->prefix == '\0')
+        && ctx->indent == 0) {
+        /*
+         * We do note if what comes next will be a new line, though, so we're
+         * prepared to handle prefix and indentation the next time around.
+         */
+        if (outl > 0)
+            ctx->linestart = (out[outl-1] == '\n');
+        return BIO_write_ex(BIO_next(b), out, outl, numwritten);
+    }
+
+    *numwritten = 0;
+
+    while (outl > 0) {
+        size_t i;
+        char c;
+
+        /*
+         * If we know that we're at the start of the line, output prefix and
+         * indentation.
+         */
+        if (ctx->linestart) {
+            size_t dontcare;
+
+            if (ctx->prefix != NULL
+                && !BIO_write_ex(BIO_next(b), ctx->prefix, strlen(ctx->prefix),
+                                 &dontcare))
+                return 0;
+            BIO_printf(BIO_next(b), "%*s", ctx->indent, "");
+            ctx->linestart = 0;
+        }
+
+        /* Now, go look for the next LF, or the end of the string */
+        for (i = 0, c = '\0'; i < outl && (c = out[i]) != '\n'; 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;
+            outl -= 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;
+    PREFIX_CTX *ctx = BIO_get_data(b);
+
+    if (ctx == NULL)
+        return -1;
+
+    switch (cmd) {
+    case BIO_CTRL_SET_PREFIX:
+        OPENSSL_free(ctx->prefix);
+        if (ptr == NULL) {
+            ctx->prefix = NULL;
+            ret = 1;
+        } else {
+            ctx->prefix = OPENSSL_strdup((const char *)ptr);
+            ret = ctx->prefix != NULL;
+        }
+        break;
+    case BIO_CTRL_SET_INDENT:
+        if (num >= 0) {
+            ctx->indent = (unsigned int)num;
+            ret = 1;
+        }
+        break;
+    case BIO_CTRL_GET_INDENT:
+        ret = (long)ctx->indent;
+        break;
+    default:
+        /* Commands that we intercept before passing them along */
+        switch (cmd) {
+        case BIO_C_FILE_SEEK:
+        case BIO_CTRL_RESET:
+            ctx->linestart = 1;
+            break;
+        }
+        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));
+}
diff --git a/crypto/bio/build.info b/crypto/bio/build.info
index 3f84bb824c..8e3f530f88 100644
--- a/crypto/bio/build.info
+++ b/crypto/bio/build.info
@@ -15,4 +15,4 @@ SOURCE[../../libcrypto]=\
 
 # Filters
 SOURCE[../../libcrypto]=\
-        bf_null.c bf_buff.c bf_lbuf.c bf_nbio.c
+        bf_null.c bf_buff.c bf_lbuf.c bf_nbio.c bf_prefix.c