guacamole-spice-protocol/src/libguac/string.c
Joshua Roys f84db7d166 GUACAMOLE-745: Support OpenSSH private keys & ED25519
Let libssh2 parse PEM and ssh-native keys. Requires libssh2 1.9.0+
compiled against a crypto backend supporting ed25519.
2022-01-12 09:02:11 -05:00

151 lines
4.5 KiB
C

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#include "config.h"
#include <stddef.h>
#include <string.h>
/**
* Returns the space remaining in a buffer assuming that the given number of
* bytes have already been written. If the number of bytes exceeds the size
* of the buffer, zero is returned.
*
* @param n
* The size of the buffer in bytes.
*
* @param length
* The number of bytes which have been written to the buffer so far. If
* the routine writing the bytes will automatically truncate its writes,
* this value may exceed the size of the buffer.
*
* @return
* The number of bytes remaining in the buffer. This value will always
* be non-negative. If the number of bytes written already exceeds the
* size of the buffer, zero will be returned.
*/
#define REMAINING(n, length) (((n) < (length)) ? 0 : ((n) - (length)))
size_t guac_strlcpy(char* restrict dest, const char* restrict src, size_t n) {
#ifdef HAVE_STRLCPY
return strlcpy(dest, src, n);
#else
/* Calculate actual length of desired string */
size_t length = strlen(src);
/* Copy nothing if there is no space */
if (n == 0)
return length;
/* Calculate length of the string which will be copied */
size_t copy_length = length;
if (copy_length >= n)
copy_length = n - 1;
/* Copy only as much of string as possible, manually adding a null
* terminator */
memcpy(dest, src, copy_length);
dest[copy_length] = '\0';
/* Return the overall length of the desired string */
return length;
#endif
}
size_t guac_strlcat(char* restrict dest, const char* restrict src, size_t n) {
#ifdef HAVE_STRLCPY
return strlcat(dest, src, n);
#else
size_t length = strnlen(dest, n);
return length + guac_strlcpy(dest + length, src, REMAINING(n, length));
#endif
}
char* guac_strnstr(const char *haystack, const char *needle, size_t len) {
#ifdef HAVE_STRNSTR
return strnstr(haystack, needle, len);
#else
char* chr;
size_t nlen = strlen(needle), off = 0;
/* Follow documented API: return haystack if needle is the empty string. */
if (nlen == 0)
return (char *)haystack;
/* Use memchr to find candidates. It might be optimized in asm. */
while (off < len && NULL != (chr = memchr(haystack + off, needle[0], len - off))) {
/* chr is guaranteed to be in bounds of and >= haystack. */
off = chr - haystack;
/* If needle would go beyond provided len, it doesn't exist in haystack. */
if (off + nlen > len)
return NULL;
/* Now that we know we have at least nlen bytes, compare them. */
if (!memcmp(chr, needle, nlen))
return chr;
/* Make sure we make progress. */
off += 1;
}
/* memchr ran out of candidates, needle wasn't found. */
return NULL;
#endif
}
char* guac_strdup(const char* str) {
/* Return NULL if no string provided */
if (str == NULL)
return NULL;
/* Otherwise just invoke strdup() */
return strdup(str);
}
size_t guac_strljoin(char* restrict dest, const char* restrict const* elements,
int nmemb, const char* restrict delim, size_t n) {
size_t length = 0;
const char* restrict const* current = elements;
/* If no elements are provided, nothing to do but ensure the destination
* buffer is null terminated */
if (nmemb <= 0)
return guac_strlcpy(dest, "", n);
/* Initialize destination buffer with first element */
length += guac_strlcpy(dest, *current, n);
/* Copy all remaining elements, separated by delimiter */
for (current++; nmemb > 1; current++, nmemb--) {
length += guac_strlcat(dest + length, delim, REMAINING(n, length));
length += guac_strlcat(dest + length, *current, REMAINING(n, length));
}
return length;
}