string.hpp

//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2022 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

// General purpose string-manipulation functions.

#ifndef OPENVPN_COMMON_STRING_H
#define OPENVPN_COMMON_STRING_H

#include <string>
#include <vector>
#include <cstring>
#include <locale>
#include <algorithm>

#include <openvpn/common/platform.hpp>
#include <openvpn/common/size.hpp>

namespace openvpn {
namespace string {
// case insensitive compare functions

inline int strcasecmp(const char *s1, const char *s2)
{
#ifdef OPENVPN_PLATFORM_WIN
    return ::_stricmp(s1, s2);
#else
    return ::strcasecmp(s1, s2);
#endif
}

inline int strcasecmp(const std::string &s1, const char *s2)
{
    return strcasecmp(s1.c_str(), s2);
}

inline int strcasecmp(const char *s1, const std::string &s2)
{
    return strcasecmp(s1, s2.c_str());
}

inline int strcasecmp(const std::string &s1, const std::string &s2)
{
    return strcasecmp(s1.c_str(), s2.c_str());
}

// Like strncpy but makes sure dest is always null terminated
inline void strncpynt(char *dest, const char *src, size_t maxlen)
{
    strncpy(dest, src, maxlen);
    if (maxlen > 0)
        dest[maxlen - 1] = 0;
}

// Copy string to dest, make sure dest is always null terminated,
// and fill out trailing chars in dest with '\0' up to dest_size.
inline void copy_fill(void *dest, const std::string &src, const size_t dest_size)
{
    if (dest_size > 0)
    {
        const size_t ncopy = std::min(dest_size - 1, src.length());
        std::memcpy(dest, src.c_str(), ncopy);
        std::memset(static_cast<unsigned char *>(dest) + ncopy, 0, dest_size - ncopy);
    }
}

inline bool is_true(const std::string &str)
{
    return str == "1" || !strcasecmp(str.c_str(), "true");
}

template <typename STRING>
inline bool starts_with(const STRING &str, const std::string &prefix)
{
    const size_t len = str.length();
    const size_t plen = prefix.length();
    if (plen <= len)
        return std::memcmp(str.c_str(), prefix.c_str(), plen) == 0;
    else
        return false;
}

template <typename STRING>
inline bool starts_with(const STRING &str, const char *prefix)
{
    const size_t len = str.length();
    const size_t plen = std::strlen(prefix);
    if (plen <= len)
        return std::memcmp(str.c_str(), prefix, plen) == 0;
    else
        return false;
}

// Return true if str == prefix or if str starts with prefix + delim
template <typename STRING>
inline bool starts_with_delim(const STRING &str, const std::string &prefix, const char delim)
{
    if (prefix.length() < str.length())
        return str[prefix.length()] == delim && string::starts_with(str, prefix);
    else
        return prefix == str;
}

template <typename STRING>
inline bool ends_with(const STRING &str, const std::string &suffix)
{
    const size_t len = str.length();
    const size_t slen = suffix.length();
    if (slen <= len)
        return std::memcmp(str.c_str() + (len - slen), suffix.c_str(), slen) == 0;
    else
        return false;
}

template <typename STRING>
inline bool ends_with(const STRING &str, const char *suffix)
{
    const size_t len = str.length();
    const size_t slen = std::strlen(suffix);
    if (slen <= len)
        return std::memcmp(str.c_str() + (len - slen), suffix, slen) == 0;
    else
        return false;
}

// return true if string ends with char c
template <typename STRING>
inline bool ends_with(const STRING &str, const char c)
{
    return str.length() && str.back() == c;
}

// return true if string ends with a newline
template <typename STRING>
inline bool ends_with_newline(const STRING &str)
{
    return ends_with(str, '\n');
}

// return true if string ends with a CR or LF
template <typename STRING>
inline bool ends_with_crlf(const STRING &str)
{
    if (str.length())
    {
        const char c = str.back();
        return c == '\n' || c == '\r';
    }
    else
        return false;
}

// Prepend leading characters (c) to str to obtain a minimum string length (min_len).
// Useful for adding leading zeros to numeric values or formatting tables.
inline std::string add_leading(const std::string &str, const size_t min_len, const char c)
{
    if (min_len <= str.length())
        return str;
    size_t len = min_len - str.length();
    std::string ret;
    ret.reserve(min_len);
    while (len--)
        ret += c;
    ret += str;
    return ret;
}

// make sure that string ends with char c, if not append it
inline std::string add_trailing_copy(const std::string &str, const char c)
{
    if (ends_with(str, c))
        return str;
    else
        return str + c;
}

// make sure that string ends with char c, if not append it
inline void add_trailing(std::string &str, const char c)
{
    if (!ends_with(str, c))
        str += c;
}

// make sure that string ends with CRLF, if not append it
inline void add_trailing_crlf(std::string &str)
{
    if (ends_with(str, "\r\n"))
        ;
    else if (ends_with(str, '\r'))
        str += '\n';
    else if (ends_with(str, '\n'))
    {
        str.pop_back();
        str += "\r\n";
    }
    else
        str += "\r\n";
}

// make sure that string ends with CRLF, if not append it
inline std::string add_trailing_crlf_copy(std::string str)
{
    add_trailing_crlf(str);
    return str;
}

// make sure that string ends with char c, if not append it (unless the string is empty)
inline std::string add_trailing_unless_empty_copy(const std::string &str, const char c)
{
    if (str.empty() || ends_with(str, c))
        return str;
    else
        return str + c;
}

// remove trailing \r or \n chars
template <typename STRING>
inline void trim_crlf(STRING &str)
{
    while (ends_with_crlf(str))
        str.pop_back();
}

// remove trailing \r or \n chars
inline std::string trim_crlf_copy(std::string str)
{
    trim_crlf(str);
    return str;
}

// return true if str of size len contains an embedded null
inline bool embedded_null(const char *str, size_t len)
{
    while (len--)
        if (!*str++)
            return true;
    return false;
}

// return the length of a string, omitting trailing nulls
inline size_t len_without_trailing_nulls(const char *str, size_t len)
{
    while (len > 0 && str[len - 1] == '\0')
        --len;
    return len;
}

// return true if string contains at least one newline
inline bool is_multiline(const std::string &str)
{
    return str.find_first_of('\n') != std::string::npos;
}

// Return string up to a delimiter (without the delimiter).
// Returns the entire string if no delimiter is found.
inline std::string to_delim(const std::string &str, const char delim)
{
    const size_t pos = str.find_first_of(delim);
    if (pos != std::string::npos)
        return str.substr(0, pos);
    else
        return str;
}

// return the first line (without newline) of a multi-line string
inline std::string first_line(const std::string &str)
{
    return to_delim(str, '\n');
}

// Define a common interpretation of what constitutes a space character.
// Return true if c is a space char.
inline bool is_space(const char c)
{
    return std::isspace(static_cast<unsigned char>(c)) != 0;
}

inline bool is_digit(const char c)
{
    return std::isdigit(static_cast<unsigned char>(c)) != 0;
}

inline bool is_alpha(const char c)
{
    return std::isalpha(static_cast<unsigned char>(c)) != 0;
}

inline bool is_alphanumeric(const char c)
{
    return std::isalnum(static_cast<unsigned char>(c)) != 0;
}

inline bool is_printable(const char c)
{
    return std::isprint(static_cast<unsigned char>(c)) != 0;
}

inline bool is_printable(const unsigned char c)
{
    return std::isprint(c) != 0;
}

inline bool is_ctrl(const char c)
{
    return std::iscntrl(static_cast<unsigned char>(c)) != 0;
}

inline bool is_ctrl(const unsigned char c)
{
    return std::iscntrl(c) != 0;
}

// return true if string conforms to regex \w*
inline bool is_word(const std::string &str)
{
    for (auto &c : str)
        if (!(is_alphanumeric(c) || c == '_'))
            return false;
    return true;
}

// return true if all string characters are printable (or if string is empty)
inline bool is_printable(const std::string &str)
{
    for (auto &c : str)
        if (!is_printable(c))
            return false;
    return true;
}

// return true if str contains at least one non-space control char
inline bool contains_non_space_ctrl(const std::string &str)
{
    for (auto &c : str)
        if ((!is_space(c) && is_ctrl(c)) || c == 127)
            return true;
    return false;
}

// return true if str contains at least one space char
inline bool contains_space(const std::string &str)
{
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
        if (is_space(*i))
            return true;
    return false;
}

// remove all spaces in string
inline std::string remove_spaces(const std::string &str)
{
    std::string ret;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        if (!is_space(c))
            ret += c;
    }
    return ret;
}

// replace all spaces in string with rep
inline std::string replace_spaces(const std::string &str, const char rep)
{
    std::string ret;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        if (is_space(c))
            c = rep;
        ret += c;
    }
    return ret;
}

// replace all spaces in string with rep, reducing instances of multiple
// consecutive spaces to a single instance of rep and removing leading
// and trailing spaces
inline std::string reduce_spaces(const std::string &str, const char rep)
{
    std::string ret;
    bool last_space = true;
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        char c = *i;
        const bool space = is_space(c);
        if (is_space(c))
            c = rep;
        if (!(space && last_space))
            ret += c;
        last_space = space;
    }
    if (last_space && !ret.empty())
        ret.pop_back();
    return ret;
}

// generate a string with n instances of char c
inline std::string repeat(const char c, size_t n)
{
    std::string ret;
    ret.reserve(n);
    while (n-- > 0)
        ret += c;
    return ret;
}

// generate a string with spaces
inline std::string spaces(size_t n)
{
    return repeat(' ', n);
}

// indent a multiline string
inline std::string indent(const std::string &str, const int first, const int remaining)
{
    std::string ret;
    int n_spaces = first;
    for (auto &c : str)
    {
        if (n_spaces)
            ret += spaces(n_spaces);
        n_spaces = 0;
        ret += c;
        if (c == '\n')
            n_spaces = remaining;
    }
    return ret;
}

// replace instances of char 'from' in string with char 'to'
inline std::string replace_copy(const std::string &str, const char from, const char to)
{
    std::string ret;
    ret.reserve(str.length());
    for (auto &c : str)
        ret.push_back(c == from ? to : c);
    return ret;
}

// return true if str is empty or contains only space chars
inline bool is_empty(const std::string &str)
{
    for (const auto &c : str)
        if (!is_space(c))
            return false;
    return true;
}

// return true if str is empty or contains only space chars
inline bool is_empty(const char *str)
{
    if (!str)
        return true;
    char c;
    while ((c = *str++) != '\0')
        if (!is_space(c))
            return false;
    return true;
}

// convert \n to \r\n
inline std::string unix2dos(const std::string &str, const bool force_eol = false)
{
    std::string ret;
    bool last_char_was_cr = false;

    ret.reserve(str.length() + str.length() / 8);
    for (std::string::const_iterator i = str.begin(); i != str.end(); ++i)
    {
        const char c = *i;
        if (c == '\n' && !last_char_was_cr)
            ret += '\r';
        ret += c;
        last_char_was_cr = (c == '\r');
    }
    if (force_eol)
        add_trailing_crlf(ret);
    return ret;
}

// Split a string on sep delimiter.  The size of the
// returned string vector will be at least 1 and at
// most maxsplit + 1 (unless maxsplit is passed as -1).
inline std::vector<std::string> split(const std::string &str,
                                      const char sep,
                                      const int maxsplit = -1)
{
    std::vector<std::string> ret;
    int nterms = 0;
    std::string term;

    if (maxsplit >= 0)
        ret.reserve(maxsplit + 1);

    for (const auto c : str)
    {
        if (c == sep && (maxsplit < 0 || nterms < maxsplit))
        {
            ret.push_back(std::move(term));
            ++nterms;
            term.clear();
        }
        else
            term += c;
    }
    ret.push_back(std::move(term));
    return ret;
}

template <class T>
inline std::string join(const T &strings,
                        const std::string &delim,
                        const bool tail = false)
{
    /* ensure we have a container with strings as values */
    static_assert(std::is_same_v<typename T::value_type, std::string>);
    std::string ret;
    bool first = true;
    for (const auto &s : strings)
    {
        if (!first)
            ret += delim;
        ret += s;
        first = false;
    }
    if (tail && !ret.empty())
        ret += delim;
    return ret;
}

inline std::vector<std::string> from_argv(int argc, char *argv[], const bool skip_first)
{
    std::vector<std::string> ret;
    for (int i = (skip_first ? 1 : 0); i < argc; ++i)
        ret.emplace_back(argv[i]);
    return ret;
}

inline std::string trim_left_copy(const std::string &str)
{
    for (size_t i = 0; i < str.length(); ++i)
    {
        if (!is_space(str[i]))
            return str.substr(i);
    }
    return std::string();
}

inline std::string trim_copy(const std::string &str)
{
    for (size_t i = 0; i < str.length(); ++i)
    {
        if (!is_space(str[i]))
        {
            size_t last_nonspace = i;
            for (size_t j = i + 1; j < str.length(); ++j)
            {
                if (!is_space(str[j]))
                    last_nonspace = j;
            }
            return str.substr(i, last_nonspace - i + 1);
        }
    }
    return std::string();
}

inline std::string to_upper_copy(const std::string &str)
{
    std::string ret;
    std::locale loc;
    ret.reserve(str.length());
    for (const auto &c : str)
        ret.push_back(std::toupper(c, loc));
    return ret;
}

inline std::string to_lower_copy(const std::string &str)
{
    std::string ret;
    std::locale loc;
    ret.reserve(str.length());
    for (const auto &c : str)
        ret.push_back(std::tolower(c, loc));
    return ret;
}

inline void trim(std::string &str)
{
    str = trim_copy(str);
}

inline void trim_left(std::string &str)
{
    str = trim_left_copy(str);
}

inline void to_lower(std::string &str)
{
    str = to_lower_copy(str);
}

inline void to_upper(std::string &str)
{
    str = to_upper_copy(str);
}

// Replace any subsequence of consecutive space chars containing
// at least one newline with a single newline char.  If string
// is non-empty and doesn't include a trailing newline, add one.
inline std::string remove_blanks(const std::string &str)
{
    std::string ret;
    ret.reserve(str.length() + 1);

    std::string spaces;
    bool in_space = false;
    bool has_nl = false;

    for (auto &c : str)
    {
        const bool s = is_space(c);
    reprocess:
        if (in_space)
        {
            if (s)
            {
                if (c == '\n')
                    has_nl = true;
                spaces += c;
            }
            else
            {
                if (has_nl)
                    ret += '\n';
                else
                    ret += spaces;
                in_space = false;
                has_nl = false;
                spaces.clear();
                goto reprocess;
            }
        }
        else
        {
            if (s)
            {
                in_space = true;
                goto reprocess;
            }
            else
                ret += c;
        }
    }
    if (!ret.empty() && !ends_with_newline(ret))
        ret += '\n';
    return ret;
}

// copy str to the return value, removing all instances of
// chars that match remove
inline std::string remove_char(const std::string &str, const char remove)
{
    std::string ret;
    ret.reserve(str.length());
    for (const auto c : str)
    {
        if (c != remove)
            ret.push_back(c);
    }
    return ret;
}

} // namespace string

} // namespace openvpn

#endif // OPENVPN_COMMON_STRING_H