text: /*
   * nghttp2 - HTTP/2 C Library
   *
   * Copyright (c) 2012 Tatsuhiro Tsujikawa
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  #include "shrpx_log.h"
  
  #ifdef HAVE_SYSLOG_H
  #include <syslog.h>
  #endif // HAVE_SYSLOG_H
  #ifdef HAVE_UNISTD_H
  #include <unistd.h>
  #endif // HAVE_UNISTD_H
  #ifdef HAVE_INTTYPES_H
  #include <inttypes.h>
  #endif // HAVE_INTTYPES_H
  #include <sys/types.h>
  #include <sys/stat.h>
  #ifdef HAVE_FCNTL_H
  #include <fcntl.h>
  #endif // HAVE_FCNTL_H
  #include <sys/wait.h>
  
  #include <cerrno>
  #include <cstdio>
  #include <cstring>
  #include <ctime>
  #include <iostream>
  #include <iomanip>
  
  #include "shrpx_config.h"
  #include "shrpx_downstream.h"
  #include "shrpx_worker.h"
  #include "util.h"
  #include "template.h"
  
  using namespace nghttp2;
  
  namespace shrpx {
  
  namespace {
  constexpr StringRef SEVERITY_STR[] = {
      StringRef::from_lit("INFO"), StringRef::from_lit("NOTICE"),
      StringRef::from_lit("WARN"), StringRef::from_lit("ERROR"),
      StringRef::from_lit("FATAL")};
  } // namespace
  
  namespace {
  constexpr const char *SEVERITY_COLOR[] = {
      "\033[1;32m", // INFO
      "\033[1;36m", // NOTICE
      "\033[1;33m", // WARN
      "\033[1;31m", // ERROR
      "\033[1;35m", // FATAL
  };
  } // namespace
  
  int Log::severity_thres_ = NOTICE;
  
  void Log::set_severity_level(int severity) { severity_thres_ = severity; }
  
  int Log::set_severity_level_by_name(const StringRef &name) {
    for (size_t i = 0, max = array_size(SEVERITY_STR); i < max; ++i) {
      if (name == SEVERITY_STR[i]) {
        severity_thres_ = i;
        return 0;
      }
    }
    return -1;
  }
  
  int severity_to_syslog_level(int severity) {
    switch (severity) {
    case (INFO):
      return LOG_INFO;
    case (NOTICE):
      return LOG_NOTICE;
    case (WARN):
      return LOG_WARNING;
    case (ERROR):
      return LOG_ERR;
    case (FATAL):
      return LOG_CRIT;
    default:
      return -1;
    }
  }
  
  Log::Log(int severity, const char *filename, int linenum)
      : filename_(filename), severity_(severity), linenum_(linenum) {}
  
  Log::~Log() {
    int rv;
    auto config = get_config();
  
    if (!config) {
      return;
    }
  
    auto lgconf = log_config();
  
    auto &errorconf = config->logging.error;
  
    if (!log_enabled(severity_) ||
        (lgconf->errorlog_fd == -1 && !errorconf.syslog)) {
      return;
    }
  
    if (errorconf.syslog) {
      if (severity_ == NOTICE) {
        syslog(severity_to_syslog_level(severity_), "[%s] %s",
               SEVERITY_STR[severity_].c_str(), stream_.str().c_str());
      } else {
        syslog(severity_to_syslog_level(severity_), "[%s] %s (%s:%d)",
               SEVERITY_STR[severity_].c_str(), stream_.str().c_str(), filename_,
               linenum_);
      }
  
      return;
    }
  
    char buf[4_k];
    auto tty = lgconf->errorlog_tty;
  
    lgconf->update_tstamp_millis(std::chrono::system_clock::now());
  
    // Error log format: <datetime> <master-pid> <current-pid>
    // <thread-id> <level> (<filename>:<line>) <msg>
    rv = snprintf(buf, sizeof(buf), "%s %d %d %s %s%s%s (%s:%d) %s\n",
                  lgconf->tstamp->time_iso8601.c_str(), config->pid, lgconf->pid,
                  lgconf->thread_id.c_str(), tty ? SEVERITY_COLOR[severity_] : "",
                  SEVERITY_STR[severity_].c_str(), tty ? "\033[0m" : "",
                  filename_, linenum_, stream_.str().c_str());
  
    if (rv < 0) {
      return;
    }
  
    auto nwrite = std::min(static_cast<size_t>(rv), sizeof(buf) - 1);
  
    while (write(lgconf->errorlog_fd, buf, nwrite) == -1 && errno == EINTR)
      ;
  }
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator> copy(const char *src, size_t srclen,
                                                 OutputIterator d_first,
                                                 OutputIterator d_last) {
    auto nwrite =
        std::min(static_cast<size_t>(std::distance(d_first, d_last)), srclen);
    return std::make_pair(std::copy_n(src, nwrite, d_first), d_last);
  }
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator>
  copy(const char *src, OutputIterator d_first, OutputIterator d_last) {
    return copy(src, strlen(src), d_first, d_last);
  }
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator>
  copy(const StringRef &src, OutputIterator d_first, OutputIterator d_last) {
    return copy(src.c_str(), src.size(), d_first, d_last);
  }
  } // namespace
  
  namespace {
  template <size_t N, typename OutputIterator>
  std::pair<OutputIterator, OutputIterator>
  copy_l(const char (&src)[N], OutputIterator d_first, OutputIterator d_last) {
    return copy(src, N - 1, d_first, d_last);
  }
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator> copy(char c, OutputIterator d_first,
                                                 OutputIterator d_last) {
    if (d_first == d_last) {
      return std::make_pair(d_last, d_last);
    }
    *d_first++ = c;
    return std::make_pair(d_first, d_last);
  }
  } // namespace
  
  namespace {
  constexpr char LOWER_XDIGITS[] = "0123456789abcdef";
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator>
  copy_hex_low(const uint8_t *src, size_t srclen, OutputIterator d_first,
               OutputIterator d_last) {
    auto nwrite = std::min(static_cast<size_t>(std::distance(d_first, d_last)),
                           srclen * 2) /
                  2;
    for (size_t i = 0; i < nwrite; ++i) {
      *d_first++ = LOWER_XDIGITS[src[i] >> 4];
      *d_first++ = LOWER_XDIGITS[src[i] & 0xf];
    }
    return std::make_pair(d_first, d_last);
  }
  } // namespace
  
  namespace {
  template <typename OutputIterator, typename T>
  std::pair<OutputIterator, OutputIterator> copy(T n, OutputIterator d_first,
                                                 OutputIterator d_last) {
    if (static_cast<size_t>(std::distance(d_first, d_last)) <
        NGHTTP2_MAX_UINT64_DIGITS) {
      return std::make_pair(d_last, d_last);
    }
    return std::make_pair(util::utos(d_first, n), d_last);
  }
  } // namespace
  
  namespace {
  // 1 means that character must be escaped as "\xNN", where NN is ascii
  // code of the character in hex notation.
  constexpr uint8_t ESCAPE_TBL[] = {
      1 /* NUL  */, 1 /* SOH  */, 1 /* STX  */, 1 /* ETX  */, 1 /* EOT  */,
      1 /* ENQ  */, 1 /* ACK  */, 1 /* BEL  */, 1 /* BS   */, 1 /* HT   */,
      1 /* LF   */, 1 /* VT   */, 1 /* FF   */, 1 /* CR   */, 1 /* SO   */,
      1 /* SI   */, 1 /* DLE  */, 1 /* DC1  */, 1 /* DC2  */, 1 /* DC3  */,
      1 /* DC4  */, 1 /* NAK  */, 1 /* SYN  */, 1 /* ETB  */, 1 /* CAN  */,
      1 /* EM   */, 1 /* SUB  */, 1 /* ESC  */, 1 /* FS   */, 1 /* GS   */,
      1 /* RS   */, 1 /* US   */, 0 /* SPC  */, 0 /* !    */, 1 /* "    */,
      0 /* #    */, 0 /* $    */, 0 /* %    */, 0 /* &    */, 0 /* '    */,
      0 /* (    */, 0 /* )    */, 0 /* *    */, 0 /* +    */, 0 /* ,    */,
      0 /* -    */, 0 /* .    */, 0 /* /    */, 0 /* 0    */, 0 /* 1    */,
      0 /* 2    */, 0 /* 3    */, 0 /* 4    */, 0 /* 5    */, 0 /* 6    */,
      0 /* 7    */, 0 /* 8    */, 0 /* 9    */, 0 /* :    */, 0 /* ;    */,
      0 /* <    */, 0 /* =    */, 0 /* >    */, 0 /* ?    */, 0 /* @    */,
      0 /* A    */, 0 /* B    */, 0 /* C    */, 0 /* D    */, 0 /* E    */,
      0 /* F    */, 0 /* G    */, 0 /* H    */, 0 /* I    */, 0 /* J    */,
      0 /* K    */, 0 /* L    */, 0 /* M    */, 0 /* N    */, 0 /* O    */,
      0 /* P    */, 0 /* Q    */, 0 /* R    */, 0 /* S    */, 0 /* T    */,
      0 /* U    */, 0 /* V    */, 0 /* W    */, 0 /* X    */, 0 /* Y    */,
      0 /* Z    */, 0 /* [    */, 1 /* \    */, 0 /* ]    */, 0 /* ^    */,
      0 /* _    */, 0 /* `    */, 0 /* a    */, 0 /* b    */, 0 /* c    */,
      0 /* d    */, 0 /* e    */, 0 /* f    */, 0 /* g    */, 0 /* h    */,
      0 /* i    */, 0 /* j    */, 0 /* k    */, 0 /* l    */, 0 /* m    */,
      0 /* n    */, 0 /* o    */, 0 /* p    */, 0 /* q    */, 0 /* r    */,
      0 /* s    */, 0 /* t    */, 0 /* u    */, 0 /* v    */, 0 /* w    */,
      0 /* x    */, 0 /* y    */, 0 /* z    */, 0 /* {    */, 0 /* |    */,
      0 /* }    */, 0 /* ~    */, 1 /* DEL  */, 1 /* 0x80 */, 1 /* 0x81 */,
      1 /* 0x82 */, 1 /* 0x83 */, 1 /* 0x84 */, 1 /* 0x85 */, 1 /* 0x86 */,
      1 /* 0x87 */, 1 /* 0x88 */, 1 /* 0x89 */, 1 /* 0x8a */, 1 /* 0x8b */,
      1 /* 0x8c */, 1 /* 0x8d */, 1 /* 0x8e */, 1 /* 0x8f */, 1 /* 0x90 */,
      1 /* 0x91 */, 1 /* 0x92 */, 1 /* 0x93 */, 1 /* 0x94 */, 1 /* 0x95 */,
      1 /* 0x96 */, 1 /* 0x97 */, 1 /* 0x98 */, 1 /* 0x99 */, 1 /* 0x9a */,
      1 /* 0x9b */, 1 /* 0x9c */, 1 /* 0x9d */, 1 /* 0x9e */, 1 /* 0x9f */,
      1 /* 0xa0 */, 1 /* 0xa1 */, 1 /* 0xa2 */, 1 /* 0xa3 */, 1 /* 0xa4 */,
      1 /* 0xa5 */, 1 /* 0xa6 */, 1 /* 0xa7 */, 1 /* 0xa8 */, 1 /* 0xa9 */,
      1 /* 0xaa */, 1 /* 0xab */, 1 /* 0xac */, 1 /* 0xad */, 1 /* 0xae */,
      1 /* 0xaf */, 1 /* 0xb0 */, 1 /* 0xb1 */, 1 /* 0xb2 */, 1 /* 0xb3 */,
      1 /* 0xb4 */, 1 /* 0xb5 */, 1 /* 0xb6 */, 1 /* 0xb7 */, 1 /* 0xb8 */,
      1 /* 0xb9 */, 1 /* 0xba */, 1 /* 0xbb */, 1 /* 0xbc */, 1 /* 0xbd */,
      1 /* 0xbe */, 1 /* 0xbf */, 1 /* 0xc0 */, 1 /* 0xc1 */, 1 /* 0xc2 */,
      1 /* 0xc3 */, 1 /* 0xc4 */, 1 /* 0xc5 */, 1 /* 0xc6 */, 1 /* 0xc7 */,
      1 /* 0xc8 */, 1 /* 0xc9 */, 1 /* 0xca */, 1 /* 0xcb */, 1 /* 0xcc */,
      1 /* 0xcd */, 1 /* 0xce */, 1 /* 0xcf */, 1 /* 0xd0 */, 1 /* 0xd1 */,
      1 /* 0xd2 */, 1 /* 0xd3 */, 1 /* 0xd4 */, 1 /* 0xd5 */, 1 /* 0xd6 */,
      1 /* 0xd7 */, 1 /* 0xd8 */, 1 /* 0xd9 */, 1 /* 0xda */, 1 /* 0xdb */,
      1 /* 0xdc */, 1 /* 0xdd */, 1 /* 0xde */, 1 /* 0xdf */, 1 /* 0xe0 */,
      1 /* 0xe1 */, 1 /* 0xe2 */, 1 /* 0xe3 */, 1 /* 0xe4 */, 1 /* 0xe5 */,
      1 /* 0xe6 */, 1 /* 0xe7 */, 1 /* 0xe8 */, 1 /* 0xe9 */, 1 /* 0xea */,
      1 /* 0xeb */, 1 /* 0xec */, 1 /* 0xed */, 1 /* 0xee */, 1 /* 0xef */,
      1 /* 0xf0 */, 1 /* 0xf1 */, 1 /* 0xf2 */, 1 /* 0xf3 */, 1 /* 0xf4 */,
      1 /* 0xf5 */, 1 /* 0xf6 */, 1 /* 0xf7 */, 1 /* 0xf8 */, 1 /* 0xf9 */,
      1 /* 0xfa */, 1 /* 0xfb */, 1 /* 0xfc */, 1 /* 0xfd */, 1 /* 0xfe */,
      1 /* 0xff */,
  };
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator>
  copy_escape(const char *src, size_t srclen, OutputIterator d_first,
              OutputIterator d_last) {
    auto safe_first = src;
    for (auto p = src; p != src + srclen && d_first != d_last; ++p) {
      unsigned char c = *p;
      if (!ESCAPE_TBL[c]) {
        continue;
      }
  
      auto n =
          std::min(std::distance(d_first, d_last), std::distance(safe_first, p));
      d_first = std::copy_n(safe_first, n, d_first);
      if (std::distance(d_first, d_last) < 4) {
        return std::make_pair(d_first, d_last);
      }
      *d_first++ = '\\';
      *d_first++ = 'x';
      *d_first++ = LOWER_XDIGITS[c >> 4];
      *d_first++ = LOWER_XDIGITS[c & 0xf];
      safe_first = p + 1;
    }
  
    auto n = std::min(std::distance(d_first, d_last),
                      std::distance(safe_first, src + srclen));
    return std::make_pair(std::copy_n(safe_first, n, d_first), d_last);
  }
  } // namespace
  
  namespace {
  template <typename OutputIterator>
  std::pair<OutputIterator, OutputIterator> copy_escape(const StringRef &src,
                                                        OutputIterator d_first,
                                                        OutputIterator d_last) {
    return copy_escape(src.c_str(), src.size(), d_first, d_last);
  }
  } // namespace
  
  namespace {
  // Construct absolute request URI from |Request|, mainly to log
  // request URI for proxy request (HTTP/2 proxy or client proxy).  This
  // is mostly same routine found in
  // HttpDownstreamConnection::push_request_headers(), but vastly
  // simplified since we only care about absolute URI.
  StringRef construct_absolute_request_uri(BlockAllocator &balloc,
                                           const Request &req) {
    if (req.authority.empty()) {
      return req.path;
    }
  
    auto len = req.authority.size() + req.path.size();
    if (req.scheme.empty()) {
      len += str_size("http://");
    } else {
      len += req.scheme.size() + str_size("://");
    }
  
    auto iov = make_byte_ref(balloc, len + 1);
    auto p = iov.base;
  
    if (req.scheme.empty()) {
      // We may have to log the request which lacks scheme (e.g.,
      // http/1.1 with origin form).
      p = util::copy_lit(p, "http://");
    } else {
      p = std::copy(std::begin(req.scheme), std::end(req.scheme), p);
      p = util::copy_lit(p, "://");
    }
    p = std::copy(std::begin(req.authority), std::end(req.authority), p);
    p = std::copy(std::begin(req.path), std::end(req.path), p);
    *p = '\0';
  
    return StringRef{iov.base, p};
  }
  } // namespace
  
  void upstream_accesslog(const std::vector<LogFragment> &lfv,
                          const LogSpec &lgsp) {
    auto config = get_config();
    auto lgconf = log_config();
    auto &accessconf = get_config()->logging.access;
  
    if (lgconf->accesslog_fd == -1 && !accessconf.syslog) {
      return;
    }
  
    std::array<char, 4_k> buf;
  
    auto downstream = lgsp.downstream;
  
    const auto &req = downstream->request();
    const auto &resp = downstream->response();
    const auto &tstamp = req.tstamp;
    auto &balloc = downstream->get_block_allocator();
  
    auto downstream_addr = downstream->get_addr();
    auto method = http2::to_method_string(req.method);
    auto path = req.method == HTTP_CONNECT
                    ? req.authority
                    : config->http2_proxy
                          ? construct_absolute_request_uri(balloc, req)
                          : req.path.empty() ? req.method == HTTP_OPTIONS
                                                   ? StringRef::from_lit("*")
                                                   : StringRef::from_lit("-")
                                             : req.path;
  
    auto p = std::begin(buf);
    auto last = std::end(buf) - 2;
  
    for (auto &lf : lfv) {
      switch (lf.type) {
      case SHRPX_LOGF_LITERAL:
        std::tie(p, last) = copy(lf.value, p, last);
        break;
      case SHRPX_LOGF_REMOTE_ADDR:
        std::tie(p, last) = copy(lgsp.remote_addr, p, last);
        break;
      case SHRPX_LOGF_TIME_LOCAL:
        std::tie(p, last) = copy(tstamp->time_local, p, last);
        break;
      case SHRPX_LOGF_TIME_ISO8601:
        std::tie(p, last) = copy(tstamp->time_iso8601, p, last);
        break;
      case SHRPX_LOGF_REQUEST:
        std::tie(p, last) = copy(method, p, last);
        std::tie(p, last) = copy(' ', p, last);
        std::tie(p, last) = copy_escape(path, p, last);
        std::tie(p, last) = copy_l(" HTTP/", p, last);
        std::tie(p, last) = copy(req.http_major, p, last);
        if (req.http_major < 2) {
          std::tie(p, last) = copy('.', p, last);
          std::tie(p, last) = copy(req.http_minor, p, last);
        }
        break;
      case SHRPX_LOGF_STATUS:
        std::tie(p, last) = copy(resp.http_status, p, last);
        break;
      case SHRPX_LOGF_BODY_BYTES_SENT:
        std::tie(p, last) = copy(downstream->response_sent_body_length, p, last);
        break;
      case SHRPX_LOGF_HTTP: {
        auto hd = req.fs.header(lf.value);
        if (hd) {
          std::tie(p, last) = copy_escape((*hd).value, p, last);
          break;
        }
  
        std::tie(p, last) = copy('-', p, last);
  
        break;
      }
      case SHRPX_LOGF_AUTHORITY:
        if (!req.authority.empty()) {
          std::tie(p, last) = copy(req.authority, p, last);
          break;
        }
  
        std::tie(p, last) = copy('-', p, last);
  
        break;
      case SHRPX_LOGF_REMOTE_PORT:
        std::tie(p, last) = copy(lgsp.remote_port, p, last);
        break;
      case SHRPX_LOGF_SERVER_PORT:
        std::tie(p, last) = copy(lgsp.server_port, p, last);
        break;
      case SHRPX_LOGF_REQUEST_TIME: {
        auto t = std::chrono::duration_cast<std::chrono::milliseconds>(
                     lgsp.request_end_time - downstream->get_request_start_time())
                     .count();
        std::tie(p, last) = copy(t / 1000, p, last);
        std::tie(p, last) = copy('.', p, last);
        auto frac = t % 1000;
        if (frac < 100) {
          auto n = frac < 10 ? 2 : 1;
          std::tie(p, last) = copy("000", n, p, last);
        }
        std::tie(p, last) = copy(frac, p, last);
        break;
      }
      case SHRPX_LOGF_PID:
        std::tie(p, last) = copy(lgsp.pid, p, last);
        break;
      case SHRPX_LOGF_ALPN:
        std::tie(p, last) = copy_escape(lgsp.alpn, p, last);
        break;
      case SHRPX_LOGF_TLS_CIPHER:
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy(SSL_get_cipher_name(lgsp.ssl), p, last);
        break;
      case SHRPX_LOGF_TLS_PROTOCOL:
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) =
            copy(nghttp2::tls::get_tls_protocol(lgsp.ssl), p, last);
        break;
      case SHRPX_LOGF_TLS_SESSION_ID: {
        auto session = SSL_get_session(lgsp.ssl);
        if (!session) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        unsigned int session_id_length = 0;
        auto session_id = SSL_SESSION_get_id(session, &session_id_length);
        if (session_id_length == 0) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy_hex_low(session_id, session_id_length, p, last);
        break;
      }
      case SHRPX_LOGF_TLS_SESSION_REUSED:
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) =
            copy(SSL_session_reused(lgsp.ssl) ? 'r' : '.', p, last);
        break;
      case SHRPX_LOGF_TLS_SNI:
        if (lgsp.sni.empty()) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy_escape(lgsp.sni, p, last);
        break;
      case SHRPX_LOGF_TLS_CLIENT_FINGERPRINT_SHA1:
      case SHRPX_LOGF_TLS_CLIENT_FINGERPRINT_SHA256: {
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        auto x = SSL_get_peer_certificate(lgsp.ssl);
        if (!x) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::array<uint8_t, 32> buf;
        auto len = tls::get_x509_fingerprint(
            buf.data(), buf.size(), x,
            lf.type == SHRPX_LOGF_TLS_CLIENT_FINGERPRINT_SHA256 ? EVP_sha256()
                                                                : EVP_sha1());
        X509_free(x);
        if (len <= 0) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy_hex_low(buf.data(), len, p, last);
        break;
      }
      case SHRPX_LOGF_TLS_CLIENT_ISSUER_NAME:
      case SHRPX_LOGF_TLS_CLIENT_SUBJECT_NAME: {
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        auto x = SSL_get_peer_certificate(lgsp.ssl);
        if (!x) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        auto name = lf.type == SHRPX_LOGF_TLS_CLIENT_ISSUER_NAME
                        ? tls::get_x509_issuer_name(balloc, x)
                        : tls::get_x509_subject_name(balloc, x);
        X509_free(x);
        if (name.empty()) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy(name, p, last);
        break;
      }
      case SHRPX_LOGF_TLS_CLIENT_SERIAL: {
        if (!lgsp.ssl) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        auto x = SSL_get_peer_certificate(lgsp.ssl);
        if (!x) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        auto sn = tls::get_x509_serial(balloc, x);
        X509_free(x);
        if (sn.empty()) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy(sn, p, last);
        break;
      }
      case SHRPX_LOGF_BACKEND_HOST:
        if (!downstream_addr) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy(downstream_addr->host, p, last);
        break;
      case SHRPX_LOGF_BACKEND_PORT:
        if (!downstream_addr) {
          std::tie(p, last) = copy('-', p, last);
          break;
        }
        std::tie(p, last) = copy(downstream_addr->port, p, last);
        break;
      case SHRPX_LOGF_NONE:
        break;
      default:
        break;
      }
    }
  
    *p = '\0';
  
    if (accessconf.syslog) {
      syslog(LOG_INFO, "%s", buf.data());
  
      return;
    }
  
    *p++ = '\n';
  
    auto nwrite = std::distance(std::begin(buf), p);
    while (write(lgconf->accesslog_fd, buf.data(), nwrite) == -1 &&
           errno == EINTR)
      ;
  }
  
  int reopen_log_files(const LoggingConfig &loggingconf) {
    int res = 0;
    int new_accesslog_fd = -1;
    int new_errorlog_fd = -1;
  
    auto lgconf = log_config();
    auto &accessconf = loggingconf.access;
    auto &errorconf = loggingconf.error;
  
    if (!accessconf.syslog && !accessconf.file.empty()) {
      new_accesslog_fd = open_log_file(accessconf.file.c_str());
  
      if (new_accesslog_fd == -1) {
        LOG(ERROR) << "Failed to open accesslog file " << accessconf.file;
        res = -1;
      }
    }
  
    if (!errorconf.syslog && !errorconf.file.empty()) {
      new_errorlog_fd = open_log_file(errorconf.file.c_str());
  
      if (new_errorlog_fd == -1) {
        if (lgconf->errorlog_fd != -1) {
          LOG(ERROR) << "Failed to open errorlog file " << errorconf.file;
        } else {
          std::cerr << "Failed to open errorlog file " << errorconf.file
                    << std::endl;
        }
  
        res = -1;
      }
    }
  
    close_log_file(lgconf->accesslog_fd);
    close_log_file(lgconf->errorlog_fd);
  
    lgconf->accesslog_fd = new_accesslog_fd;
    lgconf->errorlog_fd = new_errorlog_fd;
    lgconf->errorlog_tty =
        (new_errorlog_fd == -1) ? false : isatty(new_errorlog_fd);
  
    return res;
  }
  
  void log_chld(pid_t pid, int rstatus, const char *msg) {
    std::string signalstr;
    if (WIFSIGNALED(rstatus)) {
      signalstr += "; signal ";
      auto sig = WTERMSIG(rstatus);
      auto s = strsignal(sig);
      if (s) {
        signalstr += s;
        signalstr += '(';
      } else {
        signalstr += "UNKNOWN(";
      }
      signalstr += util::utos(sig);
      signalstr += ')';
    }
  
    LOG(NOTICE) << msg << ": [" << pid << "] exited "
                << (WIFEXITED(rstatus) ? "normally" : "abnormally")
                << " with status " << std::hex << rstatus << std::oct
                << "; exit status " << WEXITSTATUS(rstatus)
                << (signalstr.empty() ? "" : signalstr.c_str());
  }
  
  void redirect_stderr_to_errorlog(const LoggingConfig &loggingconf) {
    auto lgconf = log_config();
    auto &errorconf = loggingconf.error;
  
    if (errorconf.syslog || lgconf->errorlog_fd == -1) {
      return;
    }
  
    dup2(lgconf->errorlog_fd, STDERR_FILENO);
  }
  
  namespace {
  int STDERR_COPY = -1;
  int STDOUT_COPY = -1;
  } // namespace
  
  void store_original_fds() {
    // consider dup'ing stdout too
    STDERR_COPY = dup(STDERR_FILENO);
    STDOUT_COPY = STDOUT_FILENO;
    // no race here, since it is called early
    util::make_socket_closeonexec(STDERR_COPY);
  }
  
  void restore_original_fds() { dup2(STDERR_COPY, STDERR_FILENO); }
  
  void close_log_file(int &fd) {
    if (fd != STDERR_COPY && fd != STDOUT_COPY && fd != -1) {
      close(fd);
    }
    fd = -1;
  }
  
  int open_log_file(const char *path) {
  
    if (strcmp(path, "/dev/stdout") == 0 ||
        strcmp(path, "/proc/self/fd/1") == 0) {
      return STDOUT_COPY;
    }
  
    if (strcmp(path, "/dev/stderr") == 0 ||
        strcmp(path, "/proc/self/fd/2") == 0) {
      return STDERR_COPY;
    }
  #if defined O_CLOEXEC
  
    auto fd = open(path, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC,
                   S_IRUSR | S_IWUSR | S_IRGRP);
  #else // !O_CLOEXEC
  
    auto fd =
        open(path, O_WRONLY | O_APPEND | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP);
  
    // We get race condition if execve is called at the same time.
    if (fd != -1) {
      util::make_socket_closeonexec(fd);
    }
  
  #endif // !O_CLOEXEC
  
    if (fd == -1) {
      return -1;
    }
  
    return fd;
  }
  
  } // namespace shrpx
  