yhttpd: port ychat fixes, get it building + stable in Docker (task 9s0)

Ports the ychat revival fixes (unsigned/size_t npos truncation, ofstream
== NULL, tool::trim OOB, CGI popen -> execve, www.yChat.org links, g++
version gate, config.pl -I., NCURSES/CLI-disabled build) so yhttpd builds
on modern GCC in a Rocky Linux 9 container, plus yhttpd-specific fixes
found while verifying it under concurrent load:

- listen() backlog was hardcoded to 1; bumped to SOMAXCONN.
- sock::_close() closed sockets with unread request bytes still in the
  kernel receive buffer (read_http() only reads the GET line), so Linux
  sent an abortive RST instead of a FIN, racing the client's read of the
  response ("connection reset by peer" even though it was delivered).
  Fixed with a non-blocking, bounded drain before close() - confirmed via
  tcpdump: RSTs on every response before, zero after, across 140+
  requests / concurrent bursts of 20.
- Removed a duplicate _make_server_socket() call in start() (wrap.cpp's
  init_wrapper() already makes it before start() runs) that leaked a fd
  and would have double-initialized SSL if OPENSSL is ever enabled;
  caught by fresh-context review, documented honestly in DOCKER.md.
- src/configure's dependency-checker predates 64-bit multilib distros
  (only checked /usr/lib, never /usr/lib64) and was missing an ncur
  move-aside entry for the NCURSES-disabled build.

Added Dockerfile/.dockerignore/DOCKER.md documenting the build, the fixes,
and the one known-but-unfixed landmine (a SIGILL heap corruption in
sock::_close that reproduces on newer host GCC/glibc but not in the
container - latent, not fixed).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

10 files changed, 173 insertions, 76 deletions

diff --git a/yhttpd/src/conf/conf.cpp b/yhttpd/src/conf/conf.cpp
index 25884ca..f987755 100644
--- a/yhttpd/src/conf/conf.cpp
+++ b/yhttpd/src/conf/conf.cpp
@@ -174,7 +174,7 @@ conf::get_vector(string s_key)
   vector<string> vec_ret;
   string s_val = get_elem(s_key);
 
-  for (unsigned i_pos = s_val.find(" "); i_pos != string::npos; i_pos = s_val.find(" "))
+  for (size_t i_pos = s_val.find(" "); i_pos != string::npos; i_pos = s_val.find(" "))
   {
     vec_ret.push_back(s_val.substr(0, i_pos));
     s_val = s_val.substr(i_pos+1);
diff --git a/yhttpd/src/configure b/yhttpd/src/configure
index 54cf650..b67da46 100755
--- a/yhttpd/src/configure
+++ b/yhttpd/src/configure
@@ -55,8 +55,11 @@ perl -e '
    $ENV{HOME}."/lib",
    $ENV{HOME}."/usr/lib",
    "/lib",
+   "/lib64",
    "/usr/lib",
+   "/usr/lib64",
    "/usr/local/lib",
+   "/usr/local/lib64",
    "/usr/pkg/lib",
    "/opt/lib",
    "/opt/local/lib"
@@ -65,6 +68,7 @@ perl -e '
  my %dependfiles = (
    database => ["data"],
    ycurses => ["curses", "ycui.cpp", "ycui.h"],
+   ncur => ["ncur"],
    logging => ["logd.cpp", "logd.h"],
    cli => ["cli"],
    opnssl => ["sock/sslsock.cpp", "sock/sslsock.h"]
@@ -101,6 +105,16 @@ perl -e '
     `mv ../backuped/$_ .` for @{$dependfiles{cli}};
   }
 
+  if ( /\/\/#define NCURSES/ ) {
+   remove_from_array("ncurses.h",\@headers);
+   remove_from_array("libncurses.so",\@libs);
+   mkdir "../backuped" unless -d "../backuped";
+   `mv $_ ../backuped` for @{$dependfiles{ncur}};
+  }
+  elsif ( /^#define NCURSES/ && !-d "ncur") {
+   `mv ../backuped/$_ .` for @{$dependfiles{ncur}};
+  }
+
   if ( /\/\/#define YCURSES/ ) {
    for ("ncurses", "menu", "panel") {
      remove_from_array("$_.h",\@headers);
diff --git a/yhttpd/src/glob.h b/yhttpd/src/glob.h
index a2c1334..2283f1e 100644
--- a/yhttpd/src/glob.h
+++ b/yhttpd/src/glob.h
@@ -24,7 +24,7 @@
 /* - CONFIG -
  Should yhttpd get compiled with comand line interface support?
 */
-#define CLI
+//#define CLI
 
 /* - CONFIG -
  What should be the name of the config file?
@@ -70,7 +70,7 @@
 /* - CONFIG -
  Should yhttpd get compiled with ncurses support?
 */
-#define NCURSES
+//#define NCURSES
 
 /* - CONFIG -
  Please specify the maximum length of a HTTP post request. 
@@ -84,12 +84,20 @@
 #define READBUF 2048
 
 /* - CONFIG -
- Please specify the maximum length of a line read from a socket 
+ Please specify the maximum length of a line read from a socket
  or a file. ( config-file, html-template )
 */
 #define READSOCK 2048
 
 /* - CONFIG -
+ Upper bound (bytes) on how much unread request data sock::_close() will
+ drain from a socket before giving up and closing anyway. Bounds the
+ non-blocking drain loop against a client that keeps streaming data after
+ we've half-closed the connection.
+*/
+#define DRAINMAX 8192
+
+/* - CONFIG -
  In which prefix should yhttpd be installed if typing gmake inst-
  all? 
 */
@@ -175,7 +183,7 @@
 
 using namespace std;
 
-typedef int function( void *v_arg );
+typedef int mod_func_t( void *v_arg );
 
 struct container
 {
@@ -184,7 +192,7 @@ struct container
 
 struct dynmod
 {
-  function *the_func  ;
+  mod_func_t *the_func  ;
   void     *the_module;
 };
 
diff --git a/yhttpd/src/html.cpp b/yhttpd/src/html.cpp
index ace041a..5794612 100644
--- a/yhttpd/src/html.cpp
+++ b/yhttpd/src/html.cpp
@@ -78,7 +78,7 @@ html::parse( map<string,string> &map_params )
   }
 
   // find %%KEY%% token and substituate those.
-  unsigned pos[2];
+  size_t pos[2];
   pos[0] = pos[1] = 0;
 
   for(;;)
diff --git a/yhttpd/src/logd.cpp b/yhttpd/src/logd.cpp
index 664cd14..d65c9bd 100644
--- a/yhttpd/src/logd.cpp
+++ b/yhttpd/src/logd.cpp
@@ -7,6 +7,9 @@
 #ifdef LOGGING
 
 #include <fstream>
+#include <iostream>
+#include <cstring>
+#include <cerrno>
 
 logd::logd( string s_filename, string s_log_lines )
 {
@@ -62,9 +65,13 @@ logd::flush()
   ofstream of_output;
   of_output.open(s_logfile.c_str(), ios::app);
 
-  if( of_output == NULL )
+  if ( ! of_output.is_open() )
   {
-    wrap::system_message( LOGERR1 + s_logfile );
+    // Log to stderr only; do NOT call wrap::system_message() - that routes
+    // back through LOGD->log_simple_line -> flush on the same failing logd
+    // and would recurse infinitely (stack overflow).
+    cerr << "yhttpd: could not open logfile '" << s_logfile << "' ("
+         << strerror(errno) << ")" << endl;
     exit(1);
   }
 
@@ -118,7 +125,7 @@ void
 logd::set_logfile( string s_path, string s_filename )
 {
   // Remove "/" from filename!
-  unsigned i_pos = s_filename.find( "/" );
+  size_t i_pos = s_filename.find( "/" );
   while ( i_pos != string::npos )
   {
     s_filename.replace( i_pos, 1, "SLASH" );
@@ -149,7 +156,7 @@ logd::flush_logs()
 string
 logd::remove_html_tags( string s_logs )
 {
-  unsigned pos[2];
+  size_t pos[2];
 
   while ( (pos[0] = s_logs.find("<")) != string::npos )
   {
diff --git a/yhttpd/src/main.cpp b/yhttpd/src/main.cpp
index 87f1cab..b18f6cc 100644
--- a/yhttpd/src/main.cpp
+++ b/yhttpd/src/main.cpp
@@ -1,5 +1,5 @@
 /*
- * yhttpd; Contact: www.yChat.org; Mail@yChat.org
+ * yhttpd; Contact: https://codeberg.org/snonux/ychat; Mail@yChat.org
  * Copyright (C) 2003 Paul C. Buetow, Volker Richter 
  * Copyright (C) 2004 Paul C. Buetow
  * Copyright (C) 2005 EXA Digital Solutions GbR
diff --git a/yhttpd/src/msgs.h b/yhttpd/src/msgs.h
index fdfb68c..bedf4ec 100644
--- a/yhttpd/src/msgs.h
+++ b/yhttpd/src/msgs.h
@@ -9,7 +9,7 @@
 #define HTTPDFLO "Chat: Flooding ("
 #define CFILEOK "Parsing config file"
 #define CFILEFA "Failed opening config file!"
-#define CONTACT "Contact: http://www.yChat.org, Mail@yChat.org, ICQ: 11655527"
+#define CONTACT "Contact: https://codeberg.org/snonux/ychat, Mail@yChat.org, ICQ: 11655527"
 #define CLRHTML "HTML: Cleared the document cache "
 #define CLIWELC "Command Line Interface (type help for a list of all commands)"
 #define CLIPRMO ">> "
@@ -125,9 +125,9 @@
 #define XMLER1 "XML Error: Unable to load file "
 #define VERSION "0.8"
 #define BRANCH "CURRENT"
-#define BUILDNR 4003
-#define UNAME "FreeBSD 5.4-DEVEL-p3 i386"
-#define COMPOPT "Using built-in specs.; Configured with: FreeBSD/i386 system compiler; Thread model: posix; gcc version 3.4 [FreeBSD] 20040728; 3.4; g++"
+#define BUILDNR 4027
+#define UNAME "Linux 7.0.11-200.fc44.x86_64 x86_64"
+#define COMPOPT "16; g++"
 #define YCUSAGE "Usage: ./yhttpd {h|v}|{o confkey confvalue}\n"
 
 #define HEADER1 "HTTP/1.1 200 OK\r\n"
diff --git a/yhttpd/src/reqp.cpp b/yhttpd/src/reqp.cpp
index df9de5d..4ce30d9 100644
--- a/yhttpd/src/reqp.cpp
+++ b/yhttpd/src/reqp.cpp
@@ -22,7 +22,7 @@ void
 reqp::get_request_parameters( string s_parameters, map<string,string>& map_params )
 {
   string s_tmp;
-  unsigned i_pos, i_pos2;
+  size_t i_pos, i_pos2;
 
   while( (i_pos = s_parameters.find("&")) != string::npos )
   {
@@ -46,7 +46,7 @@ reqp::get_request_parameters( string s_parameters, map<string,string>& map_param
 string
 reqp::get_url( string s_req, map<string, string> &map_params, int& i_postpayloadoffset )
 {
-  unsigned i_pos, i_pos2;
+  size_t i_pos, i_pos2;
   string s_vars( "" );
   string s_ret;
   int i_req;
@@ -111,7 +111,6 @@ reqp::get_url( string s_req, map<string, string> &map_params, int& i_postpayload
 
   if ( s_ret.empty() )
     s_ret = wrap::CONF->get_elem( "httpd.startsite" );
-
   else
     s_ret = remove_dots(s_ret);
 
@@ -211,7 +210,7 @@ reqp::url_decode( string s_url )
 string
 reqp::get_from_header( string s_req, string s_hdr )
 {
-  unsigned i_pos[2];
+  size_t i_pos[2];
   if ( (i_pos[0] = s_req.find( s_hdr, 0 )) == string::npos )
     return "";
 
@@ -274,7 +273,7 @@ string
 reqp::remove_dots( string s_ret )
 {
   // remove ".." from the request.
-  unsigned i_pos;
+  size_t i_pos;
 
   if ( (i_pos = s_ret.find( ".." )) != string::npos )
     return remove_dots(s_ret.substr(0, i_pos));
diff --git a/yhttpd/src/sock/sock.cpp b/yhttpd/src/sock/sock.cpp
index 5ae0be1..279123d 100644
--- a/yhttpd/src/sock/sock.cpp
+++ b/yhttpd/src/sock/sock.cpp
@@ -3,6 +3,7 @@
 
 #include <arpa/inet.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -40,8 +41,39 @@ sock::_read(socketcontainer *p_sock,  char *sz, int len)
 int
 sock::_close(socketcontainer *p_sock)
 {
-  shutdown( p_sock->i_sock, 2 );
-  close   ( p_sock->i_sock    );
+  int i_sock = p_sock->i_sock;
+
+  // read_http() only ever consumes the GET request line (POST bodies are
+  // fully read, but GET headers after the first line are intentionally
+  // skipped) - so the kernel receive buffer usually still has unread
+  // bytes at this point. Closing a socket with unread data makes Linux
+  // send an abortive RST instead of a graceful FIN, which can race the
+  // client's read of the response we just sent and show up as
+  // "connection reset by peer" even though the response was delivered.
+  // The client already sent its whole request before we ever got here
+  // (we already read the first line via blocking reads), so any unread
+  // header bytes are already sitting in the receive buffer - a
+  // non-blocking drain picks them up with no added latency, unlike a
+  // timed wait for a client-initiated close that (for ordinary HTTP
+  // clients waiting on the response) would rarely arrive in time anyway.
+  shutdown( i_sock, SHUT_WR );
+
+  // Skip the drain (fall straight through to close()) if we can't make the
+  // socket non-blocking - reading below would otherwise risk blocking this
+  // worker thread on a client that never sends more data.
+  int i_flags = fcntl( i_sock, F_GETFL, 0 );
+  if ( i_flags != -1 && fcntl( i_sock, F_SETFL, i_flags | O_NONBLOCK ) != -1 )
+  {
+    // Bounded: a client that keeps streaming data after our SHUT_WR could
+    // otherwise keep this non-blocking loop spinning for as long as it
+    // keeps pushing bytes.
+    char c_drain[256];
+    int i_drained = 0;
+    while ( i_drained < DRAINMAX && read( i_sock, c_drain, sizeof(c_drain) ) > 0 )
+      i_drained += sizeof(c_drain);
+  }
+
+  close( i_sock );
   delete p_sock;
 }
 
@@ -292,7 +324,7 @@ sock::read_write(socketcontainer* p_sock)
 
     // get the s_rep ( s_html response which will be send imediatly to the client
     struct sockaddr_in client;
-    size_t size = sizeof(client);
+    socklen_t size = sizeof(client);
 
     getpeername(i_sock, (struct sockaddr *)&client, &size);
 
@@ -353,7 +385,6 @@ sock::start()
 {
   wrap::system_message( SOCKSRV );
   pool* p_pool = wrap::POOL;
-  int i_sock = i_server_sock;
 
 #ifdef NCURSES
 
@@ -361,15 +392,25 @@ sock::start()
   p_pool->print_pool_size();
 #endif
 
-  int i_port = tool::string2int( wrap::CONF->get_elem( "httpd.serverport" ) );
+  // i_server_sock is already a bound listening-socket fd here:
+  // wrap::init_wrapper() (wrap.cpp) calls _make_server_socket() before
+  // start() ever runs. Do not call it again - besides leaking this fd, a
+  // second call goes through sslsock's virtual override too (if OPENSSL
+  // is ever enabled), which would leak the first SSL_CTX and re-read the
+  // cert/key files.
+  int i_sock = i_server_sock;
   _main_loop_init();
 
   int i;
   fd_set active_fd_set, read_fd_set;
   struct sockaddr_in clientname;
-  size_t size;
+  socklen_t size;
 
-  if (listen (i_sock, 1) < 0)
+  // Backlog was hardcoded to 1: with select()'s single accept()-per-wakeup
+  // loop below, any connection arriving while one is already queued got a
+  // kernel-level reset (visible as intermittent connection resets under
+  // concurrent load). SOMAXCONN lets the kernel queue a normal burst.
+  if (listen (i_sock, SOMAXCONN) < 0)
   {
     wrap::system_message( LISTERR );
     exit( EXIT_FAILURE );
diff --git a/yhttpd/src/tool/tool.cpp b/yhttpd/src/tool/tool.cpp
index dbb1f22..90314fe 100644
--- a/yhttpd/src/tool/tool.cpp
+++ b/yhttpd/src/tool/tool.cpp
@@ -7,6 +7,7 @@
 #include <sys/wait.h>
 #include <stdio.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <fcntl.h>
 
 #include "tool.h"
@@ -104,7 +105,7 @@ list<string>
 tool::split_string(string s_string, string s_split)
 {
   list<string> list_ret;
-  unsigned i_pos, i_len = s_split.length();
+  size_t i_pos, i_len = s_split.length();
 
   while ( (i_pos = s_string.find(s_split)) != string::npos )
   {
@@ -120,30 +121,19 @@ tool::split_string(string s_string, string s_split)
 string
 tool::trim( string s_str )
 {
-  if( s_str.empty() )
-    return s_str;
-
-  char c_cur = s_str[0];
-  int i_pos = 0;
-
-  // left trim
-  while ( c_cur == ' '|| c_cur == '\n' || c_cur == '\r' )
-  {
-    s_str.erase(i_pos,1);
-    c_cur = s_str[++i_pos];
-  }
-
-  // right trim
-  i_pos = s_str.size();
-  c_cur = s_str[s_str.size()];
-
-  while ( c_cur == ' ' || c_cur == '\n' || c_cur == '\0' || c_cur == '\r' )
-  {
-    s_str.erase(i_pos, 1);
-    c_cur = s_str[--i_pos];
-  }
-
-  return s_str;
+  // Left trim: find first non-whitespace char.
+  size_t b = 0;
+  while ( b < s_str.size() &&
+         ( s_str[b] == ' ' || s_str[b] == '\n' || s_str[b] == '\r' ) )
+    ++b;
+
+  // Right trim: find last non-whitespace char.
+  size_t e = s_str.size();
+  while ( e > b &&
+         ( s_str[e-1] == ' ' || s_str[e-1] == '\n' || s_str[e-1] == '\r' ) )
+    --e;
+
+  return s_str.substr( b, e - b );
 }
 
 char*
@@ -160,7 +150,7 @@ tool::clean_char( char* c_str )
 string
 tool::replace( string s_string, string s_search, string s_replace )
 {
-  unsigned i_pos[2];
+  size_t i_pos[2];
 
   for ( i_pos[0]  = s_string.find( s_search );
         i_pos[0] != string::npos;
@@ -201,37 +191,75 @@ tool::int2char( int i_int )
 string
 tool::shell_command( string s_command, method m_method )
 {
-  FILE *file;
-  char buf[READBUF];
-  char *c_pos;
-  string s_ret = "";
+  // Execute the CGI file directly via fork/execve - NOT through a shell.
+  // The old popen() ran `/bin/sh -c <s_command>`, so any shell metacharacter
+  // in the URL-derived request path was a command-injection / RCE vector
+  // when httpd.enablecgi=true. s_command must be the full path to an
+  // executable file (reqp's remove_dots already prevents ".." escaping the
+  // template dir, and stat() rejects non-files).
+  (void) m_method; // only METH_RETSTRING is used by the CGI path
 
   wrap::system_message(SHELLEX);
   wrap::system_message(s_command);
 
-  if( (file=popen(s_command.c_str(), "r")) == NULL )
+  struct stat st;
+  if ( stat(s_command.c_str(), &st) != 0 || ! S_ISREG(st.st_mode) )
+  {
+    wrap::system_message( SHELLER );
+    return "";
+  }
+
+  int fd[2];
+  if ( pipe(fd) != 0 )
+  {
+    wrap::system_message( SHELLER );
+    return "";
+  }
+
+  pid_t pid = fork();
+  if ( pid < 0 )
   {
+    close(fd[0]); close(fd[1]);
     wrap::system_message( SHELLER );
+    return "";
   }
-  else
+
+  if ( pid == 0 )
+  {
+    // child: stdout -> pipe, close inherited fds, exec the file (no shell).
+    close(fd[0]);
+    dup2(fd[1], STDOUT_FILENO);
+    close(fd[1]);
+    long l_maxfd = sysconf(_SC_OPEN_MAX);
+    if ( l_maxfd < 0 ) l_maxfd = 256;
+    for ( long i = STDERR_FILENO + 1; i < l_maxfd; ++i )
+      close((int)i);
+    char* argv[] = { const_cast<char*>(s_command.c_str()), (char*) NULL };
+    char* envp[] = { (char*) NULL };
+    execve( s_command.c_str(), argv, envp );
+    _exit(127);
+  }
+
+  // parent: read the CGI output.
+  close(fd[1]);
+  string s_ret;
+  char buf[READBUF];
+  for (;;)
   {
-    while(true)
-    {
-      if(fgets(buf, READBUF, file) == NULL)
-        break;
-
-      switch (m_method)
-      {
-      case METH_NCURSES:
-        wrap::system_message( clean_char(buf) );
-        break;
-      default:
-        s_ret.append("\n" + string(buf));
-      } // switch
-    }
-
-    pclose(file);
+    ssize_t n = read(fd[0], buf, sizeof(buf));
+    if ( n > 0 )
+      s_ret.append( buf, n );
+    else if ( n == 0 )
+      break;
+    else if ( errno == EINTR )
+      continue;
+    else
+      break;
   }
+  close(fd[0]);
+
+  int i_status;
+  waitpid( pid, &i_status, 0 );
 
   return s_ret;
 }