Experimental decoupling of socketbinders and daemons in ucspi servers.

 Rewrite of s6-ipcserver as a small wrapper.
 s6-tcpserver4 and s6-tcpserver6 will follow.

1 files changed, 373 insertions, 0 deletions

diff --git a/src/conn-tools/s6-tcpserver6d.c b/src/conn-tools/s6-tcpserver6d.c
new file mode 100644
index 0000000..3e535c5
--- /dev/null
+++ b/src/conn-tools/s6-tcpserver6d.c
@@ -0,0 +1,373 @@
+/* ISC license. */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <skalibs/gccattributes.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/uint16.h>
+#include <skalibs/uint.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/fmtscan.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/sig.h>
+#include <skalibs/selfpipe.h>
+#include <skalibs/iopause.h>
+#include <skalibs/socket.h>
+
+#define ABSOLUTE_MAXCONN 1000
+
+#define USAGE "s6-tcpserver6d [ -v verbosity ] [ -1 ] [ -c maxconn ] [ -C localmaxconn ] prog..."
+
+typedef struct ipnum_s ipnum_t, *ipnum_t_ref ;
+struct ipnum_s
+{
+  char ip[16] ;
+  unsigned int num ;
+} ;
+#define IPNUM_ZERO { "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 0 }
+
+static unsigned int maxconn = 40 ;
+static unsigned int localmaxconn = 40 ;
+static unsigned int verbosity = 1 ;
+static int cont = 1 ;
+static ipnum_t_ref pidip = 0 ;
+static unsigned int numconn = 0 ;
+static ipnum_t_ref ipnum = 0 ;
+static unsigned int iplen = 0 ;
+
+static char fmtmaxconn[UINT_FMT+1] = "/" ;
+static char fmtlocalmaxconn[UINT_FMT+1] = "/" ;
+
+
+ /* Utility functions */
+
+static inline void dieusage ()
+{
+  strerr_dieusage(100, USAGE) ;
+}
+
+static inline void X (void)
+{
+  strerr_dief1x(101, "internal inconsistency. Please submit a bug-report.") ;
+}
+
+
+ /* Lookup primitives */
+ 
+static unsigned int lookup_pid (unsigned int pid)
+{
+  register unsigned int i = 0 ;
+  for (; i < numconn ; i++) if (pid == pidip[i].num) break ;
+  return i ;
+}
+
+static unsigned int lookup_ip (char const *ip)
+{
+  register unsigned int i = 0 ;
+  for (; i < iplen ; i++) if (!byte_diff(ip, 16, ipnum[i].ip)) break ;
+  return i ;
+}
+
+
+ /* Logging */
+
+static void log_start (void)
+{
+  strerr_warni1x("starting") ;
+}
+
+static inline void log_exit (void)
+{
+  strerr_warni1x("exiting") ;
+}
+
+static void log_status (void)
+{
+  char fmt[UINT_FMT] ;
+  fmt[uint_fmt(fmt, numconn)] = 0 ;
+  strerr_warni3x("status: ", fmt, fmtmaxconn) ;
+}
+
+static void log_deny (char const *ip, uint16 port, unsigned int num)
+{
+  char fmtip[IP6_FMT] ;
+  char fmtport[UINT16_FMT] ;
+  char fmtnum[UINT_FMT] ;
+  fmtip[ip6_fmt(fmtip, ip)] = 0 ;
+  fmtport[uint16_fmt(fmtport, port)] = 0 ;
+  fmtnum[uint_fmt(fmtnum, num)] = 0 ;
+  strerr_warni7sys("deny ", fmtip, " port ", fmtport, " count ", fmtnum, fmtlocalmaxconn) ;
+}
+
+static void log_accept (unsigned int pid, char const *ip, uint16 port, unsigned int num)
+{
+  char fmtipport[IP6_FMT + UINT16_FMT + 6] ;
+  char fmtpid[UINT_FMT] ;
+  char fmtnum[UINT_FMT] ;
+  register unsigned int n ;
+  n = ip6_fmt(fmtipport, ip) ;
+  byte_copy(fmtipport + n, 6, " port ") ; n += 6 ;
+  n += uint16_fmt(fmtipport + n, port) ;
+  fmtipport[n] = 0 ;
+  fmtnum[uint_fmt(fmtnum, num)] = 0 ;
+  fmtpid[uint_fmt(fmtpid, pid)] = 0 ;
+  strerr_warni7x("allow ", fmtipport, " pid ", fmtpid, " count ", fmtnum, fmtlocalmaxconn) ;
+}
+
+static void log_close (unsigned int pid, char const *ip, int w)
+{
+  char fmtpid[UINT_FMT] ;
+  char fmtip[IP6_FMT] = "?" ;
+  char fmtw[UINT_FMT] ;
+  fmtpid[uint_fmt(fmtpid, pid)] = 0 ;
+  fmtip[ip6_fmt(fmtip, ip)] = 0 ;
+  fmtw[uint_fmt(fmtw, WIFSIGNALED(w) ? WTERMSIG(w) : WEXITSTATUS(w))] = 0 ;
+  strerr_warni6x("end pid ", fmtpid, " ip ", fmtip, WIFSIGNALED(w) ? " signal " : " exitcode ", fmtw) ;
+}
+
+
+ /* Signal handling */
+
+static void killthem (int sig)
+{
+  register unsigned int i = 0 ;
+  for (; i < numconn ; i++) kill(pidip[i].num, sig) ;
+}
+
+static void wait_children (void)
+{
+  for (;;)
+  {
+    unsigned int i ;
+    int w ;
+    register pid_t pid = wait_nohang(&w) ;
+    if (pid < 0)
+      if (errno != ECHILD) strerr_diefu1sys(111, "wait_nohang") ;
+      else break ;
+    else if (!pid) break ;
+    i = lookup_pid(pid) ;
+    if (i < numconn) /* it's one of ours ! */
+    {
+      register unsigned int j = lookup_ip(pidip[i].ip) ;
+      if (j >= iplen) X() ;
+      if (!--ipnum[j].num) ipnum[j] = ipnum[--iplen] ;
+      --numconn ;
+      if (verbosity >= 2)
+      {
+        log_close(pid, pidip[i].ip, w) ;
+        log_status() ;
+      }
+      pidip[i] = pidip[numconn] ;
+    }
+  }
+}
+
+static void handle_signals (void)
+{
+  for (;;) switch (selfpipe_read())
+  {
+    case -1 : strerr_diefu1sys(111, "read selfpipe") ;
+    case 0 : return ;
+    case SIGCHLD : wait_children() ; break ;
+    case SIGTERM :
+    {
+      if (verbosity >= 2)
+        strerr_warni3x("received ", "SIGTERM,", " quitting") ;
+      cont = 0 ;
+      break ;
+    }
+    case SIGHUP :
+    {
+      if (verbosity >= 2)
+        strerr_warni5x("received ", "SIGHUP,", " sending ", "SIGTERM+SIGCONT", " to all connections") ;
+      killthem(SIGTERM) ;
+      killthem(SIGCONT) ;
+      break ;
+    }
+    case SIGQUIT :
+    {
+      if (verbosity >= 2)
+        strerr_warni6x("received ", "SIGQUIT,", " sending ", "SIGTERM+SIGCONT", " to all connections", " and quitting") ;
+      cont = 0 ;
+      killthem(SIGTERM) ;
+      killthem(SIGCONT) ;
+      break ;
+    }
+    case SIGABRT :
+    {
+      if (verbosity >= 2)
+        strerr_warni6x("received ", "SIGABRT,", " sending ", "SIGKILL", " to all connections", " and quitting") ;
+      cont = 0 ;
+      killthem(SIGKILL) ;
+      break ;
+    }
+    default : X() ;
+  }
+}
+
+
+ /* New connection handling */
+
+static void run_child (int, char const *, uint16, unsigned int, char const *const *, char const *const *) gccattr_noreturn ;
+static void run_child (int s, char const *ip, uint16 port, unsigned int num, char const *const *argv, char const *const *envp)
+{
+  char fmt[98] ;
+  unsigned int n = 0 ;
+  PROG = "s6-tcpserver6 (child)" ;
+  if ((fd_move(0, s) < 0) || (fd_copy(1, 0) < 0))
+    strerr_diefu1sys(111, "move fds") ;
+  byte_copy(fmt+n, 24, "PROTO=TCP\0TCPREMOTEIP=") ; n += 22 ;
+  n += ip6_fmt(fmt+n, ip) ; fmt[n++] = 0 ;
+  byte_copy(fmt+n, 14, "TCPREMOTEPORT=") ; n += 14 ;
+  n += uint16_fmt(fmt+n, port) ; fmt[n++] = 0 ;
+  byte_copy(fmt+n, 11, "TCPCONNNUM=") ; n += 11 ;
+  n += uint_fmt(fmt+n, num) ; fmt[n++] = 0 ;
+  pathexec_r(argv, envp, env_len(envp), fmt, n) ;
+  strerr_dieexec(111, argv[0]) ;
+}
+
+static void new_connection (int s, char const *ip, uint16 port, char const *const *argv, char const *const *envp)
+{
+  unsigned int i = lookup_ip(ip) ;
+  unsigned int num = (i < iplen) ? ipnum[i].num : 0 ;
+  register pid_t pid ;
+  if (num >= localmaxconn)
+  {
+    log_deny(ip, port, num) ;
+    return ;
+  }
+  pid = fork() ;
+  if (pid < 0)
+  {
+    if (verbosity) strerr_warnwu1sys("fork") ;
+    return ;
+  }
+  else if (!pid)
+  {
+    selfpipe_finish() ;
+    run_child(s, ip, port, num+1, argv, envp) ;
+  }
+
+  if (i < iplen) ipnum[i].num = num + 1 ;
+  else
+  {
+    byte_copy(ipnum[iplen].ip, 16, ip) ;
+    ipnum[iplen++].num = 1 ;
+  }
+  pidip[numconn].num = pid ;
+  byte_copy(pidip[numconn++].ip, 16, ip) ;
+  if (verbosity >= 2)
+  {
+    log_accept(pid, ip, port, ipnum[i].num) ;
+    log_status() ;
+  }
+}
+
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .fd = 0, .events = IOPAUSE_READ | IOPAUSE_EXCEPT } } ;
+  PROG = "s6-tcpserver6d" ;
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    int flag1 = 0 ;
+    for (;;)
+    {
+      register int opt = subgetopt_r(argc, argv, "1c:C:v:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case '1' : flag1 = 1 ; break ;
+        case 'c' : if (!uint0_scan(l.arg, &maxconn)) dieusage() ; break ;
+        case 'C' : if (!uint0_scan(l.arg, &localmaxconn)) dieusage() ; break ;
+        case 'v' : if (!uint0_scan(l.arg, &verbosity)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+    if (!argc || !*argv[0]) dieusage() ;
+    {
+      struct stat st ;
+      if (fstat(0, &st) < 0) strerr_diefu1sys(111, "fstat stdin") ;
+      if (!S_ISSOCK(st.st_mode)) strerr_dief1x(100, "stdin is not a socket") ;
+    }
+    if (coe(0) < 0) strerr_diefu1sys(111, "make socket close-on-exec") ;
+    if (flag1)
+    {
+      if (fcntl(1, F_GETFD) < 0)
+        strerr_dief1sys(100, "called with option -1 but stdout said") ;
+    }
+    else close(1) ;
+    if (!maxconn) maxconn = 1 ;
+    if (maxconn > ABSOLUTE_MAXCONN) maxconn = ABSOLUTE_MAXCONN ;
+    if (localmaxconn > maxconn) localmaxconn = maxconn ;
+
+    x[0].fd = selfpipe_init() ;
+    if (x[0].fd == -1) strerr_diefu1sys(111, "create selfpipe") ;
+    if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;
+    {
+      sigset_t set ;
+      sigemptyset(&set) ;
+      sigaddset(&set, SIGCHLD) ;
+      sigaddset(&set, SIGTERM) ;
+      sigaddset(&set, SIGHUP) ;
+      sigaddset(&set, SIGQUIT) ;
+      sigaddset(&set, SIGABRT) ;
+      if (selfpipe_trapset(&set) < 0) strerr_diefu1sys(111, "trap signals") ;
+    }
+    if (flag1)
+    {
+      fd_write(1, "\n", 1) ;
+      fd_close(1) ;
+    }
+    fmtlocalmaxconn[1+uint_fmt(fmtlocalmaxconn+1, localmaxconn)] = 0 ;
+    if (verbosity >= 2)
+    {
+      fmtmaxconn[1+uint_fmt(fmtmaxconn+1, maxconn)] = 0 ;
+      log_start() ;
+      log_status() ;
+    }
+  }
+
+  {
+    ipnum_t inyostack[maxconn<<1] ;
+    pidip = inyostack ; ipnum = inyostack + maxconn ;
+    while (cont)
+    {
+      if (iopause_g(x, 1 + (numconn < maxconn), 0) < 0)
+        strerr_diefu1sys(111, "iopause") ;
+
+      if (x[0].revents & IOPAUSE_EXCEPT) strerr_dief1x(111, "trouble with selfpipe") ;
+      if (x[0].revents & IOPAUSE_READ) handle_signals() ;
+      if (numconn < maxconn)
+      {
+        if (x[1].revents & IOPAUSE_EXCEPT) strerr_dief1x(111, "trouble with socket") ;
+        if (x[1].revents & IOPAUSE_READ)
+        {
+          char ip[16] ;
+          uint16 port ;
+          register int fd = socket_accept6(x[1].fd, ip, &port) ;
+          if (fd < 0)
+          {
+            if (verbosity) strerr_warnwu1sys("accept") ;
+          }
+          else
+          {
+            new_connection(fd, ip, port, argv, envp) ;
+            fd_close(fd) ;
+          }
+        }
+      }
+    }
+  }
+  if (verbosity >= 2) log_exit() ;
+  return 0 ;
+}