initial commit

.gitattributes

@@ -0,0 +1 @@
+example.input -text

.gitignore

@@ -0,0 +1 @@
+/build/

README

@@ -0,0 +1,24 @@
+nobotgate
+=========
+
+When you run a private site (that still uses a
+super-serve), you can use nobotgate to require users to
+provide an http bearer token. This way, bots won't flood
+your site with spam.
+
+usage
+-----
+
+use nobotgate(1) together with a super-server such as inetd(8),
+tcpserver(1) or s6-tcpserver:
+  # tcpserver 0.0.0.0 80 nobotgate /etc/wwwtokens ./on-valid ./on-invalid
+where /etc/wwwtokens contains:
+
+and ./on-valid contains:
+  #!/bin/sh
+  exec busybox httpd -i -h /var/www
+and ./on-invalid contains:
+  #!/bin/sh
+  exec nobotgate-access cat usage
+and usage contains:
+  No bearer token specified!

check_token.c

@@ -0,0 +1,39 @@
+#include <libowfat/stralloc.h>
+#include <libowfat/errmsg.h>
+#include <libowfat/open.h>
+#include <libowfat/str.h>
+#include <errno.h>
+
+#include "nobotgate.h"
+
+int check_token(char *tokenfile, stralloc *token)
+{
+  int fd;
+  char buf[4096];
+  buffer b;
+  int r,found;
+  stralloc line;
+  fd = open_read(tokenfile);
+  if (fd < 0)
+    diesys(errno == ENOENT ? 100 : 111, "open_read ", tokenfile);
+  buffer_init_read(&b, fd, buf, sizeof(buf));
+  stralloc_init(&line);
+
+  found = 0;
+  for (;;) {
+    r = buffer_getnewline_sa(&b, &line);
+    if (r == 0) break;
+    if (r < 0) diesys(111, "failed reading tokenfile ", tokenfile);
+    stralloc_chomp(&line);
+    stralloc_0(&line);
+    line.s[str_chr(line.s, ' ')] = 0;
+    if (stralloc_equals(token, line.s)) {
+      found = 1;
+      break;
+    }
+  }
+
+  buffer_close(&b);
+  stralloc_free(&line);
+  return found;
+}

example.input

@@ -0,0 +1,2 @@
+Authorization: Bearer 1234
+

example.service/on-invalid

@@ -0,0 +1,4 @@
+#!/bin/sh
+exec \
+  nobotgate-access \
+  cat usage

example.service/on-valid

@@ -0,0 +1,3 @@
+#!/bin/sh
+exec \
+  busybox httpd -i -h .

example.service/run

@@ -0,0 +1,10 @@
+#!/bin/sh
+# service that runs a web server protected with nobotgate.
+# if the user provided a valid token, it will exec into
+# ./on-valid, if not, into ./on-invalid.
+exec \
+  envuidgid www \
+  tcpserver -U 127.0.0.1 80 \
+    ../build/nobotgate ./tokens \
+    ./on-valid \
+    ./on-invalid

example.service/tokens

@@ -0,0 +1,2 @@
+1234 a pretty insecure token
+11aa this token is a lot more secure

example.service/trace

@@ -0,0 +1,91 @@
+2783  execve("/usr/bin/envuidgid", ["envuidgid", "www", "tcpserver", "-U", "127.0.0.1", "80"], 0x7ffed7055678 /* 11 vars */) = 0
+2783  brk(NULL)                         = 0x558000b69000
+2783  access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3</etc/ld.so.cache>
+2783  fstat(3</etc/ld.so.cache>, {st_mode=S_IFREG|0644, st_size=129031, ...}) = 0
+2783  mmap(NULL, 129031, PROT_READ, MAP_PRIVATE, 3</etc/ld.so.cache>, 0) = 0x7f13d3dfa000
+2783  close(3</etc/ld.so.cache>)        = 0
+2783  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f13d3df8000
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/usr/lib/libc.so.6", O_RDONLY|O_CLOEXEC) = 3</usr/lib/libc.so.6>
+2783  read(3</usr/lib/libc.so.6>, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\300\255\2\0\0\0\0\0@\0\0\0\0\0\0\08\264\301\0\0\0\0\0\0\0\0\0@\08\0\16\0@\0G\0F\0\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0"..., 832) = 832
+2783  pread64(3</usr/lib/libc.so.6>, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\235\216\25\0\0\0\0\0\235\216\25\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0"..., 784, 64) = 784
+2783  fstat(3</usr/lib/libc.so.6>, {st_mode=S_IFREG|0755, st_size=12699128, ...}) = 0
+2783  pread64(3</usr/lib/libc.so.6>, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\235\216\25\0\0\0\0\0\235\216\25\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0"..., 784, 64) = 784
+2783  mmap(NULL, 2006680, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0) = 0x7f13d3c0e000
+2783  mmap(0x7f13d3c36000, 1413120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x28000) = 0x7f13d3c36000
+2783  mmap(0x7f13d3d8f000, 352256, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x181000) = 0x7f13d3d8f000
+2783  mmap(0x7f13d3de5000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x1d6000) = 0x7f13d3de5000
+2783  mmap(0x7f13d3deb000, 52888, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f13d3deb000
+2783  close(3</usr/lib/libc.so.6>)      = 0
+2783  mmap(NULL, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f13d3c0b000
+2783  arch_prctl(ARCH_SET_FS, 0x7f13d3c0b740) = 0
+2783  set_tid_address(0x7f13d3c0ba10)   = 2783
+2783  set_robust_list(0x7f13d3c0ba20, 24) = 0
+2783  rseq({cpu_id_start=0, cpu_id=RSEQ_CPU_ID_UNINITIALIZED, rseq_cs=NULL, flags=0, node_id=0, mm_cid=0, slice_ctrl={request=0, granted=0, __reserved=0}, __reserved=0}, 32, 0, 0x53053053) = 0
+2783  mprotect(0x7f13d3de5000, 16384, PROT_READ) = 0
+2783  mprotect(0x557fcb203000, 4096, PROT_READ) = 0
+2783  mprotect(0x7f13d3e55000, 8192, PROT_READ) = 0
+2783  prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
+2783  munmap(0x7f13d3dfa000, 129031)    = 0
+2783  getrandom("\x50\xa4\x5b\x1a\x33\xa9\x65\xde", 8, GRND_NONBLOCK) = 8
+2783  brk(NULL)                         = 0x558000b69000
+2783  brk(0x558000b8a000)               = 0x558000b8a000
+2783  socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3<UNIX-STREAM:[57002340]>
+2783  connect(3<UNIX-STREAM:[57002340]>, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
+2783  close(3<UNIX-STREAM:[57002340]>)  = 0
+2783  socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3<UNIX-STREAM:[57002341]>
+2783  connect(3<UNIX-STREAM:[57002341]>, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
+2783  close(3<UNIX-STREAM:[57002341]>)  = 0
+2783  newfstatat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/etc/nsswitch.conf", {st_mode=S_IFREG|0644, st_size=216, ...}, 0) = 0
+2783  newfstatat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/", {st_mode=S_IFDIR|0755, st_size=4096, ...}, 0) = 0
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 3</etc/nsswitch.conf>
+2783  fstat(3</etc/nsswitch.conf>, {st_mode=S_IFREG|0644, st_size=216, ...}) = 0
+2783  read(3</etc/nsswitch.conf>, "# /etc/nsswitch.conf\n#\n# See nsswitch.conf(5) for information.\n#\npasswd: \tfiles\ngroup: \t\tfiles\nshadow: \tfiles\n\nhosts: \t\tfiles mdns dns\nnetworks: \tfiles\n\nprotocols: \tfiles\nservices: \tfiles\nethers: \tfiles\nrpc: \t\tfiles\n", 4096) = 216
+2783  read(3</etc/nsswitch.conf>, "", 4096) = 0
+2783  fstat(3</etc/nsswitch.conf>, {st_mode=S_IFREG|0644, st_size=216, ...}) = 0
+2783  close(3</etc/nsswitch.conf>)      = 0
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 3</etc/passwd>
+2783  fstat(3</etc/passwd>, {st_mode=S_IFREG|0644, st_size=5894, ...}) = 0
+2783  lseek(3</etc/passwd>, 0, SEEK_SET) = 0
+2783  read(3</etc/passwd>, "root:x:0:0:root:/root:/bedrock/cross/bin/sh\nnobody:x:99:99:Unprivileged User:/dev/null:/bedrock/cross/bin/false\nchrony:x:999:999:chrony unprivileged user:/var/lib/chrony:/bedrock/cross/bin/nologin\n_dhcpcd:x:998:998:_dhcpcd unprivileged user:/var/db/dhcpcd:"..., 4096) = 4096
+2783  read(3</etc/passwd>, "6 unprivileged user:/var/empty:/bedrock/cross/bin/nologin\nnixbld7:x:979:952:nixbld7 unprivileged user:/var/empty:/bedrock/cross/bin/nologin\nnixbld8:x:978:952:nixbld8 unprivileged user:/var/empty:/bedrock/cross/bin/nologin\nnixbld9:x:977:952:nixbld9 unprivil"..., 4096) = 1798
+2783  close(3</etc/passwd>)             = 0
+2783  execve("/home/a/.local/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/bedrock/cross/pin/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/bedrock/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/home/a/.nix-profile/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/nix/var/nix/profiles/default/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/usr/local/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/usr/local/sbin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = -1 ENOENT (No such file or directory)
+2783  execve("/usr/bin/tcpserver", ["tcpserver", "-U", "127.0.0.1", "80"], 0x557fcb2047f0 /* 13 vars */) = 0
+2783  brk(NULL)                         = 0x5605f057b000
+2783  access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3</etc/ld.so.cache>
+2783  fstat(3</etc/ld.so.cache>, {st_mode=S_IFREG|0644, st_size=129031, ...}) = 0
+2783  mmap(NULL, 129031, PROT_READ, MAP_PRIVATE, 3</etc/ld.so.cache>, 0) = 0x7f9752158000
+2783  close(3</etc/ld.so.cache>)        = 0
+2783  mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9752156000
+2783  openat(AT_FDCWD</home/a/src/kento2/nobotgate/example.service>, "/usr/lib/libc.so.6", O_RDONLY|O_CLOEXEC) = 3</usr/lib/libc.so.6>
+2783  read(3</usr/lib/libc.so.6>, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\300\255\2\0\0\0\0\0@\0\0\0\0\0\0\08\264\301\0\0\0\0\0\0\0\0\0@\08\0\16\0@\0G\0F\0\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0"..., 832) = 832
+2783  pread64(3</usr/lib/libc.so.6>, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\235\216\25\0\0\0\0\0\235\216\25\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0"..., 784, 64) = 784
+2783  fstat(3</usr/lib/libc.so.6>, {st_mode=S_IFREG|0755, st_size=12699128, ...}) = 0
+2783  pread64(3</usr/lib/libc.so.6>, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0\20\3\0\0\0\0\0\0\20\3\0\0\0\0\0\0\10\0\0\0\0\0\0\0\3\0\0\0\4\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0\240q\32\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0 \0\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\210t\2\0\0\0\0\0\210t\2\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\5\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\0\200\2\0\0\0\0\0\235\216\25\0\0\0\0\0\235\216\25\0\0\0\0\0\0\20\0\0\0\0\0\0\1\0\0\0\4\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0\0\20\30\0\0\0\0\0"..., 784, 64) = 784
+2783  mmap(NULL, 2006680, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0) = 0x7f9751f6c000
+2783  mmap(0x7f9751f94000, 1413120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x28000) = 0x7f9751f94000
+2783  mmap(0x7f97520ed000, 352256, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x181000) = 0x7f97520ed000
+2783  mmap(0x7f9752143000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3</usr/lib/libc.so.6>, 0x1d6000) = 0x7f9752143000
+2783  mmap(0x7f9752149000, 52888, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9752149000
+2783  close(3</usr/lib/libc.so.6>)      = 0
+2783  mmap(NULL, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9751f69000
+2783  arch_prctl(ARCH_SET_FS, 0x7f9751f69740) = 0
+2783  set_tid_address(0x7f9751f69a10)   = 2783
+2783  set_robust_list(0x7f9751f69a20, 24) = 0
+2783  rseq({cpu_id_start=0, cpu_id=RSEQ_CPU_ID_UNINITIALIZED, rseq_cs=NULL, flags=0, node_id=0, mm_cid=0, slice_ctrl={request=0, granted=0, __reserved=0}, __reserved=0}, 32, 0, 0x53053053) = 0
+2783  mprotect(0x7f9752143000, 16384, PROT_READ) = 0
+2783  mprotect(0x5605de88f000, 4096, PROT_READ) = 0
+2783  mprotect(0x7f97521b3000, 8192, PROT_READ) = 0
+2783  prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
+2783  munmap(0x7f9752158000, 129031)    = 0
+2783  write(2</dev/pts/1<char 136:1>>, "tcpserver: usage: tcpserver [ -461UXpPhHrRoOdDqQv ] [ -c limit ] [ -x rules.cdb ] [ -B banner ] [ -g gid ] [ -u uid ] [ -b backlog ] [ -l localname ] [ -t timeout ] [ -I interface ] host port program\n", 200) = 200
+2783  exit_group(100)                   = ?
+2783  +++ exited with 100 +++

example.service/usage

@@ -0,0 +1 @@
+curl -H 'Authorization: Bearer <your token>' http://localhost:80

meson.build

@@ -0,0 +1,28 @@
+project(
+	'nobotgate', 'c',
+	default_options: [
+		'c_std=c99',
+		'warning_level=2',
+	],
+)
+
+cc = meson.get_compiler('c')
+deps = [
+  cc.find_library('libowfat'),
+]
+
+add_project_arguments(
+  '-DPATH_TMP="'+get_option('path_tmp')+'"', 
+  language: 'c',
+)
+
+executable('nobotgate', files(
+  './nobotgate.c',
+  './parse_token.c',
+  './check_token.c',
+  './send_headers.c',
+), dependencies:deps, install:true)
+
+executable('nobotgate-access', files(
+  './nobotgate-access.c',
+), dependencies:deps, install:true)

meson.options

@@ -0,0 +1,6 @@
+option(
+  'path_tmp',
+  type : 'string',
+  value : '/tmp',
+  description : 'path to tmpfs',
+)

nobotgate-access.c

@@ -0,0 +1,36 @@
+#include <libowfat/buffer.h>
+#include <libowfat/errmsg.h>
+#include <libowfat/str.h>
+#include <unistd.h>
+
+#define dieusage() die(100, argv0, " PROG ARGS");
+
+static void consume_headers(void) {
+  char buf[2048];
+  int r;
+  for (;;) {
+    r=buffer_getline(buffer_0, buf, sizeof buf);
+    if (r==0) die(100,"EOF before header end");
+    if (buf[0]=='\r')
+      break;
+  }
+}
+
+int main(int argc, char **argv)
+{
+  char *header;
+  (void)argc;
+  errmsg_iam(*argv);
+
+  if (argc<2) dieusage();
+
+  consume_headers();
+
+  header = "HTTP/1.0 200 OK\r\n"
+    "Connection: close\r\n"
+    "\r\n";
+  if (write(1, header, str_len(header)) < 0)
+    diesys(111, "write to stdout");
+  execvp(argv[1], argv+1);
+  diesys(111, "exec ", argv[1]);
+}

nobotgate.c

@@ -0,0 +1,57 @@
+#define _XOPEN_SOURCE 700
+#include <libowfat/buffer.h>
+#include <libowfat/errmsg.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "nobotgate.h"
+
+#define dieusage() die(100,"usage: ",argv0," tokenfile allowed-handler denied-handler")
+
+static stralloc token;
+static char *tokenfile, *cmd_valid, *cmd_invalid;
+
+static void run(void) {
+  char tmp[] = PATH_TMP"/nobotgate.XXXXXX";
+  int tmpfd;
+  char buf[8192];
+  buffer b;
+  char *cmd;
+  tmpfd = mkstemp(tmp);
+
+  buffer_init_write(&b,tmpfd,buf,sizeof buf);
+  if (!send_headers(buffer_0, &b))
+    die(111,"copy stdin to temporary file");
+
+  lseek(tmpfd,0,SEEK_SET);
+  buffer_init_read(&b,tmpfd,buf,sizeof buf);
+  if (!parse_token(&b,&token)) {
+    carp("failed to parse token");
+    goto err;
+  }
+
+  cmd=check_token(tokenfile,&token)
+    ? cmd_valid
+    : cmd_invalid;
+  lseek(tmpfd,0,SEEK_SET);
+  dup2(tmpfd,0);
+  unlink(tmp);
+  buffer_close(&b);
+  stralloc_free(&token);
+  carp("execing ",cmd);
+  execlp(cmd,cmd,NULL);
+err:
+  unlink(tmp);
+  exit(111);
+}
+
+int main(int argc,char **argv)
+{
+  errmsg_iam(*argv);
+  argv++; argc--;
+  if (argc != 3) dieusage();
+  tokenfile=argv[0];
+  cmd_valid=argv[1];
+  cmd_invalid=argv[2];
+  run();
+}

nobotgate.h

@@ -0,0 +1,19 @@
+#ifndef NOBOTGATE
+#define NOBOTGATE
+
+#include <libowfat/buffer.h>
+#include <libowfat/stralloc.h>
+
+/* buffer shall stream an http request.
+ * it stores the found bearer token to result or
+ * returns 0 if none is found.
+ * always succeeds. */
+int parse_token(buffer *b, stralloc *result);
+
+/* return: 1 if the token is valid(i.e. in tokenfile),
+ * 0 else */
+int check_token(char *tokenfile, stralloc *token);
+
+int send_headers(buffer *from, buffer *to);
+
+#endif

parse_token.c

@@ -0,0 +1,34 @@
+#include <libowfat/stralloc.h>
+#include <libowfat/buffer.h>
+#include <libowfat/errmsg.h>
+#include <libowfat/str.h>
+
+#define AUTH_HEADER "Authorization: Bearer " 
+#define AUTH_HEADER_LEN str_len(AUTH_HEADER) 
+
+// TODO make case insensitive according to https://www.rfc-editor.org/info/rfc7230/#section-3.2
+int parse_token(buffer *b, stralloc *result)
+{
+  stralloc line;
+  int r;
+  stralloc_init(result);
+  for (;;) {
+    r=buffer_getnewline_sa(b,&line);
+    if (r==0) break;
+    if (r<0) { carpsys("read line"); goto err; } 
+
+    if (stralloc_starts(&line,AUTH_HEADER)) {
+      stralloc_chomp(&line); 
+      if (!stralloc_copyb(result, line.s+AUTH_HEADER_LEN,
+            line.len-AUTH_HEADER_LEN)
+      ) { carpsys("out of memory"); goto err; }
+      break;
+    }
+  }
+
+  stralloc_free(&line);
+  return 1;
+err:
+  stralloc_free(&line);
+  return 0;
+}

send_headers.c

@@ -0,0 +1,27 @@
+#include <unistd.h>
+#include <libowfat/errmsg.h>
+
+#include "nobotgate.h"
+
+int send_headers(buffer *from, buffer *to)
+{
+  char buf[8192];
+  int nread;
+  for (;;) {
+    nread=buffer_getline(from,buf,sizeof buf);
+    if (nread==0) { carp("EOF before header end"); return 0; }
+    if (nread<0) { carpsys("failed reading"); return 0; }
+    /* include \n */
+    nread++;
+
+    if (buffer_put(to,buf,nread)<0) return 0;
+    if (buf[0]=='\r')
+      break;
+  }
+
+  if (buffer_flush(to)<0) {
+    carpsys("buffer flush");
+    return 0;
+  }
+  return 1;
+}

tool/debug

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -eux
+gdb \
+  -ex 'set args ./example.service/tokens ./example.service/on-valid ./example.service/on-invalid < ./example.input' \
+  ./build/nobotgate