diff --git a/array/array_catb.c b/array/array_catb.c
index ea46fd5..939cff9 100644
--- a/array/array_catb.c
+++ b/array/array_catb.c
@@ -10,7 +10,7 @@ fail:
     return;
   }
   l=to->initialized;
-  if (!array_allocate(to,1,to->initialized+len))
+  if (!array_allocate(to,1,to->initialized+len-1))
     goto fail;
   byte_copy(to->p+l,to->initialized-l,from);
 }
diff --git a/io/io_dontwantwrite.c b/io/io_dontwantwrite.c
index f76bd98..0584847 100644
--- a/io/io_dontwantwrite.c
+++ b/io/io_dontwantwrite.c
@@ -15,7 +15,7 @@ void io_dontwantwrite(int64 d) {
   int newfd;
   io_entry* e=array_get(&io_fds,sizeof(io_entry),d);
   if (!e || !e->wantwrite) return;
-  newfd=(!e->wantread && e->wantwrite); --io_wanted_fds;
+  newfd=(!e->wantread && e->wantwrite);
   io_wanted_fds-=newfd;
 #ifdef HAVE_EPOLL
   if (io_waitmode==EPOLL) {
diff --git a/iob.h b/iob.h
index 8a6a8df..d555e26 100644
--- a/iob.h
+++ b/iob.h
@@ -13,8 +13,13 @@
  * option. */
 
 #include "io.h"
+#include "array.h"
 
-typedef struct io_batch io_batch;
+typedef struct io_batch {
+  array b;
+  uint64 bytesleft;
+  long next,bufs,files;
+} io_batch;
 
 io_batch* iob_new(int hint_entries);
 int iob_addbuf(io_batch* b,const void* buf,uint64 n);
diff --git a/iob_internal.h b/iob_internal.h
index 93a85a2..b690ae4 100644
--- a/iob_internal.h
+++ b/iob_internal.h
@@ -1,12 +1,6 @@
 #include "iob.h"
 #include "array.h"
 
-struct io_batch {
-  array b;
-  uint64 bytesleft;
-  long next,bufs,files;
-};
-
 typedef struct io_entry {
   enum { FROMBUF, FROMFILE } type;
   int64 fd;
diff --git a/test/httpd.c b/test/httpd.c
new file mode 100644
index 0000000..8429bdd
--- /dev/null
+++ b/test/httpd.c
@@ -0,0 +1,285 @@
+#include "socket.h"
+#include "io.h"
+#include "buffer.h"
+#include "ip6.h"
+#include "array.h"
+#include "case.h"
+#include "fmt.h"
+#include "iob.h"
+#include "str.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+
+static void carp(const char* routine) {
+  buffer_puts(buffer_2,routine);
+  buffer_puts(buffer_2,": ");
+  buffer_puterror(buffer_2);
+  buffer_putnlflush(buffer_2);
+}
+
+static void panic(const char* routine) {
+  carp(routine);
+  exit(111);
+}
+
+struct http_data {
+  array r;
+  io_batch iob;
+  char* hdrbuf;
+  int hlen;
+  int keepalive;
+};
+
+int header_complete(struct http_data* r) {
+  long i;
+  long l=array_bytes(&r->r);
+  const char* c=array_start(&r->r);
+  for (i=0; i+1<l; ++i) {
+    if (c[i]=='\n' && c[i+1]=='\n')
+      return i+2;
+    if (i+3<l &&
+	c[i]=='\r' && c[i+1]=='\n' &&
+	c[i+2]=='\r' && c[i+3]=='\n')
+      return i+4;
+  }
+  return 0;
+}
+
+void httperror(struct http_data* r,const char* title,const char* message) {
+  int i;
+  char* c;
+  c=r->hdrbuf=(char*)malloc(strlen(message)+strlen(title)+200);
+  if (!c) {
+    r->hdrbuf="HTTP/1.0 500 internal error\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\nout of memory\n";
+    r->hlen=strlen(r->hdrbuf);
+  } else {
+    i=fmt_str(c,"HTTP/1.0 ");
+    c+=fmt_str(c,title);
+    c+=fmt_str(c,"\r\nContent-Type: text/html\r\nConnection: ");
+    c+=fmt_str(c,r->keepalive?"keep-alive":"close");
+    c+=fmt_str(c,"\r\nContent-Length: ");
+    c+=fmt_ulong(c,strlen(message)+strlen(title)+16-4);
+    c+=fmt_str(c,"\r\n\r\n<title>");
+    c+=fmt_str(c,title+4);
+    c+=fmt_str(c,"</title>\n");
+    r->hlen=c - r->hdrbuf;
+  }
+  iob_addbuf(&r->iob,r->hdrbuf,r->hlen);
+}
+
+static struct mimeentry { const char* name, *type; } mimetab[] = {
+  { "html",	"text/html" },
+  { "css",	"text/css" },
+  { "dvi",	"application/x-dvi" },
+  { "ps",	"application/postscript" },
+  { "pdf",	"application/pdf" },
+  { "gif",	"image/gif" },
+  { "png",	"image/png" },
+  { "jpeg",	"image/jpeg" },
+  { "jpg",	"image/jpeg" },
+  { "mpeg",	"video/mpeg" },
+  { "mpg",	"video/mpeg" },
+  { "avi",	"video/x-msvideo" },
+  { "mov",	"video/quicktime" },
+  { "qt",	"video/quicktime" },
+  { "mp3",	"audio/mpeg" },
+  { "ogg",	"audio/x-oggvorbis" },
+  { "wav",	"audio/x-wav" },
+  { "pac",	"application/x-ns-proxy-autoconfig" },
+  { "sig",	"application/pgp-signature" },
+  { "torrent",	"application/x-bittorrent" },
+  { "class",	"application/octet-stream" },
+  { "js",	"application/x-javascript" },
+  { "tar",	"application/x-tar" },
+  { "zip",	"application/zip" },
+  { "dtd",	"text/xml" },
+  { "xml",	"text/xml" },
+  { "xbm",	"image/x-xbitmap" },
+  { "xpm",	"image/x-xpixmap" },
+  { "xwd",	"image/x-xwindowdump" },
+  { 0 } };
+
+const char* mimetype(const char* filename) {
+  int i,e=str_rchr(filename,'.');
+  if (filename[e]==0) return "text/plain";
+  ++e;
+  for (i=0; mimetab[i].name; ++i)
+    if (str_equal(mimetab[i].name,filename+e))
+      return mimetab[i].type;
+  return "application/octet-stream";
+}
+
+const char* http_header(struct http_data* r,const char* h) {
+  long i;
+  long l=array_bytes(&r->r);
+  long sl=strlen(h);
+  const char* c=array_start(&r->r);
+  for (i=0; i+sl+2<l; ++i)
+    if (c[i]=='\n' && case_equalb(c+i+1,sl,h) && c[i+sl+1]==':') {
+      c+=i+sl+1;
+      if (*c==' ' || *c=='\t') ++c;
+      return c;
+    }
+}
+
+void httpresponse(struct http_data* h,int64 s) {
+  int i;
+  char* c;
+  const char* m;
+  array_cat0(&h->r);
+  c=array_start(&h->r);
+  if (byte_diff(c,4,"GET ")) {
+e400:
+    httperror(h,"400 Invalid Request","This server only understands GET.");
+  } else {
+    char *d;
+    int64 fd;
+    struct stat s;
+    c+=4;
+    for (d=c; *d!=' '&&*d!='\t'&&*d!='\n'&&*d!='\r'; ++d) ;
+    if (*d!=' ') goto e400;
+    *d=0;
+    if (c[0]!='/') goto e404;
+    if (!io_readfile(&fd,c+1)) {
+e404:
+      httperror(h,"404 Not Found","No such file or directory.");
+    } else {
+      if (fstat(fd,&s)==-1) {
+	io_close(fd);
+	goto e404;
+      }
+      if (m=http_header(h,"Connection")) {
+	if (str_equal(m,"keep-alive"))
+	  h->keepalive=1;
+	else
+	  h->keepalive=0;
+      } else {
+	if (byte_equal(d+1,8,"HTTP/1.0"))
+	  h->keepalive=0;
+	else
+	  h->keepalive=1;
+      }
+      m=mimetype(c);
+      c=h->hdrbuf=(char*)malloc(500);
+      c+=fmt_str(c,"HTTP/1.1 Coming Up\r\nContent-Type: ");
+      c+=fmt_str(c,m);
+      c+=fmt_str(c,"\r\nContent-Length: ");
+      c+=fmt_ulonglong(c,s.st_size);
+      c+=fmt_str(c,"\r\nLast-Modified: ");
+      c+=fmt_httpdate(c,s.st_mtime);
+      c+=fmt_str(c,"\r\nConnection: ");
+      c+=fmt_str(c,h->keepalive?"keep-alive":"close");
+      c+=fmt_str(c,"\r\n\r\n");
+      iob_addbuf(&h->iob,h->hdrbuf,c - h->hdrbuf);
+      iob_addfile(&h->iob,fd,0,s.st_size);
+    }
+  }
+  io_dontwantread(s);
+  io_wantwrite(s);
+}
+
+main() {
+  static array a;
+  int s=socket_tcp6();
+  uint32 scope_id;
+  char ip[16];
+  uint16 port;
+  if (socket_bind6_reuse(s,V6any,8000,0)==-1)
+    panic("socket_bind6_reuse");
+  if (socket_listen(s,16)==-1)
+    panic("socket_listen");
+  io_nonblock(s);
+  if (!io_fd(s))
+    panic("io_fd");
+  io_wantread(s);
+  for (;;) {
+    int64 i;
+    io_wait();
+    while ((i=io_canread())!=-1) {
+      if (i==s) {
+	int n;
+	while ((n=socket_accept6(s,ip,&port,&scope_id))!=-1) {
+	  char buf[IP6_FMT];
+	  buffer_puts(buffer_2,"accepted new connection from ");
+	  buffer_put(buffer_2,buf,fmt_ip6(buf,ip));
+	  buffer_puts(buffer_2,":");
+	  buffer_putulong(buffer_2,port);
+	  buffer_puts(buffer_2," (fd ");
+	  buffer_putulong(buffer_2,n);
+	  buffer_puts(buffer_2,")");
+	  io_nonblock(n);
+	  if (io_fd(n)) {
+	    struct http_data* h=(struct http_data*)malloc(sizeof(struct http_data));
+	    io_wantread(n);
+	    if (h) {
+	      byte_zero(h,sizeof(struct http_data));
+	      io_setcookie(n,h);
+	    } else
+	      io_close(n);
+	  } else {
+	    buffer_puts(buffer_2,", but io_fd failed.");
+	    io_close(n);
+	  }
+	  buffer_putnlflush(buffer_2);
+	}
+	if (errno!=EAGAIN)
+	  carp("socket_accept6");
+      } else {
+	char buf[8192];
+	struct http_data* h=io_getcookie(i);
+	int l=io_tryread(i,buf,sizeof buf);
+	if (l==-1) {
+	  if (h) {
+	    array_reset(&h->r);
+	    iob_reset(&h->iob);
+	    free(h->hdrbuf);
+	  }
+	  buffer_puts(buffer_2,"io_tryread(");
+	  buffer_putulong(buffer_2,i);
+	  buffer_puts(buffer_2,"): ");
+	  buffer_puterror(buffer_2);
+	  buffer_putnlflush(buffer_2);
+	  io_close(i);
+	} else if (l==0) {
+	  if (h) {
+	    array_reset(&h->r);
+	    iob_reset(&h->iob);
+	    free(h->hdrbuf);
+	  }
+	  buffer_puts(buffer_2,"eof on fd #");
+	  buffer_putulong(buffer_2,i);
+	  buffer_putnlflush(buffer_2);
+	  io_close(i);
+	} else {
+	  array_catb(&h->r,buf,l);
+	  if (array_failed(&h->r)) {
+	    httperror(h,"500 Server Error","request too long.");
+emerge:
+	    io_dontwantread(i);
+	    io_wantwrite(i);
+	  } else if (array_bytes(&h->r)>8192) {
+	    httperror(h,"500 request too long","You sent too much headers");
+	    goto emerge;
+	  } else if (l=header_complete(h))
+	    httpresponse(h,i);
+	}
+      }
+    }
+    while ((i=io_canwrite())!=-1) {
+      struct http_data* h=io_getcookie(i);
+      if (iob_send(i,&h->iob)<=0) {
+	array_trunc(&h->r);
+	iob_reset(&h->iob);
+	free(h->hdrbuf);
+	if (h->keepalive) {
+	  io_dontwantwrite(i);
+	  io_wantread(i);
+	} else
+	  io_close(i);
+      }
+    }
+  }
+}