Expose getaddrinfo errors. Was: Return empty list on EAI_ errors for getaddrinfo@luv (#351)

lib_eio/net.ml

@@ -198,6 +198,41 @@ let datagram_socket ?(reuse_addr=false) ?(reuse_port=false) ~sw (t:#t) addr =
   let addr = (addr :> [Sockaddr.datagram | `UdpV4 | `UdpV6]) in 
   t#datagram_socket ~reuse_addr ~reuse_port ~sw addr
 
+(* keep in sync with C stubs *)
+type getaddrinfo_error =
+  | EAI_ADDRFAMILY
+  | EAI_AGAIN
+  | EAI_BADFLAGS
+  | EAI_BADHINTS
+  | EAI_FAIL
+  | EAI_FAMILY
+  | EAI_MEMORY
+  | EAI_NODATA
+  | EAI_NONAME
+  | EAI_OVERFLOW
+  | EAI_PROTOCOL
+  | EAI_SERVICE
+  | EAI_SOCKTYPE
+  | EAI_SYSTEM
+
+exception Getaddrinfo_error of getaddrinfo_error
+
+let getaddrinfo_error_to_string = function
+  | EAI_ADDRFAMILY -> "address family for name not supported"
+  | EAI_AGAIN      -> "temporary failure in name resolution"
+  | EAI_BADFLAGS   -> "invalid value for ai_flags"
+  | EAI_BADHINTS   -> "invalid value for hints"
+  | EAI_FAIL       -> "non-recoverable failure in name resolution"
+  | EAI_FAMILY     -> "ai_family not supported"
+  | EAI_MEMORY     -> "memory allocation failure"
+  | EAI_NODATA     -> "no address associated with name"
+  | EAI_NONAME     -> "name or service is not known"
+  | EAI_OVERFLOW   -> "argument buffer overflow"
+  | EAI_PROTOCOL   -> "resolved protocol is unknown"
+  | EAI_SERVICE    -> "service not supported for ai_socktype"
+  | EAI_SOCKTYPE   -> "ai_socktype not supported"
+  | EAI_SYSTEM     -> "system error"
+
 let getaddrinfo ?(service="") (t:#t) hostname = t#getaddrinfo ~service hostname
 
 let getaddrinfo_stream ?service t hostname =

lib_eio/net.mli

@@ -220,22 +220,53 @@ val recv : #datagram_socket -> Cstruct.t -> Sockaddr.datagram * int
     returned along with the sender address and port. If the [buf] is too small then excess bytes may be discarded
     depending on the type of the socket the message is received from. *)
 
-(** {2 DNS queries} *)
+(** {2 Getaddrinfo queries}
+
+    Note that unlike {!Unix.getaddrinfo}, EIO's [getaddrinfo] family
+    of functions raise an exception {!Getaddrinfo_error} with an error
+    code instead of returning an empty list. *)
+
+(* keep in sync with C stubs *)
+type getaddrinfo_error =
+  | EAI_ADDRFAMILY
+  | EAI_AGAIN
+  | EAI_BADFLAGS
+  | EAI_BADHINTS
+  | EAI_FAIL
+  | EAI_FAMILY
+  | EAI_MEMORY
+  | EAI_NODATA
+  | EAI_NONAME
+  | EAI_OVERFLOW
+  | EAI_PROTOCOL
+  | EAI_SERVICE
+  | EAI_SOCKTYPE
+  | EAI_SYSTEM
+  (** Possible errors raised by getaddrinfo functions, check
+      getaddrinfo(3) and gai_strerror(3) for more information. *)
+
+exception Getaddrinfo_error of getaddrinfo_error
+
+val getaddrinfo_error_to_string : getaddrinfo_error -> string
+(** [getaddrinfo_error_to_string e] returns a string representation of [e], like gai_strerror(3). *)
 
 val getaddrinfo: ?service:string -> #t -> string -> Sockaddr.t list
 (** [getaddrinfo ?service t node] returns a list of IP addresses for [node]. [node] is either a domain name or
     an IP address.
+    May raise {!Getaddrinfo_error} and never returns an empty list.
 
     @param service is a human friendly textual name for internet services assigned by IANA., eg.
     'http', 'https', 'ftp', etc.
 
     For a more thorough treatment, see {{:https://man7.org/linux/man-pages/man3/getaddrinfo.3.html} getaddrinfo}. *)
 
 val getaddrinfo_stream: ?service:string -> #t -> string -> Sockaddr.stream list
-(** [getaddrinfo_stream] is like {!getaddrinfo}, but filters out non-stream protocols. *)
+(** [getaddrinfo_stream] is like {!getaddrinfo}, but filters out non-stream protocols.
+    May raise {!Getaddrinfo_error} and never returns an empty list. *)
 
 val getaddrinfo_datagram: ?service:string -> #t -> string -> Sockaddr.datagram list
-(** [getaddrinfo_datagram] is like {!getaddrinfo}, but filters out non-datagram protocols. *)
+(** [getaddrinfo_datagram] is like {!getaddrinfo}, but filters out non-datagram protocols.
+    May raise {!Getaddrinfo_error} and never returns an empty list. *)
 
 val getnameinfo : #t -> Sockaddr.t -> (string * string)
 (** [getnameinfo t sockaddr] is [(hostname, service)] corresponding to [sockaddr]. [hostname] is the

lib_eio_linux/dune

@@ -6,4 +6,7 @@
   (language c)
   (flags :standard -D_LARGEFILE64_SOURCE)
   (names eio_stubs))
+ (foreign_stubs
+  (language c)
+  (names getaddrinfo_stubs))
  (libraries eio eio.utils eio.unix uring logs fmt))

lib_eio_linux/eio_linux.ml

@@ -858,6 +858,10 @@ module Low_level = struct
 
   external eio_getdents : Unix.file_descr -> string list = "caml_eio_getdents"
 
+  external eio_getaddrinfo : string -> string -> Unix.getaddrinfo_option list ->
+    (Unix.addr_info list, Eio.Net.getaddrinfo_error) result
+    = "caml_eio_getaddrinfo"
+
   let getrandom { Cstruct.buffer; off; len } =
     let rec loop n =
       if n = len then
@@ -954,7 +958,9 @@ module Low_level = struct
       | _ -> None
     in
     Eio_unix.run_in_systhread @@ fun () ->
-    Unix.getaddrinfo node service []
+    (match (eio_getaddrinfo node service []) with
+     | Ok l -> l
+     | Error e -> raise (Eio.Net.Getaddrinfo_error e))
     |> List.filter_map to_eio_sockaddr_t
 end
 

lib_eio_linux/eio_linux.mli

@@ -251,4 +251,7 @@ module Low_level : sig
   (** [getaddrinfo host] returns a list of IP addresses for [host]. [host] is either a domain name or
       an ipaddress. *)
 
+  val eio_getaddrinfo : string -> string -> Unix.getaddrinfo_option list ->
+    (Unix.addr_info list, Eio.Net.getaddrinfo_error) result
+
 end

lib_eio_linux/getaddrinfo_stubs.c

@@ -0,0 +1,181 @@
+/**************************************************************************/
+/*                                                                        */
+/*                                 OCaml                                  */
+/*                                                                        */
+/*             Xavier Leroy, projet Cristal, INRIA Rocquencourt,          */
+/*             Christiano Haesbaert, Tarides                              */
+/*   Copyright 2004 Institut National de Recherche en Informatique et     */
+/*     en Automatique.                                                    */
+/*   Copyright 2022 Tarides                                               */
+/*                                                                        */
+/*   All rights reserved.  This file is distributed under the terms of    */
+/*   the GNU Lesser General Public License version 2.1, with the          */
+/*   special exception on linking described in the file LICENSE.          */
+/*                                                                        */
+/**************************************************************************/
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <errno.h>
+#include <netdb.h>
+
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/alloc.h>
+#include <caml/unixsupport.h>
+#include <caml/socketaddr.h>
+
+extern value caml_unix_cst_to_constr(int, int *, int, int);
+extern int caml_unix_socket_domain_table[]; /* from socket.c */
+extern int caml_unix_socket_type_table[];   /* from socket.c */
+
+static value convert_addrinfo(struct addrinfo * a)
+{
+  CAMLparam0();
+  CAMLlocal3(vres,vaddr,vcanonname);
+  union sock_addr_union sa;
+  socklen_param_type len;
+
+  len = a->ai_addrlen;
+  if (len > sizeof(sa)) len = sizeof(sa);
+  memcpy(&sa.s_gen, a->ai_addr, len);
+  vaddr = caml_unix_alloc_sockaddr(&sa, len, -1);
+  vcanonname = caml_copy_string(a->ai_canonname == NULL ? "" : a->ai_canonname);
+  vres = caml_alloc_small(5, 0);
+  Field(vres, 0) =
+    caml_unix_cst_to_constr(a->ai_family, caml_unix_socket_domain_table, 3, 0);
+  Field(vres, 1) =
+    caml_unix_cst_to_constr(a->ai_socktype, caml_unix_socket_type_table, 4, 0);
+  Field(vres, 2) = Val_int(a->ai_protocol);
+  Field(vres, 3) = vaddr;
+  Field(vres, 4) = vcanonname;
+  CAMLreturn(vres);
+}
+
+/* glibc doesn't define a bunch of EAI_, so fake one since code gets copied around */
+
+#ifndef EAI_ADDRFAMILY
+#define EAI_ADDRFAMILY (-3000)
+#endif /* EAI_ADDRFAMILY */
+
+#ifndef EAI_BADHINTS
+#define EAI_BADHINTS (-3013)
+#endif /* EAI_BADHINTS */
+
+#ifndef EAI_NODATA
+#define EAI_NODATA (-3007)
+#endif /* EAI_NODATA */
+
+#ifndef EAI_OVERFLOW
+#define EAI_OVERFLOW (-3009)
+#endif /* EAI_OVERFLOW */
+
+#ifndef EAI_PROTOCOL
+#define EAI_PROTOCOL (-3014)
+#endif /* EAI_PROTOCOL */
+
+static int gai_errors[] = {
+  EAI_ADDRFAMILY,
+  EAI_AGAIN,
+  EAI_BADFLAGS,
+  EAI_BADHINTS,
+  EAI_FAIL,
+  EAI_FAMILY,
+  EAI_MEMORY,
+  EAI_NODATA,
+  EAI_NONAME,
+  EAI_OVERFLOW,
+  EAI_PROTOCOL,
+  EAI_SERVICE,
+  EAI_SOCKTYPE,
+  EAI_SYSTEM /* NOTE: must be last */
+};
+
+#define nmemb_gai_errors (sizeof(gai_errors) / sizeof(int))
+
+CAMLprim value caml_eio_getaddrinfo(value vnode, value vserv, value vopts)
+{
+  CAMLparam3(vnode, vserv, vopts);
+  CAMLlocal4(vres, v, e, vret);
+  char * node, * serv;
+  struct addrinfo hints;
+  struct addrinfo * res, * r;
+  int retcode, i;
+
+  if (! (caml_string_is_c_safe(vnode) && caml_string_is_c_safe(vserv)))
+    CAMLreturn (Val_emptylist);
+
+  /* Extract "node" parameter */
+  if (caml_string_length(vnode) == 0) {
+    node = NULL;
+  } else {
+    node = caml_stat_strdup(String_val(vnode));
+  }
+  /* Extract "service" parameter */
+  if (caml_string_length(vserv) == 0) {
+    serv = NULL;
+  } else {
+    serv = caml_stat_strdup(String_val(vserv));
+  }
+  /* Parse options, set hints */
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = PF_UNSPEC;
+  for (/*nothing*/; vopts != Val_emptylist; vopts = Field(vopts, 1)) {
+    v = Field(vopts, 0);
+    if (Is_block(v))
+      switch (Tag_val(v)) {
+      case 0:                   /* AI_FAMILY of socket_domain */
+        hints.ai_family = caml_unix_socket_domain_table[Int_val(Field(v, 0))];
+        break;
+      case 1:                   /* AI_SOCKTYPE of socket_type */
+        hints.ai_socktype = caml_unix_socket_type_table[Int_val(Field(v, 0))];
+        break;
+      case 2:                   /* AI_PROTOCOL of int */
+        hints.ai_protocol = Int_val(Field(v, 0));
+        break;
+      }
+    else
+      switch (Int_val(v)) {
+      case 0:                   /* AI_NUMERICHOST */
+        hints.ai_flags |= AI_NUMERICHOST; break;
+      case 1:                   /* AI_CANONNAME */
+        hints.ai_flags |= AI_CANONNAME; break;
+      case 2:                   /* AI_PASSIVE */
+        hints.ai_flags |= AI_PASSIVE; break;
+      }
+  }
+  /* Do the call */
+  caml_enter_blocking_section();
+  retcode = getaddrinfo(node, serv, &hints, &res);
+  caml_leave_blocking_section();
+  if (node != NULL) caml_stat_free(node);
+  if (serv != NULL) caml_stat_free(serv);
+  /* Convert result */
+  vres = Val_emptylist;
+  if (retcode == 0) {
+    for (r = res; r != NULL; r = r->ai_next) {
+      e = convert_addrinfo(r);
+      v = caml_alloc_small(2, Tag_cons);
+      Field(v, 0) = e;
+      Field(v, 1) = vres;
+      vres = v;
+    }
+    vret = caml_alloc_small(1, 0); /* 0 = Ok */
+    Field(vret, 0) = vres;
+    freeaddrinfo(res);
+  } else {
+    for (i = 0; i < nmemb_gai_errors; i++)
+      if (gai_errors[i] == retcode)
+        break;
+    /* Paranoia keeps the world spinning */
+    if (i == nmemb_gai_errors) {
+      errno = EINVAL;
+      i = gai_errors[nmemb_gai_errors - 1]; /* EAI_SYSTEM */
+    }
+    vret = caml_alloc_small(1, 1); /* 1 = Error */
+    Field(vret, 0) = Val_int(i);
+  }
+
+  CAMLreturn(vret);
+}

lib_eio_luv/eio_luv.ml

@@ -654,10 +654,26 @@ module Low_level = struct
       | _ -> None
     in
     let request = Luv.DNS.Addr_info.Request.make () in
-    await_with_cancel ~request (fun loop -> Luv.DNS.getaddrinfo ~loop ~request ~service ~node ())
-    |> or_raise
-    |> List.filter_map to_eio_sockaddr_t
-
+    let r e = raise (Eio.Net.Getaddrinfo_error e) in
+    match (await_with_cancel ~request
+             (fun loop -> Luv.DNS.getaddrinfo ~loop ~request ~service ~node ()))
+    with
+    | Ok nl -> List.filter_map to_eio_sockaddr_t nl
+    | Error `EAI_ADDRFAMILY -> r EAI_ADDRFAMILY
+    | Error `EAI_AGAIN      -> r EAI_AGAIN
+    | Error `EAI_BADFLAGS   -> r EAI_BADFLAGS
+    | Error `EAI_BADHINTS   -> r EAI_BADHINTS
+    | Error `EAI_CANCELED   -> r EAI_FAIL (* note *)
+    | Error `EAI_FAIL       -> r EAI_FAIL
+    | Error `EAI_FAMILY     -> r EAI_FAMILY
+    | Error `EAI_MEMORY     -> r EAI_MEMORY
+    | Error `EAI_NODATA     -> r EAI_NODATA
+    | Error `EAI_NONAME     -> r EAI_NONAME
+    | Error `EAI_OVERFLOW   -> r EAI_OVERFLOW
+    | Error `EAI_PROTOCOL   -> r EAI_PROTOCOL
+    | Error `EAI_SERVICE    -> r EAI_SERVICE
+    | Error `EAI_SOCKTYPE   -> r EAI_SOCKTYPE
+    | Error e -> raise (Luv_error e)
 end
 
 open Low_level