From: Mark Wooding <mdw@distorted.org.uk>
Date: Sat, 24 May 2014 13:00:03 +0000 (+0100)
Subject: src/addrfam.c, src/...: Abstract out address-family-specific details.
X-Git-Tag: wip.ipv6.2014-10-13.reentrancy-base~14
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=adns.git;a=commitdiff_plain;h=07554ccd8286775b4f88a608ba3b94ff7b9efaf9

src/addrfam.c, src/...: Abstract out address-family-specific details.

Functions which know about the internals of particular address types and
socket-address structures live in a new file `addrfam.c'.

Some details aren't handled yet: notably, we don't have conversions
between internal address structures and external formats such as text
strings or reverse-lookup domain names.

Signed-off-by: Mark Wooding <mdw@distorted.org.uk>
---

diff --git a/src/addrfam.c b/src/addrfam.c
new file mode 100644
index 0000000..f606612
--- /dev/null
+++ b/src/addrfam.c
@@ -0,0 +1,212 @@
+/*
+ * addrfam.c
+ * - address-family specific code
+ */
+/*
+ *  This file is part of adns, which is
+ *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
+ *    Copyright (C) 1999-2000,2003,2006  Tony Finch
+ *    Copyright (C) 1991 Massachusetts Institute of Technology
+ *  (See the file INSTALL for full details.)
+ *  
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *  
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *  
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software Foundation,
+ *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include "internal.h"
+
+/*
+ * General address-family operations.
+ */
+
+#define SIN(sa) ((struct sockaddr_in *)(sa))
+#define CSIN(sa) ((const struct sockaddr_in *)(sa))
+
+#define SIN6(sa) ((struct sockaddr_in6 *)(sa))
+#define CSIN6(sa) ((const struct sockaddr_in6 *)(sa))
+
+/* This gadget (thanks, Richard Kettlewell) makes sure that we handle the
+ * same set of address families in each switch. */
+#define AF_CASES(pre)							\
+  case AF_INET: goto pre##_inet;					\
+  case AF_INET6: goto pre##_inet6
+
+static void unknown_af(int af) {
+  fprintf(stderr, "ADNS INTERNAL: unknown address family %d\n", af);
+  abort();
+}
+
+#define IN6_ADDR_EQUALP(a, b)						\
+  (!memcmp((a).s6_addr, (b).s6_addr, sizeof((a).s6_addr)))
+
+int adns__genaddr_equal_p(int af, const union gen_addr *a,
+			  int bf, const void *b) {
+  const union gen_addr *bb= b;
+  if (af != bf) return 0;
+  switch (af) {
+  AF_CASES(af);
+  af_inet: return a->v4.s_addr == bb->v4.s_addr;
+  af_inet6: return IN6_ADDR_EQUALP(a->v6, bb->v6);
+  default: unknown_af(af); return -1;
+  }
+}
+
+int adns__sockaddr_equal_p(const struct sockaddr *sa,
+			   const struct sockaddr *sb) {
+  if (sa->sa_family != sb->sa_family) return 0;
+  switch (sa->sa_family) {
+  AF_CASES(af);
+  af_inet: {
+    const struct sockaddr_in *sina= CSIN(sa), *sinb= CSIN(sb);
+    return (sina->sin_addr.s_addr == sinb->sin_addr.s_addr &&
+	    sina->sin_port == sinb->sin_port);
+  }
+  af_inet6: {
+    /* Don't check the flowlabel.  That's apparently useful for routing
+     * performance, but doesn't affect the address in any important
+     * respect. */
+    const struct sockaddr_in6 *sin6a= CSIN6(sa), *sin6b= CSIN6(sb);
+    return (IN6_ADDR_EQUALP(sin6a->sin6_addr, sin6b->sin6_addr) &&
+	    sin6a->sin6_port == sin6b->sin6_port &&
+	    sin6a->sin6_scope_id == sin6b->sin6_scope_id);
+  }
+  default:
+    unknown_af(sa->sa_family);
+    return -1;
+  }
+}
+
+int adns__addr_width(int af) {
+  switch (af) {
+  AF_CASES(af);
+  af_inet: return 32;
+  af_inet6: return 128;
+  default: unknown_af(af); return -1;
+  }
+}
+
+void adns__prefix_mask(int af, int len, union gen_addr *mask_r) {
+  switch (af) {
+  AF_CASES(af);
+  af_inet:
+    assert(len <= 32);
+    mask_r->v4.s_addr= htonl(!len ? 0 : 0xffffffff << (32-len));
+    break;
+  af_inet6: {
+    int i= len/8, j= len%8;
+    unsigned char *m= mask_r->v6.s6_addr;
+    assert(len <= 128);
+    memset(m, 0xff, i);
+    if (j) m[i++]= (0xff << (8-j)) & 0xff;
+    memset(m+i, 0, 16-i);
+  } break;
+  default:
+    unknown_af(af);
+    break;
+  }
+}
+
+int adns__guess_prefix_length(int af, const union gen_addr *addr) {
+  switch (af) {
+  AF_CASES(af);
+  af_inet: {
+    unsigned a= (ntohl(addr->v4.s_addr) >> 24) & 0xff;
+    if (a < 128) return 8;
+    else if (a < 192) return 16;
+    else if (a < 224) return 24;
+    else return -1;
+  } break;
+  af_inet6:
+    return 64;
+  default:
+    unknown_af(af);
+    return -1;
+  }
+}
+
+int adns__addr_match_p(int addraf, const union gen_addr *addr,
+		       int netaf, const union gen_addr *base,
+		       const union gen_addr *mask)
+{
+  if (addraf != netaf) return 0;
+  switch (addraf) {
+  AF_CASES(af);
+  af_inet:
+    return (addr->v4.s_addr & mask->v4.s_addr) == base->v4.s_addr;
+  af_inet6: {
+    int i;
+    const char *a= addr->v6.s6_addr;
+    const char *b= base->v6.s6_addr;
+    const char *m= mask->v6.s6_addr;
+    for (i = 0; i < 16; i++)
+      if ((a[i] & m[i]) != b[i]) return 0;
+    return 1;
+  } break;
+  default:
+    unknown_af(addraf);
+    return -1;
+  }
+}
+
+void adns__sockaddr_extract(const struct sockaddr *sa,
+			    union gen_addr *a_r, int *port_r) {
+  switch (sa->sa_family) {
+  AF_CASES(af);
+  af_inet: {
+    const struct sockaddr_in *sin = CSIN(sa);
+    if (port_r) *port_r= ntohs(sin->sin_port);
+    if (a_r) a_r->v4= sin->sin_addr;
+    break;
+  }
+  af_inet6: {
+    const struct sockaddr_in6 *sin6 = CSIN6(sa);
+    if (port_r) *port_r= ntohs(sin6->sin6_port);
+    if (a_r) a_r->v6= sin6->sin6_addr;
+    break;
+  }
+  default:
+    unknown_af(sa->sa_family);
+  }
+}
+
+void adns__sockaddr_inject(const union gen_addr *a, int port,
+			   struct sockaddr *sa) {
+  switch (sa->sa_family) {
+  AF_CASES(af);
+  af_inet: {
+    struct sockaddr_in *sin = SIN(sa);
+    if (port != -1) sin->sin_port= htons(port);
+    if (a) sin->sin_addr= a->v4;
+    break;
+  }
+  af_inet6: {
+    struct sockaddr_in6 *sin6 = SIN6(sa);
+    if (port != -1) sin6->sin6_port= htons(port);
+    if (a) sin6->sin6_addr= a->v6;
+    break;
+  }
+  default:
+    unknown_af(sa->sa_family);
+  }
+}
diff --git a/src/adns.make b/src/adns.make
index b0ba693..1c35eb1 100644
--- a/src/adns.make
+++ b/src/adns.make
@@ -21,4 +21,4 @@
 #  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 
 LIBOBJS=	types.o event.o query.o reply.o general.o setup.o transmit.o \
-		parse.o poll.o check.o
+		parse.o poll.o check.o addrfam.o
diff --git a/src/check.c b/src/check.c
index 44f52b9..3972ebe 100644
--- a/src/check.c
+++ b/src/check.c
@@ -81,12 +81,8 @@ static void checkc_global(adns_state ads) {
   assert(ads->udpsocket >= 0);
 
   for (i=0; i<ads->nsortlist; i++) {
-    assert(ads->sortlist[i].af==AF_INET);
-    assert(!(ads->sortlist[i].base.v4.s_addr &
-	     ~ads->sortlist[i].mask.v4.s_addr));
     sl= &ads->sortlist[i];
-    assert(sl->af==AF_INET);
-    assert(!(sl->base.v4.s_addr & ~sl->mask.v4.s_addr));
+    assert(adns__addr_match_p(sl->af,&sl->base, sl->af,&sl->base,&sl->mask));
   }
 
   assert(ads->tcpserver >= 0 && ads->tcpserver < ads->nservers);
diff --git a/src/event.c b/src/event.c
index ee4e5f7..433a4d0 100644
--- a/src/event.c
+++ b/src/event.c
@@ -415,9 +415,8 @@ int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
       }
       for (serv= 0;
 	   serv < ads->nservers &&
-	     (assert(ads->servers[serv].addr.sa.sa_family==AF_INET),
-	      ads->servers[serv].addr.inet.sin_addr.s_addr !=
-		udpaddr.sin_addr.s_addr);
+	     !adns__sockaddr_equal_p(&ads->servers[serv].addr.sa,
+				     (const struct sockaddr *)&udpaddr);
 	   serv++);
       if (serv >= ads->nservers) {
 	adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
diff --git a/src/internal.h b/src/internal.h
index 97af49e..9a55519 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -374,6 +374,65 @@ struct adns__state {
   unsigned short rand48xsubi[3];
 };
 
+/* From addrfam.c: */
+
+extern int adns__af_supported_p(int af);
+/* Return nonzero if the address family af known to the library and supported
+ * by the other addrfam operations.  Note that the other operations will
+ * abort on an unrecognized address family rather than returning an error
+ * code.
+ */
+
+extern int adns__genaddr_equal_p(int af, const union gen_addr *a,
+				 int bf, const void *b);
+/* b should point to a `struct in_addr' or equivalent for the address family
+ * bf.  Returns nonzero if the two addresses are equal.
+ */
+
+extern int adns__sockaddr_equal_p(const struct sockaddr *sa,
+				  const struct sockaddr *sb);
+/* Return nonzero if the two socket addresses are equal (in all significant
+ * respects).
+ */
+
+extern int adns__addr_width(int af);
+/* Return the width of addresses of family af, in bits. */
+
+extern void adns__prefix_mask(int af, int len, union gen_addr *mask_r);
+/* Store in mask_r an address mask for address family af, whose first len
+ * bits are set and the remainder are clear.  This is what you want for
+ * converting a prefix length into a netmask.
+ */
+
+extern int adns__guess_prefix_length(int af, const union gen_addr *addr);
+/* Given a network base address, guess the appropriate prefix length based on
+ * the appropriate rules for the address family (e.g., for IPv4, this uses
+ * the old address classes).
+ */
+
+extern int adns__addr_match_p(int addraf, const union gen_addr *addr,
+			      int netaf, const union gen_addr *base,
+			      const union gen_addr *mask);
+/* Given an address af (with family addraf) and a network (with family netaf,
+ * base address base, and netmask mask), return nonzero if the address lies
+ * within the network.
+ */
+
+extern void adns__sockaddr_extract(const struct sockaddr *sa,
+				   union gen_addr *a_r, int *port_r);
+/* Extract fields from the socket address, filling in *a_r and *port_r with
+ * the address and (integer, host byte-order) port number, respectively.
+ * Either (or, pointlessly, both) of a_r and port_r may be null to mean
+ * `don't care'.
+ */
+
+extern void adns__sockaddr_inject(const union gen_addr *a, int port,
+				  struct sockaddr *sa);
+/* Inject fields into the socket adress sa.  If a is not null, copy the
+ * address in; if port is not -1, then copy the port (converting from host
+ * byte-order).  Assumes that sa->sa_family is already set correctly.
+ */
+
 /* From setup.c: */
 
 int adns__setnonblock(adns_state ads, int fd); /* => errno value */
diff --git a/src/setup.c b/src/setup.c
index ce44055..03d737e 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -46,12 +46,11 @@ static void addserver(adns_state ads, const struct sockaddr *sa, int n) {
   adns_rr_addr *ss;
   const struct sockaddr_in *sin;
 
-  assert(sa->sa_family==AF_INET); assert(n>=sizeof(*sin));
+  assert(sa->sa_family==AF_INET); /* for inet_ntoa */
   sin= (const void *)sa;
   
   for (i=0; i<ads->nservers; i++) {
-    assert(ads->servers[i].addr.sa.sa_family==AF_INET);
-    if (ads->servers[i].addr.inet.sin_addr.s_addr == sin->sin_addr.s_addr) {
+    if (adns__sockaddr_equal_p(sa, &ads->servers[i].addr.sa)) {
       adns__debug(ads,-1,0,"duplicate nameserver %s ignored",
 		  inet_ntoa(sin->sin_addr));
       return;
@@ -165,9 +164,10 @@ static void ccf_sortlist(adns_state ads, const char *fn,
   const char *word;
   char tbuf[200], *slash, *ep;
   const char *maskwhat;
-  struct in_addr base, mask;
+  struct sortlist *sl;
   int l;
-  unsigned long initial, baselocal;
+  int af= AF_UNSPEC;
+  int initial= -1;
 
   if (!buf) return;
   
@@ -187,55 +187,54 @@ static void ccf_sortlist(adns_state ads, const char *fn,
     memcpy(tbuf,word,l); tbuf[l]= 0;
     slash= strchr(tbuf,'/');
     if (slash) *slash++= 0;
-    
-    if (!inet_aton(tbuf,&base)) {
+
+    sl= &ads->sortlist[ads->nsortlist];
+    if (!inet_aton(tbuf, &sl->base.v4)) {
       configparseerr(ads,fn,lno,"invalid address `%s' in sortlist",tbuf);
       continue;
     }
+    af= AF_INET;
 
     if (slash) {
-      if (strchr(slash,'.')) {
+      if (slash[strspn(slash, "0123456789")]) {
 	maskwhat = "mask";
-	if (!inet_aton(slash,&mask)) {
+	if (!inet_aton(slash, &sl->mask.v4)) {
 	  configparseerr(ads,fn,lno,"invalid mask `%s' in sortlist",slash);
 	  continue;
 	}
       } else {
 	maskwhat = "prefix length";
 	initial= strtoul(slash,&ep,10);
-	if (*ep || initial>32) {
+	if (*ep || initial>adns__addr_width(af)) {
 	  configparseerr(ads,fn,lno,"mask length `%s' invalid",slash);
 	  continue;
 	}
-	mask.s_addr= htonl((0x0ffffffffUL) << (32-initial));
+	adns__prefix_mask(af, initial, &sl->mask);
       }
     } else {
-      maskwhat = "implied mask";
-      baselocal= ntohl(base.s_addr);
-      if (!(baselocal & 0x080000000UL)) /* class A */
-	mask.s_addr= htonl(0x0ff000000UL);
-      else if ((baselocal & 0x0c0000000UL) == 0x080000000UL)
-	mask.s_addr= htonl(0x0ffff0000UL); /* class B */
-      else if ((baselocal & 0x0f0000000UL) == 0x0e0000000UL)
-	mask.s_addr= htonl(0x0ff000000UL); /* class C */
-      else {
+      maskwhat = "implied prefix length";
+      initial= adns__guess_prefix_length(af, &sl->base);
+      if (initial < 0) {
 	configparseerr(ads,fn,lno, "network address `%s'"
 		       " in sortlist is not in classed ranges,"
 		       " must specify mask explicitly", tbuf);
 	continue;
       }
+      adns__prefix_mask(af, initial, &sl->mask);
     }
 
-    if (base.s_addr & ~mask.s_addr) {
-      configparseerr(ads,fn,lno, "%s `%s' in sortlist"
-		     " overlaps address `%s'",maskwhat,
-		     slash ? slash : inet_ntoa(mask), tbuf);
+    if (!adns__addr_match_p(af,&sl->base, af,&sl->base,&sl->mask)) {
+      if (initial >= 0) {
+	configparseerr(ads,fn,lno, "%s %d in sortlist"
+		       " overlaps address `%s'",maskwhat,initial,tbuf);
+      } else {
+	configparseerr(ads,fn,lno, "%s `%s' in sortlist"
+		       " overlaps address `%s'",maskwhat,slash,tbuf);
+      }
       continue;
     }
 
-    ads->sortlist[ads->nsortlist].af= AF_INET;
-    ads->sortlist[ads->nsortlist].base.v4= base;
-    ads->sortlist[ads->nsortlist].mask.v4= mask;
+    sl->af= af;
     ads->nsortlist++;
   }
 }
diff --git a/src/types.c b/src/types.c
index 431fe19..e0ff9e2 100644
--- a/src/types.c
+++ b/src/types.c
@@ -258,15 +258,11 @@ static adns_status pa_inaddr(const parseinfo *pai, int cbyte,
 
 static int search_sortlist(adns_state ads, int af, const void *ad) {
   const struct sortlist *slp;
-  const struct in_addr *a4;
   int i;
   
-  assert(af==AF_INET);
-  a4= ad;
   for (i=0, slp=ads->sortlist;
        i<ads->nsortlist &&
-	 (assert(slp->af==AF_INET),
-	  !((a4->s_addr & slp->mask.v4.s_addr) == slp->base.v4.s_addr));
+	 !adns__addr_match_p(af,ad, slp->af,&slp->base,&slp->mask);
        i++, slp++);
   return i;
 }
@@ -313,10 +309,11 @@ static adns_status pa_addr(const parseinfo *pai, int cbyte,
 }
 
 static int search_sortlist_sa(adns_state ads, const struct sockaddr *sa) {
-  assert(sa->sa_family == AF_INET);
-  return search_sortlist(ads, sa->sa_family,
-			 &((const struct sockaddr_in *)sa)->sin_addr);
+  union gen_addr a;
+  adns__sockaddr_extract(sa, &a, 0);
+  return search_sortlist(ads, sa->sa_family, &a);
 }
+
 static int dip_sockaddr(adns_state ads,
 			const struct sockaddr *sa,
 			const struct sockaddr *sb) {
@@ -772,10 +769,9 @@ static void icb_ptr(adns_query parent, adns_query child) {
   }
 
   queried= &parent->ctx.tinfo.ptr.addr;
-  assert(queried->af == AF_INET);
   assert(cans->type == adns_r_a);
   for (i=0, found=cans->rrs.bytes; i<cans->nrrs; i++, found+=cans->rrsz) {
-    if (queried->addr.v4.s_addr == ((const struct in_addr *)found)->s_addr) {
+    if (adns__genaddr_equal_p(queried->af,&queried->addr, AF_INET,found)) {
       if (!parent->children.head) {
 	adns__query_done(parent);
 	return;