support mix of IPv4 and v6 nameservers in resolv.conf

[android-x86/external-musl-libc.git] / src / network / __dns.c

diff --git a/src/network/__dns.c b/src/network/__dns.c
index 8f3c637..97d8031 100644 (file)
--- a/src/network/__dns.c
+++ b/src/network/__dns.c
@@ -11,6 +11,7 @@
 #include <ctype.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <errno.h>
 #include "__dns.h"
 #include "stdio_impl.h"
 
@@ -35,9 +36,9 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
                struct sockaddr_in sin;
                struct sockaddr_in6 sin6;
        } sa = {0}, ns[3] = {{0}};
-       socklen_t sl;
+       socklen_t sl = sizeof sa.sin;
        int nns = 0;
-       int family = AF_UNSPEC;
+       int family = AF_INET;
        unsigned char q[280] = "", *r = dest;
        int ql;
        int rlen;
@@ -75,10 +76,12 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
                for (s=line+11; isspace(*s); s++);
                for (z=s; *z && !isspace(*z); z++);
                *z=0;
-               if (__ipparse(ns+nns, family, s) < 0) continue;
+               if (__ipparse(ns+nns, AF_UNSPEC, s) < 0) continue;
                ns[nns].sin.sin_port = htons(53);
-               family = ns[nns++].sin.sin_family;
-               sl = family==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
+               if (ns[nns++].sin.sin_family == AF_INET6) {
+                       family = AF_INET6;
+                       sl = sizeof sa.sin6;
+               }
        }
        if (f) __fclose_ca(f);
        if (!nns) {
@@ -93,6 +96,29 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
        sa.sin.sin_family = family;
        fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 
+       /* Handle case where system lacks IPv6 support */
+       if (fd < 0 && errno == EAFNOSUPPORT) {
+               if (family != AF_INET6) return EAI_SYSTEM;
+               fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+               family = AF_INET;
+       }
+       if (fd < 0) return EAI_SYSTEM;
+
+       /* Convert any IPv4 addresses in a mixed environment to v4-mapped */
+       if (family == AF_INET6) {
+               setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &(int){0}, sizeof 0);
+               for (i=0; i<nns; i++) {
+                       if (ns[i].sin.sin_family != AF_INET) continue;
+                       memcpy(ns[i].sin6.sin6_addr.s6_addr+12,
+                               &ns[i].sin.sin_addr, 4);
+                       memcpy(ns[i].sin6.sin6_addr.s6_addr,
+                               "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
+                       ns[i].sin6.sin6_family = AF_INET6;
+                       ns[i].sin6.sin6_flowinfo = 0;
+                       ns[i].sin6.sin6_scope_id = 0;
+               }
+       }
+
        pthread_cleanup_push(cleanup, (void *)(intptr_t)fd);
        pthread_setcancelstate(cs, 0);