improve gethostbyname2_r using new resolver backend

these changes reduce the size of the function somewhat and remove many
of its dependencies, including free. in principle it should now be
async-signal-safe, but this has not been verified in detail.

minor changes to error handling are also made.

diff --git a/src/network/gethostbyname2_r.c b/src/network/gethostbyname2_r.c
index 27eb080..aa8b0a9 100644 (file)
--- a/src/network/gethostbyname2_r.c
+++ b/src/network/gethostbyname2_r.c
@@ -6,41 +6,31 @@
 #include <netinet/in.h>
 #include <errno.h>
 #include <stdint.h>
+#include "lookup.h"
 
 int gethostbyname2_r(const char *name, int af,
        struct hostent *h, char *buf, size_t buflen,
        struct hostent **res, int *err)
 {
-       struct addrinfo hint = {
-               .ai_family = af==AF_INET6 ? af : AF_INET,
-               .ai_flags = AI_CANONNAME
-       };
-       struct addrinfo *ai, *p;
-       int i;
-       size_t need;
-       const char *canon;
+       struct address addrs[MAXADDRS];
+       char canon[256];
+       int i, cnt;
+       size_t align, need;
 
-       af = hint.ai_family;
-
-       /* Align buffer */
-       i = (uintptr_t)buf & sizeof(char *)-1;
-       if (i) {
-               if (buflen < sizeof(char *)-i) return ERANGE;
-               buf += sizeof(char *)-i;
-               buflen -= sizeof(char *)-i;
-       }
-
-       switch (getaddrinfo(name, 0, &hint, &ai)) {
+       cnt = __lookup_name(addrs, canon, name, af, AI_CANONNAME);
+       if (cnt<0) switch (cnt) {
        case EAI_NONAME:
                *err = HOST_NOT_FOUND;
-               return errno;
+               return ENOENT;
        case EAI_AGAIN:
                *err = TRY_AGAIN;
-               return errno;
+               return EAGAIN;
        default:
+       case EAI_FAIL:
+               *err = NO_RECOVERY;
+               return EBADMSG;
        case EAI_MEMORY:
        case EAI_SYSTEM:
-       case EAI_FAIL:
                *err = NO_RECOVERY;
                return errno;
        case 0:
@@ -50,22 +40,22 @@ int gethostbyname2_r(const char *name, int af,
        h->h_addrtype = af;
        h->h_length = af==AF_INET6 ? 16 : 4;
 
-       canon = ai->ai_canonname ? ai->ai_canonname : name;
+       /* Align buffer */
+       align = -(uintptr_t)buf & sizeof(char *)-1;
+
        need = 4*sizeof(char *);
-       for (i=0, p=ai; p; i++, p=p->ai_next)
-               need += sizeof(char *) + h->h_length;
+       need += (cnt + 1) * (sizeof(char *) + h->h_length);
        need += strlen(name)+1;
        need += strlen(canon)+1;
+       need += align;
 
-       if (need > buflen) {
-               freeaddrinfo(ai);
-               return ERANGE;
-       }
+       if (need > buflen) return ERANGE;
 
+       buf += align;
        h->h_aliases = (void *)buf;
        buf += 3*sizeof(char *);
        h->h_addr_list = (void *)buf;
-       buf += (i+1)*sizeof(char *);
+       buf += (cnt+1)*sizeof(char *);
 
        h->h_name = h->h_aliases[0] = buf;
        strcpy(h->h_name, canon);
@@ -79,16 +69,13 @@ int gethostbyname2_r(const char *name, int af,
 
        h->h_aliases[2] = 0;
 
-       for (i=0, p=ai; p; i++, p=p->ai_next) {
+       for (i=0; i<cnt; i++) {
                h->h_addr_list[i] = (void *)buf;
                buf += h->h_length;
-               memcpy(h->h_addr_list[i],
-                       &((struct sockaddr_in *)p->ai_addr)->sin_addr,
-                       h->h_length);
+               memcpy(h->h_addr_list[i], addrs[i].addr, h->h_length);
        }
        h->h_addr_list[i] = 0;
 
        *res = h;
-       freeaddrinfo(ai);
        return 0;
 }