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improve gethostbyname2_r using new resolver backend

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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.
This commit is contained in:
Rich Felker 2014-06-01 00:09:28 -04:00
commit e8f39ca489
1 changed files with 22 additions and 35 deletions
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57
src/network/gethostbyname2_r.c
View file

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