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Make opensips behave consistently in respect of nsswitch regardless o…
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…f DNS caching.
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Andriy Pylypenko committed Mar 12, 2021
1 parent efb9e16 commit 83cc7f1
Showing 1 changed file with 8 additions and 328 deletions.
336 changes: 8 additions & 328 deletions resolve.c
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Original file line number Diff line number Diff line change
Expand Up @@ -80,14 +80,8 @@ static struct bl_head *failover_bl=0;
#define DNS_REVOLVER_BL_NAME "dns"
#define DNS_BL_EXPIRE 4*60

#define MAX_BUFF_SIZE 8192
#define MAXALIASES 36
#define MAXADDRS 36
#define DNS_MAX_NAME 256
struct hostent global_he;
static char hostbuf[MAX_BUFF_SIZE];
static char *h_addr_ptrs[MAXADDRS];
static char *host_aliases[MAXALIASES];

stat_var *dns_total_queries;
stat_var *dns_slow_queries;
Expand Down Expand Up @@ -126,288 +120,14 @@ typedef union {
(s) = ntohl (t_cp); \
} while (0)

static inline unsigned int dns_get16(const u_char *src) {
unsigned int dst;

DNS_GET16(dst, src);
return dst;
}

static inline unsigned int dns_get32(const u_char *src) {
unsigned int dst;

DNS_GET32(dst, src);
return dst;
}

int get_dns_answer(union dns_query *answer,int anslen,char *qname,int qtype,int *min_ttl)
{
register const HEADER *hp;
register int n;
register const unsigned char *cp;
const char* tname;
const unsigned char *eom,*erdata;
int type, class,ttl, buflen, ancount;
int haveanswer, had_error;
char *bp,**ap,**hap;
char tbuf[DNS_MAX_NAME];
int toobig=0;

tname = qname;
global_he.h_name = NULL;
eom = answer->buff + anslen;

hp = &answer->hdr;
ancount = ntohs(hp->ancount);
bp = hostbuf;
buflen = sizeof hostbuf;

cp = answer->buff;
BOUNDED_INCR(DNS_HDR_SIZE);

n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
LM_ERR("Error expanding name\n");
return -1;
}
BOUNDED_INCR(n+4);

if (qtype == T_A || qtype == T_AAAA) {
n = strlen(bp) + 1;
if (n >= DNS_MAX_NAME) {
LM_ERR("Name too large\n");
return -1;
}
global_he.h_name = bp;
bp += n;
buflen -= n;
/* The qname can be abbreviated, but h_name is now absolute. */
qname = global_he.h_name;
}

ap = host_aliases;
*ap = NULL;
global_he.h_aliases = host_aliases;
hap = h_addr_ptrs;
*hap = NULL;
global_he.h_addr_list = h_addr_ptrs;
haveanswer = 0;
had_error = 0;
while (ancount-- > 0 && cp < eom && !had_error) {
n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
had_error++;
continue;
}
cp += n; /* name */
BOUNDS_CHECK(cp,3*2+4);
type = dns_get16(cp);
cp += 2; /* type */
class = dns_get16(cp);
cp += 2; /* class*/
ttl = dns_get32(cp);
if (ttl<*min_ttl)
*min_ttl=ttl;
cp +=4;
n = dns_get16(cp);
cp += 2; /* len */
BOUNDS_CHECK(cp, n);
erdata = cp + n;

if (class != C_IN) {
LM_ERR("Got response class != C_IN");
had_error++;
continue;
}

if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
if (ap >= &host_aliases[MAXALIASES-1])
continue;
n = dn_expand(answer->buff, eom, cp, tbuf, sizeof tbuf);
if (n < 0) {
LM_ERR("failed to expand alias\n");
had_error++;
continue;
}
cp += n;
if (cp != erdata)
return -1;
/* Store alias. */
*ap++ = bp;
n = strlen(bp) + 1;
if (n >= DNS_MAX_NAME) {
LM_ERR("alias too long\n");
had_error++;
continue;
}
bp += n;
buflen -= n;
/* Get canonical name. */
n = strlen(tbuf) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
had_error++;
continue;
}

strcpy(bp, tbuf);
global_he.h_name = bp;
bp += n;
buflen -= n;
continue;
}

if (qtype == T_PTR && type == T_CNAME) {
n = dn_expand(answer->buff, eom, cp, tbuf, sizeof tbuf);
if (n < 0) {
LM_ERR("failed to expand for t_ptr\n");
had_error++;
continue;
}

cp += n;
if (cp != erdata) {
LM_ERR("failure\n");
return -1;
}
/* Get canonical name. */
n = strlen(tbuf) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
LM_ERR("ptr name too long\n");
had_error++;
continue;
}
strcpy(bp, tbuf);
tname = bp;
bp += n;
buflen -= n;
continue;
}

if (type != qtype) {
LM_ERR("asked for %d, got %d\n",qtype,type);
cp+=n;
continue;
}

switch (type) {
case T_PTR:
if (strcasecmp(tname, bp) != 0) {
LM_ERR("asked for %s, got %s\n",tname,bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
n = dn_expand(answer->buff, eom, cp, bp, buflen);
if (n < 0) {
had_error++;
break;
}
cp += n;
if (cp != erdata) {
LM_ERR("errdata err\n");
return -1;
}
if (!haveanswer)
global_he.h_name = bp;
else if (ap < &host_aliases[MAXALIASES-1])
*ap++ = bp;
else
n = -1;
if (n != -1) {
n = strlen(bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN) {
had_error++;
break;
}
bp += n;
buflen -= n;
}
break;
case T_A:
case T_AAAA:
if (strcasecmp(global_he.h_name, bp) != 0) {
LM_ERR("asked for %s, got %s\n",global_he.h_name,bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
if (n != global_he.h_length) {
cp += n;
continue;
}
if (!haveanswer) {
register int nn;

global_he.h_name = bp;
nn = strlen(bp) + 1;
bp += nn;
buflen -= nn;
}

buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
bp += sizeof(align) - ((u_long)bp % sizeof(align));

if (bp + n >= &hostbuf[sizeof hostbuf]) {
LM_ERR("size (%d) too big\n", n);
had_error++;
continue;
}
if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
if (!toobig++)
LM_ERR("Too many addresses (%d)\n",MAXADDRS);
cp += n;
continue;
}

memmove(*hap++ = bp, cp, n);
bp += n;
buflen -= n;
cp += n;
if (cp != erdata) {
LM_ERR("failure\n");
return -1;
}
break;
default:
LM_ERR("should never get here\n");
return -1;
}
if (!had_error)
haveanswer++;
}

if (haveanswer) {
*ap = NULL;
*hap = NULL;
if (!global_he.h_name) {
n = strlen(qname) + 1;
if (n > buflen || n >= DNS_MAX_NAME) {
LM_ERR("name too long\n");
return -1;
}
strcpy(bp, qname);
global_he.h_name = bp;
bp += n;
buflen -= n;
}
}

return 0;
}

struct hostent* own_gethostbyname2(char *name,int af)
{
int size,type;
struct hostent *cached_he;
static union dns_query buff;
int min_ttl = INT_MAX;

switch (af) {
case AF_INET:
size=4;
type=T_A;
break;
case AF_INET6:
size=16;
type=T_AAAA;
break;
default:
LM_ERR("Only A and AAAA queries\n");
Expand All @@ -427,25 +147,17 @@ struct hostent* own_gethostbyname2(char *name,int af)
}

query:
global_he.h_addrtype=af;
global_he.h_length=size;

size=res_search(name, C_IN, type, buff.buff, sizeof(buff));
if (size < 0) {
cached_he = gethostbyname2(name, af);
if (cached_he == NULL) {
LM_DBG("Domain name not found\n");
if (dnscache_put_func(name,af==AF_INET?T_A:T_AAAA,NULL,0,1,0) < 0)
LM_ERR("Failed to store %s - %d in cache\n",name,af);
return NULL;
}

if (get_dns_answer(&buff,size,name,type,&min_ttl) < 0) {
LM_ERR("Failed to get dns answer\n");
return NULL;
}

if (dnscache_put_func(name,af==AF_INET?T_A:T_AAAA,&global_he,-1,0,min_ttl) < 0)
if (dnscache_put_func(name,af==AF_INET?T_A:T_AAAA,cached_he,-1,0,min_ttl) < 0)
LM_ERR("Failed to store %s - %d in cache\n",name,af);
return &global_he;
return cached_he;
}

inline struct hostent* resolvehost(char* name, int no_ip_test)
Expand Down Expand Up @@ -510,12 +222,7 @@ struct hostent * own_gethostbyaddr(void *addr, socklen_t len, int af)
const unsigned char *uaddr = (const u_char *)addr;
static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
int n;
int ret;
static union dns_query ptr_buff;
socklen_t size;
char qbuf[DNS_MAX_NAME+1];
char *qp=NULL;
int min_ttl=INT_MAX;
struct hostent *cached_he;

Expand Down Expand Up @@ -559,44 +266,17 @@ struct hostent * own_gethostbyaddr(void *addr, socklen_t len, int af)
}

query:
switch (af) {
case AF_INET:
sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
(uaddr[3] & 0xff),
(uaddr[2] & 0xff),
(uaddr[1] & 0xff),
(uaddr[0] & 0xff));
break;
case AF_INET6:
qp = qbuf;
for (n = 15; n >= 0; n--) {
qp += sprintf(qp, "%x.%x.",
uaddr[n] & 0xf,
(uaddr[n] >> 4) & 0xf);
}
strcpy(qp, "ip6.arpa");
break;
}

global_he.h_addrtype=af;
global_he.h_length=len;

ret=res_search(qbuf,C_IN,T_PTR,ptr_buff.buff,sizeof(ptr_buff.buff));
if (ret < 0) {
cached_he = gethostbyaddr(addr, len, af);
if (cached_he == NULL) {
LM_DBG("ptr not found\n");
if (dnscache_put_func(addr,T_PTR,NULL,len,1,0) < 0)
LM_ERR("Failed to store PTR in cache\n");
return NULL;
}

if (get_dns_answer(&ptr_buff,ret,qbuf,T_PTR,&min_ttl) < 0) {
LM_ERR("Failed to get dns answer\n");
return NULL;
}

if (dnscache_put_func(addr,T_PTR,&global_he,len,0,min_ttl) < 0)
if (dnscache_put_func(addr,T_PTR,cached_he,len,0,min_ttl) < 0)
LM_ERR("Failed to store PTR in cache\n");
return &global_he;
return cached_he;
}


Expand Down

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