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Added getnameinfo with only name lookup (#172)

Browse source 
Added necessary constants (DNS_TYPE_PTR, NI_NUMERICHOST etc.).
Implementation of getnameinfo is similar to getaddrinfo, with internal
functions:

* ResolveDnsReverse: performs rDNS query and parses the PTR record
* ResolveHostsReverse: reads /etc/hosts to map hostname to
  address

Earlier, the HOSTS.txt would only need to be sorted at loading time,
because the only kind of lookup was name -> address. Now since address
-> name lookups are also possible, so the HostsTxt struct, the sorting
method (and the related tests) was changed to reflect this.
This commit is contained in:
Gautham 2021-06-10 08:05:44 +05:30 • committed by GitHub
parent 05350eca60
commit 248c6d54bb
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
12 changed files with 334 additions and 10 deletions
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4
libc/dns/consts.h
View file

@ -3,7 +3,9 @@
#include "libc/sock/sock.h"
#if !(__ASSEMBLER__ + __LINKER__ + 0)
#define DNS_TYPE_A 1
#define DNS_TYPE_A 0x01
#define DNS_TYPE_PTR 0x0c
#define DNS_CLASS_IN 1
#define kMinSockaddr4Size \

5
libc/dns/dns.h
View file

@ -1,5 +1,6 @@
#ifndef COSMOPOLITAN_LIBC_DNS_DNS_H_
#define COSMOPOLITAN_LIBC_DNS_DNS_H_
#include "libc/calls/weirdtypes.h"
#include "libc/dns/resolvconf.h"
#include "libc/sock/sock.h"
@ -56,11 +57,15 @@ struct addrinfo {
int getaddrinfo(const char *, const char *, const struct addrinfo *,
struct addrinfo **) paramsnonnull((4));
int freeaddrinfo(struct addrinfo *);
int getnameinfo(const struct sockaddr *, socklen_t, char *, socklen_t, char *,
socklen_t, int);
const char *gai_strerror(int);
int CompareDnsNames(const char *, const char *) paramsnonnull();
int PascalifyDnsName(uint8_t *, size_t, const char *) paramsnonnull();
int ResolveDns(const struct ResolvConf *, int, const char *, struct sockaddr *,
uint32_t) paramsnonnull();
int ResolveDnsReverse(const struct ResolvConf *resolvconf, int, const char *,
char *, size_t) paramsnonnull();
struct addrinfo *newaddrinfo(uint16_t);
COSMOPOLITAN_C_END_

3
libc/dns/gethoststxt.c
View file

@ -61,6 +61,7 @@ const struct HostsTxt *GetHostsTxt(void) {
init = &g_hoststxt_init;
if (!g_hoststxt) {
g_hoststxt = &init->ht;
init->ht.sorted_by = HOSTSTXT_NOT_SORTED;
init->ht.entries.n = pushpop(ARRAYLEN(init->entries));
init->ht.entries.p = init->entries;
init->ht.strings.n = pushpop(ARRAYLEN(init->strings));
@ -74,7 +75,7 @@ const struct HostsTxt *GetHostsTxt(void) {
/* TODO(jart): Elevate robustness. */
}
fclose(f);
SortHostsTxt(g_hoststxt);
SortHostsTxt(g_hoststxt, HOSTSTXT_SORTEDBYNAME);
}
return g_hoststxt;
}

107
libc/dns/getnameinfo.c Normal file
View file

@ -0,0 +1,107 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ This is free and unencumbered software released into the public domain. │
│ │
│ Anyone is free to copy, modify, publish, use, compile, sell, or │
│ distribute this software, either in source code form or as a compiled │
│ binary, for any purpose, commercial or non-commercial, and by any │
│ means. │
│ │
│ In jurisdictions that recognize copyright laws, the author or authors │
│ of this software dedicate any and all copyright interest in the │
│ software to the public domain. We make this dedication for the benefit │
│ of the public at large and to the detriment of our heirs and │
│ successors. We intend this dedication to be an overt act of │
│ relinquishment in perpetuity of all present and future rights to this │
│ software under copyright law. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
│ IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR │
│ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │
│ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR │
│ OTHER DEALINGS IN THE SOFTWARE. │
│ │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.internal.h"
#include "libc/calls/calls.h"
#include "libc/dns/consts.h"
#include "libc/dns/dns.h"
#include "libc/dns/hoststxt.h"
#include "libc/dns/resolvconf.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/fmt.h"
#include "libc/mem/mem.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/inaddr.h"
#include "libc/sysv/errfuns.h"
/**
* Resolves name/service for socket address.
*
* @param addr
* @param addrlen
* @param name
* @param namelen
* @param service
* @param servicelen
* @param flags
*
* @return 0 on success or EAI_xxx value
*/
int getnameinfo(const struct sockaddr *addr, socklen_t addrlen, char *name,
socklen_t namelen, char *service, socklen_t servicelen,
int flags) {
char rdomain[1 + sizeof "255.255.255.255.in-addr.arpa"];
char info[512];
int rc, port;
uint8_t *ip;
unsigned int valid_flags;
valid_flags =
(NI_NAMEREQD | NI_NUMERICHOST | NI_NUMERICSERV | NI_NOFQDN | NI_DGRAM);
if (flags & ~(valid_flags)) return EAI_BADFLAGS;
if (!name && !service) return EAI_NONAME;
if (addr->sa_family != AF_INET || addrlen < sizeof(struct sockaddr_in))
return EAI_FAMILY;
ip = (uint8_t *)&(((struct sockaddr_in *)addr)->sin_addr);
sprintf(rdomain, "%d.%d.%d.%d.in-addr.arpa", ip[3], ip[2], ip[1], ip[0]);
info[0] = '\0';
if (name != NULL && namelen != 0) {
if ((flags & NI_NUMERICHOST) && (flags & NI_NAMEREQD)) return EAI_NONAME;
if ((flags & NI_NUMERICHOST) &&
inet_ntop(AF_INET, ip, info, sizeof(info)) == NULL)
return EAI_SYSTEM;
else if (!info[0] && ResolveHostsReverse(GetHostsTxt(), AF_INET, ip, info,
sizeof(info)) < 0)
return EAI_SYSTEM;
else if (!info[0] && ResolveDnsReverse(GetResolvConf(), AF_INET, rdomain,
info, sizeof(info)) < 0)
return EAI_SYSTEM;
else if (!info[0] && (flags & NI_NAMEREQD))
return EAI_NONAME;
else if (!info[0] && inet_ntop(AF_INET, ip, info, sizeof(info)) == NULL)
return EAI_SYSTEM;
if (strlen(info) + 1 > namelen) return EAI_OVERFLOW;
strcpy(name, info);
}
port = ntohs(((struct sockaddr_in *)addr)->sin_port);
info[0] = '\0';
if (service != NULL && servicelen != 0) {
itoa(port, info, 10);
/* TODO: reverse lookup on /etc/services to get name of service */
if (strlen(info) + 1 > servicelen) return EAI_OVERFLOW;
strcpy(service, info);
}
return 0;
}

9
libc/dns/hoststxt.h
View file

@ -21,7 +21,12 @@ struct HostsTxtStrings {
char *p;
};
#define HOSTSTXT_NOT_SORTED 0
#define HOSTSTXT_SORTEDBYNAME 1
#define HOSTSTXT_SORTEDBYADDR 2
struct HostsTxt {
int sorted_by;
struct HostsTxtEntries entries;
struct HostsTxtStrings strings;
};
@ -29,10 +34,12 @@ struct HostsTxt {
const struct HostsTxt *GetHostsTxt(void) returnsnonnull;
void FreeHostsTxt(struct HostsTxt **) paramsnonnull();
int ParseHostsTxt(struct HostsTxt *, FILE *) paramsnonnull();
void SortHostsTxt(struct HostsTxt *) paramsnonnull();
void SortHostsTxt(struct HostsTxt *, int) paramsnonnull();
int ResolveHostsTxt(const struct HostsTxt *, int, const char *,
struct sockaddr *, uint32_t, const char **)
paramsnonnull((1, 3));
int ResolveHostsReverse(const struct HostsTxt *, int, const uint8_t *, char *,
size_t);
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

132
libc/dns/resolvednsreverse.c Normal file
View file

@ -0,0 +1,132 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ This is free and unencumbered software released into the public domain. │
│ │
│ Anyone is free to copy, modify, publish, use, compile, sell, or │
│ distribute this software, either in source code form or as a compiled │
│ binary, for any purpose, commercial or non-commercial, and by any │
│ means. │
│ │
│ In jurisdictions that recognize copyright laws, the author or authors │
│ of this software dedicate any and all copyright interest in the │
│ software to the public domain. We make this dedication for the benefit │
│ of the public at large and to the detriment of our heirs and │
│ successors. We intend this dedication to be an overt act of │
│ relinquishment in perpetuity of all present and future rights to this │
│ software under copyright law. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
│ IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR │
│ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │
│ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR │
│ OTHER DEALINGS IN THE SOFTWARE. │
│ │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/bits.h"
#include "libc/calls/calls.h"
#include "libc/dns/consts.h"
#include "libc/dns/dns.h"
#include "libc/dns/dnsheader.h"
#include "libc/dns/dnsquestion.h"
#include "libc/dns/resolvconf.h"
#include "libc/mem/mem.h"
#include "libc/rand/rand.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/ipproto.h"
#include "libc/sysv/consts/sock.h"
#include "libc/sysv/errfuns.h"
#define kMsgMax 512
/**
* Performs reverse DNS lookup with IP address.
*
* @param resolvconf can be GetResolvConf()
* @param af can be AF_INET, AF_UNSPEC
* @param name is a reversed IP address string ending with .in-addr.arpa
* @param buf to store the obtained hostname if any
* @param bufsize is size of buf
*
* @return 0 on success, or -1 w/ errno
* @error EAFNOSUPPORT, ENETDOWN, ENAMETOOLONG, EBADMSG
*/
int ResolveDnsReverse(const struct ResolvConf *resolvconf, int af,
const char *name, char *buf, size_t bufsize) {
int rc, fd, n;
struct DnsQuestion q;
struct DnsHeader h, h2;
uint8_t *p, *pe, msg[512];
uint16_t rtype, rclass, rdlength;
if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
if (!resolvconf->nameservers.i) return 0;
memset(&h, 0, sizeof(h));
rc = ebadmsg();
h.id = rand32();
h.bf1 = 1; /* recursion desired */
h.qdcount = 1;
q.qname = name;
q.qtype = DNS_TYPE_PTR;
q.qclass = DNS_CLASS_IN;
memset(msg, 0, sizeof(msg));
SerializeDnsHeader(msg, &h);
if ((n = SerializeDnsQuestion(msg + 12, 500, &q)) == -1) return -1;
if ((fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) return -1;
if (sendto(fd, msg, 12 + n, 0, resolvconf->nameservers.p,
sizeof(*resolvconf->nameservers.p)) == 12 + n &&
(n = read(fd, msg, 512)) >= 12) {
DeserializeDnsHeader(&h2, msg);
if (h2.id == h.id) {
rc = 0;
if (h2.ancount) {
p = msg + 12;
pe = msg + n;
while (p < pe && h2.qdcount) {
p += strnlen((char *)p, pe - p) + 1 + 4;
h2.qdcount--;
}
if (p + 1 < pe) {
if ((p[0] & 0b11000000) == 0b11000000) { /* name pointer */
p += 2;
} else {
p += strnlen((char *)p, pe - p) + 1;
}
if (p + 2 + 2 + 4 + 2 < pe) {
rtype = READ16BE(p), p += 2;
rclass = READ16BE(p), p += 2;
/* ttl */ p += 4;
rdlength = READ16BE(p), p += 2;
if (p + rdlength <= pe && rtype == DNS_TYPE_PTR &&
rclass == DNS_CLASS_IN) {
if (strnlen((char *)p, pe - p) + 1 > bufsize)
rc = -1;
else {
/* domain name starts with a letter */
for (; !isalnum((char)(*p)) && p < pe; p++) rdlength--;
for (char *tmp = (char *)p; rdlength > 0 && *tmp != '\0';
tmp++) {
/* each label is alphanumeric or hyphen
* any other character is assumed separator */
if (!isalnum(*tmp) && *tmp != '-') *tmp = '.';
rdlength--;
}
strcpy(buf, (char *)p);
}
} else
rc = -1;
}
}
}
}
}
close(fd);
return rc;
}

44
libc/dns/resolvehostsreverse.c Normal file
View file

@ -0,0 +1,44 @@
#include "libc/alg/alg.h"
#include "libc/dns/consts.h"
#include "libc/dns/dns.h"
#include "libc/dns/hoststxt.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/errfuns.h"
static int hoststxtcmpaddr(const uint8_t *ip1, const struct HostsTxtEntry *he2) {
uint32_t v1 = *((uint32_t *)ip1), v2 = *((uint32_t *)he2->ip);
return (v1 == v2 ? 0 : (v1 > v2 ? 1 : -1));
}
/**
* Finds name associated with address in HOSTS.TXT table.
*
* @param ht can be GetHostsTxt()
* @param af can be AF_INET
* @param ip is IP address in binary (sin_addr)
* @param buf is buffer to store the name
* @param bufsize is length of buf
*
* @return 1 if found, 0 if not found, or -1 w/ errno
* @error EAFNOSUPPORT
*/
int ResolveHostsReverse(const struct HostsTxt *ht, int af, const uint8_t *ip,
char *buf, size_t bufsize) {
struct HostsTxtEntry *entry;
if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
if (!ht->entries.p) return -1;
if (ht->sorted_by != HOSTSTXT_SORTEDBYADDR)
SortHostsTxt(ht, HOSTSTXT_SORTEDBYADDR);
entry = bsearch(ip, ht->entries.p, ht->entries.i,
sizeof(struct HostsTxtEntry), (void *)hoststxtcmpaddr);
if (entry) {
strncpy(buf, &ht->strings.p[entry->name], bufsize);
return 1;
}
return 0;
}

2
libc/dns/resolvehoststxt.c
View file

@ -52,6 +52,8 @@ int ResolveHostsTxt(const struct HostsTxt *ht, int af, const char *name,
struct sockaddr_in *addr4;
struct HostsTxtEntry *entry;
if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
if (ht->sorted_by != HOSTSTXT_SORTEDBYNAME)
SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
if ((entry = bsearch_r(name, ht->entries.p, ht->entries.i,
sizeof(struct HostsTxtEntry), (void *)hoststxtgetcmp,
ht->strings.p))) {

20
libc/dns/sorthoststxt.c
View file

@ -30,6 +30,17 @@ static int cmphoststxt(const struct HostsTxtEntry *e1,
return CompareDnsNames(&strings[e1->name], &strings[e2->name]);
}
/**
* Compares addresses in HOSTS.TXT table.
* @see ResolveHostsReverse()
*/
static int cmphostsaddr(const struct HostsTxtEntry *e1,
const struct HostsTxtEntry *e2) {
if (e1 == e2) return 0;
uint32_t v1 = *((uint32_t *)e1->ip), v2 = *((uint32_t *)e2->ip);
return (v1 == v2 ? 0 : (v1 > v2 ? 1 : -1));
}
/**
* Sorts entries in HOSTS.TXT table.
*
@ -41,9 +52,16 @@ static int cmphoststxt(const struct HostsTxtEntry *e1,
* possible to efficiently search for subdomains, once the initial sort
* is done.
*/
void SortHostsTxt(struct HostsTxt *ht) {
void SortHostsTxt(struct HostsTxt *ht, int sort_by) {
if (ht->entries.p) {
if (sort_by == HOSTSTXT_SORTEDBYNAME) {
qsort_r(ht->entries.p, ht->entries.i, sizeof(*ht->entries.p),
(void *)cmphoststxt, ht->strings.p);
ht->sorted_by = HOSTSTXT_SORTEDBYNAME;
} else {
qsort(ht->entries.p, ht->entries.i, sizeof(*ht->entries.p),
(void *)cmphostsaddr);
ht->sorted_by = HOSTSTXT_SORTEDBYADDR;
}
}
}

6
libc/sock/sock.h
View file

@ -9,7 +9,13 @@ COSMOPOLITAN_C_START_
#define INET_ADDRSTRLEN 22
#define NI_NUMERICHOST 0x01
#define NI_NUMERICSERV 0x02
#define NI_NOFQDN 0x04
#define NI_NAMEREQD 0x08
#define NI_DGRAM 0x10
#define NI_MAXHOST 0xff
#define NI_MAXSERV 0x20
#define htons(u16) bswap_16(u16)

2
test/libc/dns/parsehoststxt_test.c
View file

@ -48,7 +48,7 @@ TEST(ParseHostsTxt, testCorrectlyTokenizesAndSorts) {
ASSERT_EQ(1, fwrite(kInput, strlen(kInput), 1, f));
rewind(f);
ASSERT_EQ(0, ParseHostsTxt(ht, f));
SortHostsTxt(ht);
SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
ASSERT_EQ(4, ht->entries.i);
EXPECT_STREQ("cat.example.", &ht->strings.p[ht->entries.p[0].name]);
EXPECT_STREQ("cat.example.", &ht->strings.p[ht->entries.p[0].canon]);

4
test/libc/dns/resolvehoststxt_test.c
View file

@ -49,7 +49,7 @@ TEST(ResolveHostsTxt, testBasicLookups) {
struct HostsTxt *ht = calloc(1, sizeof(struct HostsTxt));
FILE *f = fmemopen(kInput, strlen(kInput), "r+");
ASSERT_EQ(0, ParseHostsTxt(ht, f));
SortHostsTxt(ht);
SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
ASSERT_EQ(5, ht->entries.i);
EXPECT_STREQ("127.0.0.1", EzIp4Lookup(ht, "localhost"));
EXPECT_STREQ("203.0.113.1", EzIp4Lookup(ht, "lol"));
@ -66,7 +66,7 @@ TEST(ResolveHostsTxt, testCanonicalize) {
struct HostsTxt *ht = calloc(1, sizeof(struct HostsTxt));
FILE *f = fmemopen(kInput, strlen(kInput), "r+");
ASSERT_EQ(0, ParseHostsTxt(ht, f));
SortHostsTxt(ht);
SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
ASSERT_EQ(5, ht->entries.i);
EXPECT_STREQ("localhost", EzCanonicalize(ht, "localhost"));
EXPECT_STREQ("lol.example.", EzCanonicalize(ht, "lol"));