diff options
Diffstat (limited to 'src/network/lookup_name.c')
| -rw-r--r-- | src/network/lookup_name.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c new file mode 100644 index 00000000..b1f1ffd0 --- /dev/null +++ b/src/network/lookup_name.c @@ -0,0 +1,168 @@ +#include <sys/socket.h> +#include <netinet/in.h> +#include <netdb.h> +#include <arpa/inet.h> +#include <ctype.h> +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include "lookup.h" +#include "stdio_impl.h" +#include "syscall.h" +#include "__dns.h" + +static int is_valid_hostname(const char *host) +{ + const unsigned char *s; + if (strnlen(host, 255)-1 > 254 || mbstowcs(0, host, 0) > 255) return 0; + for (s=(void *)host; *s>=0x80 || *s=='.' || *s=='-' || isalnum(*s); s++); + return !*s; +} + +static int name_from_null(struct address buf[static 2], const char *name, int family, int flags) +{ + int cnt = 0; + if (name) return 0; + if (flags & AI_PASSIVE) { + if (family != AF_INET6) + buf[cnt++] = (struct address){ .family = AF_INET }; + if (family != AF_INET) + buf[cnt++] = (struct address){ .family = AF_INET6 }; + } else { + if (family != AF_INET6) + buf[cnt++] = (struct address){ .family = AF_INET, .addr = { 127,0,0,1 } }; + if (family != AF_INET) + buf[cnt++] = (struct address){ .family = AF_INET6, .addr = { [15] = 1 } }; + } + return cnt; +} + +static int name_from_numeric(struct address buf[static 1], const char *name, int family) +{ + struct in_addr a4; + struct in6_addr a6; + if (family != AF_INET6 && inet_aton(name, &a4)>0) { + memcpy(&buf[0].addr, &a4, sizeof a4); + buf[0].family = AF_INET; + return 1; + } + if (family != AF_INET && inet_pton(AF_INET6, name, &a6)>0) { + memcpy(&buf[0].addr, &a6, sizeof a6); + buf[0].family = AF_INET6; + return 1; + } + return 0; +} + +static int name_from_hosts(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family) +{ + char line[512]; + size_t l = strlen(name); + int cnt = 0; + unsigned char _buf[1032]; + FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf); + if (!f) return 0; + while (fgets(line, sizeof line, f) && cnt < MAXADDRS) { + char *p, *z; + + if ((p=strchr(line, '#'))) *p++='\n', *p=0; + for(p=line+1; (p=strstr(p, name)) && + (!isspace(p[-1]) || !isspace(p[l])); p++); + if (!p) continue; + + /* Isolate IP address to parse */ + for (p=line; *p && !isspace(*p); p++); + *p++ = 0; + if (name_from_numeric(buf+cnt, line, family)) + cnt++; + + /* Extract first name as canonical name */ + for (; *p && isspace(*p); p++); + for (z=p; *z && !isspace(*z); z++); + *z = 0; + if (is_valid_hostname(p)) memcpy(canon, p, z-p+1); + } + __fclose_ca(f); + return cnt; +} + +static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family) +{ + unsigned char reply[1024] = { 0 }, *p = reply; + char tmp[256]; + int i, cnt = 0; + + /* Perform one or more DNS queries for host */ + int result = __dns_query(reply, name, family, 0); + if (result < 0) return result; + + for (i=0; i<result; i++) { + if (family != AF_INET6) { + int j = __dns_get_rr(&buf[cnt].addr, sizeof *buf, 4, MAXADDRS-cnt, p, RR_A, 0); + while (j--) buf[cnt++].family = AF_INET; + } + if (family != AF_INET) { + int j = __dns_get_rr(&buf[cnt].addr, sizeof *buf, 16, MAXADDRS-cnt, p, RR_AAAA, 0); + while (j--) buf[cnt++].family = AF_INET6; + } + p += 512; + } + __dns_get_rr(tmp, 0, 256, 1, reply, RR_CNAME, 1); + if (is_valid_hostname(tmp)) strcpy(canon, tmp); + return cnt; +} + +int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, int flags) +{ + int cnt = 0, i, j; + + *canon = 0; + if (name) { + size_t l; + if ((l = strnlen(name, 255))-1 > 254) + return EAI_NONAME; + memcpy(canon, name, l+1); + } + + /* Procedurally, a request for v6 addresses with the v4-mapped + * flag set is like a request for unspecified family, followed + * by filtering of the results. */ + if (flags & AI_V4MAPPED) { + if (family == AF_INET6) family = AF_UNSPEC; + else flags -= AI_V4MAPPED; + } + + /* Try each backend until there's at least one result. */ + cnt = name_from_null(buf, name, family, flags); + if (cnt<=0) cnt = name_from_numeric(buf, name, family); + if (cnt<=0 && !(flags & AI_NUMERICHOST)) { + cnt = name_from_hosts(buf, canon, name, family); + if (cnt<=0) cnt = name_from_dns(buf, canon, name, family); + } + if (cnt<=0) return cnt ? cnt : EAI_NONAME; + + /* Filter/transform results for v4-mapped lookup, if requested. */ + if (flags & AI_V4MAPPED) { + if (!(flags & AI_ALL)) { + /* If any v6 results exist, remove v4 results. */ + for (i=0; i<cnt && buf[i].family != AF_INET6; i++); + if (i<cnt) { + for (j=0; i<cnt; i++) { + if (buf[i].family == AF_INET6) + buf[j++] = buf[i]; + } + cnt = i = j; + } + } + /* Translate any remaining v4 results to v6 */ + for (i=0; i<cnt; i++) { + if (buf[i].family != AF_INET) continue; + memcpy(buf[i].addr+12, buf[i].addr, 4); + memcpy(buf[i].addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12); + buf[i].scopeid = 0; + buf[i].family = AF_INET6; + } + } + + return cnt; +} |