149 lines
3.2 KiB
C
Executable file
149 lines
3.2 KiB
C
Executable file
#include <arpa/inet.h>
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#include <assert.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <netdb.h>
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#include <unistd.h>
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static size_t first_component_len(const char *s)
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{
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const char *first = s;
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/* find the first dot or end of string */
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while (*s && *s != '.')
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s++;
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/* return length */
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return s - first;
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}
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static int getnameinfo_get_host(const struct sockaddr_in *sockaddr,
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char *node, socklen_t nodelen, int flags)
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{
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struct hostent *hostent;
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const char *ipaddr;
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/* perform look-up */
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if ((flags & NI_NUMERICHOST) != NI_NUMERICHOST)
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{
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hostent = gethostbyaddr(
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(char *) &sockaddr->sin_addr,
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sizeof(sockaddr->sin_addr),
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AF_INET);
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if (hostent && hostent->h_name)
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{
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/* return the hostname that was found */
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if (nodelen <= strlen(hostent->h_name))
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return EAI_OVERFLOW;
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strcpy(node, hostent->h_name);
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return 0;
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}
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}
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if ((flags & NI_NAMEREQD) == NI_NAMEREQD)
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return EAI_NONAME;
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/* basic implementation to provide numeric values */
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ipaddr = inet_ntoa(sockaddr->sin_addr);
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if (nodelen <= strlen(ipaddr))
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return EAI_OVERFLOW;
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strcpy(node, ipaddr);
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return 0;
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}
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static int getnameinfo_get_serv(const struct sockaddr_in *sockaddr,
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char *service, socklen_t servicelen, int flags)
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{
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struct servent *servent;
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unsigned short port;
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/* perform look-up */
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if ((flags & NI_NUMERICSERV) != NI_NUMERICSERV)
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{
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servent = getservbyport(sockaddr->sin_port,
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((flags & NI_DGRAM) == NI_DGRAM) ? "udp" : "tcp");
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if (servent && servent->s_name)
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{
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/* return the service name that was found */
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if (strlen(servent->s_name) >= servicelen)
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return EAI_OVERFLOW;
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strcpy(service, servent->s_name);
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return 0;
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}
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}
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/* return port number */
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port = ntohs(sockaddr->sin_port);
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if (snprintf(service, servicelen, "%u", port) >= servicelen)
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return EAI_OVERFLOW;
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return 0;
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}
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/*
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* getnameinfo is based on
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* http://www.opengroup.org/onlinepubs/009695399/functions/getnameinfo.html
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*/
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int getnameinfo(const struct sockaddr *sa, socklen_t salen,
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char *node, socklen_t nodelen, char *service,
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socklen_t servicelen, int flags)
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{
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int r;
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const struct sockaddr_in *sockaddr;
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/*
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* The following flags are really supported:
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* - NI_NUMERICHOST
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* - NI_NAMEREQD
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* - NI_NUMERICSERV
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* - NI_DGRAM
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*
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* The following flag is not supported:
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* - NI_NUMERICSCOPE
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*
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* The following flags could have been supported but is not implemented:
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* - NI_NOFQDN
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*/
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/* check for invalid parameters; only support IPv4 */
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if (sa == NULL)
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{
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errno = EINVAL;
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return EAI_SYSTEM;
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}
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if (sa->sa_family != AF_INET || salen != sizeof(struct sockaddr_in))
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return EAI_FAMILY;
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if (flags & ~(NI_NUMERICHOST | NI_NAMEREQD | NI_NUMERICSERV | NI_DGRAM))
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return EAI_BADFLAGS;
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if ((!node || !nodelen) && (!service || !servicelen))
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return EAI_NONAME;
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/* look up host */
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sockaddr = (const struct sockaddr_in *) sa;
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if (node && nodelen > 0)
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{
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r = getnameinfo_get_host(sockaddr, node, nodelen, flags);
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if (r)
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return r;
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}
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/* look up service */
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if (service && servicelen > 0)
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{
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r = getnameinfo_get_serv(sockaddr, service, servicelen, flags);
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if (r)
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return r;
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}
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return 0;
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}
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