fusl/src/network/getservbyname_r.c

#define _GNU_SOURCE
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include "lookup.h"

#define ALIGN      \
  (sizeof(struct { \
     char a;       \
     char* b;      \
   }) -            \
   sizeof(char*))

int getservbyname_r(const char* name,
                    const char* prots,
                    struct servent* se,
                    char* buf,
                    size_t buflen,
                    struct servent** res) {
  struct service servs[MAXSERVS];
  int cnt, proto, align;

  /* Align buffer */
  align = -(uintptr_t)buf & ALIGN - 1;
  if (buflen < 2 * sizeof(char*) + align)
    return ERANGE;
  buf += align;

  if (!prots)
    proto = 0;
  else if (!strcmp(prots, "tcp"))
    proto = IPPROTO_TCP;
  else if (!strcmp(prots, "udp"))
    proto = IPPROTO_UDP;
  else
    return EINVAL;

  cnt = __lookup_serv(servs, name, proto, 0, 0);
  if (cnt < 0)
    switch (cnt) {
      case EAI_MEMORY:
      case EAI_SYSTEM:
        return ENOMEM;
      default:
        return ENOENT;
    }

  se->s_name = (char*)name;
  se->s_aliases = (void*)buf;
  se->s_aliases[0] = se->s_name;
  se->s_aliases[1] = 0;
  se->s_port = htons(servs[0].port);
  se->s_proto = servs[0].proto == IPPROTO_TCP ? "tcp" : "udp";

  *res = se;
  return 0;
}