fusl/src/network/lookup_serv.c

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <ctype.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include "lookup.h"
#include "stdio_impl.h"

int __lookup_serv(struct service buf[static MAXSERVS],
                  const char* name,
                  int proto,
                  int socktype,
                  int flags) {
  char line[128];
  int cnt = 0;
  char *p, *z = "";
  unsigned long port = 0;

  switch (socktype) {
    case SOCK_STREAM:
      switch (proto) {
        case 0:
          proto = IPPROTO_TCP;
        case IPPROTO_TCP:
          break;
        default:
          return EAI_SERVICE;
      }
      break;
    case SOCK_DGRAM:
      switch (proto) {
        case 0:
          proto = IPPROTO_UDP;
        case IPPROTO_UDP:
          break;
        default:
          return EAI_SERVICE;
      }
    case 0:
      break;
    default:
      if (name)
        return EAI_SERVICE;
      buf[0].port = 0;
      buf[0].proto = proto;
      buf[0].socktype = socktype;
      return 1;
  }

  if (name) {
    if (!*name)
      return EAI_SERVICE;
    port = strtoul(name, &z, 10);
  }
  if (!*z) {
    if (port > 65535)
      return EAI_SERVICE;
    if (proto != IPPROTO_UDP) {
      buf[cnt].port = port;
      buf[cnt].socktype = SOCK_STREAM;
      buf[cnt++].proto = IPPROTO_TCP;
    }
    if (proto != IPPROTO_TCP) {
      buf[cnt].port = port;
      buf[cnt].socktype = SOCK_DGRAM;
      buf[cnt++].proto = IPPROTO_UDP;
    }
    return cnt;
  }

  if (flags & AI_NUMERICSERV)
    return EAI_SERVICE;

  size_t l = strlen(name);

  unsigned char _buf[1032];
  FILE _f, *f = __fopen_rb_ca("/etc/services", &_f, _buf, sizeof _buf);
  if (!f)
    switch (errno) {
      case ENOENT:
      case ENOTDIR:
      case EACCES:
        return EAI_SERVICE;
      default:
        return EAI_SYSTEM;
    }

  while (fgets(line, sizeof line, f) && cnt < MAXSERVS) {
    if ((p = strchr(line, '#')))
      *p++ = '\n', *p = 0;

    /* Find service name */
    for (p = line; (p = strstr(p, name)); p++) {
      if (p > line && !isspace(p[-1]))
        continue;
      if (p[l] && !isspace(p[l]))
        continue;
      break;
    }
    if (!p)
      continue;

    /* Skip past canonical name at beginning of line */
    for (p = line; *p && !isspace(*p); p++)
      ;

    port = strtoul(p, &z, 10);
    if (port > 65535 || z == p)
      continue;
    if (!strncmp(z, "/udp", 4)) {
      if (proto == IPPROTO_TCP)
        continue;
      buf[cnt].port = port;
      buf[cnt].socktype = SOCK_DGRAM;
      buf[cnt++].proto = IPPROTO_UDP;
    }
    if (!strncmp(z, "/tcp", 4)) {
      if (proto == IPPROTO_UDP)
        continue;
      buf[cnt].port = port;
      buf[cnt].socktype = SOCK_STREAM;
      buf[cnt++].proto = IPPROTO_TCP;
    }
  }
  __fclose_ca(f);
  return cnt > 0 ? cnt : EAI_SERVICE;
}