third_party/ulib/musl/src/network/getservbyport_r.c

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

int getservbyport_r(int port, const char* prots, struct servent* se, char* buf, size_t buflen,
                    struct servent** res) {
    int i;
    struct sockaddr_in sin = {
        .sin_family = AF_INET, .sin_port = port,
    };

    if (!prots) {
        int r = getservbyport_r(port, "tcp", se, buf, buflen, res);
        if (r)
            r = getservbyport_r(port, "udp", se, buf, buflen, res);
        return r;
    }

    /* Align buffer */
    i = (uintptr_t)buf & (sizeof(char*) - 1);
    if (!i)
        i = sizeof(char*);
    if (buflen < 3 * sizeof(char*) - i)
        return ERANGE;
    buf += sizeof(char*) - i;
    buflen -= sizeof(char*) - i;

    if (strcmp(prots, "tcp") && strcmp(prots, "udp"))
        return EINVAL;

    se->s_port = port;
    se->s_proto = (char*)prots;
    se->s_aliases = (void*)buf;
    buf += 2 * sizeof(char*);
    buflen -= 2 * sizeof(char*);
    se->s_aliases[1] = 0;
    se->s_aliases[0] = se->s_name = buf;

    switch (getnameinfo((void*)&sin, sizeof sin, 0, 0, buf, buflen,
                        strcmp(prots, "udp") ? 0 : NI_DGRAM)) {
    case EAI_MEMORY:
    case EAI_SYSTEM:
        return ENOMEM;
    default:
        return ENOENT;
    case 0:
        break;
    }

    *res = se;
    return 0;
}