/*
 * Socket interface API
 */
#include <netdb.h>              /* getaddrinfo() */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>

#include "nvt_log.h"
#include "nvt_socket.h"


typedef struct {
    unsigned short  type;       // socket type
    unsigned short  slen;       // sockaddr length
    union {
        struct sockaddr gen;
        struct sockaddr_in ipv4;
        struct sockaddr_in6 ipv6;
        struct sockaddr_un un;
    };
} sa_t;


static int _sa_host_lookup(sa_t *sa, const char *host, const char *port)
{
    struct addrinfo hint, *adrinf = NULL, *p;
    int             ret = -1;

    memset(&hint, 0, sizeof(struct addrinfo));

    if (getaddrinfo(host, port, &hint, &adrinf) != 0)
    {
        nvt_log(LOG_ERR, "Cannot resolve host name: %m\n");
        return -1;
    }

    // Priority is given to the use of IPv4
    // This code must be modified if the preffered protocol is changed or varied.
    for (p = adrinf; p; p = p->ai_next)
    {
        if (p->ai_family == AF_INET)
        {
            sa->slen = sizeof(sa->ipv4);
            memcpy(&sa->ipv4, p->ai_addr, sizeof(struct sockaddr_in));
            ret = 0;
            goto exit_host_lookup;
        }
    }
    for (p = adrinf; p; p = p->ai_next)
    {
        if (p->ai_family == AF_INET6)
        {
            sa->slen = sizeof(sa->ipv6);
            memcpy(&sa->ipv6, p->ai_addr, sizeof(struct sockaddr_in6));
            ret = 0;
            goto exit_host_lookup;
        }
    }
  exit_host_lookup:
    freeaddrinfo(adrinf);
    return ret;
}

static int _sa_addr_parse(sa_t *sa, const char *addr)
{
    ssize_t         host_len;
    char            host[64];
    const char     *port;

    memset(sa, 0, sizeof(sa_t));

    if (strncmp(addr, "unix:", 5) == 0)
    {                           // case of unix domain sockets ...
        addr += 5;              // skip "unix:" prefix
        if (strlen(addr) > sizeof(sa->un.sun_path) - 1)
        {
            nvt_log(LOG_ERR, "UNIX domain socket path is too long.\n");
            return -1;
        }
        sa->slen = sizeof(sa->un);
        sa->un.sun_family = AF_UNIX;
        strcpy(sa->un.sun_path, addr);
        sa->type = SOCK_STREAM;
        return 0;
    }

    if (!(port = strrchr(addr, ':')))
    {
        nvt_log(LOG_ERR, "bad server address format.\n");
        return -1;
    }
    host_len = (port++) - addr;
    // *port indicates the last ':', its next is 1st char of the port number
    if (host_len >= 2 && addr[0] == '[' && addr[host_len - 1] == ']')
    {
        // IPv6 addresses are enclosed in pair of square brackets.
        addr += 1;
        host_len -= 2;
    }
    else
    {
        if (strchr(addr, ':') != port - 1)
        {
            nvt_log(LOG_ERR,
                    "addresses containing colons must be enclosed in square brackets.\n");
            return -1;
        }
    }
    if ((ssize_t) sizeof(host) <= host_len)
    {
        nvt_log(LOG_ERR, "host name is too long.\n");
        return -1;
    }
    strncpy(host, addr, host_len);
    host[host_len] = '\0';      // strncpy doesn't add null char

    if (_sa_host_lookup(sa, host, port) != 0)
        return -1;

    sa->type = SOCK_STREAM;

    return 0;
}

int socket_create_client(const char *addr)
{
    sa_t            sa;
    int             fd, err;

    if (_sa_addr_parse(&sa, addr) != 0)
        return -1;

    fd = socket(sa.gen.sa_family, sa.type, 0);
    if (fd < 0)
    {
        nvt_log(LOG_ERR, "%s: Could not find address: '%s'", __func__, addr);
        return fd;
    }

    err = connect(fd, &sa.gen, sa.slen);
    if (err < 0)
    {
        nvt_log(LOG_ERR, "Failed to connect to: %s: %m\n", addr);
        close(fd);
        return -1;
    }

    return fd;
}

int socket_create_server(const char *addr)
{
    sa_t            sa;
    int             err, fd, opt;

    err = _sa_addr_parse(&sa, addr);
    if (err != 0)
    {
        nvt_log(LOG_ERR, "%s: Could not find address: '%s'", __func__, addr);
        return -1;
    }

    fd = socket(sa.gen.sa_family, sa.type, 0);
    if (fd < 0)
    {
        nvt_log(LOG_ERR, "%s: *** socket(%s): %m", __func__, addr);
        return -1;
    }

    if (sa.gen.sa_family == AF_INET || sa.gen.sa_family == AF_INET6)
    {
        /* Avoid TIME_WAIT state on socket close */
        opt = 1;
        setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    }

    err = bind(fd, &sa.gen, sa.slen);
    if (err != 0)
    {
        nvt_log(LOG_ERR, "%s: *** bind(%s): %m", __func__, addr);
        close(fd);
        return -1;
    }

    if (sa.type == SOCK_STREAM)
    {
        err = listen(fd, 5);
        if (err != 0)
        {
            nvt_log(LOG_ERR, "%s: *** listen(%s): %m", __func__, addr);
            close(fd);
            return -1;
        }
    }

    return fd;
}

int socket_create_server_client(int sfd)
{
    int             cfd;
    socklen_t       slen;

    slen = 0;
    cfd = accept(sfd, NULL, &slen);
    if (cfd < 0)
    {
        nvt_log(LOG_ERR, "%s: *** accept(): %m", __func__);
        return -1;
    }

    return cfd;
}