/*
 * dhcpcd - DHCP client daemon
 * Copyright (c) 2006-2013 Roy Marples <roy@marples.name>
 * All rights reserved

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "config.h"
#include "common.h"
#include "dhcp-common.h"
#include "dhcp.h"

int make_option_mask(const struct dhcp_opt *dopts,
    uint8_t *mask, const char *opts, int add)
{
	char *token, *o, *p, *t;
	const struct dhcp_opt *opt;
	int match, n;

	o = p = strdup(opts);
	if (opts == NULL)
		return -1;
	while ((token = strsep(&p, ", "))) {
		if (*token == '\0')
			continue;
		for (opt = dopts; opt->option; opt++) {
			if (!opt->var)
				continue;
			match = 0;
			if (strcmp(opt->var, token) == 0)
				match = 1;
			else {
				errno = 0;
				n = strtol(token, &t, 0);
				if (errno == 0 && !*t)
					if (opt->option == n)
						match = 1;
			}
			if (match) {
				if (add == 2 && !(opt->type & ADDRIPV4)) {
					free(o);
					errno = EINVAL;
					return -1;
				}
				if (add == 1 || add == 2)
					add_option_mask(mask,
					    opt->option);
				else
					del_option_mask(mask,
					    opt->option);
				break;
			}
		}
		if (!opt->option) {
			free(o);
			errno = ENOENT;
			return -1;
		}
	}
	free(o);
	return 0;
}

size_t
encode_rfc1035(const char *src, uint8_t *dst)
{
	uint8_t *p;
	uint8_t *lp;
	size_t len;
	uint8_t has_dot;

	if (src == NULL || *src == '\0')
		return 0;

	if (dst) {
		p = dst;
		lp = p++;
	}
	/* Silence bogus GCC warnings */
	else
		p = lp = NULL;

	len = 1;
	has_dot = 0;
	for (; *src; src++) {
		if (*src == '\0')
			break;
		if (*src == '.') {
			/* Skip the trailing . */
			if (src[1] == '\0')
				break;
			has_dot = 1;
			if (dst) {
				*lp = p - lp - 1;
				if (*lp == '\0')
					return len;
				lp = p++;
			}
		} else if (dst)
			*p++ = (uint8_t)*src;
		len++;
	}

	if (dst) {
		*lp = p - lp - 1;
		if (has_dot)
			*p++ = '\0';
	}

	if (has_dot)
		len++;

	return len;
}

/* Decode an RFC3397 DNS search order option into a space
 * separated string. Returns length of string (including
 * terminating zero) or zero on error. out may be NULL
 * to just determine output length. */
ssize_t
decode_rfc3397(char *out, ssize_t len, int pl, const uint8_t *p)
{
	const char *start;
	ssize_t start_len;
	const uint8_t *r, *q = p;
	int count = 0, l, hops;
	uint8_t ltype;

	start = out;
	start_len = len;
	while (q - p < pl) {
		r = NULL;
		hops = 0;
		/* We check we are inside our length again incase
		 * the data is NOT terminated correctly. */
		while ((l = *q++) && q - p < pl) {
			ltype = l & 0xc0;
			if (ltype == 0x80 || ltype == 0x40)
				return 0;
			else if (ltype == 0xc0) { /* pointer */
				l = (l & 0x3f) << 8;
				l |= *q++;
				/* save source of first jump. */
				if (!r)
					r = q;
				hops++;
				if (hops > 255)
					return 0;
				q = p + l;
				if (q - p >= pl)
					return 0;
			} else {
				/* straightforward name segment, add with '.' */
				count += l + 1;
				if (out) {
					if ((ssize_t)l + 1 > len) {
						errno = ENOBUFS;
						return -1;
					}
					memcpy(out, q, l);
					out += l;
					*out++ = '.';
					len -= l;
					len--;
				}
				q += l;
			}
		}
		/* change last dot to space */
		if (out && out != start)
			*(out - 1) = ' ';
		if (r)
			q = r;
	}

	/* change last space to zero terminator */
	if (out) {
		if (out != start)
			*(out - 1) = '\0';
		else if (start_len > 0)
			*out = '\0';
	}

	return count;
}

ssize_t
print_string(char *s, ssize_t len, int dl, const uint8_t *data)
{
	uint8_t c;
	const uint8_t *e, *p;
	ssize_t bytes = 0;
	ssize_t r;

	e = data + dl;
	while (data < e) {
		c = *data++;
		if (c == '\0') {
			/* If rest is all NULL, skip it. */
			for (p = data; p < e; p++)
				if (*p != '\0')
					break;
			if (p == e)
				break;
		}
		if (!isascii(c) || !isprint(c)) {
			if (s) {
				if (len < 5) {
					errno = ENOBUFS;
					return -1;
				}
				r = snprintf(s, len, "\\%03o", c);
				len -= r;
				bytes += r;
				s += r;
			} else
				bytes += 4;
			continue;
		}
		switch (c) {
		case '"':  /* FALLTHROUGH */
		case '\'': /* FALLTHROUGH */
		case '$':  /* FALLTHROUGH */
		case '`':  /* FALLTHROUGH */
		case '\\': /* FALLTHROUGH */
		case '|':  /* FALLTHROUGH */
		case '&':
			if (s) {
				if (len < 3) {
					errno = ENOBUFS;
					return -1;
				}
				*s++ = '\\';
				len--;
			}
			bytes++;
			break;
		}
		if (s) {
			*s++ = c;
			len--;
		}
		bytes++;
	}

	/* NULL */
	if (s)
		*s = '\0';
	bytes++;
	return bytes;
}

ssize_t
print_option(char *s, ssize_t len, int type, int dl, const uint8_t *data,
    const char *ifname)
{
	const uint8_t *e, *t;
	uint16_t u16;
	int16_t s16;
	uint32_t u32;
	int32_t s32;
	struct in_addr addr;
	ssize_t bytes = 0;
	ssize_t l;
	char *tmp;

	if (type & RFC3397) {
		l = decode_rfc3397(NULL, 0, dl, data);
		if (l < 1)
			return l;
		tmp = malloc(l);
		if (tmp == NULL)
			return -1;
		decode_rfc3397(tmp, l, dl, data);
		l = print_string(s, len, l - 1, (uint8_t *)tmp);
		free(tmp);
		return l;
	}

#ifdef INET
	if (type & RFC3361) {
		if ((tmp = decode_rfc3361(dl, data)) == NULL)
			return -1;
		l = strlen(tmp);
		l = print_string(s, len, l - 1, (uint8_t *)tmp);
		free(tmp);
		return l;
	}

	if (type & RFC3442)
		return decode_rfc3442(s, len, dl, data);

	if (type & RFC5969)
		return decode_rfc5969(s, len, dl, data);
#endif

	if (type & STRING) {
		/* Some DHCP servers return NULL strings */
		if (*data == '\0')
			return 0;
		return print_string(s, len, dl, data);
	}

	if (type & FLAG) {
		if (s) {
			*s++ = '1';
			*s = '\0';
		}
		return 2;
	}

	/* DHCPv6 status code */
	if (type & SCODE && dl >= (int)sizeof(u16)) {
		if (s) {
			memcpy(&u16, data, sizeof(u16));
			u16 = ntohs(u16);
			l = snprintf(s, len, "%d ", u16);
			len -= l;
		} else
			l = 7;
		data += sizeof(u16);
		dl -= sizeof(u16);
		if (dl)
			l += print_option(s, len, STRING, dl, data, ifname);
		return l;
	}

	if (!s) {
		if (type & UINT8)
			l = 3;
		else if (type & UINT16) {
			l = 5;
			dl /= 2;
		} else if (type & SINT16) {
			l = 6;
			dl /= 2;
		} else if (type & UINT32) {
			l = 10;
			dl /= 4;
		} else if (type & SINT32) {
			l = 11;
			dl /= 4;
		} else if (type & ADDRIPV4) {
			l = 16;
			dl /= 4;
		}
#ifdef INET6
		else if (type & ADDRIPV6) {
			e = data + dl;
			l = 0;
			while (data < e) {
				if (l)
					l++; /* space */
				dl = ipv6_printaddr(NULL, 0, data, ifname);
				if (dl != -1)
					l += dl;
				data += 16;
			}
			return l + 1;
		}
#endif
		else if (type & BINHEX) {
			l = 2;
		} else {
			errno = EINVAL;
			return -1;
		}
		return (l + 1) * dl;
	}

	t = data;
	e = data + dl;
	while (data < e) {
		if (data != t && type != BINHEX) {
			*s++ = ' ';
			bytes++;
			len--;
		}
		if (type & UINT8) {
			l = snprintf(s, len, "%d", *data);
			data++;
		} else if (type & UINT16) {
			memcpy(&u16, data, sizeof(u16));
			u16 = ntohs(u16);
			l = snprintf(s, len, "%d", u16);
			data += sizeof(u16);
		} else if (type & SINT16) {
			memcpy(&s16, data, sizeof(s16));
			s16 = ntohs(s16);
			l = snprintf(s, len, "%d", s16);
			data += sizeof(s16);
		} else if (type & UINT32) {
			memcpy(&u32, data, sizeof(u32));
			u32 = ntohl(u32);
			l = snprintf(s, len, "%d", u32);
			data += sizeof(u32);
		} else if (type & SINT32) {
			memcpy(&s32, data, sizeof(s32));
			s32 = ntohl(s32);
			l = snprintf(s, len, "%d", s32);
			data += sizeof(s32);
		} else if (type & ADDRIPV4) {
			memcpy(&addr.s_addr, data, sizeof(addr.s_addr));
			l = snprintf(s, len, "%s", inet_ntoa(addr));
			data += sizeof(addr.s_addr);
		}
#ifdef INET6
		else if (type & ADDRIPV6) {
			dl = ipv6_printaddr(s, len, data, ifname);
			if (dl != -1)
				l = dl;
			else
				l = 0;
			data += 16;
		}
#endif
		else if (type & BINHEX) {
			l = snprintf(s, len, "%.2x", data[0]);
			data++;
		} else
			l = 0;
		len -= l;
		bytes += l;
		s += l;
	}

	return bytes;
}