diff options
Diffstat (limited to 'dhcp.c')
| -rw-r--r-- | dhcp.c | 112 |
1 files changed, 81 insertions, 31 deletions
@@ -63,6 +63,11 @@ static struct opt opts[255]; #define OPT_MIN 60 /* RFC 951 */ +/* Total option size (excluding end option) is 576 (RFC 2131), minus + * offset of options (268), minus end option (1). + */ +#define OPT_MAX 307 + /** * dhcp_init() - Initialise DHCP options */ @@ -122,7 +127,7 @@ struct msg { uint8_t sname[64]; uint8_t file[128]; uint32_t magic; - uint8_t o[308]; + uint8_t o[OPT_MAX + 1 /* End option */ ]; } __attribute__((__packed__)); /** @@ -130,15 +135,28 @@ struct msg { * @m: Message to fill * @o: Option number * @offset: Current offset within options field, updated on insertion + * + * Return: false if m has space to write the option, true otherwise */ -static void fill_one(struct msg *m, int o, int *offset) +static bool fill_one(struct msg *m, int o, int *offset) { + size_t slen = opts[o].slen; + + /* If we don't have space to write the option, then just skip */ + if (*offset + 2 /* code and length of option */ + slen > OPT_MAX) + return true; + m->o[*offset] = o; - m->o[*offset + 1] = opts[o].slen; - memcpy(&m->o[*offset + 2], opts[o].s, opts[o].slen); + m->o[*offset + 1] = slen; + + /* Move to option */ + *offset += 2; + + memcpy(&m->o[*offset], opts[o].s, slen); opts[o].sent = 1; - *offset += 2 + opts[o].slen; + *offset += slen; + return false; } /** @@ -159,21 +177,23 @@ static int fill(struct msg *m) * Put it there explicitly, unless requested via option 55. */ if (opts[55].clen > 0 && !memchr(opts[55].c, 53, opts[55].clen)) - fill_one(m, 53, &offset); + if (fill_one(m, 53, &offset)) + debug("DHCP: skipping option 53"); for (i = 0; i < opts[55].clen; i++) { o = opts[55].c[i]; if (opts[o].slen != -1) - fill_one(m, o, &offset); + if (fill_one(m, o, &offset)) + debug("DHCP: skipping option %i", o); } for (o = 0; o < 255; o++) { if (opts[o].slen != -1 && !opts[o].sent) - fill_one(m, o, &offset); + if (fill_one(m, o, &offset)) + debug("DHCP: skipping option %i", o); } m->o[offset++] = 255; - m->o[offset++] = 0; if (offset < OPT_MIN) { memset(&m->o[offset], 0, OPT_MIN - offset); @@ -276,33 +296,35 @@ static void opt_set_dns_search(const struct ctx *c, size_t max_len) /** * dhcp() - Check if this is a DHCP message, reply as needed * @c: Execution context - * @p: Packet pool, single packet with Ethernet buffer + * @data: Single packet with Ethernet buffer * * Return: 0 if it's not a DHCP message, 1 if handled, -1 on failure */ -int dhcp(const struct ctx *c, const struct pool *p) +int dhcp(const struct ctx *c, struct iov_tail *data) { - size_t mlen, dlen, offset = 0, opt_len, opt_off = 0; char macstr[ETH_ADDRSTRLEN]; + size_t mlen, dlen, opt_len; struct in_addr mask, dst; + struct ethhdr eh_storage; + struct iphdr iph_storage; + struct udphdr uh_storage; const struct ethhdr *eh; const struct iphdr *iph; const struct udphdr *uh; struct msg const *m; struct msg reply; unsigned int i; + struct msg m_storage; - eh = packet_get(p, 0, offset, sizeof(*eh), NULL); - offset += sizeof(*eh); - - iph = packet_get(p, 0, offset, sizeof(*iph), NULL); + eh = IOV_REMOVE_HEADER(data, eh_storage); + iph = IOV_PEEK_HEADER(data, iph_storage); if (!eh || !iph) return -1; - offset += iph->ihl * 4UL; - uh = packet_get(p, 0, offset, sizeof(*uh), &mlen); - offset += sizeof(*uh); + if (!iov_drop_header(data, iph->ihl * 4UL)) + return -1; + uh = IOV_REMOVE_HEADER(data, uh_storage); if (!uh) return -1; @@ -312,7 +334,10 @@ int dhcp(const struct ctx *c, const struct pool *p) if (c->no_dhcp) return 1; - m = packet_get(p, 0, offset, offsetof(struct msg, o), &opt_len); + mlen = iov_tail_size(data); + m = (struct msg const *)iov_remove_header_(data, &m_storage, + offsetof(struct msg, o), + __alignof__(struct msg)); if (!m || mlen != ntohs(uh->len) - sizeof(*uh) || mlen < offsetof(struct msg, o) || @@ -335,27 +360,28 @@ int dhcp(const struct ctx *c, const struct pool *p) memset(&reply.file, 0, sizeof(reply.file)); reply.magic = m->magic; - offset += offsetof(struct msg, o); - for (i = 0; i < ARRAY_SIZE(opts); i++) opts[i].clen = -1; - while (opt_off + 2 < opt_len) { - const uint8_t *olen, *val; + opt_len = iov_tail_size(data); + while (opt_len >= 2) { + uint8_t olen_storage, type_storage; + const uint8_t *olen; uint8_t *type; - type = packet_get(p, 0, offset + opt_off, 1, NULL); - olen = packet_get(p, 0, offset + opt_off + 1, 1, NULL); + type = IOV_REMOVE_HEADER(data, type_storage); + olen = IOV_REMOVE_HEADER(data, olen_storage); if (!type || !olen) return -1; - val = packet_get(p, 0, offset + opt_off + 2, *olen, NULL); - if (!val) + opt_len = iov_tail_size(data); + if (opt_len < *olen) return -1; - memcpy(&opts[*type].c, val, *olen); + iov_to_buf(&data->iov[0], data->cnt, data->off, &opts[*type].c, *olen); opts[*type].clen = *olen; - opt_off += *olen + 2; + iov_drop_header(data, *olen); + opt_len -= *olen; } opts[80].slen = -1; @@ -397,7 +423,7 @@ int dhcp(const struct ctx *c, const struct pool *p) &c->ip4.guest_gw, sizeof(c->ip4.guest_gw)); } - if (c->mtu != -1) { + if (c->mtu) { opts[26].slen = 2; opts[26].s[0] = c->mtu / 256; opts[26].s[1] = c->mtu % 256; @@ -411,6 +437,30 @@ int dhcp(const struct ctx *c, const struct pool *p) if (!opts[6].slen) opts[6].slen = -1; + opt_len = strlen(c->hostname); + if (opt_len > 0) { + opts[12].slen = opt_len; + memcpy(opts[12].s, &c->hostname, opt_len); + } + + opt_len = strlen(c->fqdn); + if (opt_len > 0) { + opt_len += 3 /* flags */ + + 2; /* Length byte for first label, and terminator */ + + if (sizeof(opts[81].s) >= opt_len) { + opts[81].s[0] = 0x4; /* flags (E) */ + opts[81].s[1] = 0xff; /* RCODE1 */ + opts[81].s[2] = 0xff; /* RCODE2 */ + + encode_domain_name((char *)opts[81].s + 3, c->fqdn); + + opts[81].slen = opt_len; + } else { + debug("DHCP: client FQDN option doesn't fit, skipping"); + } + } + if (!c->no_dhcp_dns_search) opt_set_dns_search(c, sizeof(m->o)); |