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DHCP: Don't enforce the message came port 67

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RFC2131 and updates make no mention of what the source port
should or must be.

Update for #179.
This commit is contained in:
Roy Marples 2023-05-08 15:52:11 +01:00
parent 53e2f6de4b
commit 6e127eac69
2 changed files with 9 additions and 6 deletions
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11
src/bpf.c
View File

@ -612,16 +612,19 @@ static const struct bpf_insn bpf_bootp_base[] = {
#define BPF_BOOTP_BASE_LEN __arraycount(bpf_bootp_base)
static const struct bpf_insn bpf_bootp_read[] = {
/* Make sure it's from and to the right port. */
BPF_STMT(BPF_LD + BPF_W + BPF_IND, 0),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (BOOTPS << 16) + BOOTPC, 1, 0),
/* Make sure it's to the right port.
* RFC2131 makes no mention of enforcing a source port. */
BPF_STMT(BPF_LD + BPF_H + BPF_IND, offsetof(struct udphdr, uh_dport)),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTPC, 1, 0),
BPF_STMT(BPF_RET + BPF_K, 0),
};
#define BPF_BOOTP_READ_LEN __arraycount(bpf_bootp_read)
#ifdef BIOCSETWF
static const struct bpf_insn bpf_bootp_write[] = {
/* Make sure it's from and to the right port. */
/* Make sure it's from and to the right port.
* RFC2131 makes no mention of encforcing a source port,
* but dhcpcd does enforce it for sending. */
BPF_STMT(BPF_LD + BPF_W + BPF_IND, 0),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (BOOTPC << 16) + BOOTPS, 1, 0),
BPF_STMT(BPF_RET + BPF_K, 0),

4
src/dhcp.c
View File

@ -3459,8 +3459,8 @@ is_packet_udp_bootp(void *packet, size_t plen)
if (ip_hlen + ntohs(udp.uh_ulen) > plen)
return false;
/* Check it's to and from the right ports. */
if (udp.uh_dport != htons(BOOTPC) || udp.uh_sport != htons(BOOTPS))
/* Check it's to the right port. */
if (udp.uh_dport != htons(BOOTPC))
return false;
return true;