DHCP: Don't enforce the message came port 67

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

Update for #179.

diff --git a/src/bpf.c b/src/bpf.c
index b75bfb04ca3f1b68392152e655f0b5a025451c9f..caf9fda6c3282d0d95aa7d0e13da2be80a57a5ca 100644 (file)
--- a/src/bpf.c
+++ b/src/bpf.c
@@ -610,16 +610,19 @@ 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),

diff --git a/src/dhcp.c b/src/dhcp.c
index 233bd10736d4a7a7ba8f5ec5e00b2c912714c5ec..edd1c011bb08f8954b2bc569692db19fa658d652 100644 (file)
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -3436,8 +3436,8 @@ 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;