dhcp: Fix incoming verification and checksum routines

While here remove unused get_option_raw define.

diff --git a/src/dhcp.c b/src/dhcp.c
index ab0ae90b3a1be7e15c4062b047becc7927ece49e..ed0ffa4802bee796dbc1b56fcc614a5edf8af0db 100644 (file)
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -164,8 +164,6 @@ dhcp_printoptions(const struct dhcpcd_ctx *ctx,
        }
 }
 
-#define get_option_raw(ctx, bootp, bootp_len, opt)     \
-       get_option((ctx), (bootp), (bootp_len), NULL)
 static const uint8_t *
 get_option(struct dhcpcd_ctx *ctx,
     const struct bootp *bootp, size_t bootp_len,
@@ -3277,7 +3275,7 @@ is_packet_udp_bootp(void *packet, size_t plen)
        size_t ip_hlen;
        struct udphdr *udp;
 
-       if (sizeof(*ip) > plen)
+       if (plen < sizeof(*ip))
                return false;
 
        if (ip->ip_v != IPVERSION || ip->ip_p != IPPROTO_UDP)
@@ -3288,12 +3286,21 @@ is_packet_udp_bootp(void *packet, size_t plen)
                return false;
 
        ip_hlen = (size_t)ip->ip_hl * 4;
+       if (ip_hlen < sizeof(*ip))
+               return false;
+
        /* Check we have a UDP header and BOOTP. */
        if (ip_hlen + sizeof(*udp) + offsetof(struct bootp, vend) > plen)
                return false;
 
-       /* Check it's to and from the right ports. */
+       /* Sanity. */
        udp = (struct udphdr *)(void *)((char *)ip + ip_hlen);
+       if (ntohs(udp->uh_ulen) < sizeof(*udp))
+               return false;
+       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))
                return false;
 
@@ -3324,11 +3331,11 @@ checksums_valid(void *packet,
                return false;
 
        if (flags & BPF_PARTIALCSUM)
-               return 0;
+               return true;
 
        udp = (struct udphdr *)(void *)((char *)ip + ip_hlen);
        if (udp->uh_sum == 0)
-               return 0;
+               return true;
 
        /* UDP checksum is based on a pseudo IP header alongside
         * the UDP header and payload. */