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3f79300e37
In arpping.h, fix structure alignment of "struct arpMsg". GCC can insert padding in the structure which causes udhcpd to send an invalid ARP packet on the network. It will then not receive a valid reply, which can cause it to assign an IP address that's already in use on the network. (With kernels before 2.4.20, the "struct ethhdr" in linux/if_ether.h wasn't marked as packed. This is also an issue if your toolchain was built with a pre-2.4.20 kernel).
36 lines
1.0 KiB
C
36 lines
1.0 KiB
C
/*
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* arpping .h
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*/
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#ifndef ARPPING_H
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#define ARPPING_H
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#include <netinet/if_ether.h>
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#include <net/if_arp.h>
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#include <net/if.h>
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#include <netinet/in.h>
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struct arpMsg {
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/* Ethernet header */
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u_char h_dest[6]; /* destination ether addr */
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u_char h_source[6]; /* source ether addr */
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u_short h_proto; /* packet type ID field */
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/* ARP packet */
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uint16_t htype; /* hardware type (must be ARPHRD_ETHER) */
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uint16_t ptype; /* protocol type (must be ETH_P_IP) */
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uint8_t hlen; /* hardware address length (must be 6) */
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uint8_t plen; /* protocol address length (must be 4) */
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uint16_t operation; /* ARP opcode */
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uint8_t sHaddr[6]; /* sender's hardware address */
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uint8_t sInaddr[4]; /* sender's IP address */
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uint8_t tHaddr[6]; /* target's hardware address */
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uint8_t tInaddr[4]; /* target's IP address */
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uint8_t pad[18]; /* pad for min. Ethernet payload (60 bytes) */
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} __attribute__ ((packed));
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/* function prototypes */
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int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *arp, char *interface);
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#endif
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