[lwip-users] LwIP issue: "undefined reference".

[DaMunky89]

Hi, I'm working on a project for school that will be using lwIP, and I need
to familiarize myself with how it works. For now I'm just trying to write a
simple test program. It doesn't even do anything yet, but I cannot for the
life of me get it to compile:

#include "lwip\udp.h"

void udp_packet_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct     
                        
ip_addr *addr, u16_t port);

main(){
        // Create a new pcb.
        struct udp_pcb * pcb;
        pcb = udp_new();
        if (pcb == NULL)
                return -1;

        // Bind to any IP on port 60,000.
        if (udp_bind(pcb, IP_ADDR_ANY, 60000) != ERR_OK)
                return -2;

        // On datagram receipt, call udp_packet_recv.
        udp_recv(pcb, udp_packet_recv, NULL);
}

void udp_packet_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct     
                        
ip_addr *addr, u16_t port){
        if (p != NULL){
                // TODO: Case handling GET packet.
                // TODO: Case handling data receipt.
        
                pbuf_free(p); // Free pbuf when finished.
        }
}

Every time I try to compile this, I get the following errors:

C:\Users\ZACHAR~1\AppData\Local\Temp\cc1kZ7BP.o:client.c:(.text+0xf):
undefined reference to `udp_new()'

C:\Users\ZACHAR~1\AppData\Local\Temp\cc1kZ7BP.o:client.c:(.text+0x3d):
undefined reference to `udp_bind(udp_pcb*, ip_addr*, unsigned short)'

C:\Users\ZACHAR~1\AppData\Local\Temp\cc1kZ7BP.o:client.c:(.text+0x5d):
undefined reference to `udp_packet_recv(void*, udp_pcb*, pbuf*, ip_addr*,
unsigned short)'

C:\Users\ZACHAR~1\AppData\Local\Temp\cc1kZ7BP.o:client.c:(.text+0x69):
undefined reference to `udp_recv(udp_pcb*, void (*)(void*, udp_pcb*, pbuf*,
ip_addr*, unsigned short), void*)'

C:\Users\ZACHAR~1\AppData\Local\Temp\cc1kZ7BP.o:client.c:(.text+0x8e):
undefined reference to `pbuf_free(pbuf*)'

collect2: ld returned 1 exit status

I read something online about linking "lwip4", but have not been able to
find anything about that file elsewhere. (I can't even figure out where I
originally read that...)  I believe I've included all the requisite files!
http://old.nabble.com/file/p30674968/files.png 
 
I'm using "lwip-win32-msvc-0.1", which is based on the CVS version of lwIP
from 23-01-2002. It is available for download here:
http://ishare.iask.sina.com.cn/f/5245596.html

The computer I am attempting to compile on is a Sony VPCF126FM, with no
hardware modifications of any kind:
www.docs.sony.com/release/specs/VPCF126FMB_mksp.pdf

I'm using MiniGW command line " g++ client.c -o client.exe" to compile.
(Nothing fancy.)
Can anybody help me out here? This has become a real sticking point.
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