tcpdump doesn't appear to call any libpcap's exported function

Question

Digging into tcpdump implementation, I can see that it actually loads the libpcap.so dynamic library in userspace.

However, by use of strace, I can't see any occurrence of calls to any function exported by libpcap.

Is the above an expected behaviour of tcpdump? Thank you.

root@eve-ng02:~# tcpdump --help
tcpdump version 4.9.2
libpcap version 1.7.4
OpenSSL 1.0.2g  1 Mar 2016

Edit: from received comments I tried with ltrace but it seems no call to dynamic library is done as well.

root@eve-ng02:~# ltrace tcpdump -i lo
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
    
^C--- SIGINT (Interrupt) ---

0 packets captured
126 packets received by filter
98 packets dropped by kernel
+++ exited (status 0) +++
root@eve-ng02:~# 

Answer 1

strace shows only system calls. ltrace is a tool for showing library calls (see Difference between system call and library call).

If you want to see both system calls AND library calls, you can add the -S flag for ltrace ("Display system calls as well as library calls")

You can also add the -k to your strace ("Print the execution stack trace of the traced processes after each system call") if your strace version supports it. It won't show all the library calls, but it will show you the execution trace of every system call, in which you can see which library triggered the system call.

17212 eventfd2(0, EFD_NONBLOCK)         = 3
 > /lib64/libc-2.31.so(eventfd+0x7) [0x117b87]
 > /usr/lib64/libpcap.so.1.10.1() [0xb8fa]
 > /usr/lib64/libpcap.so.1.10.1(pcap_create+0xaa) [0x10a9a]
 > /usr/sbin/tcpdump() [0x3efbf]
 > /usr/sbin/tcpdump() [0x3c891]
 > /lib64/libc-2.31.so(__libc_start_main+0xee) [0x3524c]
 > /usr/sbin/tcpdump() [0x3e149]
17212 socket(AF_PACKET, SOCK_DGRAM, htons(0 /* ETH_P_??? */)) = 4
 > /lib64/libc-2.31.so(__socket+0x7) [0x1190d7]
 > /usr/lib64/libpcap.so.1.10.1() [0xa0c0]
 > /usr/lib64/libpcap.so.1.10.1(pcap_activate+0x1c) [0x1191c]
 > /usr/sbin/tcpdump() [0x3f0d2]
 > /usr/sbin/tcpdump() [0x3c891]
 > /lib64/libc-2.31.so(__libc_start_main+0xee) [0x3524c]
 > /usr/sbin/tcpdump() [0x3e149]