Mosquitto with Cygwin - gcc

Question

I want to run Mosquitto on Windows using Cygwin and I have installed Cygwin and downloaded Mosquitto as they describe on Mosquitto's site.
I have a simple example-file taken from mosquitto's site.
When I compile with this gcc-line:
gcc -Wall -o test test.c -I /home/Mathias/mosquitto-1.1.3/lib/ -L/home/Mathias/mosquitto-1.1.3/lib/ -lmosquitto
I get this error output:
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(mosquitto.o): In function `_mosquitto_destroy':
/home/Mathias/mosquitto-1.1.3/lib/mosquitto.c:285: undefined reference to `_SSL_free'
/home/Mathias/mosquitto-1.1.3/lib/mosquitto.c:288: undefined reference to `_SSL_CTX_free'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `psk_client_callback':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:201: undefined reference to `_SSL_get_ex_data'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_net_init':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:94: undefined reference to `_SSL_load_error_strings'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:95: undefined reference to `_SSL_library_init'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:96: undefined reference to `_OPENSSL_add_all_algorithms_noconf'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:98: undefined reference to `_SSL_get_ex_new_index'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_net_cleanup':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:106: undefined reference to `_ERR_free_strings'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_socket_close':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:175: undefined reference to `_SSL_shutdown'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:176: undefined reference to `_SSL_free'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:180: undefined reference to `_SSL_CTX_free'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_socket_connect':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:274: undefined reference to `_SSL_shutdown'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:275: undefined reference to `_SSL_free'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:279: undefined reference to `_SSL_CTX_free'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:308: undefined reference to `_TLSv1_client_method'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:308: undefined reference to `_SSL_CTX_new'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:321: undefined reference to `_SSL_CTX_ctrl'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:325: undefined reference to `_SSL_CTX_ctrl'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:329: undefined reference to `_SSL_CTX_set_cipher_list'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:337: undefined reference to `_SSL_CTX_load_verify_locations'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:360: undefined reference to `_SSL_CTX_set_verify'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:366: undefined reference to `_SSL_CTX_set_default_passwd_cb'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:367: undefined reference to `_SSL_CTX_set_default_passwd_cb_userdata'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:371: undefined reference to `_SSL_CTX_use_certificate_file'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:402: undefined reference to `_SSL_CTX_set_psk_client_callback'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:406: undefined reference to `_SSL_new'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:411: undefined reference to `_SSL_set_ex_data'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:412: undefined reference to `_BIO_new_socket'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:417: undefined reference to `_SSL_set_bio'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:419: undefined reference to `_SSL_connect'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:421: undefined reference to `_SSL_get_error'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:362: undefined reference to `_SSL_CTX_set_verify'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:383: undefined reference to `_SSL_CTX_use_PrivateKey_file'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:393: undefined reference to `_SSL_CTX_check_private_key'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_net_read':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:543: undefined reference to `_SSL_read'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:545: undefined reference to `_SSL_get_error'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:555: undefined reference to `_ERR_get_error'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:557: undefined reference to `_ERR_error_string'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:558: undefined reference to `_ERR_get_error'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_net_write':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:593: undefined reference to `_SSL_write'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:595: undefined reference to `_SSL_get_error'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:605: undefined reference to `_ERR_get_error'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:607: undefined reference to `_ERR_error_string'
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:608: undefined reference to `_ERR_get_error'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(net_mosq.o): In function `_mosquitto_net_cleanup':
/home/Mathias/mosquitto-1.1.3/lib/net_mosq.c:107: undefined reference to `_EVP_cleanup'
/home/Mathias/mosquitto-1.1.3/lib//libmosquitto.a(util_mosq.o): In function `_mosquitto_hex2bin':
/home/Mathias/mosquitto-1.1.3/lib/util_mosq.c:309: undefined reference to `_BN_hex2bn'
/home/Mathias/mosquitto-1.1.3/lib/util_mosq.c:319: undefined reference to `_BN_free'
/home/Mathias/mosquitto-1.1.3/lib/util_mosq.c:313: undefined reference to `_BN_num_bits'
/home/Mathias/mosquitto-1.1.3/lib/util_mosq.c:318: undefined reference to `_BN_bn2bin'
/home/Mathias/mosquitto-1.1.3/lib/util_mosq.c:314: undefined reference to `_BN_free'
collect2: ld returned 1 exit status
I dont know how top go from here...
Appreciate any kind of help!

Answer 1

Given that the error messages are SSL related, it looks like SSL wasn't installed in cygwin.
Rerun setup.exe and answer the prompts to get back to the Select Packages screen.
Enter in SSL into the Search box
Open up the Libs section and select the libraries you need.
Alternatively, you could install the entire openssl package from the Net section and let cygwin install all required dependencies.

Answer 2

I solved the SSL errors by adding -lsslto the gcc line.
Final gcc line:
$ gcc -Wall -Imosquitto-1.1.3/lib/ -Lmosquitto-1.1.3/lib/ -lssl -lmosquitto -o test test.c mosquitto-1.1.3/lib/libmosquitto.so.1
When solved this, another problem occured when running the application, which I have asked another question about: https://stackoverflow.com/questions/16517320/running-mosquitto-on-windows-using-cygwin