### Create and Start a Thread with libosip2

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht5-portability.dox

Demonstrates how to create and start a new thread using libosip2's thread creation function. The thread executes a specified function until a stop condition is met.

```c
void *_my_thread (void *arg)
{
  struct sometype_t *excontext = (struct sometype_t *) arg;
  int i;

  while (stopthread == 0) {
      do_actions (excontext);
  }
  osip_thread_exit ();
  return NULL;
}


struct osip_thread *thread;
thread = osip_thread_create (20000, _my_thread, argpointer);
```

--------------------------------

### Via Header API Examples

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Provides code examples for common operations related to the 'Via' SIP header, including getting a Via header from a message, adding a new Via header, and parsing a Via header string.

```APIDOC
## Via Header API

### Description
This section provides examples for interacting with the 'Via' SIP header using the libosip2 library. It covers retrieving, adding, and parsing 'Via' headers.

### Method
Various `osip_via_t` functions and `osip_message_get_via`, `osip_message_set_via`.

### Endpoint
N/A (Library functions)

### Parameters
Refer to individual function documentation within libosip2.

### Get Via from message

#### Description
Retrieves the first 'Via' header from a SIP message.

#### Request Example
```c
  osip_via_t *dest;
  osip_message_get_via (msg, 0, &dest);
```

### Add Via in message

#### Description
Constructs a 'Via' header string and adds it to a SIP message.

#### Request Example
```c
  char tmp[200];
  snprintf (tmp, 200, "SIP/2.0/UDP %s:%s;rport;branch=z9hG4bK%u", ip, port, osip_build_random_number ());
  osip_message_set_via (msg, tmp);
```

### Parse Via

#### Description
Initializes a `osip_via_t` structure, parses a 'Via' header string into it, and then frees the structure.

#### Request Example
```c
  osip_via_t *header;
  char tmp[200];
  snprintf (tmp, 200, "SIP/2.0/UDP %s:%s;rport;branch=z9hG4bK%u", ip, port, osip_build_random_number ());
  osip_via_init (&header);
  osip_via_parse (header, tmp);
  osip_free(header);
```

### Response
- **dest** (*osip_via_t**) - Pointer to the retrieved 'Via' header structure.
- The `osip_message_set_via` and `osip_via_parse` functions modify the message or the header structure in place.
```

--------------------------------

### Initialize oSIP Library

Source: https://context7.com/distrotech/libosip2/llms.txt

Demonstrates the mandatory initialization steps for the oSIP parser and transaction management system. This setup must be performed before executing any other library functions.

```c
#include <osipparser2/osip_parser.h>
#include <osip2/osip.h>

int main(void) {
    osip_t *osip;
    int ret;

    /* Initialize the parser */
    parser_init();

    /* Initialize the oSIP transaction management */
    ret = osip_init(&osip);
    if (ret != 0) {
        fprintf(stderr, "Failed to initialize osip\n");
        return -1;
    }

    /* Set application context for callbacks */
    osip_set_application_context(osip, my_app_data);

    /* ... use the library ... */

    /* Clean up */
    osip_release(osip);
    return 0;
}
```

--------------------------------

### Construct SIP Messages

Source: https://context7.com/distrotech/libosip2/llms.txt

Provides an example of building a SIP INVITE request programmatically. It covers setting the method, URI, mandatory headers, and serializing the object into a string.

```c
#include <osipparser2/osip_parser.h>
#include <osipparser2/osip_port.h>

int create_invite_request(void) {
    osip_message_t *invite;
    char *dest;
    size_t length;
    int ret;

    /* Initialize message */
    osip_message_init(&invite);

    /* Set request method and version */
    osip_message_set_method(invite, osip_strdup("INVITE"));
    osip_message_set_version(invite, osip_strdup("SIP/2.0"));

    /* Set Request-URI */
    osip_uri_t *uri;
    osip_uri_init(&uri);
    osip_uri_set_scheme(uri, osip_strdup("sip"));
    osip_uri_set_username(uri, osip_strdup("bob"));
    osip_uri_set_host(uri, osip_strdup("example.com"));
    osip_message_set_uri(invite, uri);

    /* Set mandatory headers */
    osip_message_set_to(invite, "Bob <sip:bob@example.com>");
    osip_message_set_from(invite, "Alice <sip:alice@example.com>;tag=12345");
    osip_message_set_call_id(invite, "call-id-12345@192.168.1.1");
    osip_message_set_cseq(invite, "1 INVITE");
    osip_message_set_via(invite, "SIP/2.0/UDP 192.168.1.1:5060;branch=z9hG4bK776asdhds");
    osip_message_set_max_forwards(invite, "70");
    osip_message_set_contact(invite, "<sip:alice@192.168.1.1:5060>");
    osip_message_set_content_length(invite, "0");

    /* Convert to string */
    ret = osip_message_to_str(invite, &dest, &length);
    if (ret == 0) {
        printf("Generated INVITE:\n%s\n", dest);
        osip_free(dest);
    }

    osip_message_free(invite);
    return 0;
}
```

--------------------------------

### Manage SIP Transactions in C

Source: https://context7.com/distrotech/libosip2/llms.txt

Illustrates the setup and management of SIP transactions using libosip2's state machine. It covers initializing transactions (ICT), registering callbacks for message sending and specific events (like 2xx responses), adding events, and executing the transaction loop for timer and event handling. Dependencies include osip2/osip.h.

```c
#include <osip2/osip.h>

/* Callback for outgoing messages */
int send_message_callback(osip_transaction_t *tr, osip_message_t *msg,
                          char *host, int port, int out_socket) {
    char *dest;
    size_t length;

    osip_message_to_str(msg, &dest, &length);
    printf("Sending to %s:%d\n%s\n", host, port, dest);

    /* Actually send the message via socket */
    /* send(out_socket, dest, length, 0); */

    osip_free(dest);
    return 0;
}

/* Callback when INVITE receives 2xx response */
void cb_ict_2xx_received(int type, osip_transaction_t *tr, osip_message_t *msg) {
    printf("INVITE successful! Call established.\n");
}

int setup_transaction(osip_t *osip, osip_message_t *request) {
    osip_transaction_t *tr;
    osip_event_t *evt;
    int ret;

    /* Register callbacks */
    osip_set_cb_send_message(osip, send_message_callback);
    osip_set_message_callback(osip, OSIP_ICT_STATUS_2XX_RECEIVED, cb_ict_2xx_received);

    /* Create Invite Client Transaction (ICT) */
    ret = osip_transaction_init(&tr, ICT, osip, request);
    if (ret != 0) {
        fprintf(stderr, "Failed to create transaction\n");
        return -1;
    }

    /* Set custom application data */
    osip_transaction_set_your_instance(tr, my_call_context);

    /* Create and add send event */
    evt = osip_new_outgoing_sipmessage(request);
    osip_transaction_add_event(tr, evt);

    /* Execute transaction */
    osip_ict_execute(osip);

    return 0;
}

/* Main event loop */
void transaction_event_loop(osip_t *osip) {
    struct timeval timeout;

    while (1) {
        /* Get minimum timeout for next timer event */
        osip_timers_gettimeout(osip, &timeout);

        /* Wait for network data or timeout */
        /* select() or poll() here */

        /* Execute pending timer events */
        osip_timers_ict_execute(osip);
        osip_timers_ist_execute(osip);
        osip_timers_nict_execute(osip);
        osip_timers_nist_execute(osip);

        /* Execute pending transaction events */
        osip_ict_execute(osip);
        osip_ist_execute(osip);
        osip_nict_execute(osip);
        osip_nist_execute(osip);

        /* Handle retransmissions */
        osip_retransmissions_execute(osip);
    }
}

```

--------------------------------

### SIP Header API (Example: To Header)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

API functions for manipulating SIP headers, with 'To' header as an example. The same API structure applies to other headers by replacing 'osip_to_' with the respective header prefix.

```APIDOC
## osip_to_init

### Description
Allocate and initialize the structure _to_.

### Method
`int osip_to_init(osip_to_t **to);`

### Endpoint
N/A (Library Function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
None

### Response
#### Success Response (0)
Returns 0 on success.

#### Response Example
`0`
```

```APIDOC
## osip_to_free

### Description
Free resources contained in _to_.

### Method
`void osip_to_free(osip_to_t **to);`

### Endpoint
N/A (Library Function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
None

### Response
#### Success Response
None

#### Response Example
None
```

```APIDOC
## osip_to_parse

### Description
Parse _field_value_ and store results in _to_.

### Method
`int osip_to_parse(osip_to_t *to, char *field_value);`

### Endpoint
N/A (Library Function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
None

### Response
#### Success Response (0)
Returns 0 on success.

#### Response Example
`0`
```

```APIDOC
## osip_to_to_str

### Description
Allocate a string in _field_value_ with the information stored in the _to_ parameter.

### Method
`int osip_to_to_str(osip_to_t *to, char **field_value);`

### Endpoint
N/A (Library Function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
None

### Response
#### Success Response (0)
Returns 0 on success.

#### Response Example
`0`
```

--------------------------------

### SIP INVITE Request Example

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

This snippet demonstrates the structure of a SIP INVITE request, used to initiate or modify sessions. It includes essential headers like Via, To, From, Call-ID, CSeq, and Contact, along with the SDP payload for media negotiation.

```sip
INVITE sip:jacK@atosc.org SIP/2.0
Via: SIP/2.0/UDP home.sipworld.org;branch=z9hG4bK776asdhds
Max-Forwards: 70
To: sip:jacK@atosc.org
From: sip:cha@sipworld.org
Call-ID: 35778645354@home.sipworld.org
CSeq: 1 INVITE
Contact: sip:cha@home.sipworld.org
Content-type: application/sdp
Content-length: 267

v=0
o=user1 53655765 2353687637 IN IP4 128.3.4.5
s=Mbone Audio
i=Discussion of Mbone Engineering Issues
e=mbone@somewhere.com
c=IN IP4 128.3.4.5
t=0 0
m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000
```

--------------------------------

### Get SIP Message Header by Name (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Finds the first header matching a given name, starting the search from a specified position. Returns the header as a pointer to a header_t structure. Returns 0 on success.

```c
int osip_message_header_get_byname(char *hname, osip_message_t *sip, int pos, header_t **dest);
```

--------------------------------

### Get and Compensate Time with libosip2

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht5-portability.dox

Provides function signatures for getting the current time and compensating for time drift, particularly useful on systems like Android where the monotonic clock might not advance during deep sleep.

```c
int osip_gettimeofday (struct timeval *tp, void *tz);
void osip_compensatetime ();
```

--------------------------------

### Manage SIP Message Headers

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Provides examples for adding custom headers to a SIP message and retrieving specific headers by name. It includes logic for iterating through multiple headers with the same name.

```c
/* Adding a header */
osip_message_set_header (msg, "Refer-to", refer_to_header);

/* Finding the first header */
osip_message_header_get_byname (msg, "min-se", 0, &min_se_header);
if (min_se_header != NULL && min_se_header->hvalue != NULL) { }

/* Finding all headers with the same name */
int pos=0;
while (1) {
  pos = osip_message_header_get_byname (msg, "x-header", pos, &min_se_new);
  if (min_se_new == NULL) {
     break;
  }
}
```

--------------------------------

### SIP INVITE Transaction Call Flow

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

This example illustrates a basic SIP INVITE transaction, showing the interaction between a User Agent Client (UAC) and a User Agent Server (UAS) during call initiation. It includes the initial INVITE, provisional responses (100 Trying, 180 Ringing), the final success response (200 OK), and the ACK message.

```sip
          UAC1               UAS2

	  jacks    |   INVITE         |
	initiate a |----------------->|
	  call     |                  |
	           |       100 Trying |
	           |<-----------------|
	           |       180 Ringing|
	           |<-----------------|
	           |                  |
        	   |                  |
	           |           200 OK |
	           |<-----------------|
	           |   ACK            |
	           |----------------->|
```

--------------------------------

### Get osip_uri_param_t by Name from List (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Finds and retrieves an osip_uri_param_t element from a list based on its name. It populates the provided double pointer with the found parameter. Returns 0 on success.

```c
void osip_uri_param_get_byname(list_t *osip_uri_params, char *pname, osip_uri_param_t **osip_uri_param);
```

--------------------------------

### Initialize and Free SIP Structures

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Demonstrates the mandatory allocation and deallocation pattern for libosip2 structures like osip_message_t and osip_uri_t using init and free methods.

```C
osip_message_t *msg;
osip_message_init(&msg);
osip_message_free(msg);

osip_uri_t *url;
osip_uri_init(&url);
osip_uri_free(url);
```

--------------------------------

### Build SIP Request Line

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Shows how to construct a SIP request line by initializing a URI, setting its components, and assigning it to an INVITE message.

```C
osip_uri_t *uri;
osip_uri_init(&uri);
osip_uri_set_scheme(url,osip_strdup("sip"));
osip_uri_set_username(url,osip_strdup("jack"));
osip_uri_set_host(url,osip_strdup("atosc.org"));

osip_message_set_method(msg,osip_strdup("INVITE"));
osip_message_set_uri(msg,uri);
osip_message_set_version(msg,osip_strdup("2.0"));
```

--------------------------------

### Initiating a SIP Session and Sending Messages

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Demonstrates how to initialize a SIP transaction and send a message. It involves creating a message object, initializing the transaction context, and dispatching the event to the transaction's FIFO queue.

```c
int create_session(osip_t *osip) {
  osip_message_t *invite;
  osip_transaction_t *transaction;
  osip_message_init (&invite);
  your_own_method_to_setup_messages(invite);
  osip_transaction_init(&transaction, osip, invite->to, invite->from, invite->callid, invite->cseq);
  osip_sendmsg(transaction, invite);
}

int osip_sendmsg(osip_transaction_t *transaction, osip_message_t *msg) {
  osip_event_t *evt = osip_new_outgoing_sipmessage(msg);
  osip_fifo_add(transaction->transactionff, evt);
  osip_transaction_execute(transaction, evt);
  return 0;
}
```

--------------------------------

### To Header Manipulation API

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Functions for cloning, setting, and getting display names and URLs for the 'To' header.

```APIDOC
## osip_to_clone

### Description
Duplicates the 'To' element into a new destination element.

### Method
`int osip_to_clone(osip_to_t *to, osip_to_t **dest)`

### Parameters
- **to** (osip_to_t *) - The source 'To' element to clone.
- **dest** (osip_to_t **) - Pointer to the destination 'To' element.

### Response
- **Success Response (0)**: Indicates successful cloning.

## osip_to_set_displayname

### Description
Sets the display name in the 'To' element.

### Method
`void osip_to_set_displayname(osip_to_t *to, char *value)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to modify.
- **value** (char *) - The display name string to set.

## osip_to_get_displayname

### Description
Retrieves the display name from the 'To' element.

### Method
`char *osip_to_get_displayname(osip_to_t *to)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to query.

### Response
- **Return Value** (char *): The display name string, or NULL if not set.

## osip_to_set_url

### Description
Sets the URL in the 'To' element.

### Method
`void osip_to_set_url(osip_to_t *to, osip_uri_t *url)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to modify.
- **url** (osip_uri_t *) - Pointer to the URI structure to set.

## osip_to_get_url

### Description
Retrieves the URL from the 'To' element.

### Method
`osip_uri_t *osip_to_get_url(osip_to_t *to)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to query.

### Response
- **Return Value** (osip_uri_t *): Pointer to the URI structure, or NULL if not set.
```

--------------------------------

### To Header Generic Parameter API

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Functions for adding, getting, and managing generic parameters within the 'To' header.

```APIDOC
## osip_to_param_add

### Description
Adds a generic parameter to the 'To' element.

### Method
`int osip_to_param_add(osip_to_t *to, char *name, char *value)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to modify.
- **name** (char *) - The name of the parameter.
- **value** (char *) - The value of the parameter.

### Response
- **Success Response (0)**: Indicates successful addition.

## osip_to_param_get

### Description
Retrieves a generic parameter from the 'To' element by its position.

### Method
`int osip_to_param_get(osip_to_t *to, int pos, generic_param_t **gp)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to query.
- **pos** (int) - The index (position) of the parameter to retrieve.
- **gp** (generic_param_t **) - Pointer to store the retrieved generic parameter.

### Response
- **Success Response (0)**: Indicates successful retrieval.

## osip_to_get_tag

### Description
Retrieves the value associated with the 'tag' parameter from the 'To' element.

### Method
`void osip_to_get_tag(osip_to_t *to, generic_param_t **dest)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to query.
- **dest** (generic_param_t **) - Pointer to store the 'tag' generic parameter.

## osip_to_set_tag

### Description
Sets the 'tag' parameter in the 'To' element.

### Method
`void osip_to_set_tag(osip_to_t *to, char *tag)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to modify.
- **tag** (char *) - The value of the 'tag' parameter.

## osip_to_param_get_byname

### Description
Retrieves a generic parameter from the 'To' element by its name.

### Method
`int osip_to_param_get_byname(osip_to_t *to, char *pname, generic_param_t **dest)`

### Parameters
- **to** (osip_to_t *) - The 'To' element to query.
- **pname** (char *) - The name of the parameter to retrieve.
- **dest** (generic_param_t **) - Pointer to store the retrieved generic parameter.

### Response
- **Success Response (0)**: Indicates successful retrieval.
```

--------------------------------

### Create Dialog as UAS

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht4-dialog.dox

Shows how to initialize a dialog as a User Agent Server upon receiving an INVITE request, requiring a valid response with a tag.

```c
osip_dialog_t *dialog;
osip_dialog_init_as_uas(&dialog, original_invite, response_that_you_build);
```

--------------------------------

### Get SIP To (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the To attribute from the SIP message. Returns a pointer to the osip_to_t structure. Returns 0 on success.

```c
osip_to_t *osip_message_get_to(osip_message_t *sip);
```

--------------------------------

### Get SIP From (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the From attribute from the SIP message. Returns a pointer to the osip_from_t structure. Returns 0 on success.

```c
osip_from_t *osip_message_get_from(osip_message_t *sip);
```

--------------------------------

### Handle SIP Dialogs as UAC with libosip2

Source: https://context7.com/distrotech/libosip2/llms.txt

Demonstrates how to initialize and manage a SIP dialog as a User Agent Client (UAC) using libosip2. This includes creating the dialog from a response, setting application-specific data, checking dialog states (early, confirmed), accessing dialog properties like Call-ID and tags, and matching incoming requests to the dialog. It also shows how to update the dialog state based on incoming messages. Requires the osip2/osip_dialog.h header.

```c
#include <osip2/osip_dialog.h>

int handle_dialog(osip_message_t *invite, osip_message_t *response) {
    osip_dialog_t *dialog;
    int ret;

    /* Create dialog as UAC (caller) from received response */
    ret = osip_dialog_init_as_uac(&dialog, response);
    if (ret != 0) {
        fprintf(stderr, "Failed to create dialog\n");
        return -1;
    }

    /* Store application-specific data */
    osip_dialog_set_instance(dialog, my_call_data);

    /* Check dialog state */
    if (dialog->state == DIALOG_EARLY) {
        printf("Dialog is in early state (provisional response)\n");
    } else if (dialog->state == DIALOG_CONFIRMED) {
        printf("Dialog confirmed (2xx response)\n");
    }

    /* Access dialog properties */
    printf("Call-ID: %s\n", dialog->call_id);
    printf("Local tag: %s\n", dialog->local_tag);
    printf("Remote tag: %s\n", dialog->remote_tag);
    printf("Local CSeq: %d\n", dialog->local_cseq);

    /* Check if we are the caller or callee */
    if (osip_dialog_is_originator(dialog)) {
        printf("We initiated this call\n");
    }

    /* Match incoming request to dialog */
    osip_message_t *incoming_request = /* received from network */;
    if (osip_dialog_match_as_uac(dialog, incoming_request) == 0) {
        printf("Request matches our dialog\n");
        /* Update dialog state */
        osip_dialog_update_osip_cseq_as_uas(dialog, incoming_request);
    }

    /* Clean up */
    osip_dialog_free(dialog);
    return 0;
}
```

--------------------------------

### Get Name from Generic Parameter (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the name of a generic parameter. This function allows inspection of the parameter's name.

```c
char *generic_param_get_name(generic_param_t *gen_param);
```

--------------------------------

### Get SIP CSeq (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the CSeq attribute from the SIP message. Returns a pointer to the osip_cseq_t structure. Returns 0 on success.

```c
osip_cseq_t *osip_message_get_cseq(osip_message_t *sip);
```

--------------------------------

### Initialize libosip2 Parser

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht0-initialize.dox

Initializes the osip parser and state machine. This must be performed before any other libosip2 functions are called.

```c
#include <osip2/osip.h>

int i;
osip_t *osip;
i=osip_init(&osip);
if (i!=0)
  return -1;
```

--------------------------------

### Get SIP Call-ID (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the Call-ID attribute from the SIP message. Returns a pointer to the osip_call_id_t structure. Returns 0 on success.

```c
osip_call_id_t *osip_message_get_call_id(osip_message_t *sip);
```

--------------------------------

### INITIALIZE /osip_global_init

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Initializes the oSIP stack and the internal parser. This must be called exactly once before any other stack operations.

```APIDOC
## INITIALIZE /osip_global_init

### Description
Initializes the oSIP stack and the internal parser. This method must be called once at runtime before using the stack.

### Method
FUNCTION

### Endpoint
osip_global_init()

### Parameters
None

### Request Example
osip_global_init();

### Response
#### Success Response (0)
- **status** (int) - Returns 0 on success, non-zero on failure.
```

--------------------------------

### Get Value from Generic Parameter (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the value of a generic parameter. This function allows inspection of the parameter's associated value.

```c
char *generic_param_get_value(generic_param_t *gen_param);
```

--------------------------------

### Initialize libosip2 Dialog Header

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht4-dialog.dox

Includes the necessary header file to access the dialog management API in libosip2.

```c
#include <osip2/osip_dialog.h>
```

--------------------------------

### Get Tag Parameter from To Header (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the value of the 'tag' parameter from the 'To' header element. The 'tag' is a common parameter in SIP.

```c
void osip_to_get_tag(osip_to_t *to, generic_param_t **dest);
```

--------------------------------

### Parse and Serialize SIP Messages

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Demonstrates how to initialize a SIP message structure, parse raw buffer data into it, and convert the message back into a printable string. Note that the output string must be manually freed to prevent memory leaks.

```c
osip_message_t *sip;
int i;
i=osip_message_init(&sip);
if (i!=0) { fprintf(stderr, "cannot allocate\n"); return -1; }
i=osip_message_parse(sip, buffer, length_of_buffer);
if (i!=0) { fprintf(stderr, "cannot parse sip message\n"); }
osip_message_free(sip);

char *dest=NULL;
int length=0;
i = osip_message_to_str(sip, &dest, &length);
if (i!=0) { fprintf(stderr, "cannot get printable message\n"); return -1; }
fprintf(stdout, "message:\n%s\n", dest);
osip_free(dest);
```

--------------------------------

### Get Parameter from To Header by Index (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a generic parameter from the 'To' header element at a specific index. This allows iteration through all parameters.

```c
int osip_to_param_get(osip_to_t *to, int pos, generic_param_t **gp);
```

--------------------------------

### Get URL from To Header (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the SIP URI associated with the 'To' header element. This function provides access to the destination address details.

```c
osip_uri_t *osip_to_get_url(osip_to_t *to);
```

--------------------------------

### POST /osip/transaction/init

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht3-fsm.dox

Initializes a new SIP transaction context and adds an outgoing message event to the state machine.

```APIDOC
## POST /osip/transaction/init

### Description
Initializes a new transaction context in the oSIP stack and triggers the state machine with an outgoing SIP message event.

### Method
POST

### Endpoint
/osip/transaction/init

### Parameters
#### Request Body
- **transaction_type** (enum) - Required - The type of transaction (ICT, NICT, IST, NIST).
- **osip_context** (pointer) - Required - The global oSIP library context.
- **sip_message** (object) - Required - The pre-built SIP message object.

### Request Example
{
  "transaction_type": "NICT",
  "osip_context": "global_osip_ctx",
  "sip_message": "<osip_message_t>"
}

### Response
#### Success Response (200)
- **transaction_id** (int) - The unique identifier for the created transaction.

#### Response Example
{
  "status": "success",
  "transaction_id": 1024
}
```

--------------------------------

### Create SIP Transaction Events

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Shows how to create an event object for transaction management from a received SIP message buffer.

```c
osip_event_t *evt;
int length = size_of_buffer;
evt = osip_parse(buffer, i);
```

--------------------------------

### Get Parameter from To Header by Name (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a generic parameter from the 'To' header element by its name. This provides a direct way to access a specific parameter.

```c
int osip_to_param_get_byname(osip_to_t *to, char *pname, generic_param_t **dest);
```

--------------------------------

### Library Initialization

Source: https://context7.com/distrotech/libosip2/llms.txt

Initializes the oSIP parser and transaction management system required for library operations.

```APIDOC
## Initialization

### Description
Initializes the oSIP parser and the transaction management system. This must be called before any other library functions.

### Method
N/A (C Function Call)

### Parameters
- **osip** (osip_t**) - Required - Pointer to the oSIP structure to be initialized.

### Response
- **int** - Returns 0 on success, non-zero on failure.
```

--------------------------------

### Initialize Generic Parameter Structure (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Allocates and initializes a generic parameter structure. This is the first step before setting name and value for a parameter.

```c
int generic_param_init(generic_param_t * gen_param);
```

--------------------------------

### Initialize and manage oSIP library

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Core API functions for initializing the oSIP element, executing event processing, and freeing allocated resources.

```c
int osip_init(osip_t **osip);
int osip_execute(osip_t *osip);
void osip_free(osip_t *osip);
```

--------------------------------

### Get Display Name from To Header (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves the display name from a 'To' header element. This function allows access to the human-readable name part of the SIP address.

```c
char *osip_to_get_displayname(osip_to_t *to);
```

--------------------------------

### Get Via Header from SIP Message

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Retrieves the first Via header from a SIP message object. This function is part of the Via header manipulation API in libosip2.

```c
osip_via_t *dest;
osip_message_get_via (msg, 0, &dest);
```

--------------------------------

### Create Dialog as UAC

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht4-dialog.dox

Demonstrates how to create a dialog in a callback function when receiving a 1xx or 2xx response to an INVITE request.

```c
void cb_rcv1xx(osip_transaction_t *tr,osip_message_t *sip)
{
  osip_dialog_t *dialog;
  if (MSG_IS_RESPONSEFOR(sip, "INVITE")&&!MSG_TEST_CODE(sip, 100))
  {
    dialog = my_application_search_existing_dialog(sip);
    if (dialog==NULL) //NO EXISTING DIALOG
    {
      i = osip_dialog_init_as_uac(&dialog, sip);
      my_application_add_existing_dialog(dialog);
    }
  }
  else
  {
    //no dialog establishment for other REQUEST
  }
}
```

--------------------------------

### Manage Mutexes with libosip2

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht5-portability.dox

Illustrates the lifecycle of a mutex using libosip2 functions, including initialization, locking, unlocking, and destruction. This is essential for protecting shared resources.

```c
struct osip_mutex *mutex;
mutex = osip_mutex_init ();

osip_mutex_lock (mutex);
do_actions ();
osip_mutex_unlock (mutex);

osip_mutex_destroy (mutex);
```

--------------------------------

### Initialize osip_to_t Structure (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Allocates and initializes the osip_to_t structure, which represents a SIP 'To' header. This function is the first step in creating or manipulating a 'To' header. It returns 0 on success.

```c
int osip_to_init(osip_to_t **to);
```

--------------------------------

### Get SIP Contact by Index (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a specific Contact header from the SIP message at a given position. Returns the contact as a pointer to a contact_t structure. Returns 0 on success.

```c
int osip_message_get_contact(osip_message_t *sip, int pos, contact_t **contact);
```

--------------------------------

### Get SIP Message Header by Index (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a specific header from the SIP message at a given position. The header is returned as a pointer to a header_t structure. Returns 0 on success.

```c
int osip_message_get_header(osip_message_t *sip, int pos, header_t **header);
```

--------------------------------

### Initialize osip_uri_param_t Element (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Allocates and initializes an osip_uri_param_t element. This structure is used to represent parameters within a SIP URI. It returns 0 on success.

```c
int osip_uri_param_init(osip_uri_param_t **osip_uri_param);
```

--------------------------------

### Create and Send SIP Transaction

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Demonstrates the process of creating a new SIP session, initializing a transaction, and sending an initial INVITE message.

```APIDOC
## Create and Send SIP Transaction

### Description
This section outlines the steps to create a new SIP session, initialize a transaction, and send an initial INVITE request.

### Method
create_session(osip_t *osip)

### Endpoint
N/A (Function Call)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```c
int create_session(osip_t *osip)
{
  osip_message_t  *invite;
  osip_transaction_t   *transaction;

  // Initialize a new SIP message
  osip_message_init (&invite);
  your_own_method_to_setup_messages(invite); // Placeholder for message setup

  // Initialize a new transaction for the first invite
  osip_transaction_init(&transaction,
		   osip,
		   invite->to,
		   invite->from,
		   invite->callid,
		   invite->cseq);

  // Send the INVITE message within the transaction
  osip_sendmsg(transaction, invite);
  return 0;
}
```

### Response
None (This is a function call, not an API endpoint)

#### Success Response (200)
None

#### Response Example
None
```

```APIDOC
## osip_sendmsg Function

### Description
This function creates an outgoing SIP message event and adds it to the transaction's FIFO, then executes the transaction with the event.

### Method
osip_sendmsg(osip_transaction_t *transaction, osip_message_t *msg)

### Endpoint
N/A (Function Call)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```c
int osip_sendmsg(osip_transaction_t *transaction, osip_message_t *msg)
{
    osip_event_t *evt;

    // Create a new outgoing SIP message event
    evt = osip_new_outgoing_sipmessage(msg);

    // Add the event to the transaction's FIFO
    osip_fifo_add(transaction->transactionff, evt);
    // Execute the transaction with the event
    osip_transaction_execute(transaction, evt);

    return 0;
}
```

### Response
None (This is a function call, not an API endpoint)

#### Success Response (200)
None

#### Response Example
None
```

--------------------------------

### Get osip_uri_uparam by Name (C)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a URI parameter by its name from a given URI structure. This function is used to access specific parameters within a SIP URI. It returns 0 on success.

```c
int osip_uri_uparam_get_byname(osip_uri_t *url, char *pname, osip_uri_param_t **osip_uri_param);
```

--------------------------------

### Include libosip2 Header Parsers

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Demonstrates how to include specific header parser definitions from the libosip2 library. This allows for structured parsing and manipulation of various built-in SIP headers.

```c
#include <osipparser2/headers/osip_header.h>
#include <osipparser2/headers/osip_accept.h>
#include <osipparser2/headers/osip_accept_encoding.h>
#include <osipparser2/headers/osip_accept_language.h>
#include <osipparser2/headers/osip_alert_info.h>
#include <osipparser2/headers/osip_allow.h>
#include <osipparser2/headers/osip_authentication_info.h>
#include <osipparser2/headers/osip_authorization.h>
#include <osipparser2/headers/osip_call_id.h>
#include <osipparser2/headers/osip_call_info.h>
#include <osipparser2/headers/osip_contact.h>
#include <osipparser2/headers/osip_content_disposition.h>
#include <osipparser2/headers/osip_content_encoding.h>
#include <osipparser2/headers/osip_content_length.h>
#include <osipparser2/headers/osip_content_type.h>
#include <osipparser2/headers/osip_cseq.h>
#include <osipparser2/headers/osip_error_info.h>
#include <osipparser2/headers/osip_from.h>
#include <osipparser2/headers/osip_mime_version.h>
#include <osipparser2/headers/osip_proxy_authenticate.h>
#include <osipparser2/headers/osip_proxy_authentication_info.h>
#include <osipparser2/headers/osip_proxy_authorization.h>
#include <osipparser2/headers/osip_record_route.h>
#include <osipparser2/headers/osip_route.h>
#include <osipparser2/headers/osip_to.h>
#include <osipparser2/headers/osip_via.h>
#include <osipparser2/headers/osip_www_authenticate.h>
```

--------------------------------

### INITIALIZE /osip_init

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Allocates and initializes an osip_t structure, which acts as a container for SIP transactions and agent instances.

```APIDOC
## INITIALIZE /osip_init

### Description
Allocates and initializes an osip_t element. This structure is required for managing SIP transactions for UAS, UAC, registrar, or redirect servers.

### Method
FUNCTION

### Endpoint
osip_init(osip_t **osip)

### Parameters
#### Path Parameters
- **osip** (osip_t**) - Required - Pointer to the osip_t structure to be initialized.

### Request Example
osip_t *osip;
osip_init(&osip);

### Response
#### Success Response (0)
- **status** (int) - Returns 0 on success, -1 if mutex initialization fails.
```

--------------------------------

### Get URL Parameter by Name - C

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Retrieves a URL parameter from an osip_uri_t structure based on its name. This function is used to access specific parameters within a SIP URI. The description is incomplete in the provided text.

```c
#include <osipparser2/osip_uri.h>

// Function signature is incomplete in the provided text.
```

--------------------------------

### Get SIP Header by Name (with short name fallback)

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht2-parser.dox

Retrieves a SIP header by its full name, and if not found, attempts to retrieve it using a common short name. This is useful for headers like 'session-expires' which can also be represented by 'x'.

```c
osip_message_header_get_byname (msg, "session-expires", 0, &exp);
if (exp == NULL)
  osip_message_header_get_byname (msg, "x", 0, &exp);
```

--------------------------------

### Initialize libosip2 Parser

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Initializes the oSIP parser at runtime. This function must be called exactly once before using any other parser features.

```C
int parser_init();
```

--------------------------------

### Add SIP Headers and Body

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/man/osip.html

Illustrates how to create and add various SIP headers (To, From, Via, CSeq, Call-ID) and a message body to an existing osip_message_t structure.

```C
osip_to_t *to;
osip_to_init(&to);
osip_to_set_url(to,url);
osip_to_set_displayname(to,osip_strdup("Aymeric MOIZARD"));
osip_message_set_to(msg, to);

osip_message_set_header(msg,osip_strdup("SuBjecT"),osip_strdup("Need support for oSIP!"));
osip_message_set_body(msg,"v=0\r\no=user1 53655765 2353687637 IN IP4 128.3.4.5\r\ns=Mbone Audio\r\ni=Discussion of Mbone Engineering Issues\r\ne=mbone@somewhere.com\r\nc=IN IP4 128.3.4.5\r\nt=0 0\r\nm=audio 3456 RTP/AVP 0\r\na=rtpmap:0 PCMU/8000\r\n");
```

--------------------------------

### Create SIP Dialog as UAS with libosip2

Source: https://context7.com/distrotech/libosip2/llms.txt

Illustrates how to initialize a SIP dialog as a User Agent Server (UAS) using libosip2. This function is used when receiving an incoming call, creating a dialog based on the initial INVITE request and the subsequent 200 OK response. It signifies the establishment of a dialog for an incoming call. Requires the osip2/osip_dialog.h header.

```c
#include <osip2/osip_dialog.h>

int create_dialog_as_uas(osip_message_t *invite, osip_message_t *response_200ok) {
    osip_dialog_t *dialog;
    int ret;

    ret = osip_dialog_init_as_uas(&dialog, invite, response_200ok);
    if (ret != 0) {
        return -1;
    }

    /* Dialog is now established for incoming call */
    printf("Dialog established for incoming call\n");

    osip_dialog_free(dialog);
    return 0;
}
```

--------------------------------

### Handle Incoming SIP Events and Transactions

Source: https://context7.com/distrotech/libosip2/llms.txt

Shows how to parse raw network buffers into SIP events and route them to transaction state machines. It handles both incoming requests and responses, ensuring the appropriate transaction layer (ICT, IST, NICT, NIST) is executed.

```c
#include <osip2/osip.h>

int handle_incoming_message(osip_t *osip, const char *buffer, size_t length) {
	osip_event_t *evt = osip_parse(buffer, length);
	if (evt == NULL) return -1;
	if (EVT_IS_INCOMINGREQ(evt)) {
		osip_create_transaction(osip, evt);
	} else if (EVT_IS_INCOMINGRESP(evt)) {
		if (osip_find_transaction_and_add_event(osip, evt) != 0) {
			osip_event_free(evt);
		}
	}
	osip_ict_execute(osip);
	osip_ist_execute(osip);
	osip_nict_execute(osip);
	osip_nist_execute(osip);
	return 0;
}
```

--------------------------------

### Include libosip2 Portability Headers

Source: https://github.com/distrotech/libosip2/blob/distrotech-libosip2/help/doxygen/ht5-portability.dox

Includes necessary headers for using libosip2's portability features, such as thread management, FIFO queues, condition variables, and time functions.

```c
#include <osip2/osip_mt.h>
#include <osip2/osip_fifo.h>
#include <osip2/osip_condv.h>
#include <osip2/osip_time.h>
```